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Effect of pre-deformation on the stress corrosion cracking susceptibility of aluminum alloy 2519

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Rare Metals 2007年第4期26卷 385-390页

作者： LI Huizhong ZHANG xinming chen Mingan LI Yanfang LIANG Xiaopeng School of Materials Science and Engineering Central South University Changsha 410083 China

The effects of pre-deformation and strain rate on the stress corrosion cracking （SCC） behavior of aluminum alloy 2519 in air and in 3.5% NaCI water solution were investigated by means of slow strain rate tension （SSRT）, scanning electron microscopy （SEM）, and transmission electron microscopy （TEM）. The results indicate that the alloy is susceptible to SCC in 3.5% NaCI water solution and not in air. At the same pre-deformation, the alloy is more susceptible to SCC at 1.33 × 10^-5 s^-1 than at 6.66 × 10^-5 s^-1. Moreover, it is more susceptible to SCC at free pre-deformation than at 10% pre-deformation at the same strain rate. The number of 0 precipitated along the grain boundaries is reduced and distributed discontinuously, at the same time, the precipitate-free zones （PFZ） become narrow and the susceptibility to stress corrosion cracking is reduced after 10% pre-deformation.

关键词： 2519 aluminum alloy pre-deformation slow strain rate tension susceptibility to stress corrosion cracking

Collaborative Network Security in Multi-Tenant Data Center for Cloud Computing

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Tsinghua Science and Technology 2014年第1期19卷 82-94页

作者： Zhen chen Wenyu Dong Hang Li Peng Zhang xinming chen Junwei Cao Research Institute of Information Technology and Tsinghua National Lab for Information Science and Technology Tsinghua University Department of Computer Science and Technology Tsinghua University Department of Computer Science and Technology PLA Univ. of Info. & Eng. Department of Electronic and Information Engineering Xi’an Jiaotong University Department of Electrical and Computer Engineering University of Massachusetts

A data center is an infrastructure that supports Internet service. Cloud comput the face of the Internet service infrastructure, enabling even small organizations to quickly ng is rapidly changing build Web and mobile applications for millions of users by taking advantage of the scale and flexibility of shared physical infrastructures provided by cloud computing. In this scenario, multiple tenants save their data and applications in shared data centers, blurring the network boundaries between each tenant in the cloud. In addition, different tenants have different security requirements, while different security policies are necessary for different tenants. Network virtualization is used to meet a diverse set of tenant-specific requirements with the underlying physical network enabling multi-tenant datacenters to automatically address a large and diverse set of tenants requirements. In this paper, we propose the system implementation of vCNSMS, a collaborative network security prototype system used n a multi-tenant data center. We demonstrate vCNSMS with a centralized collaborative scheme and deep packet nspection with an open source UTM system. A security level based protection policy is proposed for simplifying the security rule management for vCNSMS. Different security levels have different packet inspection schemes and are enforced with different security plugins. A smart packet verdict scheme is also integrated into vCNSMS for ntelligence flow processing to protect from possible network attacks inside a data center network

关键词： data center network network security software defined network collaborative network security multi- tenant network virtualization intelligent flow processing cloud computing

A Trust Assessment-Based Distributed Localization Algorithm for Sensor Networks Under Deception Attacks

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IEEE/CAA Journal of Automatica Sinica 2022年第10期9卷 1879-1882页

作者： Ya Wang xinming chen Lei Shi Yuhua cheng Houjun Wang the School of Automation Engineering University of Electronic Science and Technology of ChinaChengdu 611731 the School of Intelligent Manufacturing Chengdu Technological UniversityChengdu 611730China

Dear Editor,This letter is concerned with the distributed localization issue for wireless sensor networks subject to deception *** is assumed that malicious nodes randomly launch attacks to tamper the ranging information between *** order to accommodate the effects of deception attacks,a trust assessment-based distributed localization algorithm is *** with data fusion of barycentric coordinates,our algorithm can achieve accurate ***,numerical simulations are given to validate the effectiveness of the proposed localization algorithm.

关键词： wireless concerned networks

Flocculated unclassified tailings settling efficiency improvement by particle collision optimization in the feedwell

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International Journal of Minerals,Metallurgy and Materials 2022年第12期29卷 2126-2135页

作者： Huazhe Jiao Weilin chen Aixiang Wu Yang Yu Zhuen Ruan Rick Honaker xinming chen Jianxin Yu School of Civil Engineering Henan Polytechnic UniversityJiaozuo 454003China School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China School of Surveying and Land Information Engineering Henan Polytechnic UniversityJiaozuo 454000China China Geological Environmental Monitoring Institute Beijing 100081China State Collaborative Innovation Center of Coal Work Safety and Clean-efficiency Utilization Jiaozuo 454150China Mining Engineering Faculty University of KentuckyLexington 40506America

Efficient thickening of tailings is a prerequisite for the metal mine tailings backfill and surface disposal *** effective collision of ultrafine tailings particles in suspension with flocculant molecules is essential for flocs aggregates formation and *** feeding speed and flocculant adding method will lead to the failure of effective dispersion of flocculant and high particle content in thickener *** this work,the effect of turbulence intensity and flocculant adding method on floc size,strength,and movement characteristics are *** to solve the turbidity increased,a pilot-scale continuous thickening test was carried *** a single particle and multiple flocs of full tailings as the research object,the particle iterative settlement model of flocs was *** influence of turbulence intensity on collision effect is studied by tracking and simulating particle *** results show that in the process of single particle settlement,chaos appears in the iterative process owing to particle adhesion which caused by micro *** the turbulence intensity is 25.99%,the maximum particle size of tailings floc is 6.21 mm and the maximum sedimentation rate is 5.284 cm·s^(−1).The tailings floc presents a multi-scale structure of particle-force chain system when hindered settling,and the interweaving of strong and weak force chains constitutes the topological structure of *** results are applied to a thicker in plant,the flocculant addition mode and feed rate are optimized,and the flocs settling speed and overflow clarity are improved.

关键词： unclassified tailings flocculation settling rate thickener feedwell turbulence intensity flocs micro-structure

Systematic review of mixing technology for recycling waste tailings as cemented paste backfill in mines in China

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International Journal of Minerals,Metallurgy and Materials 2023年第8期30卷 1430-1443页

作者： Liuhua Yang Jincang Li Hongbin Liu Huazhe Jiao Shenghua Yin xinming chen Yang Yu School of Civil Engineering Henan Polytechnic UniversityJiaozuo454003China Department of Civil Engineering University of Ottawa161 Colonel By DriveOttawaONK1N 6N5Canada School of Civil and Resource Engineering University of Science and Technology BeijingBeijing100083China School of Surveying and Land Information Engineering Henan Polytechnic UniversityJiaozuo454000China China Geological Environmental Monitoring Institute Beijing100081China

The development of industry is inseparable from the support of ***,mining processes consume a large amount of energy,and increased tailing emissions can have a significant impact on the *** the past few decades,the mining industry developed many technologies that are related to mineral energy management,of which cemented paste backfill(CPB)is one of the representative *** has been successfully applied to mine ground control and tailings *** CPB technology,the mixing process is the key to achieving materials with good final quality and controlled ***,in the preparation process,the mixed homogeneity of the CPB is difficult to achieve because of fine tailings,high solid volume fraction,and high *** research focused on the effect of mixing ingredients on CPB properties rather than on the preparation process of the ***,improving the performance and reducing the production cost of CPB by optimizing the mixing process are *** review summarizes the current studies on the mixing technology of CPB and its application status in ***,it compares the advantages and disadvantages of multiple mixing equipment and discusses the latest results and research hotspots in paste ***,it concludes the challenges and development trends of mixing technology on the basis of the relevant application cases in China to promoting cement-based material mixing technology development.

关键词： cemented paste backfill mixed homogeneity mixing technology cement-based material

Particle aggregation and breakage kinetics in cemented paste backfill

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International Journal of Minerals,Metallurgy and Materials 2024年第9期31卷 1965-1974页

作者： Liuhua Yang Hengwei Jia Aixiang Wu Huazhe Jiao xinming chen Yunpeng Kou Mengmeng Dong School of Civil and Engineering Henan Polytechnic UniversityJiaozuo 454000China School of Civil and Environmental Engineering University of Science and Technology BeijingBeijing 100083China

The macroscopic flow behavior and rheological properties of cemented paste backfill(CPB)are highly impacted by the inherent structure of the paste *** this study,the effects of shear-induced forces and proportioning parameters on the microstructure of fresh CPB were *** size evolution and distribution of floc/agglomerate/particles of paste were monitored by focused beam reflection measuring(FBRM)technique,and the influencing factors of aggregation and breakage kinetics of CPB were *** results indicate that influenced by both internal and external factors,the paste kinetics evolution covers the dynamic phase and the stable *** the mass content or the cement-tailings ratio can accelerate aggregation kinetics,which is advantageous for the rise of average floc ***,the admixture and high shear can improve breaking kinetics,which is beneficial to reduce the average floc *** chord length resembles a normal distribution somewhat,with a peak value of approximate 20μ*** particle disaggregation con-stant(k_(2))is positively correlated with the agitation rate,and k_(2) is five orders of magnitude greater than the particle aggregation constant(k1).The kinetics model depicts the evolution law of particles over time quantitatively and provides a theoretical foundation for the micromechanics of complicated rheological behavior of paste.

关键词： cemented paste backfill particle kinetics admixture rheology

Study on Strength Reduction Law and Meso-Crack Evolution of Lower Layered Cemented Tailings Backfill

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Journal of Renewable Materials 2023年第3期11卷 1513-1529页

作者： Huazhe Jiao Wenxiang Zhang Yunfei Wang xinming chen Liuhua Yang Yangyang Rong State Collaborative Innovation Center of Coal Work Safety and Clean-Efficiency Utilization School of Civil EngineeringHenan Polytechnic UniversityJiaozuo454003China Provincial Key Laboratory of Underground Engineering and Disaster Prevention and Control School of Civil EngineeringHenan Polytechnic UniversityJiaozuo454003China School of Civil Engineering Henan Polytechnic UniversityJiaozuo454003China

The green disposal of tailings solid waste is a problem to be solved in mine *** tailings filling stoping method can realize the dual goals of solid waste resource utilization and mined-out area ***,the volume of the mined-out area of the open-pit method is larger than the filling capacity,resulting in the complex stratification of the underground backfill,and the strength of the backfill cannot meet the *** this paper,according to the delamination situation,the specimens of horizontal and inclination angle layered cemented tailings backfill(LCTB)is made for a uniaxial compression test,and the failure process of delamination backfill is reduced by *** results show that the corresponding reduction factorφof horizontal LCTB is 0.560–0.932,and the correspondingφvalue of inclination angle LCTB is 0.338–*** failure mode of backfill in different layers is mainly manifested as a tensile *** PFC numerical simulation results are consistent with laboratory test results,which verifies the correctness of backfill *** research results provide a reliable theoretical basis for the strength design of backfill in goaf,which is of great significance for solid waste utilization and environmental protection.

关键词： Solid wastes recycling LCTB uniaxial compression strength reduction granular flow

Application of Multi-agent Models to Urban Expansion in Medium and Small Cities: A Case Study in Fuyang City,Zhejiang Province,China

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Chinese Geographical Science 2013年第6期23卷 754-764页

作者： ZHANG Jing WANG Ke SONG Gengxin ZHANG Zhongchu chen xinming YU Zhoulu Institute of Remote Sensing and Information System Application Zhejiang University Ningbo Munici-pal Bureau of National Land and Resource Land Consolidation Center in Zhejiang Province

In this study, three-phase satellite images were used to define rules for the allocation of time and space in construction land resources based on a complex adaptive system and game theory. The decision behavior and rules of government agent, enterprise agent and resident agent in construction land growth were explored. A distinctive and dynamic simulation model of construction land growth was built, which integrated multi-agent, GIS technology and RS data and described the interaction among influencing agents, Taking Fuyang City in the Changjiang River Delta as an example, an assessment process for the remote sensing data in construction land and scenario planning was constructed. Repast and ArcGIS were used as simulation platforms. A simulation of the spatial pattern in land-use planning and the setting of scenario planning were conducted by using the incomplete active game, which was based on different natural, social and economic levels. Through this model, a simulation of urban planning space and decision-making for Fuyang City was created. Relevant non-structured problems arising from urban planning management could be identified, and the process and logic of urban planning spatial decision-making could thus be improved. Cell-by-cell comparison showed that the simulation accuracy was over 72%. This model has great potential for use by government and town planners in decision support and technique support in the policy-making process.

关键词： multi-agent system medium and small cities urban expansion game theory Fuyang City

The Micro-Scale Mechanism of Metal Mine Tailings Thickening Concentration Improved by Shearing in Gravity Thickener

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Journal of Renewable Materials 2021年第4期9卷 637-650页

作者： Huazhe Jiao Yachuang Wu Wei Wang xinming chen Yunfei Wang Juanhong Liu Wentao Feng International Joint Research Laboratory of Henan Province for Underground Space Development and Disaster Prevention Henan Polytechnic UniversityJiaozuo454000China College of Safety Science and Engineering Henan Polytechnic UniversityJiaozuo454000China Civil and Resource Engineering School University of Science and Technology BeijingBeijing100000China No.11 Coal Mine of Pingdingshan Tianan Coal Mining Co. Ltd.Pingdingshan467000China

Higher concentration is beneficial for the Paste and Thickened Tailings(PTT)operation in metal *** paste thickeners are produced lower density *** tailings are intended to form a water entrapped network structure in thickener,which is detrimental to underflow *** this study,the continuous thickening experiment was carried out for ultra-fine tungsten tailings to study the influence of rake shearing on *** micro pores structure and seepage flow in tailings bed before and after shearing are studied by CT and simulation approach to reveal the shearing enhancement mechanism of thickening *** results shown that,the underflow concentration is increased from 61.4 wt%to 69.6 wt%by rake shearing in a pilot scale thickener,the porosity decreased from 46.48%to 37.46%.The entrapped water discharged from sticks structure more than sphere *** items of seepage,after shearing,the seepage flow channel of tailings underflow is becoming longer,which caused the decreasing average flow rate decreases and absolute *** absolute permeability is negatively correlated with *** rake shearing can destroy the flocs structure;change the effective stress to increase the *** underflow concentration improves the waste recycling and water recovery rate,especially for arid areas.

关键词： Metal mine tailings gravity thickening shearing effect pore microstructure reverse direction seepage flow channel