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Understanding pitting corrosion behavior of AZ91 alloy and its MAO coating in 3.5%NaCl solution by cyclic potentiodynamic polarization

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Journal of Magnesium and Alloys 2022年第5期10卷 1368-1380页

作者： Yuxiang Liu Zhu Liu Anyang xu Xiaoting Liu National Key Laboratory for Remanufacturing of China 21 DujiakanFengtai DistrictBeijing 100072China School of Materials The University of ManchesterManchester M139PLUK

The pitting corrosion behavior of AZ91 alloy before and after micro-oxidation treatment in 3.5%Na Cl solution was investigated by cyclic potentiodynamic polarization(CPDP)and optical and SEM observations of corroded surfaces at different polarization *** CPDP results show that both the alloy and the MAO-coated alloy suffer from pitting corrosion and it is difficult for pits to stop growth once the pits *** is revealed that the air-formed Mg O film on AZ91 alloy,the MAO coating along with corrosion products(mainly Mg(OH))formed during CPDP can significantly influence the kinetics of the redox reactions of Mg,and further influence the propagation behavior of pitting *** optical and SEM images show that the corrosion products on AZ91 alloy are dense and protective but on the MAO-coated corrosion products are very *** observations support the analyses of CPDP results that pits on AZ91 alloy spread to the width whereas pits on MAO-coated alloy propagate to the ***,pitting corrosion on the MAO-coated alloy can be very severe once the coating ruptures and post-treatments are necessary to provide a promising corrosion protection for the Mg alloys.

关键词： AZ91 alloy MAO coating Pitting corrosion behavior Cyclic potentiodynamic polarization

WARRANTY STRATEGY IN A SUPPLY CHAIN WHEN TWO RETAILER'S EXTENDED WARRANTIES BUNDLED WITH THE PRODUCTS

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Journal of Systems Science and Systems Engineering 2015年第3期24卷 364-388页

作者： Yiwen Bian Shuai Yan Wei Zhang Hao xu SHU-UTS SILC(Sydney Institute of Language & Commerce) Business School Shanghai University School of Management Zhejiang University School of Business Anhui University

We in this paper examine warranty strategy in a two-stage supply chain consisting of a manufacturer and two competing retailers. The manufacturer produces two substitute products and markets them through the two retailers to a group of consumers, respectively. For each type of products, the manufacRtrer＇s base warranty and a retailer＇s extended warranty are bundled with the product. We use game theoretic models to explore the interactions between the two types of warranties and the competition between the retailers. For this purpose, two scenarios are considered： no retailer and both the two retailers providing the extended warranties, respectively. In each scenario, the manufacturer＇s base warranties are assumed to be offered. Our results show that when the retailers offer their extended warranties, the manufacturer has no incentive to offer the base warranties; otherwise, the manufacturer has to provide the base warranties. The competition between retailers in terms of the product substitutability has no impact on warranty decisions, but affects all players＇ profits in the supply chain. The manufacturer can provide a longer warranty length and higher customer welfare to a customer than the retailers do, if it is more efficient than the retailers in warranty cost-efficiency, and vice versa.

关键词： Base warranty extended warranty supply chain competition.

Bi Layer Formation at the Anode Interface in Cu/Sn-58Bi/Cu Solder Joints with High Current Density

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Journal of Materials Science & Technology 2012年第1期28卷 46-52页

作者： Hongwen He Haiyan Zhao Fu Guo Guangchen xu Department of Mechanical Engineering Tsinghua University Beijing 100084 China College of Materials Science and Engineering Beijing University of Technology Beijing 100124 China

Bi layer formation in Cu/Sn-58Bi/Cu solder joints was investigated with different current densities and solder thickness. Uniform and continuous Bi layers were formed at the anode interface which indicated that Bi was the main diffusing species migrating from the cathode to the anode. The electromigration force and Joule heating took on the main driving forces for Bi diffusion and migration. In addition, two appearance types of Bi layers, planar-type and groove-type, were found during current stressing. The morphology and thickness of Bi layers were affected by current density and current stressing time.

关键词： Bi layer formation Current density Electromigration Joule heating

BACH： A Bandwidth-Aware Hybrid Cache Hierarchy Design with Nonvolatile Memories

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Journal of Computer Science & Technology 2016年第1期31卷 20-35页

作者： Jishen Zhao Cong xu Tao Zhang Yuan Xie Department of Computer Engineering University of California at Santa Cruz Santa Cruz CA 95064 U.S.A. Hewlet-Packard Labs Palo Alto CA 94304 U.S.A. NVIDIA Corporation Santa Clara CA 95050 U.S.A. Department of Electrical and Computer Engineering University of California at Santa Barbara Santa Barbara CA 93106 U.S.A.

Limited main memory bandwidth is becoming a fundamental performance bottleneck in chipmultiprocessor （CMP） design. Yet directly increasing the peak memory bandwidth can incur high cost and power consumption. In this paper, we address this problem by proposing a memory, a bandwidth-aware reconfigurable cache hierarchy, BACH, with hybrid memory technologies. Components of our BACH design include a hybrid cache hierarchy, a reconfiguration mechanism, and a statistical prediction engine. Our hybrid cache hierarchy chooses different memory technologies with various bandwidth characteristics, such as spin-transfer torque memory （STT-MRAM）, resistive memory （ReRAM）, and embedded DRAM （eDRAM）, to configure each level so that the peak bandwidth of the overall cache hierarchy is optimized. Our reconfiguration mechanism can dynamically adjust the cache capacity of each level based on the predicted bandwidth demands of running workloads. The bandwidth prediction is performed by our prediction engine. We evaluate the system performance gain obtained by BACH design with a set of multithreaded and multiprogrammed workloads with and without the limitation of system power budget. Compared with traditional SRAM-based cache design, BACH improves the system throughput by 58% and 14% with multithreaded and multiprogrammed workloads respectively.

关键词： memory bandwidth hybrid cache reconfigurable cache nonvolatile memory

Numerical Simulation of 2D Supersonic Magnetohydrodynamic Channel and Study on Hall Effect

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Chinese Journal of Aeronautics 2011年第2期24卷 136-144页

作者： ZHENG Xiaomei LU Haoyu xu Dajun CAI Guobiao School of Astronautics Beihang University Beij'ing 100191 China

In this research effort,numerical simulation of two-dimensional magnetohydrodynamic（MHD） channel is performed and Hall effect is *** computational model consists of the Navier-Stokes（N-S） equations coupled with electrical-magnetic source terms,Maxwell equations and the generalized Ohm＇s *** conditions for the electrical potential equation considering Hall effect are *** start with,the MHD channel with single-pair electrodes is studied and flow of the electric current is in accordance with physical *** the MHD channel with five-pair electrodes is numerically *** results show that the electrical current concentrates on the downstream of the anode and the upstream of the cathode due to Hall effect,and the flow field becomes *** the current value of the magnetic interaction parameter,the electrical-magnetic force affects the flow remarkably,decreasing the outlet Mach number and increasing the outlet pressure;what＇s more,the flow structure in the channel becomes extremely *** of MHD channels with continual electrodes and segmented electrodes are *** results show that performance of the MHD channel with segmented electrodes is better than that with continual electrodes with the increase of Hall parameter.

关键词： hypersonic vehicles scramjet magnetohydrodynamics Hall effect numerical simulation

Wing walls for enhancing the seismic performance of reinforced concrete frame structures

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Earthquake Engineering and Engineering Vibration 2016年第2期15卷 411-423页

作者： Yang Weisong Guo xun xu Weixiao Yuan Xin School of Civil Engineering Qingdao University of Technology Qingdao 266033 China Collaborative Innovation Center of Engineering Construction and Safety in Shandong Blue Economic Zone Qingdao 266033 China Institute of Disaster Prevention Sanhe 06520 China Sichuan Provincial Architectural Design and Research Institute Chengdu 610000 China

A building retrofitted with wing walls in the bottom story, which was damaged during the 2008 M8.0 Wenchuan earthquake in China, is introduced and a corresponding 1/4 scale wing wall-frame model was subjected to shake table motions to study the seismic behavior of this retrofitted structural system. The results show that wing walls can effectively protect columns from damage by moving areas that bear reciprocating tension and compression to the sections of the wing walls, thus achieving an extra measure of seismic fortification. A ‘strong column-weak beam＇ mechanism was realized, the flexural rigidity of the vertical member was strengthened, and a more uniform distribution of deformation among all the stories was measured. In addition, the joint between the wing walls and the beams suffered severe damage during the tests, due to an area of local stress concentration. A longer area of intensive stirrup is suggested in the end of the beams.

关键词： story walls flexural shake columns suffered sections drift reinforced frames

Dynamic Positioning Capability Analysis for Marine Vessels Based on A DPCap Polar Plot Program

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China Ocean Engineering 2018年第1期32卷 90-98页

作者： WANG Lei YANG Jian-min xu Sheng-wen State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center for Advanced Shipand Deep-Sea Exploration(CISSE) Shanghai 200240China

Dynamic positioning capability(DPCap) analysis is essential in the selection of thrusters, in their configuration, and during preliminary investigation of the positioning ability of a newly designed vessel dynamic positioning *** analysis can help determine the maximum environmental forces, in which the DP system can counteract in given headings. The accuracy of the DPCap analysis is determined by the precise estimation of the environmental forces as well as the effectiveness of the thrust allocation logic. This paper is dedicated to developing an effective and efficient software program for the DPCap analysis for marine vessels. Estimation of the environmental forces can be obtained by model tests, hydrodynamic computation and empirical formulas. A quadratic programming method is adopted to allocate the total thrust on every thruster of the vessel. A detailed description of the thrust allocation logic of the software program is given. The effectiveness of the new program DPCap Polar Plot(DPCPP)was validated by a DPCap analysis for a supply vessel. The present study indicates that the developed program can be used in the DPCap analysis for marine vessels. Moreover, DPCap analysis considering the thruster failure mode might give guidance to the designers of vessels whose thrusters need to be safer.

关键词： DPCap analysis thrust allocation logic quadratic programming method

Thermodynamic Analysis and Conceptual Design for Partial Coal Gasification Air Preheating Coal-fired Combined Cycle

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Journal of Thermal Science 2004年第1期13卷 85-90页

作者： Yue xu Yining Wu Shimin Deng Shirang Wei Energy and Power Engineering School of Xi’an Jiaotong University Xi’anChina710048 Thermal Power Research Institute State Power CorporationXi’an China710032

The partial coal gasification air pre-heating coal-fired combined cycle (PGACC) is a cleaning coal power system, which integrates the coal gasification technology, circulating fluidized bed technology, and combined cycle technology. It has high efficiency and simple construction, and is a new selection of the cleaning coal power systems. A thermodynamic analysis of the PGACC is carried out. The effects of coal gasifying rate, pre-heating air temperature, and coal gas temperature on the performances of the power system are studied. In order to repower the power plant rated 100 MW by using the PGACC, a conceptual design is suggested. The computational results show that the PGACC is feasible for modernizing the old steam power plants and building the new cleaning power plants.

关键词： coal gasification thermodynamic analysis coal-fired combined cycle clean coal technology.

Performance and recent improvement in microbial fuel cells for simultaneous carbon and nitrogen removal: A review

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Journal of Environmental Sciences 2016年第1期28卷 242-248页

作者： Haishu Sun Shengjun xu Guoqiang Zhuang xuliang Zhuang Research Center for Eco-Environmental Sciences Chinese Academy of Sciences

Microbial fuel cells（MFCs） have become a promising technology for wastewater treatment accompanying electricity generation. Carbon and nitrogen removal can be achieved by utilizing the electron transfer between the anode and cathode in an MFC. However,large-scale power production and high removal efficiency must be achieved at a low cost to make MFCs practical and economically competitive in the future. This article reviews the principles, feasibility and bottlenecks of MFCs for simultaneous carbon and nitrogen removal, the recent advances and prospective strategies for performance improvement, as well as the involved microbes and electron transfer mechanisms.

关键词： Microbial fuel cells Wastewater treatment Electricity generation Simultaneous carbon and nitrogen removal Electron transfer