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Progress in Natural Science:Materials International 2019年第1期29卷 81-87页

作者： Yajun Luo zhifeng zhang Department of Mechanical Engineering Hunan Institute of Engineering General Research Institute for Non-Ferrous Metals Hunan Provincial Key Laboratory of Vehicle Power and Transmission System Hunan Institute of Engineering

Uniform direct chill(UDC) casting method was developed by combining annular electromagnetic stirring(AEMS) with intercooling in direct chill casting. In order to investigate effect of UDC on flow patterns, temperature profiles and solidification during the casting, a numerical model of the UDC casting process was developed and used to simulate the UDC casting process for preparing 7005 aluminum alloy billets. The comparison of the calculated results of UDC casting with normal direct chill(NDC) casting indicated that flow patterns, temperature profiles and the sump depth are modified remarkably by the application of annular electromagnetic stirring and intercooling during the direct chill casting. The sump profile and the temperature history during UDC casing were studied, and the mechanism of the casting process were discussed. The comparisons between the simulations and experimental results suggested that the proposed model provides good agreement for the sump profiles and the temperature history within the billets.

关键词： Aluminum alloy Direct chill casting Simulation Electromagnetic stirring Intercooling

Study on Multiple Electromagnetic Continuous Casting of Aluminum Alloy

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Journal of Materials Science & Technology 2006年第4期22卷 437-440页

作者： zhifeng zhang Jun XUN Likai SHI National Engineering Research Center for Non-ferrous Metal Composites General Research Institute for Non-ferrous Metals Beijing 100088 China

To obtain semi-solid Al alloy billet with high quality, an investigation was carried out by imposing a multiple magnetic field from the outside of a copper mold in the continuous casting. AISi6Mg2 alloy designed for semi-solid metal （SSM） processing was continuously cast through a submerged entry nozzle under various conditions. Effects of multiple magnetic field on meniscus motion, temperature distribution and billet quality were examined. The experimental results showed that meniscus disturbance caused by electromagnetic stirring could be controlled effectively and the surface quality of semi-solid AI alloy billet was improved greatly, and an uniformly fine, globular microstructure across the transverse section of the billet was achieved by optimizing the distribution of multiple magnetic field.

关键词： Continuous casting Multiple magnetic field Aluminum alloy Semi-solid Microstructure

Extraction and separation of yttrium from other rare earths in chloride medium by phosphorylcarboxylic acids

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Journal of Rare Earths 2022年第6期40卷 958-964,I0004页

作者： Guolong Wu zhifeng zhang Yanling Li Wuping Liao State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China University of Science and Technology of China Hefei 230026China Ganjiang Innovation Academy Chinese Academy of SciencesGanzhou 341000China

Two phosphorylcarboxylic acids,3-((bis(2-ethylhexyloxy))phosphoryl)propanoic acid(PPA) and 3-((bis(2-ethylhexyloxy))phosphoryl)-3-phenylpropanoic acid(PPPA),were synthesized for separating yttrium from other rare earths in the chloride feed of ion-adsorption type rare earth *** effect of the factors such as pH_(1/2),temperature,saponification degree and phase modifiers was *** separation efficiencies of PPA and PPPA are obviously better than the typical extractants such as sec-octylphenoxy acetic acid(CA-12) and naphthenic acid(NA).The extraction process of rare earths by PPA and PPPA is a cation exchanging reaction,which is similar to those of CA-12 and *** loaded rare earths in both PPA and PPPA systems can be effectively back-extracted by 0.5 mol/L HCl or higher concentration.A cascade extraction process for separating yttrium from other rare earths was developed using PPPA as the *** yttrium product with the purity of 97.20 wt% was obtained by 35 stages of extraction and 12 stages of scrubbing.

关键词： Phosphorylcarboxylic acids Extraction Separation Yttrium Chloride Ion-adsorption type rare earth concentrate

Fault tolerant control for near space vehicle:a survey and some new results

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Journal of Systems Engineering and Electronics 2011年第1期22卷 88-94页

作者： Yufei Xu Bin Jiang zhifeng Gao Ke zhang College of Automation Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 P. R. China

A review on fault-tolerant control（FTC） for near space vehicle（NSV） is ***,the concept of near space is introduced,the background of NSV is emphasized,and the model characteristics of NSV in faulty case are ***,a comparison of different existing approaches is briefly carried out,and achievements on the current research in this field are also presented in the view of the practical ***,several existing advanced FTC results for nonlinear flight control systems are ***,the recent literature of NSV are presented to provide an overall view of future developments in this area.

关键词： near space vehicle(NSV) fault-tolerant control(FTC) adaptive sliding mode.

Semisolid microstructure evolution of AZ91D alloy under high shear rate

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Rare Metals 2011年第1期30卷 99-103页

作者： ZHU Guanglei XU Jun zhang zhifeng LIU Guojun National Engineering ＆ Technology Research Center for Nonferrous Metal Matrix Composites General Research Institute for Nonferrous MetalsBeijing 100088China

Experimental work was undertaken to investigate the effect of rotation speed on the solidification microstructure of AZ91D alloy using a twin-screw slurry *** numerical simulation was used to investigate the effect of rotation speed on the flow filed and temperature field of the *** was found that increasing the rotation speed could give rise to substantial grain refinement,which can be attributed to the increase of effective nucleation rate caused by the extremely uniform temperature and dispersing any potential clusters of nucleation agents in the bulk liquid under dispersive mixing.

关键词： magnesium alloys microstructural evolution shearing grain refinement solidification

Seasonal Gametogenesis of Host Sea Anemone(Entacmaea quadricolor) Inhabiting Hong Kong Waters

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Journal of Ocean University of China 2015年第1期14卷 143-148页

作者： BI Ying zhang Bin zhang zhifeng QIU Jianwen Key Laboratory of Marine Genetics and Breeding of Ministry of Education Ocean University of China Department of Biology Hong Kong Baptist University

Studying gonadal development of annual cycle can reveal the process of gametogenesis and reproductive period, and evaluate fertility and source utilization of a species. Host sea anemones are conspicuous members of tropical and subtropical reef ecosystems, but little is known about its biology including reproductive seasonality. Here we reported a one-year study on the gametogenesis and reproduction of host sea anemone(Entacmaea quadricolor) inhabiting Hong Kong waters. E. quadricolor tissues were sampled in 12 occasions from 5 m and 15 m depths of water, respectively. Histological sectioning of the tissues showed that E. quadricolor was dioecious, and populational ratio of female to male was 1:1.6. The gonadal development was asynchronous within an annual cycle, which included proliferating, growing, maturing, spawning, and resting stages. The spawning occurred between August and October when surface seawater temperature reached the annual maximum(28℃), suggesting that temperature is an important factor modulating the gonadal development and mature of E. quadricolor.

关键词： Entacmae aquadricolor gonad annual cycle histology seawater temperature

A Hybrid Heuristic Service Caching and Task Offloading Method for Mobile Edge Computing

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Computers, Materials & Continua 2023年第8期76卷 2483-2502页

作者： Yongxuan Sang Jiangpo Wei zhifeng zhang Bo Wang Software Engineering College Zhengzhou University of Light IndustryZhengzhou450001China

Computing-intensive and latency-sensitive user requests pose significant challenges to traditional cloud *** response to these challenges,mobile edge computing(MEC)has emerged as a new paradigm that extends the computational,caching,and communication capabilities of cloud *** caching certain services on edge nodes,computational support can be provided for requests that are offloaded to the ***,previous studies on task offloading have generally not considered the impact of caching mechanisms and the cache space occupied by *** oversight can lead to problems,such as high delays in task executions and invalidation of offloading *** optimize task response time and ensure the availability of task offloading decisions,we investigate a task offloading method that considers caching ***,we incorporate the cache information of MEC into the model of task offloading and reduce the task offloading problem as a mixed integer nonlinear programming(MINLP)***,we propose an integer particle swarm optimization and improved genetic algorithm(IPSO_IGA)to solve the ***_IGA exploits the evolutionary framework of particle swarm *** it uses a crossover operator to update the positions of particles and an improved mutation operator to maintain the diversity of ***,extensive simulation experiments are conducted to evaluate the performance of the proposed *** experimental results demonstrate that IPSO_IGA can save 20%to 82%of the task completion time,compared with state-of-theart and classical ***,IPSO_IGA is suitable for scenarios with complex network structures and computing-intensive tasks.

关键词： Mobile edge computing edge caching task offloading particle swarm optimization genetic algorithm

Annular electromagnetic stirring——a new method for the production of semi-solid A357 aluminum alloy slurry

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Acta Metallurgica Sinica(English Letters) 2009年第6期22卷 408-414页

作者： Guanglei ZHU Jun XU zhifeng zhang Yuelong BAI Likai SHI National Engineering ＆ Technology Research Center for Non-ferrous Metal Matrix Composites General Research Institute for Non-ferrous Metals Beijing 100088 China

A new method for producing semisolid slurry, annular electromagnetic stirring （AEMS）, to refine and spheroidize grains was exploited. Experimental work was undertaken to investigate the effects of cooling rate, stirring power and stirring time on the solidification behavior of A357 alloy using A-EMS. It was found that increasing the cooling rate and stirring power gave rise to substantial grain refinement, which could be attributed to the increase of effective nucleation rate caused by the extremely uniform temperature and composition fields in the bulk liquid during the initial stage of solidification. Results showed that a fully grain refined spherical structure could be obtained using proper processing conditions within 10 s.

关键词： Semisolid Annular electromagnetic stirring A357

Extraction and separation of heavy rare earths from chloride medium byα-aminophosphonic acid HEHAPP

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Journal of Rare Earths 2018年第3期36卷 304-310页

作者： Shengting Kuang zhifeng zhang Yanling Li Haiqin Wei Wuping Liao State Key Laboratory of Rare Earth Resource Utilization ERCfor the Separation and Purification of REs and ThoriumChangchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China University of Science and Technology of China Hefei 230026China

The extraction and separation of heavy rare earths（REs） using newly synthesized a-aminophosphonic acid extractant 2-ethylhexyl-3-（2-ethylhexylamino）pentan-3-yl phosphonic acid（HEHAPP, HA） in nheptane were investigated from chloride medium. The extraction stoichiometries of lanthanum, gadolinium, yttrium and lutetium are determined to be REA3 by the slope analysis method. The favorable separation factors of adjacent heavy REs（Ⅲ）,i.e. β（Y/Ho）, β（Er/Y）,β（Tm/Er）,β（Yb/Tm） and β（Lu/Yb）, are determined to be1.87,1.36, 3.21,3.22 and 1.93, respectively, when extracted from a binary system at proper condition. The loading capacities of HA for Ho, Er, Yb and Lu increase in the order Ho 〈 Er 〈 Yb 〈 Lu with the values being 0.201, 0.205, 0.216 and 0.229 mol/L, respectively. So HA would be a potential extractant for the separation of heavy REs（Ⅲ）. Among inorganic acids such as H2 SO4, HNO3 and HCl, HCl is tested to be the most effective stripping agent.

关键词： Heavy rare earths α-aminophosphonic acid Solvent extraction Separation

Expression Characteristics and Potential Function of Neuropeptide MIP in Larval Settlement of the Echiuran Worm Urechis unicinctus

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Journal of Ocean University of China 2022年第4期21卷 977-986页

作者： LU Li zhang zhifeng ZHENG Qiaojun CHEN Zongtao BAI Shumiao zhang Zhengrui Ministry of Education Key Laboratory of Marine Genetics and Breeding College of Marine Life SciencesOcean University of ChinaQingdao 266003China Key Laboratory of Tropical Aquatic Germplasm of Hainan Province Sanya Oceanographic InstitutionOcean University of ChinaSanya 572000China Qingdao Dayi HC Biotechnology Co. Ltd.Qingdao 266003China

Larval settlement and metamorphosis are important developmental events in marine *** neuropeptides may play a key role in these *** this study,we revealed the expression characteristics of myoinhibitory peptide(MIP)in the embryos and larvae of the echiuran worm Urechis unicinctus using RT-qPCR,in situ hybridization and immunofluorescence techniques,and found its location in the top cells of the upper hemisphere was conservative in ***,we used the active MIP peptide to verify its role in inducing the larval settlement of ***,and confirmed that MIP can trigger an obvious larval settlement when 10μmol L^(−1) or 15μmol L^(−1) MIP was added in the seawater where early-segmentation larvae were *** finding indicated that neuropeptide MIP participates in the larval settlement in ***.

关键词： Urechis unicinctus neuropeptide MIP larval settlement