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Achieving superior strength-ductility synergy in a heterostructured magnesium alloy via low-temperature extrusion and low-temperature annealing

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Journal of Materials Science & Technology 2023年第32期163卷 32-44页

作者： h.Wang d.T.Zhang C.Qiu W.W.Zhang d.l.chen Guangdong Key laboratory for Advanced Metallic Materials Processing and Forming National Engineering Research Center of Near-net-shape Forming for Metallic MaterialsSouth China University of TechnologyGuangzhou 510640China department of Mechanical and Industrial Engineering Toronto Metropolitan University(formerly Ryerson University)350 Victoria StreetTorontoON M5B 2K3Canada

A low-alloyed Mg-1.2Zn-0.1Ca(wt.%)alloy was fabricated via low-temperature extrusion and annealing at 250℃for different times(10,30,and 90 min)to attain heterostructures with different fine-grained fractions,focusing on the effect of heterostructure on the mechanical *** dynamic recrystallization(RX)occurred during extrusion at 150℃,and a lamellar structure consisting of fine RX grains and coarse unRX grains was *** subsequent annealing promoted static RX in the as-extruded alloy,leading to an increased fine-grained fraction from 67%to 95%.Meanwhile,the co-segregation of Zn and Ca atoms impeded the migration of grain boundaries,thus achieving a fine grain size of 0.8–1.6μ*** sample annealed for 10 min with a fine-grained fraction of 73%and an average RX grain size of 0.9μm exhibited a superior combination of high yield strength(305 MPa)and good ductility(20%).In comparison,an excellent elongation of 30%was achieved in the alloy with a nearly fully-RXed microstructure and an average grain size of 1.6μm after 90 min annealing,despite a lower yield strength of 228 *** unRX grains,the hard orientation with(01–10)parallel to the extrusion direction and high-density dislocations made it more difficult to deform compared with the RX grains,thus producing hetero-deformation induced(hdI)*** fine grains and high-density dislocations,hdI strengthening is the key to achieving the superior mechanical properties of the low-alloyed Mg alloy.

关键词： low-alloyed magnesium alloy low-temperature extrusion Annealing heterostructure Mechanical properties

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A multi-objective study on the constructal design of non-uniform heat generating disc cooled by radial-and dendritic-pattern cooling channels

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Science China(Technological Sciences) 2021年第4期64卷 729-744页

作者： chen chen YOU Jiang feng huiJun chen linGen Institute of Thermal Science and Power Engineering Wuhan Institute of TechnologyWuhan 430205China School of Mechanical&Electrical Engineering Wuhan Institute of TechnologyWuhan 430205China §School of Optical Information and Energy Engineering Wuhan Institute of TechnologyWuhan 430205China College of Power Engineering Naval University of EngineeringWuhan 430033China

A three-dimensional disc model with non-uniform heat generating is built.A series of cooling channels are inserted to cool this disc which is strewn in a hierarchical *** reveal thermal and flow characteristics,a composite objective function comprised of the maximum temperature difference(MTd)and pumping power is *** deployment pattern of cooling channels contains two cases,i.e.,the radial-pattern and *** capitalizing on constructal design method together with finite element method,the diameter of radial-pattern cooling channels is optimized in the first ***,the diameter,angle coefficient and length coefficient of dendritic-pattern cooling channels are three degrees-of-freedom to be stepwise optimized at different heat generating ***,NSGA-II algorithm is introduced into the multiobjective *** obtaining its Pareto optimal solution set,Topsis method is invoked to yield the optimal solutions under given weighted *** heat generation over the entire body and the volume ratio of cooling channels operate as the primary *** on these premises,constructal design will be stepwise performed by varying three *** obtained results state that more heating components or devices should be installed as close to the cooling water inlet as *** can further reduce MTd at the same cost of pumping power,thereby improve thermal and flow performance and prolong the lifespan of *** optimized with two degrees-of-freedom,the MTd is reduced by 18.6%compared with the counterpart obtained from single degree-of-freedom optimization,while the pumping power is increased by 59.8%.As optimized with three degrees-of-freedom,the MTd is decreased by 6.2%compared with the counterpart from two degrees-of-freedom optimization,while the pumping power is increased by 3.0%.It is manifest that when two sub-objectives form a composite objective,the performance improvement of one sub-

关键词： constructal law non-uniform heat generating disc heat convection cooling channels multi-objective optimization generalized thermodynamic optimization

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Cramer-Rao bounds for the joint delay-doppler estimation of compressive sampling pulse-doppler radar

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Journal of Systems Engineering and Electronics 2018年第1期29卷 58-66页

作者： chen Shengyao XI feng School of Electronic and Optical Engineering Nanjing University of Science and Technology

Time-delay and doppler shift estimation is a basic task for pulse-doppler radar processing. For low-rate sampling of echo signals, several kinds of compressive sampling(CS) pulse-doppler(CSPd) radar are developed with different analog-to-information conversion(AIC) systems. however, a unified metric is absent to evaluate their parameter estimation performance. Towards this end, this paper derives the deterministic Cramer-Rao bound(CRB)for the joint delay-doppler estimation of CSPd radar to quantitatively analyze the estimate performance. Theoretical results reveal that the CRBs of both time-delays and doppler shifts are inversely proportional to the received target signal-to-noise ratio(SNR), the number of transmitted pulses and the sampling rate of AIC systems. The main difference is that the CRB of doppler shifts also lies on the coherent processing interval. Numerical experiments validate these theoretical results. They also show that the structure of the AIC systems has weak influence on the CRBs, which implies that the AIC structures can be flexibly selected for the implementation of CSPd radar.

关键词： compressive sampling(CS) delay-doppler estimation Cramer-Rao bound(CRB)

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Influence of hfO2 alloying effect on microstructure and thermal conductivity of hoTaO4 ceramics

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Journal of Advanced Ceramics 2019年第4期8卷 537-544页

作者： lin chen Jing feng Faculty of Material Science and Engineering Kunming University of Science and Technology

hfO2 alloying effect has been applied to optimize thermal insulation performance of hoTaO4 ceramics.X-ray diffraction,Raman spectroscopy,and X-ray photoelectron spectroscopy are employed to decide the crystal *** electronic microscopy is utilized to detect the influence of hfO2 alloying effect on *** paper indicates that the same numbers of Ta5+and ho3+ions of hoTaO4 are substituted by hf4+cations,and it is defined as alloying *** crystal structural transition is introduced by hfO2 alloying effect,and circular pores are produced in ***2 alloying effect is efficient in decreasing thermal conductivity of hoTaO4 and it is contributed to the differences of ionic radius and atomic weight between hf4+ions and host cations(Ta5+and ho3+).The least experimental thermal conductivity is 0.8 W·K–1·m–1 at 900℃,which is detected in 6 and 9 mol%-hfO2 hoTaO4 *** results imply that hfO2–hoTaO4 ceramics are promising thermal barrier coatings(TBCs)due to their extraordinary thermal insulation performance.

关键词： thermal barrier coating(TBC) thermal conductivity rare earth tantalates microstructure alloying effect optical property

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Unleashing the Potential of Electroactive hybrid Biomaterials and Self‑Powered Systems for Bone Therapeutics

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Nano-Micro letters 2025年第2期17卷 463-497页

作者： Shichang liu Farid Manshaii Jinmiao chen Xinfei Wang Shaolei Wang Junyi Yin Ming Yang Xuxu chen Xinhua Yin Yunlei Zhou honghui hospital Xi’an Jiaotong UniversityXi’an 710018People’s Republic of China department of Bioengineering Henry Samueli School of Engineering and Applied ScienceUniversity of California Los AngelesLos Angeles 90095USA hangzhou Institute of Technology Xidian UniversityHangzhou 311231People’s Republic of China

The incidence of large bone defects caused by traumatic injury is increasing worldwide,and the tissue regeneration process requires a long recovery time due to limited self-healing *** bioelectrical phenomena have been well recognized as critical biophysical factors in bone remodeling and *** by bioelectricity,electrical stimulation has been widely considered an external intervention to induce the osteogenic lineage of cells and enhance the synthesis of the extracellular matrix,thereby accelerating bone *** ongoing advances in biomaterials and energy-harvesting techniques,electroactive biomaterials and self-powered systems have been considered biomimetic approaches to ensure functional recovery by recapitulating the natural electrophysiological microenvironment of healthy bone *** this review,we first introduce the role of bioelectricity and the endogenous electric field in bone tissue and summarize different techniques to electrically stimulate cells and ***,we highlight the latest progress in exploring electroactive hybrid biomaterials as well as self-powered systems such as triboelectric and piezoelectric-based nanogenerators and photovoltaic cell-based devices and their implementation in bone tissue ***,we emphasize the significance of simulating the target tissue’s electrophysiological microenvironment and propose the opportunities and challenges faced by electroactive hybrid biomaterials and self-powered bioelectronics for bone repair strategies.

关键词： Electroactive biomaterials Self-powered bioelectronics Bone regeneration Bone tissue

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Advances in Graphene‑Based Electrode for Triboelectric Nanogenerator

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Nano-Micro letters 2025年第1期17卷 378-403页

作者： Bin Xie Yuanhui Guo Yun chen hao Zhang Jiawei Xiao Maoxiang hou huilong liu li Ma Xin chen Chingping Wong State Key laboratory of Precision Electronic Manufacturing Technology and Equipment Guangdong University of TechnologyGuangzhou 510006People’s Republic of China School of Electromechanical Engineering Guangdong University of TechnologyGuangzhou 510006People’s Republic of China School of Materials Science and Engineering Georgia Institute of TechnologyAtlantaGA 30332USA

With the continuous development of wearable electronics,wireless sensor networks and other micro-electronic devices,there is an increasingly urgent need for miniature,flexible and efficient nanopower generation *** nanogenerator(TENG)technology can convert small mechanical energy into electricity,which is expected to address this *** the core component of TENG,the choice of electrode materials significantly affects its *** metal electrode materials often suffer from problems such as durability,which limits the further application of ***,as a novel electrode material,shows excellent prospects for application in TENG owing to its unique structure and excellent electrical *** review systematically summarizes the recent research progress and application prospects of TENGs based on graphene *** precision processing methods of graphene electrodes are introduced,and the applications of graphene electrode-based TENGs in various scenarios as well as the enhancement of graphene electrodes for TENG performance are *** addition,the future development of graphene electrode-based TENGs is also prospectively discussed,aiming to promote the continuous advancement of graphene electrode-based TENGs.

关键词： Triboelectric nanogenerator Precision processing Graphene electrode Self-powered sensor

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The associations between Parkinson’s disease and cancer: the plot thickens

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Translational Neurodegeneration 2015年第1期4卷 160-173页

作者： danielle d.feng Waijiao Cai Xiqun chen MassGeneral Institute for Neurodegenerative disease Department of NeurologyMassachusetts General HospitalHarvard Medical SchoolBostonMAUSA department of Epidemiology Harvard T.H.Chan School of Public HealthBostonMAUSA Key laboratory of Cellular and Molecular Biology Huashan HospitalFudan UniversityShanghai 200040China

Epidemiological studies support a general inverse association between the risk of cancer development and Parkinson’s disease(Pd).In recent years however,increasing amount of eclectic evidence points to a positive association between Pd and cancers through different temporal analyses and ethnic *** positive association has been supported by several common genetic mutations in SNCA,PARK2,PARK8,ATM,p53,PTEN,and MC1R resulting in cellular changes such as mitochondrial dysfunction,aberrant protein aggregation,and cell cycle ***,we review the epidemiological and biological advances of the past decade in the association between Pd and cancers to offer insight on the recent and sometimes contradictory findings.

关键词： cancer PARK thick

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Mainchain conformation ordering self-assembly tailored room temperature phosphorescence emission

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Science China Chemistry 2025年第01期 329-336页

作者： Yuzhu li Yumeng Gao feng Tian Yu Wang Yuan Yao Shaoliang lin Xiang Ma Binbin Xu Shanghai Key laboratory of Advanced Polymeric Materials Key Laboratory for Ultrafine Materials of Ministry of Education School of Materials Science and Engineering East China University of Science and Technology Shanghai Synchrotron Radiation Facility Shanghai Advanced Research Institute Chinese Academy of Sciences Key laboratory for Advance Materials and Feringa Noble Prize Scientist Joint Research Centre Frontiers Science for Materiobiology and Dynamic Chemistry School of Chemistry and Molecular Engineering East China University of Science & Technology

developing organic room-temperature phosphorescence （RTP） materials with a wide range of tunable-emission is significant in expanding the applications of RTP ***,we rationally designed amphiphilic alternating copolymers poly(1,2-bis（4-alkoxyphenyl）ethane-1,2-dione-alt-（ethylene glycol）x)(P（Bz-alt-EGx）) that combined the advantage of alternating benzil and EGxskeleton,and tunable mainchain *** a mainchain conformation ordering assembly （COA） process,P（Bz-alt-EGx） self-assembled into well-defined platelets,and such assemblies emitted blue RTP at ca.425 nm due to the ordered folded-chain conformation and confined *** contrast,traditional self-assembly （TA） of P（Bz-alt-EGx） obtained less ordered aggregates,such as asymmetric worms,vesicles,and rod-like *** resultant less ordered aggregates exhibited yellow-green RTP at ca.550 *** wide-tuning RTP emission in solution （between blue and yellow-green,over125 nm） is realized using the P（Bz-alt-EGx） alternating copolymers under the treatment of different self-assembly *** study uncovers a new strategy to tailor the RTP emission through different self-assembly pathways and holds great promise for the fabrication of advanced optical materials.

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Metal hydride work pair development and its application on automobile air conditioning systems

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第2期8卷 197-204页

作者： QIN feng chen Jiang-ping ZhANG Wen-feng chen Zhi-jiu Institute of Refrigeration and Cryogenic Engineering Shanghai Jiao Tong University Shanghai 200030 China Research Center Zhejiang Yinlun Machinery Co. Ltd. Tiantai 317200 China

Aiming at developing exhaust gas driving automobile air conditioning systems, a hydride pair laNi4.61Mn0.26A10.13/ la0.6Y0.4Ni4.8Mn0.2 was developed working at 393-473 K/293-323 K/263-273 K. Property tests showed that both alloys have flat plateau slopes and small hystereses; system theoretical coefficient of performance （COP） is 0.711. Based on this work pair, a function proving automobile metal hydride refrigeration system was constructed. The equivalent thermal conductivities of the activated reaction beds were merely 1.1-1.6 W/（m-K）, which had not met practical requirement. Intermittent refrigeration cycles were achieved and the average cooling power was 84.6 W at 423 K/303 K/273 K with COP being 0.26. By altering cycling parameters, experiment data showed that cooling power and system COP increase with the growth of heat source temperature as well as pre-heating and regeneration time while decrease with heat sink temperature increment. This study confirms the feasibility of automobile metal hydride refrigeration systems, while heat transfer properties of reaction beds still need to be improved for better performance.

关键词： Metal hydride Air conditioning Reaction bed Automobile Coefficient of performance (COP)

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Powers of General digital Sums

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Acta Mathematica Sinica,English Series 2010年第6期26卷 1133-1138页

作者： feng Juan chen School of Mathematical Sciences Nanjing Normal University Nanjing 210046 P. R. China and Department of Mathematics Suzhou University Suzhou 215006 P. R. China

let m0,m1,m2,…be positive integers with mi〉 2 for all i. It is well known that each nonnegative integer n can be uniquely represented as n= a0 ＋ a1m0＋a2m0m1＋…＋atm0m1m2…mt-1,where 0≤ai≤mi-1 for all i and at≠*** each fi be a function defined on {0,1,2…,mi-1} with fi（0）=*** S（n）=i=0∑tfi（ai）.In this paper, we give the asymptotic formula for x^-1∑n≤xS（n）^k,where k is a positive integer.

关键词： digital sum arithmetic function asymptotic formula

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