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Analysis of deformation mechanisms in magnesium single crystals using a dedicated four-point bending tester

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Journal of Magnesium and Alloys 2024年第5期12卷 1911-1917页

作者： Yutaka Yoshida Rikuto Izawa Kenji Ohkubo Faculty of engineering Kitami Institute of TechnologyKoen-choKitamiHokkaido 090-8507Japan graduate student Department of Mechanical and Electrical EngineeringKitami Institute of TechnologyKoen-choKitamiHokkaido 090-8507Japan Center for Advanced Research of Materials Faculty of EngineeringHokkaido UniversityKita-kuSapproHokkaido 060-8628Japan Kyokuto Kaihatsu Kogyo Co. Ltd.AwajiChuohuOosakaOosaka 541-0047Japan

In this study,we explored the deformation mechanisms of Mg single crystals using a combination of scanning electron microscopy and electron backscattered diffraction in conjunction with a dedicated four-point bending *** prepared two single-crystal samples,oriented along theanddirections,to assess the mechanisms of deformation when the initial basal slip was *** thesample,the primary{1012}twin(T1)was confirmed along thedirection of the sample on the compression side with an increase in bending *** thesample,T1 and the secondary twin(T2)were confirmed to be along thedirection,with an orientation of±60°with respect to the bending stress direction,and their direction matched with(0001)in T1 and *** result implies that crystallographically,the basal slip occurs *** addition,thesample showed the double twin in T1 on the compression side and the tertiary twin along thedirection on the tension *** results demonstrated that the maximum bending stress and displacement changed significantly under the bend loading because the deformation mechanisms were different for these single ***,the correlation between bending behavior and twin orientation was determined,which would be helpful for optimizing the bending properties of Mg-based materials.

关键词： Four-point bending Magnesium single crystal Twinning Basal slip Scanning electron microscopy Electron backscatter diffraction

Lift-Off Effect of Koch and Circular Differential Pickup Eddy Current Probes

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Chinese Journal of mechanical engineering 2024年第2期37卷 283-293页

作者： Guolong Chen Zheng Cao Shuaishuai Zhang Ji Wei Wei Gao Wuyin Jin School of mechanical and Electrical engineering Lanzhou University of TechnologyLanzhou 730050China

A flexible or planar eddy current probe with a differential structure can suppress the lift-off noise during the inspection of ***,the extent of the lift-off effect on differential probes,including different coil structures,*** this study,two planar eddy current probes with differential pickup structures and the same size,Koch and circular probes,were used to compare lift-off *** eddy current distributions of the probes perturbed by 0°and 90°cracks were obtained by finite element *** analysis results show that the 90°crack can impede the eddy current induced by the Koch probe even further at relatively low lift-off *** peak-to-peak values of the signal output from the two probes were compared at different lift-off distances using finite element analysis and experimental *** addition,the effects of different frequencies on the lift-off were studied *** results show that the signal peak-to-peak value of the Koch probe for the inspection of cracks in 90°orientation is larger than that of the circular probe when the lift-off distance is smaller than 1.2 *** addition,the influence of the lift-off distance on the peak-to-peak signal value of the two probes was studied via *** indicates that the influence becomes more evident with an increase in excitation *** research discloses the lift-off effect of differential planar eddy current probes with different coil shapes and proves the detection merit of the Koch probe for 90°cracks at low lift-off distances.

关键词： Eddy current testing Differential pickup probe Fractal Koch curve Flexible eddy current probe

Method of improving pedestrian navigation performance based on chest card

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Journal of Systems engineering and Electronics 2024年第4期35卷 987-998页

作者： CHENG Hao GAO Shuang CAI Xiaowen WANG Yuxuan WANG Jie School of Instrumentation and Optoelectronic engineering Beihang UniversityBeijing 100191China School of Automation and Electronic Information Xiangtan UniversityXiangtan 411105China Navigation Guidance and Control Graduate School of the Second Institute of China Aerospace Science and Industry CorporationBeijing 100854China

With the development of positioning technology,loca-tion services are constantly in demand by *** a primary location service pedestrian navigation has two main approaches based on radio and inertial *** pedestrian naviga-tion based on radio is subject to environmental occlusion lead-ing to the degradation of positioning *** pedestrian navigation based on micro-electro-mechanical system inertial measurement unit(MIMU)is less susceptible to environmental interference,but its errors dissipate over *** this paper,a chest card pedestrian navigation improvement method based on complementary correction is proposed in order to suppress the error divergence of inertial navigation *** suppress atti-tude errors,optimal feedback coefficients are established by pedestrian motion *** extend navigation time and improve positioning accuracy,the step length in subsequent movements is compensated by the first step *** experi-mental results show that the positioning accuracy of the pro-posed method is improved by more than 47%and 44%com-pared with the pure inertia-based method combined with step compensation and the traditional complementary filtering com-bined method with step *** proposed method can effectively suppress the error dispersion and improve the positioning accuracy.

关键词： pedestrian navigation micro-electro-mechanical sy-stem(MEMS) inertial navigation complementary filtering

Detachment Behavior of Gecko Toe in Functional Strategies for Bionic Toe

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Journal of Bionic engineering 2024年第2期21卷 707-717页

作者： Qingfei Han Wei Wang Huan Shen Xincheng Feng Haoran Zhang Qian Li Yi Sun Huapeng Wu Aihong Ji Lab of Locomotion Bioinspiration and Intelligent Robots College of Mechanical and Electrical EngineeringNanjing University of Aeronautics and AstronauticsNanjing210016China Laboratory of Intelligent Machines School of Energy SystemsLappeenranta-Lahti University of Technology53850LappeenrantaFinland State Key Laboratory of Mechanics and Control for aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing210016China

Geckos can efficiently navigate complex terrains due to their multi-level adhesive system that is present on their *** setae are responsible for the gecko’s extraordinary adhesion and have garnered wide attention from the scientific *** majority of the reported works in the literature that have dealt with the peeling models mainly focus on the gecko hierarchical adhesive system,with limited attention given to investigating the influence of gecko toe structure on the *** these lines,to gain a deeper understanding of the rapid and effortless detachment abilities of gecko toes,the peeling behavior of gecko toes on vertical surfaces was primarily investigated in this *** specifically,the detachment time of a single toe on a smooth acrylic plate was measured to be 0.41±0.21 ***,it was observed that the toe assumed a"U"-shaped structure upon complete ***,Finite Element Analysis(FEA)models for three different types of gecko toes were developed to simulate both the displacement-peel and the moment-peel *** the segmentation of the adhesive layer led to a gradual decrease in the resultant force,as well as the normal and tangential ***,a gecko-inspired toe model was constructed and powered by Shape Memory Alloy(SMA).A systematic comparison between the vertical drag separation and the outward flip separation was also *** our analysis,it was clearly demonstrated that outward peel separation significantly necessitated the reduction of the peeling force,thus confirming the advantageous nature of the outward motion in gecko toe *** data not only contribute to a deeper understanding of the gecko detachment behavior but also offer valuable insights for the advancement of the wall-climbing robot feet.

关键词： Gecko toes Detachment behavior Finite element analysis Gecko-inspired toe

Organic-inorganic hybrid piezotronic bipolar junction transistor for pressure sensing

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Microsystems & Nanoengineering 2024年第3期10卷 229-244页

作者： Emad Iranmanesh Zihao Liang Weiwei Li Congwei Liao Shunyu Jin Chuan Liu Kai Wang Shengdong Zhang Charalampos Doumanidis Gehan A.J.Amaratunga Hang Zhou Guangdong Provincial Key Laboratory of In-Memory Computing Chips School of Electronic and Computer EngineeringPeking University Shenzhen Graduate SchoolShenzhen 518055P.R.China School of mechanical engineering Guangdong Technion-Israel Institute of TechnologyShantou 515063P.R.China State Key Laboratory of Microelectronics Device and Integrated Technology Institute of MicroelectronicsChinese Academy of SciencesBeijing 100029P.R.China Hefei National Research Center for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 23000PR China School of Electronics and Information Technology Sun Yat-sen UniversityNo.132 East Waihuan RoadGuangzhou 510006P.R.China Department of mechanical Aerospaceand Biomedical EngineeringUniversity of South AlabamaShelby Hall3128MobileAL 36688USA Electrical engineering Division Department of EngineeringUniversity of Cambridge9 JJ Thomson AvenueCambridge CB30FAUnited Kingdom Zhejiang University International CampusHainingChina

With the rapid development of the Internet of Things(IoTs),wearable sensors are playing an increasingly important role in daily monitoring of personal health and *** signal-to-noise-ratio has become the most critical performance factor to *** enhance it,on the one hand,good sensing materials/devices have been employed;on the other hand,signal amplification and noise reduction circuits have been ***,most of these devices and circuits work in an active sampling mode,requiring frequent data acquisition and hence,entailing high-power *** this scenario,a flexible and wearable event-triggered sensor with embedded signal amplification without an external power supply is of great ***,we report a flexible two-terminal piezotronic n-p-n bipolar junction transistor(PBJT)that acts as an autonomous and highly sensitive,current-and/or voltage-mediated pressure *** PBJT is formed by two back-to-back piezotronic diodes which are defined as emitter-base and collectorbase *** force exertion on the emitter side,as a result of the piezoelectric effect,the emitter-base diode is forward biased while the collector-base diode is reverse *** to the inherent BJT amplification effect,the PBJT achieves record-high sensitivities of 139.7 kPa^(-1)(current-based)and 88.66 kPa^(-1)(voltage-based)in sensing *** PBJT also has a fast response time of<110 ms under exertion of dynamic stimuli ranging from a flying butterfly to a gentle finger ***,the PBJT advances the state of the art not only in terms of sensitivity but also in regard to being self-driven and autonomous,making it promising for pressure sensing and other IoT applications.

关键词： bipolar transistor IoT

Temperature-Dependent Tearing Behavior of Rubber Materials:Characterization and Modeling

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Acta Mechanica Solida Sinica 2024年第2期37卷 316-326页

作者： Qinyuan Yao Feilong Zhang Pan Dong Ziyuan Zhao Yi He Weiguo Li Liming Chen State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing400044China College of aerospace engineering Chongqing UniversityChongqing400044China

With the increasingly widespread application of rubber in many fields,there is a growing demand for quantitative characterization of temperature-dependent mechanical properties in high-temperature service *** critical tearing energy is an important criterion for determining whether rubber materials will experience tearing instability,while tear strength is a key parameter for rubber materials to resist *** is necessary to quantitatively characterize their evolution with *** theoretical research mainly relies on fitting a large amount of experimental data,which is not convenient for engineering ***,in this work,a temperature-dependent critical tearing energy model is firstly developed based on the force-heat equivalence energy density *** model considers the equivalent relationship between the critical tearing energy required for crack instability propagation and the thermal energy stored in the rubber *** is demonstrated that our model has higher prediction accuracy when compared to other ***,combining with the Griffith fracture theory,temperature-dependent tear strength models applicable to three different crack modes are separately *** models are validated using experimental data for Mode I opening cracks and ModeⅢtearing cracks,and good consistency is ***,a quantitative analysis of the influence of elastic modulus on tear strength at different temperatures is *** work provides a reliable way for predicting temperature-dependent tearing instability behavior and offers beneficial suggestions for improving the tear strength of rubber materials at different temperatures.

关键词： Temperature-dependent Critical tearing energy Tear strength Rubber Theoretical model

Functionally graded structure of a nitride-strengthened Mg_(2)Si-based hybrid composite

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Journal of Magnesium and Alloys 2024年第3期12卷 1239-1256页

作者： Jeongho Yang Woongbeom Heogh Hogi Ju Sukhyun Kang Tae-Sik Jang Hyun-Do Jung Mohammad Jahazi Seung Chul Han Seong Je Park Hyoung Seop Kim Susmita Bose Amit Bandyopadhyay Martin Byung-Guk Jun Young Won Kim Dae-kyeom Kim Rigoberto CAdvincula Clodualdo Aranas Jr Sang Hoon Kim School of mechanical engineering Pusan National UniversityBusan 46241Republic of Korea Department of mechanical Design engineering Hanyang UniversitySeoul 04763Republic of Korea Process Research 3 Team LG Display Co.Ltd.PajuGyeonggi-do 10845Republic of Korea Department of Materials Science and engineering Chosun UniversityGwangju 61452Republic of Korea Institute of Well-Aging Medicare&Chosun University LAMP Center Chosun UniversityGwangju 61452Republic of Korea Division of Materials Science and engineering Hanyang UniversitySeoul 04763Republic of Korea Department of mechanical engineering École de Technologie SupérieureMontrealQuebec H3C 1K3Canada Material&Component Convergence R&D Center Korea Construction Equipment Technology InstituteGunsanJeollabuk-do 54002Republic of Korea School of mechanical and aerospace engineering Nanyang Technological UniversitySingapore 639798Singapore graduate Institute of Ferrous&Eco Materials Technology Pohang University of Science and TechnologyPohangGyeongsangbuk-do 37673Republic of Korea Advanced Institute for Materials Research Tohoku UniversitySendai 980-8577Japan Institute for Convergence Research and Education in Advanced Technology Yonsei UniversitySeoul 03722Republic of Korea School of mechanical and Materials engineering Washington State UniversityPullmanWashington 99164USA School of mechanical engineering Purdue UniversityWest LafayetteIndiana 47907USA Research Institute of Advanced Manufacturing Technology Korea Institute of Industrial TechnologyIncheon 21999Republic of Korea Department of Macromolecular Science and engineering Case Western Reserve UniversityClevelandOhio 44106USA Department of Chemical and Biomolecular engineering and Joint Institute for Advanced Materials University of TennesseeKnoxvilleTennessee 37996USA Center for Nanophase Materials and Sciences Oak Ridge National LaboratoryOak RidgeTennessee 37830USA Department of mechanical engineering University of New BrunswickFrederictonNew Brunswick E3B 5A3Cana

The ex-situ incorporation of the secondary SiC reinforcement,along with the in-situ incorporation of the tertiary and quaternary Mg_(3)N_(2) and Si_(3)N_(4) phases,in the primary matrix of Mg_(2)Si is employed in order to provide ultimate wear resistance based on the laser-irradiation-induced inclusion of N_(2) gas during laser powder bed *** is substantialized based on both the thermal diffusion-and chemical reactionbased metallurgy of the Mg_(2)Si–SiC/nitride hybrid *** study also proposes a functional platform for systematically modulating a functionally graded structure and modeling build-direction-dependent architectonics during additive *** strategy enables the development of a compositional gradient from the center to the edge of each melt pool of the Mg_(2)Si–SiC/nitride hybrid ***,the coefficient of friction of the hybrid composite exhibits a 309.3%decrease to–1.67 compared to–0.54 for the conventional nonreinforced Mg_(2)Si structure,while the tensile strength exhibits a 171.3%increase to 831.5 MPa compared to 485.3 MPa for the conventional *** outstanding mechanical behavior is due to the(1)the complementary and synergistic reinforcement effects of the SiC and nitride compounds,each of which possesses an intrinsically high hardness,and(2)the strong adhesion of these compounds to the Mg_(2)Si matrix despite their small sizes and low concentrations.

关键词： Laser powder bed fusion Mg_(2)Si-SiC/nitride hybrid composite Both the thermal diffusion-and chemical reaction-based metallurgy Functionally graded structure Compositional gradient Wear resistance.

Influence of sintering time on microstructure and properties of hot oscillatory pressing sintered W–Cu refractory alloys

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Tungsten 2024年第2期6卷 323-332页

作者： Zi-Qian Wu Wei Zhao Ka Gao Shi-Hao Du Qing-Quan Kong De-Jian Sun Yang Gao School of Materials Science and engineering Zhengzhou University of AeronauticsZhengzhou 450015China School of mechanical engineering University of Shanghai for Science and TechnologyShanghai 200093China Department of General Medicine Changhai HospitalShanghai 200000China Hubei Key Laboratory of mechanical Transmission and Manufacturing engineering Wuhan University of Science and TechnologyWuhan 430081China Sichuan Province engineering Technology Research Center of Powder Metallurgy Chengdu UniversityChengdu 610106China

W–Cu refractory alloys are widely used in aerospace,aviation,electronics,power,and other fi ***,because of its large melting point diff erence between alloy elements,the conventional powder metallurgy method required a long time of high temperature sintering is very likely to cause low density and abnormal grain size ***,90W-10Cu refractory alloys were successfully prepared by hot oscillatory pressing(HOP)under diff erent sintering time in this *** the infl uence of sintering time on the microstructure,grain size,density,Vickers hardness,room-tensile property,and electrical conductivity of the W–Cu refractory alloy was systematically *** results showed that during the short sintering time(30–90 min),the density,Vickers hardness,tensile strength,and electrical conductivity of the W–Cu refractory alloy increased signifi cantly to 98.7%,163.29 HV 30,507.3 MPa,and 14.2%International Annealed Copper Standard with the sintering time increasing,respectively,while its grain size showed no obvious *** the sintering time further increased to 120 min,the density was basically consistent with the sintering time of 90 ***,the prolonged high temperature sintering resulted in the grain growth of the samples,which caused the deterioration of the Vickers hardness,room-tensile strength,and conductivity properties of the W–Cu refractory *** the same sintering time,the density,Vickers hardness,and electrical conductivity of the HOP sintered W–Cu refractory alloy were signifi cantly higher than those of the HP sintered *** was indicated that high density,fi ne-grain,and excellent properties W–Cu refractory alloys could be prepared by hot oscillatory pressing under appropriate sintering time.

关键词： W–Cu refractory alloy Hot oscillatory pressing Sintering time Microstructure Property

Unexpected divergence in magnetoreceptor MagR from robin and pigeon linked to two sequence variations

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Zoological Research 2024年第1期45卷 69-78页

作者： Shun Wang Peng Zhang Fan Fei Tianyang Tong Xiujuan Zhou Yajie Zhou Jing Zhang Mengke Wei Yanqi Zhang Lei Zhang Yulong Huang Lin Zhang Xin Zhang Tiantian Cai Can Xie Institutes of Physical Science and Information Technology Anhui UniversityHefeiAnhui 230039China High Magnetic Field Laboratory Hefei Institutes of Physical ScienceChinese Academy of SciencesScience IslandHefeiAnhui 230031China Science Island Branch of graduate School University of Science and Technology of ChinaHefeiAnhui 230036China Department of Anatomy Anhui Medical UniversityHefeiAnhui 230032China Department of mechanical and aerospace engineering University at BuffaloState University of New YorkBuffaloNY 14260 USA International Magnetobiology Frontier Research Center Science IslandHefeiAnhui 230031China

Birds exhibit extraordinary mobility and remarkable navigational skills,obtaining guidance cues from the Earth’s magnetic field for orientation and long-distance *** species also show tremendous diversity in navigation strategies,with considerable differences even within the same taxa and among individuals from the same *** highly conserved iron and iron-sulfur cluster binding magnetoreceptor(MagR)protein is suggested to enable animals,including birds,to detect the geomagnetic field and navigate ***,MagR is also implicated in other functions,such as electron transfer and biogenesis of iron-sulfur clusters,raising the question of whether variability exists in its biochemical and biophysical features among species,particularly *** the current study,we conducted a comparative analysis of MagR from two different bird species,including the migratory European robin(Erithacus rubecula)and the homing pigeon(Columba livia).Sequence alignment revealed an extremely high degree of similarity between the MagRs of these species,with only three sequence ***,two of these variations underpinned significant differences in metal binding capacity,oligomeric state,and magnetic *** findings offer compelling evidence for the marked differences in MagR between the two avian species,potentially explaining how a highly conserved protein can mediate such diverse functions.

关键词： Homing and migration Animal navigation Magnetoreceptor(MagR) Diverse navigation pattern Conserved protein