检索结果-南通市图书馆

In vitro evaluation of artificial joints: a comprehensive review

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Manufacturing 2019年第1期7卷 1-14页

作者： Gang Shen ju-fan zhang Feng-Zhou fang Centre of Micro/Nano Manufacturing Technology (MNMTDublin) University College Dublin Dublin Ireland State Key Laboratory of Precision Measuring Technology and Instruments Centre of Micro/Nano Manufacturing Technology (MNMT) Tianjin University Tianjin 300072 People's Republic of China

Development of artificial joints is a great progress for joint replacement operations of human being, but the short longevity of prostheses has concerned both industries and researchers since the advent of modem implants. Thus, continuous improvements have been made alongside the clinical applications. The methodologies to inspect the potential properties of new designs have also seen many advances. The test machines have evolved from easy pin-on-disk configuration to the modem joint simulator. Besides, various wear traces provided by testing machines are investigated greatly, and multi-directional files are recommended as motion profiles for in vitro testing. The typical testing parameters, like sliding speed or loading profile, are discussed in this article, and their working mechanisms are described in detail. Meanwhile, the calf or bovine serum has been regarded as the gold standard for testing lubricant, and the future trend of fluid will be focused on investigating the effects of lubricant composites on the tribological properties. Hard particles and proteins are discussed as well, and their effects on the wear mechanisms are the focus. Finally, various approaches to measure the wear rate, wear factor and the thickness of lubricant film are presented, and suggestions are given for the development in future.

关键词： Artificial joint Methodology Testing parameter Wear rate

Optimization of microstructure design for enhanced sensing performance in flexible piezoresistive sensors

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2024年第6期13卷 711-728页

作者： Xinghao fan Hailong Hu Bin Liao Yaqi zhang fan zhang School of Minerals Processing and Bioengineering Central South UniversityChangsha 410083China Research Institute of Aerospace Technology Central South UniversityChangsha 410083China

Flexible piezoresistive strain sensors have received significant attention due to their diverse applications in monitoring human activities and health,as well as in robotics,prosthetics,and human–computer interaction *** the various flexible sensor types,those with microstructure designs are considered promising for strain sensing due to their simple structure,high sensitivity,extensive operational range,rapid response time,and robust *** review provides a concise overview of recent advancements in flexible piezoresistive sensors based on microstructure design for enhanced strain sensing performance,including the impact of microstructure on sensing mechanisms,classification of microstructure designs,fabrication methods,and practical ***,this review delves into the analysis of piezoresistive sensor sensing mechanisms and performance parameters,exploring the relationship between microstructure design and performance ***,an in-depth discussion is presented,focusing on the primary themes of microstructure design classification,process selection,performance characteristics,and specific *** review employs mathematical modeling and hierarchical analysis to emphasize the directionality of different microstructures on performance enhancement and to highlight the performance advantages and applicable features of various microstructure *** conclusion,this review examines the multifunctionality of flexible piezoresistive sensors based on microstructure design and addresses the challenges that still need to be overcome and improved,such as achieving a wide range of stretchability,high sensitivity,and robust *** review summarizes the research directions for enhancing sensing performance through microstructure design,aiming to assist in the advancement of flexible piezoresistive sensors.

关键词： microstructure design sensing performance flexible piezoresistive strain sensors microsensing mechanism

Effect of Ti_(p) Content on the Work Hardening and Softening Behavior of Mg-Zn-Ca Alloy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 551-560页

作者： Jin-Kai zhang Cui-ju Wang Yi-Dan fan Chao Xu Kai-Bo Nie Kun-Kun Deng Shanxi Key Laboratory of Advanced Magnesium-Based Materials College of Materials Science and EngineeringTaiyuan University of TechnologyTaiyuan 030024China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

The Ti_(p)/ZX60 composites with different Ti_(p) contents were prepared by semi-solid stirring *** extrusion,the microstructure,work hardening and softening behavior of the Ti_(p)/ZX60 composites were analyzed compared with the ZX60(Mg-6Zn-0.2Ca)*** results showed that the addition of Ti_(p) could not only promote the nucleation of dynamic recrystallized(DRXed)grains,but also be propitious to the refinement of DRXed *** increasing Ti_(p) content,the size of DRXed grains decreased accompanied with increasing volume fraction of DRXed *** the Ti_(p) content increased to 15 vol.%,the average size and volume fraction of DRXed grains reached to~0.32μm and 93.2%,***,both the strength and elongation were improved by the addition of Ti_(p).With increasing content of Ti_(p),a substantial increase in the strength was achieved with little change in the ***,the elongation decreased sharply when the Ti_(p) content further increased to 15 vol.%.The addition of Ti_(p) led to an increase in the work hardening rate,which gradually increased with increasing Ti_(p) ***,the softening rate did not demonstrate the same tendency with increasing Ti_(p) *** the conventional ceramic particles,the Ti_(p) can be deformed in coordination with the matrix alloy,which imparted a higher softening rate to the matrix *** though the softening rate improved as the Ti_(p) content increased from 5 to 10 vol.%,it dropped deeply as the Ti_(p) content increased to 15 vol.%owing to the fracture of Ti_(p) during extrusion.

关键词： Titanium particle content Particle reinforced magnesium matrix composites Work hardening Softening behavior Mechanical properties

Distributed dynamic task allocation for unmanned aerial vehicle swarm systems:A networked evolutionary game-theoretic approach

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第6期37卷 182-204页

作者： Zhe zhang ju JIANG Haiyan XU Wen-An zhang College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China College of Economics and Management Nanjing University of Aeronautics and AstronauticsNanjing 211106China College of Information Engineering Zhejiang University of TechnologyHangzhou 310023China

Task allocation is a key aspect of Unmanned Aerial Vehicle(UAV)swarm collaborative *** an continuous increase of UAVs’scale and the complexity and uncertainty of tasks,existing methods have poor performance in computing efficiency,robustness,and realtime allocation,and there is a lack of theoretical analysis on the convergence and optimality of the *** paper presents a novel intelligent framework for distributed decision-making based on the evolutionary game theory to address task allocation for a UAV swarm system in uncertain scenarios.A task allocation model is designed with the local utility of an individual and the global utility of the ***,the paper analytically derives a potential function in the networked evolutionary potential game and proves that the optimal solution of the task allocation problem is a pure strategy Nash equilibrium of a finite strategy ***,a PayOff-based Time-Variant Log-linear Learning Algorithm(POTVLLA)is proposed,which includes a novel learning strategy based on payoffs for an individual and a time-dependent Boltzmann *** former aims to reduce the system’s computational burden and enhance the individual’s effectiveness,while the latter can ensure that the POTVLLA converges to the optimal Nash equilibrium with a probability of *** simulation results show that the approach is optimal,robust,scalable,and fast adaptable to environmental changes,even in some realistic situations where some UAVs or tasks are likely to be lost and increased,further validating the effectiveness and superiority of the proposed framework and algorithm.

关键词： Task allocation Unmanned Aerial Vehicles(UAV) Game theory Log-linear learning Distributed optimization algorithm

Soliton resolution and asymptotic stability of N-solutions for the defocusing Kundu–Eckhaus equation with nonzero boundary conditions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2024年第1期76卷 1-6页

作者： Engui fan Yanxi zhang School of Mathematical Sciences and Key Laboratory of Mathematics for Nonlinear Science Fudan UniversityShanghai200433China Tianjin Xinhua High School No.99 machang RoadTianjin300204China

In this paper,we address interesting soliton resolution,asymptotic stability of N-soliton solutions and the Painleve asymptotics for the Kundu-Eckhaus(KE)equation with nonzero boundary conditions iq_(t)+q_(xx)-2(l|q|^(2)-1)q+4β^(2)(lql^(4)-1)q+4iβ(lql^(2))_(x)q=0,q(x,0)=q_(0)(x)-±1,x→±∞.The key to proving these results is to establish the formulation of a Riemann-Hilbert(RH)problem associated with the above Cauchy problem and find its connection with the RH problem of the defocusing NLS *** the■-steepest descent method and the results of the defocusing NLS equation,we find complete leading order approximation formulas for the defocusing KE equation on the whole(x,t)half-plane including soliton resolution and asymptotic stability of N-soliton solutions in a solitonic region,Zakharov-Shabat asymptotics in a solitonless region and the Painlevéasymptotics in two transition regions.

关键词： defocusing Kundu-Eckhaus equation Riemann-Hilbert problems steepest descent method soliton resolution asymptotic stability Painleve transcendents

The multiple roles of crop structural change in productivity,nutrition and environment in China:A decomposition analysis

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2024年第5期23卷 1763-1773页

作者： Xiangyang zhang Yumei zhang Shenggen fan College of Economics and Management China Agricultural UniversityBejing 100083China Academy of Global Food Economics and Policy China Agricultural UniversityBejing 100083China

China's crop structure has undergone significant changes in the last two decades since 2000,with an increase in the share of cereals,vegetables,and fruit,squeezing out other *** a result,land productivity,nutrient supply,and carbon emissions have *** to reallocate limited farmland among crops to achieve the multiple goals of agrifood systems becomes an important *** study explores the sources of land productivity and nutrition supply growth and carbon emissions reduction,and identifies the multiple roles of crop structural change from 2003 to 2020 based on a decomposition *** results reveal that the growth within crops is still the primary driver in land productivity and nutrition supply and the reduction in carbon ***,structural change also plays various roles at different *** 2003 to 2010,crop structural change increased the total calorie supply but lowered land productivity and contributed at least 70%of the total growth of carbon *** crop structure was relatively stable,and their effects were modest from 2010 to *** 2015 to 2020,the crop structural change began to play a greater role and generate synergistic effects in improving land productivity,micronutrient supply,and reducing carbon emissions,contributing to approximately a quarter of the growth of land productivity and 30%of total carbon emissions *** results suggest that strategies for crop structural change should comprehensively consider its multiple impacts,aiming to achieve co-benefits while minimizing trade-offs.

关键词： crop structural change land productivity nutrition carbon emissions

Processing,microstructure,and properties of porous ceramic composites with directional channels

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2024年第1期168卷 1-15页

作者： Bo zhang Yang Yang Xueling fan Key Laboratory of Service Performance and Protection Technology in Extreme Environments Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory for Strength and Vibration of Mechanical Structures School of Aerospace EngineeringXi’an Jiaotong UniversityXi’an 710049China

Porous ceramic composites with directional microchannels from micrometer to dozens of micrometer levels have attracted more and more attention in various fields including aerospace,biomedicines,and thermal insulation due to their excellent fluid permeability,mechanical properties,*** this article,we summarize the recent directional porous ceramics developments including their main processing routes and respective ***,the properties get from different processing routes have been com-pared and analyzed in terms of microstructures,mechanical properties,and *** has been given to the deeper understanding which can allow one to control the microstructural features of these porous ceramic composites to obtain the desired *** work can provide a useful reference for the development and application of porous ceramic composites with directional microchan-nels.

关键词： Porous ceramic composites Directional microchannels Processing routes Permeability

Experimental Study on Wire Melting Control Ability of Twin-Body Plasma Arc

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2024年第2期37卷 184-194页

作者： Ruiying zhang fan Jiang Long Xue School of Mechanical Engineering Beijing Institute of Petrochemical TechnologyBeijing 102617China Beijing Academy of Safety Engineering and Technology Beijing 102617China College of Mechanical and Energy Engineering Beijing University of TechnologyBeijing 100124China

The twin-body plasma arc has the decoupling control ability of heat transfer and mass transfer,which is beneficial to shape and property control in wire arc additive *** this paper,with the wire feeding speed as a characteristic quantity,the wire melting control ability of twin-body plasma arc was studied by adjusting the current separation ratio(under the condition of a constant total current),the wire current/main current and the position of the wire in the arc axial *** results showed that under the premise that the total current remains unchanged(100 A),as the current separation ratio increased,the middle and minimum melting amounts increased approximately synchronously under the effect of anode effect power,the first melting mass range remained constant;the maximum melting amount increased twice as fast as the middle melting amount under the effect of the wire feeding speed,and the second melting mass range was *** the wire current increased,the anode effect power and the plasma arc power were both factors causing the increase in the wire melting amount;however,when the main current increased,the plasma arc power was the only factor causing the increase in the wire melting *** average wire melting increment caused by the anode effect power was approximately 2.7 times that caused by the plasma arc *** minimum melting amount was not affected by the wire-torch distance under any current separation ratio *** the current separation ratio increased and reached a threshold,the middle melting amount remained constant with increasing wire-torch *** the current separation ratio continued to increase and reached the next threshold,the maximum melting amount remained constant with the increasing wire-torch *** effect of the wire-torch distance on the wire melting amount reduced with the increase in the current separation *** this study,the decoupling mechanism and ability of this innovative

关键词： Twin-body plasma arc Melting control ability Melting amount Current separation ratio

Enhancing transboundary natural tourism resources governance:unveiling the spatial pattern and its influencing factors

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Mountain Science 2024年第3期21卷 973-986页

作者： zhang Shengrui zhang Tongyan ju Hongrun WANG Yingjie Management College Ocean University of ChinaQingdao 266100China School of Tourism and Geography Science Qingdao UniversityQingdao 266071China Institute of Geographic Sciences and Natural Resources Research Chinese Academy of SciencesBeijing 100101China

Tourism resources that span provincial boundaries in China play a pivotal role in regional development,yet effective governance poses persistent *** study addresses this issue by constructing a comprehensive database of transboundary natural tourism resources(TNTR)through amalgamation of diverse data *** the Getis-Ord Gi^(*),kernel density estimation,and geographical detectors,we scrutinize the spatial patterns of TNTR,focusing on both named and unnamed entities,while exploring the influencing *** findings reveal 7883 identified TNTR in China,with mountain tourism resources emerging as the predominant *** provinces,Hunan boasts the highest count,while Shanghai exhibits the *** China demonstrates a pronounced clustering trend in TNTR distribution,with the spatial arrangement of biological landscapes appearing more random compared to geological and water *** China,characterized by intricate terrain,exhibits fewer TNTR,concurrently unveiling a significant presence of unnamed natural tourism ***,administrative segmentation influences TNTR development,generating disparities in regional goals,developmental stages and intensities,and management *** response to these variations,we advocate for strengthening the naming of the unnamed transboundary tourism resources,constructing a geographic database of TNTR for government and establishing a collaborative management mechanism based on TNTR *** research contributes to elucidating the intricate landscape of TNTR,offering insights for tailored governance strategies in the realm of cross-provincial tourism resource management.

关键词： Transboundary natural tourism resources(TNTR) Spatial difference Spatial autocorrelation Governance optimization China