检索结果-南通市图书馆

Toward tunable shape memory effect of NiTi alloy by grain size engineering:A phase field study

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 Materials Science & Technology 2024年第1期168卷 276-289页

作者： Bo xu Chong Wang Qingyuan Wang Failure Mechanics and Engineering Disaster prevention Key Laboratory of Sichuan ProvinceSichuan UniversityChengdu 610065China Department of Mechanical Science and Engineering College of Architecture and EnvironmentSichuan UniversityChengdu 610065China Key Laboratory of Deep Underground Science and Engineering (Sichuan University)Ministry of EducationChengdu 610065China

The inelastic deformations of shape memory alloys(SMAs)always show poor controllability due to the avalanche-like martensite transformation,and the effective control for the deformation of precision de-vices has been not yet *** this work,the phase field method was used to investigate the shape memory effects(SMEs)of NiTi SMAs undergoing grain size(GS)engineering,to obtain tunable one-way and stress-assisted two-way SMEs(OWSME and SATWSME).The OWSME and SATWSME of the systems with various gradient-nanograin structures and bimodal grain structure,as well as that with geometric gradients were *** simulated results indicate that due to the GS dependences of martensite transformation and reorientation,the occurrence and expansion of martensite reorientation,martensite transformation and its reverse can be efficaciously controlled via the GS *** combining the GS engineering and geometric gradient design,since the effects of GS and stress gradient can be su-perimposed or competing,and the responses of martensite reorientation,martensite transformation and its reverse to this are different,the OWSME and SATWSME of the geometrically graded systems with various nanograin structures can exhibit different improvements in *** short,the reorienta-tion hardening modulus during OWSME is increased and the transformation temperature window during SATWSME is widened by GS engineering,indicating the improved controllability of *** optimal GS engineering schemes revealed in this work provide the basic reference and guidance for designing tun-able SMEs and producing NiTi-based driving devices catering to desired functional performance in various engineering fields.

关键词： phase field NiTi Shape memory effect Grain size engineering Geometric gradient

Linear Quadratic Optimal Control for Systems Governed by First-Order Hyperbolic partial Differential Equations

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 Systems Science & Complexity 2024年第1期37卷 230-252页

作者： xuE Xiaomin xu Juanjuan ZHANG Huanshui School of Control Science and Engineering Shandong UniversityJinan 250061China College of Electrical Engineering and Automation Shandong University of Science and TechnologyQingdao 266000China

This paper focuses on linear-quadratic(LQ)optimal control for a class of systems governed by first-order hyperbolic partial differential equations(pDEs).Different from most of the previous works,an approach of discretization-then-continuousization is proposed in this paper to cope with the infinite-dimensional nature of pDE *** contributions of this paper consist of the following aspects:(1)The differential Riccati equations and the solvability condition of the LQ optimal control problems are obtained via the discretization-then-continuousization method.(2)A numerical calculation way of the differential Riccati equations and a practical design way of the optimal controller are ***,the relationship between the optimal costate and the optimal state is established by solving a set of forward and backward partial difference equations(FBpDEs).(3)The correctness of the method used in this paper is verified by a complementary continuous method and the comparative analysis with the existing operator results is *** is shown that the proposed results not only contain the classic results of the standard LQ control problem of systems governed by ordinary differential equations as a special case,but also support the existing operator results and give a more convenient form of computation.

关键词： Discretization-then-continuousization method first-order hyperbolic partial differential equations forward and backward partial difference equations linear quadratic optimal control.

Evaluation of suitability,adaptability,and reserve potential of construction land on the Qinghai-Tibet plateau

在线全文

学校读者我要写书评

暂无评论

Journal of Geographical Sciences 2024年第1期34卷 41-61页

作者： yANG Hua xu yong ZHOU Kan WANG Lijia xu Lin Key Laboratory of Regional Sustainable Development Modeling Institute of Geographic Sciences and Natural Resources ResearchCASBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

Construction land is the leading carrier of human activities such as production and *** the construction land suitability(CLS)on the Qinghai-Tibet plateau(QTp)holds significant implications for harmonizing the relationship between ecological protection and human activity and promoting population and industry layout ***,no relevant studies provide a complete CLS assessment of the *** this study,we developed a model-based CLS evaluation framework coupling of pattern and process to calculate the global CLS on the QTp based on a previously developed CLS evaluation ***,using the land-use data of 1990,2000,2010,and 2020,we examined the adaptability of existing construction land(ECL)to the CLS assessment result through the adaptability index and vertical gradient index and further analyzed the limitations of maladaptive construction ***,we calculated the potential area of reserve suitable construction *** article includes four conclusions:(1)The highly suitable,suitable,moderately suitable,marginally suitable,and unsuitable CLS classes cover areas of 0.33×10^(4)km^(2),10.42×10^(4)km^(2),18.06×10^(4)km^(2),24.12×10^(4)km^(2),and 205.29×10^(4)km^(2),*** approximately 11%of the study area on the QTp is suitable for large-scale permanent construction land,and approximately 79.50%of the area is unsuitable under current economic and technological conditions.(2)The ECL adaptability index is 85.16%,85.93%,85.18%,and 78.01%during 1990–2020,respectively,with an average adaptability index exceeding 80%on the *** ECL distribution generally conforms to construction land suitable space characteristics but with a significant spatial difference.(3)From 1990 to 2020,the maladaptive ECL was dominated by rural settlement land,transport land,and special land,with a rapidly increasing proportion of urban and other construction *** maladaptive ECL is constrained by both elevation and slope in the southern Qinghai pla

关键词： land resource construction land suitability existing construction land adaptability human activity Qinghai-Tibet plateau

Synthesis and characterization of iron clusters with an icosahedral [Fe@Fe12]16+ Core

在线全文

学校读者我要写书评

暂无评论

National Science Review 2024年第4期11卷 123-129页

作者： Gan xu yun-Shu Cui xue-Lian Jiang Cong-Qiao xu Jun Li xu-Dong Chen Jiangsu Collaborative Innovation Center of Biomedical Functional Materials and Jiangsu Key Laboratory of New power Batteries School of Chemistry and Materials Science Nanjing Normal University Department of Chemistry and Guangdong provincial Key Laboratory of Catalytic Chemistry Southern University of Science and Technology Department of Chemistry and Engineering Research Center of Advanced Rare-Earth Materials of Ministry of Education Tsinghua University State Key Laboratory of Coordination Chemistry Nanjing University

Iron-metal clusters are crucial in a variety of critical biological and material systems,including metalloenzymes,catalysts,and magnetic storage ***,a synthetic high-nuclear iron cluster has been absent due to the extreme difficulty in stabilizing species with direct iron-iron *** this work,we have synthesized,crystallized,and characterized a（Tp*）4W4S12(Fe@Fe12) cluster(Tp*=tris（3,5-dimethyl-1-pyrazolyl）borate（1-）),which features a rare trideca-nuclear,icosahedral[Fe@Fe12] cluster core with direct multicenter iron-iron bonding between the interstitial iron（Fei） and peripheral irons（Fep）,as well as Fep…Fepferromagnetic *** chemistry studies reveal that the stability of the cluster arises from the 18-electron shell-closing of the [Fe@Fe12]16+core,assisted by its bonding interactions with the peripheral tridentate [（Tp*）WS3]4-ligands which possess both S→Fe donation and spin-polarized Fe-Wσ *** ground-state electron spin is theoretically predicted to be S=32/2 for the *** existence of low oxidation-state（OS～+1.23） iron in this compound may find interesting applications in magnetic storage,spintronics,redox chemistry,and cluster catalysis.

关键词： Fe13 cluster iron-sulfur cluster low-valence iron iron−iron bond high spin complex

A Review on Vibration Control of Multiple Cylinders Subjected to FlowInduced Vibrations

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

China Ocean Engineering 2024年第2期38卷 183-197页

作者： xu Wan-hai MA ye-xuan State Key Laboratory of Hydraulic Engineering Intelligent Construction and Operation Tianjin UniversityTianjin 300350China Institute of Mechanics Chinese Academy of SciencesBeijing 100190China

The fatigue damage caused by flow-induced vibration(FIV)is one of the major concerns for multiple cylindrical structures in many engineering *** FIV suppression is of great importance for the security of many cylindrical *** active and passive control methods have been employed for the vibration suppression of an isolated cylinder undergoing vortex-induced vibrations(VIV).The FIV suppression methods are mainly extended to the multiple cylinders from the vibration control of the isolated *** to the mutual interference between the multiple cylinders,the FIV mechanism is more complex than the VIV mechanism,which makes a great challenge for the FIV *** efforts have been devoted to vibration suppression of multiple cylinder systems undergoing FIV over the past two *** control methods,such as helical strakes,splitter plates,control rods and flexible sheets,are not always effective,depending on many influence factors,such as the spacing ratio,the arrangement geometrical shape,the flow velocity and the parameters of the vibration control *** FIV response,hydrodynamic features and wake patterns of the multiple cylinders equipped with vibration control devices are reviewed and *** FIV suppression efficiency of the vibration control methods are analyzed and compared considering different influence *** research on the FIV suppression of multiple cylinders is suggested to provide insight for the development of FIV control methods and promote engineering applications of FIV control methods.

关键词： flow-induced vibration vibration control multiple cylinders tandem side-by-side staggered

Development of a Three-Dimensional Multiscale Octree SBFEM for Viscoelastic problems of Heterogeneous Materials

在线全文

学校读者我要写书评

暂无评论

Computer Modeling in Engineering & Sciences 2024年第8期140卷 1831-1861页

作者： xu xu Xiaoteng Wang Haitian yang Zhenjun yang yiqian He State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentDepartment of Engineering MechanicsDalian University of TechnologyDalian116024China Hubei Key Laboratory of Geotechnical and Structural Safety School of Civil EngineeringWuhan UniversityWuhan430072China Mechanik–Materialtheorie Ruhr-Universität BochumBochum44801Germany

The multiscale method provides an effective approach for the numerical analysis of heterogeneous viscoelastic materials by reducing the degree of freedoms(DOFs).A basic framework of the Multiscale Scaled Boundary Finite Element Method(MsSBFEM)was presented in our previous works,but those works only addressed two-dimensional *** order to solve more realistic problems,a three-dimensional MsSBFEM is further developed in this *** the proposed method,the octree SBFEM is used to deal with the three-dimensional calculation for numerical base functions to bridge small and large scales,the three-dimensional image-based analysis can be conveniently conducted in small-scale and coarse nodes can be flexibly adjusted to improve the computational ***,the Temporally piecewise Adaptive Algorithm(TpAA)is used to maintain the computational accuracy of multiscale analysis by adaptive calculation in time *** results of numerical examples show that the proposed method can significantly reduce the DOFs for three-dimensional viscoelastic analysis with good *** instance,the DOFs can be reduced by 9021 times compared with Direct Numerical Simulation(DNS)with an average error of 1.87%in the third example,and it is very effective in dealing with three-dimensional complex microstructures directly based on images without any geometric modelling process.

关键词： Three-dimensionalmultiscale viscoelastic analysis numerical base functions octree SBFEM image-based analysis temporally piecewise adaptive algorithm

Metasurface-based computational imaging:a 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

Advanced photonics 2024年第1期6卷 43-63页

作者： xuemei Hu Weizhu xu Qingbin Fan Tao yue Feng yan yanqing Lu Ting xu Nanjing University Collaborative Innovation Center of Advanced MicrostructuresNational Laboratory of Solid-State MicrostructuresNanjingChina Nanjing University School of Electronic Sciences and EngineeringNanjingChina Nanjing University College of Engineering and Applied SciencesJiangsu Key Laboratory of Artificial Functional MaterialsNanjingChina

Metasurface-based imaging has attracted considerable attention owing to its compactness,multifunctionality,and subwavelength coding *** the integration of computational imaging techniques,researchers have actively explored the extended capabilities of metasurfaces,enabling a wide range of imaging *** present an overview of the recent progress in metasurface-based imaging techniques,focusing on the perspective of computational ***,we categorize and review existing metasurface-based imaging into three main groups,including(i)conventional metasurface design employing canonical methods,(ii)computation introduced independently in either the imaging process or postprocessing,and(iii)an end-to-end computation-optimized imaging system based upon *** highlight the advantages and challenges associated with each computational metasurface-based imaging technique and discuss the potential and future prospects of the computational boosted metaimager.

关键词： metasurface computational imaging inverse problem algorithm

Twisted Integration of Complex Oxide Magnetoelectric Heterostructures via Water‑Etching and Transfer process

在线全文

学校读者我要写书评

暂无评论

Nano-Micro Letters 2024年第1期16卷 360-369页

作者： Guannan yang Guohua Dong Butong Zhang xu xu yanan Zhao Zhongqiang Hu Ming Liu State Key Laboratory for Manufacturing Systems Engineering Electronic Materials Research LaboratoryKey Laboratory of the Ministry of EducationEngineering Research Center of Spin Quantum Sensor ChipsUniversities of Shaanxi ProvinceSchool of Electronic Science and EngineeringXi’an Jiaotong UniversityXi’an 710049People’s Republic of China

Manipulating strain mode and degree that can be applied to epitaxial complex oxide thin films have been a cornerstone of strain *** recent years,lift-off and transfer technology of the epitaxial oxide thin films have been developed that enabled the integration of heterostructures without the limitation of material types and crystal ***,twisted integration would provide a more interesting strategy in artificial magnetoelectric heterostructures.A specific twist angle between the ferroelectric and ferromagnetic oxide layers corresponds to the distinct strain regulation modes in the magnetoelectric coupling process,which could provide some insight in to the physical *** this work,the La_(0.67)Sr_(0.33)MnO_(3)(001)/0.7pb(Mg_(1/3)Nb_(2/3))O_(3)-0.3pbTiO_(3)(011)(LSMO/pMN-pT)heterostructures with *** *** angles were assembled via water-etching and transfer *** transferred LSMO films exhibit a fourfold magnetic anisotropy with easy axis along LSMO.A coexistence of uniaxial and fourfold magnetic anisotropy with LSMO[110]easy axis is observed for the 45°Sample by applying a 7.2 kV cm^(−1)electrical field,significantly different from a uniaxial anisotropy with LSMO[100]easy axis for the 0°*** fitting of the ferromagnetic resonance field reveals that the strain coupling generated by the 45°twist angle causes different lattice distortion of LSMO,thereby enhancing both the fourfold and uniaxial *** work confirms the twisting degrees of freedom for magnetoelectric coupling and opens opportunities for fabricating artificial magnetoelectric heterostructures.

关键词： Magnetoelectric heterostructures Twist angle Epitaxial lift-off Magnetic anisotropy Ferromagnetic resonance

Designing gradient nanograined dual-phase structure in duplex stainless steel for superior strength-ductility synergy

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3期170卷 122-128页

作者： Songsong xu ying Han Jiapeng Sun Guoqing Zu Mingkun Jiang Weiwei Zhu xu Ran Key Laboratory of Advanced Structural Materials Ministry of EducationChangchun University of TechnologyChangchun 130012China School of Materials Science and Engineering Changchun University of TechnologyChangchun 130012China provincial Key Laboratory of Advanced Materials processing and Application for Rail Transit Changchun University of TechnologyChangchun 130012China College of Mechanics and Materials Hohai UniversityNanjing 211100China

Similar to other metallic materials,duplex stainless steel dramatically loses its advantage of high ductility as they are ***,we produce a gradient nanograined dual-phase structure in the 2101 duplex stainless steel,thus facilitating a superior strength-ductility synergy:a yield strength of 1009.5 Mpa being two times higher than that of the as-received sample,a total elongation of 23.4%and a uniform elongation of 5.9%.This novel structure is produced through a processing route of ultrasonic severe surface rolling and annealing,which realizes a superposition of gradient nanostructure and lamellar dual-phase structure with austenite and *** the tension deformation of gradi-ent nanograined dual-phase structured duplex stainless steel,a significant accumulation of geometrically necessary dislocations *** dislocations are formed to accommodate the deformation incompat-ibility caused by the layer-by-layer difference in strength and hardness of individual phase domains,as well as the inherent difference in properties between the austenite and ferrite *** results in a stronger hetero-deformation induced strengthening and hardening significantly contributing to superior mechanical *** study provides a new avenue to develop advanced steels with high strength and ductility.

关键词： Gradient structure Duplex stainless steel Synergetic strengthening Strength Ductility