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基于角度分辨倾斜背散射拉曼光谱的单晶硅应力分量解耦分析

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Acta Mechanica Sinica 2024年第4期40卷 238-250页

作者：常颖何赛赛孙铭媛赵宇琦马路路仇巍 Tianjin Key Laboratory of Modern Engineering mechanics Department of MechanicsTianjin UniversityTianjin300072China

对于应变工程而言,应力是控制半导体器件光电性能的关键.显微拉曼光谱是一种有效的半导体材料应力无损分析技术.然而,使用传统拉曼方法得到的结果通常是特定晶体/特定晶面的面内等效应力或主应力和.本文提出了一种基于角度分辨倾斜背散... 详细信息

对于应变工程而言,应力是控制半导体器件光电性能的关键.显微拉曼光谱是一种有效的半导体材料应力无损分析技术.然而,使用传统拉曼方法得到的结果通常是特定晶体/特定晶面的面内等效应力或主应力和.本文提出了一种基于角度分辨倾斜背散射显微拉曼光谱的应力分析方法.通过在样品坐标系中求解晶格动力学方程,在特征向量坐标系中进行拉曼选择,提出了一种通用的物理力学模型.利用该模型,考虑折射率、转偏和数值孔径影响等因素,建立了任意应力状态下任意晶面(以单晶硅{100}面为例)上偏振拉曼频移与各应力分量的解析关系.验证实验表明,应力分量的分析结果与施加的应力状态非常吻合.证明了基于角度分辨倾斜背散射显微拉曼光谱的方法、模型和仪器,能够解决单晶硅特别是{100}晶面上的应力分量不能通过拉曼测量解耦的普遍问题.

关键词：显微拉曼光谱材料应力应力分量背散射半导体器件晶格动力学无损分析数值孔径

Analytical solutions of turbulent boundary layer beneath forward-leaning waves

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Applied Mathematics and mechanics(English Edition) 2024年第4期45卷 695-710页

作者： Yiqin XIE Jifu ZHOU Xu WANG Jinlong DUAN Yongjun LU Shouqian LI Laboratory for mechanics in Fluid solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing 100190China State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower ResearchBeijing 100038China School of Engineering Sciences University of Chinese Academy of SciencesBeijing 100049China State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Nanjing Hydraulic Research InstituteNanjing 210024China

As a typical nonlinear wave,forward-leaning waves can be frequently encountered in the near-shore areas,which can impact coastal sediment transport ***,it is of significance to describe the characteristics of the boundary layer beneath forward-leaning waves accurately,especially for the turbulent boundary *** this work,the linearized turbulent boundary layer model with a linear turbulent viscosity coefficient is applied,and the novel expression of the near-bed orbital velocity that has been worked out by the authors for forward-leaning waves of arbitrary forward-leaning degrees is further used to specify the free stream boundary condition of the bottom boundary ***,a variable transformation is found so as to make the equation of the turbulent boundary layer model be solved analytically through a modified Bessel ***,an explicit analytical solution of the turbulent boundary layer beneath forward-leaning waves is derived by means of variable separation and variable *** analytical solutions of the velocity profile and bottom shear stress of the turbulent boundary layer beneath forward-leaning waves are verified by comparing the present analytical results with typical experimental data available in the previous literature.

关键词： forward-leaning wave turbulent boundary layer velocity profile bottom shear stress

A brief review on the recent development of phonon engineering and manipulation at nanoscales

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International Journal of Extreme Manufacturing 2024年第1期6卷 177-206页

作者： Siqi Xie Hongxin Zhu Xing Zhang Haidong Wang Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering MechanicsTsinghua UniversityBeijing 100084People’s Republic of China

Phonons are the quantum mechanical descriptions of vibrational modes that manifest themselves in many physical properties of condensed matter systems. As the size of electronic devices continues to decrease below mean free paths of acoustic phonons, the engineering of phonon spectra at the nanoscale becomes an important topic. Phonon manipulation allows for active control and management of heat fow, enabling functions such as regulated heat transport. At the same time, phonon transmission, as a novel signal transmission method, holds great potential to revolutionize modern industry like microelectronics technology, and boasts wide-ranging applications. Unlike fermions such as electrons, polarity regulation is difficult to act on phonons as bosons, making the development of effective phonon modulation methods a daunting *** work reviews the development of phonon engineering and strategies of phonon manipulation at different scales, reports the latest research progress of nanophononic devices such as thermal rectifiers, thermal transistors, thermal memories, and thermoelectric devices,and analyzes the phonon transport mechanisms involved. Lastly, we survey feasible perspectives and research directions of phonon engineering. Thermoelectric analogies, external field regulation, and acousto-optic co-optimization are expected to become future research hotspots.

关键词： phonon engineering phononic device nanoscale

Analysis on the turning point of dynamic in-plane compressive strength for a plain weave composite

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Defence Technology（防务技术） 2024年第2期32卷 485-495页

作者： Xiaoyu Wang Zhixing Li Licheng Guo Zhenxin Wang Jiuzhou Zhao department of Astronautic Science and mechanics Harbin Institute of TechnologyHarbin150001China AECC Commercial Aircraft Engine Co LTDShanghai201108China

Experimental investigations on dynamic in-plane compressive behavior of a plain weave composite were performed using the split Hopkinson pressure bar. A quantitative criterion for calculating the constant strain rate of composites was established. Then the upper limit of strain rate, restricted by stress equilibrium and constant loading rate, was rationally estimated and confirmed by tests. Within the achievable range of 0.001/s-895/s, it was found that the strength increased first and subsequently decreased as the strain rate increased. This feature was also reflected by the turning point(579/s) of the bilinear model for strength prediction. The transition in failure mechanism, from local opening damage to completely splitting destruction, was mainly responsible for such strain rate effects. And three major failure modes were summarized under microscopic observations: fiber fracture, inter-fiber fracture, and interface delamination. Finally, by introducing a nonlinear damage variable, a simplified ZWT model was developed to characterize the dynamic mechanical response. Excellent agreement was shown between the experimental and simulated results.

关键词： Plain weave composite Dynamic strength Quantitative criterion Turning point Failure mechanism

A comprehensive review on microchannel heat sinks for electronics cooling

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International Journal of Extreme Manufacturing 2024年第2期6卷 133-162页

作者： Zhi-Qiang Yu Mo-Tong Li Bing-Yang Cao Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering MechanicsTsinghua UniversityBeijing 100084People’s Republic of China

The heat generation of electronic devices is increasing dramatically,which causes a serious bottleneck in the thermal management of electronics,and overheating will result in performance deterioration and even device *** the development of micro-machining technologies,the microchannel heat sink(MCHS)has become one of the best ways to remove the considerable amount of heat generated by high-power *** has the advantages of large specific surface area,small size,coolant saving and high heat transfer *** paper comprehensively takes an overview of the research progress in MCHSs and generalizes the hotspots and bottlenecks of this *** heat transfer mechanisms and performances of different channel structures,coolants,channel materials and some other influencing factors are ***,this paper classifies the heat transfer enhancement technology and reviews the related studies on both the single-phase and phase-change flow and heat *** comprehensive review is expected to provide a theoretical reference and technical guidance for further research and application of MCHSs in the future.

关键词： microchannel heat sink thermal management of electronics microscale heat transfer heat transfer enhancement

Numerical simulation of three dimensional concrete printing based on a unified fluid and solid mechanics formulation

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Frontiers of Structural and Civil Engineering 2024年第4期18卷 491-515页

作者： Janis REINOLD Koussay DAADOUCH Günther MESCHKE Institute for Structural mechanics Ruhr University BochumBochum 44801Germany

Deformation control constitutes one of the main technological challenges in three dimensional(3D)concrete printing,and it presents a challenge that must be addressed to achieve a precise and reliable construction ***-based information of the expected deformations and stresses is required to optimize the construction process in association with the specific properties of the concrete *** this work,a novel thermodynamically consistent finite strain constitutive model for fresh and early-age 3D-printable concrete is *** model is then used to simulate the 3D concrete printing process to assess layer shapes,deformations,forces acting on substrate layers and prognoses of possible structural collapse during the layer-by-layer *** constitutive formulation is based on a multiplicative split of the deformation gradient into elastic,aging and viscoplastic parts,in combination with a hyperelastic potential and considering evolving material properties to account for structural buildup or *** advantage of this model is the stress-update-scheme,which is similar to that of small strain plasticity and therefore enables an efficient integration with existing material *** constitutive model uses the particle finite element method,which serves as the simulation framework,allowing for modeling of the evolving free surfaces during the extrusion *** analyses of three printed layers are used to create deformation plots,which can then be used to control the deformations during 3D concrete *** study offers further investigations,on the structural level,focusing on the potential structural collapse of a 3D printed concrete *** capability of the proposed model to simulate 3D concrete printing processes across the scales—from a few printed layers to the scale of the whole printed structure—in a unified fashion with one constitutive formulation,is demonstrated.

关键词： particle finite element method 3D concrete printing multiplicative split additive manufacturing elastoviscoplasticity

Pion-photon and kaon-photon transition distribution amplitudes in the Nambu–Jona-Lasinio model

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Chinese Physics C 2024年第8期48卷 94-103页

作者： Jin-Li Zhang Jun Wu department of Mathematics and Physics Nanjing Institute of TechnologyNanjing 211167China National Laboratory of solid State Microstructures Department of PhysicsNanjing UniversityNanjing 210093China

The Nambu–Jona-Lasinio model is utilized to investigate the pion-and kaon-photon leading-twist transition distribution amplitudes using proper time ***,the properties of the vector and axial vector pion-photon transition distribution amplitudes are examined,and the results meet the desired *** study involves sum rule and polynomiality *** vector and axial vector pion-photon transition form factors that are present in theπ^(+)→γe^(+)νprocess are the first Mellin moments of the pion-photon transition distribution *** vector transition form factor originates from the internal structure of hadrons,the axial current can be coupled to a pion,this pion is virtual,and its contribution will be present independently of the external *** kaon transition form factors are *** vector form factor's value at zero momentum transfer is determined by the axial anomaly,while this is not the case for the axial *** vector and axial form factors,as well as the neutral pion vector form factor F_(πγγ)(t),are *** to our findings,the pion axial transition form factor is harder than the vector transition form factor and harder than the electromagnetic form *** also discuss the link betweenπ−γandγ−πtransitions distribution amplitudes.

关键词： transition form factors NJL model transition distribution amplitudes

Exploring the associations between skeletal muscle echogenicity and physical function in aging adults:A systematic review with meta-analyses

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Journal of Sport and Health Science 2024年第6期13卷 820-840页

作者： Dustin J.Oranchuk Stephan G.Bodkin Katie L.Boncella Michael O.Harris-Love Muscle Morphology Mechanicsand Performance LaboratoryDepartment of Physical Medicine and RehabilitationUniversity of Colorado Anschutz Medical CampusAuroraCO 80045USA department of Physical Therapy

Background:Assessment and quantification of skeletal muscle within the aging population is vital for diagnosis,treatment,and injury/disease *** clinical availability of assessing muscle quality through diagnostic ultrasound presents an opportunity to be utilized as a screening tool for function-limiting ***,relationships between muscle echogenicity and clinical functional assessments require authoritative ***,we aimed to(a) synthesize the literature to assess the relationships between skeletal muscle echogenicity and physical function in older adults(≥60 years),(b) perform pooled analyses of relationships between skeletal muscle echogenicity and physical function,and(c) perform sub-analyses to determine between-muscle ***:CINAHL,Embase,MEDLINE,PubMed,and Web of Science databases were systematically searched to identify articles relating skeletal muscle echogenicity to physical function in older ***-of-bias assessments were conducted along with funnel plot ***-analyses with and without sub-analyses for individual muscles were performed utilizing Fisher's Z transformation for the most common measures of physical ***'s Z was back-transformed to Pearson's r for ***:Fifty-one articles(n=5095,female=~2759,male=~2301,72.5± 5.8 years,mean±SD(1 study did not provide sex descriptors))were extracted for review,with previously unpublished data obtained from the authors of 13 *** rectus femoris(n=34) and isometric knee extension strength(n=22) were the most accessed muscle and physical qualities,*** relationship between quadriceps echogenicity and knee extensor strength was moderate(n=2924,r=-0.36(95% confidence interval:-0.38 to-0.32),p <0.001),with all other meta-analyses(grip strength,walking speed,sit-to-stand,timed up-and-go) resulting in slightly weaker correlations(r:-0.34 to-0.23,all p <0.001).Sub-analyses determined minimal differences in predicti

关键词： Correlations Echo intensity Elderly Intramuscular fat Strength

Three-dimensional simulation of the coupled electromagneticmechanical responses in a no-insulation racetrack coil

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Science China Technological Sciences 2024年

作者： LI DongKe CHANG ZhiXiang TANG YunKai LIU DongHui YONG HuaDong ZHOU YouHe Key Laboratory of mechanics on Disaster and Environment in Western China Ministry of Education of China Lanzhou University department of mechanics and Engineering Sciences College of Civil Engineering and Mechanics Lanzhou University

This study investigates the coupled behavior of the mechanical and electromagnetic responses of a high-temperature superconducting(HTS) no-insulation(NI) racetrack coil. A three-dimensional(3D) equivalent circuit network model and mechanical model with nonlinear contact are incorporated into the coupled model. The stress and separation of adjacent turns under a high magnetic field are analyzed by considering the electromagnetic force and cooling process. The numerical results demonstrate that the straight and curved parts of the racetrack coil exhibit distinct mechanical behaviors. Under a strong external magnetic field, the separation between adjacent turns reduces the charging delay of the coil. The maximum stress occurs in the transition regions between the curved and straight parts. The straight part exhibits a larger rotation angle, while the separation regions between adjacent turns are relatively fewer in those parts. The curved part shows a higher proportion of separation regions in the steady stage. The different separation areas in the straight and curved parts also result in distinct turn-to-turn losses during the charging process. Subsequently, a comparative study is conducted on the influence of residual currents induced by ***, the effects of overband and inner diameter on the separation behavior are investigated.

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