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Effects of rafting on the meso deformation and fracture behaviour of a Ni-based single crystal superalloy at room temperature: In-situ observation and simulation

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Science China(Technological Sciences) 2024年第7期67卷 2133-2146页

作者： tan Long YANG XiaoGuang SHI DuoQi FAN YongSheng SHI Yi School of Energy and Power Engineering Beihang UniversityBeijing 102206China Research Institute of Aero-Engine Beihang UniversityBeijing 102206China National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics Beihang UniversityBeijing 102206China School of Materials Science&Engineering Shanghai Jiao Tong UniversityShanghai 200240China

Microstructural rafting of Ni-based single-crystal(SC) superalloys is inevitable at elevated temperatures during long-term service with mechanical loading, which significantly affects the mechanical behaviour of the material. In this study, the effects of rafting on the mesodeformation and fracture behaviour of a Ni-based SC superalloy under cyclic and tensile loads were investigated using in situ scanning electron microscopy(SEM), digital image correlation(DIC), and crystal plasticity finite element method(CP-FEM) simulations. The results indicated that the tensile strength decreased significantly in the rafted specimens. In the cyclic tests, both the virgin and rafted specimens showed an increase in the maximum shear strain with cycle number. The interaction of cross-slip bands was captured by in situ SEM-DIC around the micro-notch of the virgin specimens during the tensile test, while a more homogeneous local deformation field was observed in the rafting specimens. In addition,the fracture behaviour was strongly influenced by the rafting morphology. The crack exhibited instantaneous and long-range fracture features along the octahedral plane as it propagated in the rafting specimen, whereas it deflected over a short distance between the crystallographic planes at an early stage in the virgin specimen, which is consistent with the CP-FEM ***, the CP-FEM results for the crack initiation direction on(111) dominant slip plane were consistent with the in situ SEM observations.

关键词： in-situ SEM-DIC Ni-based SC superalloys microstructural rafting deformation crack path CP-FEM

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Advancing mid-infrared microdisk laser emission with Tm:YAG

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 91-96页

作者： Zhaocong Wang Huiqi Li Lei Wang Yang tan Feng Chen School of Physics State Key Laboratory of Crystal MaterialsShandong UniversityJinan 250100China

Mid-infrared microcavity lasers have important applications in biosensing,mid-infrared spectroscopy,and environmental ***,the low output power of existing mid-infrared microcavity lasers hinders their practical *** drawback is attributed to the insufficient laser gain medium,which limits the development of mid-infrared whispering-gallerymode(WGM)*** address this issue,we have employed ion implantation-enhanced etching to fabricate Tm:YAG thin films as effective gain media for mid-infrared WGM *** Tm:YAG thin film,with a thickness of 2μm,exhibits excellent fluorescence ***,the Tm:YAG thin film is processed using focused ion beam to form microdisks with a diameter of 30μ*** 785 nm laser pumping,the maximum output power of the Tm:YAG microdisk at 2023.1 nm is229μW,with a slope efficiency of 2.9%.This work demonstrates the outstanding potential of Tm:YAG as a mid-infrared laser gain medium,providing a new option for the development of mid-infrared lasers.

关键词： microdisk microlaser ultrathin film

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Self-assembled amphiphilic NIR-Ⅱ emissive nano-micelles for imaging-guided photothermal therapy of colorectal cancer

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Science China Chemistry 2024年第8期67卷 2767-2774页

作者： Axin He Fangfang Xia Da Han Qinglai Yang Weihong tan Institute of Molecular Medicine(IMM) Renji HospitalSchool of MedicineShanghai Jiao Tong UniversityShanghai 200240China Center for Molecular Imaging Probe Hunan Province Key Laboratory of Cancer Cellular and Molecular PathologyCancer Research InstituteHengyang Medical SchoolUniversity of South ChinaHengyang 421001China The Key Laboratory of Zhejiang Province for Aptamers and Theranostics Zhejiang Cancer Hospital Hangzhou Institute of Medicine(HIM)Chinese Academy of SciencesHangzhou 310022China Molecular Science and Biomedicine Laboratory(MBL) State Key Laboratory of Chemo/Biosensing and ChemometricsCollege of Chemistry and Chemical EngineeringCollege of BiologyAptamer Engineering Center of Hunan ProvinceHunan UniversityChangsha 410082China

Colorectal cancer(CRC) is one of the major causes of cancer-related mortality worldwide. Most near-infrared(NIR) agents used in clinical CRC treatment are at NIR-I(700–900 nm) window, which has limitations on deep tissue, and fluorescent probes in the second NIR(1,000–1,700 nm) allow high-resolution bioimaging with deep tissue penetration. However, existing NIR-II fluorophores used in clinical are still rare. Herein, based on shielding-donor-acceptor-donor-shielding(S-D-A-D-S) scaffold, we developed an organic small-molecule fluorophore IR-BTGP with NIR-II emission for imaging-guided photothermal therapy(PTT) in CRC mice model. Amphiphilic IR-BTGP can be self-assembled into spherical nano-micelles, which presents reliable water solubility and photothermal conversion efficiency(30.2%). In vitro experiments indicate that cancer cells treated with IRBTGP were significantly killed upon 808 nm light irradiation. Furthermore, in vivo NIR-II fluorescence imaging confirms that IR-BTGP accumulates in the tumor region. Remarkably, a significant tumor inhibition rate(78.5%) was observed in tumorbearing mice when treated with IR-BTGP plus 808 nm irradiation. Therefore, this work shows that IR-BTGP holds great promise as an NIR-II fluorescence imaging-guided PTT platform for CRC in the future.

关键词： photothermal therapy(PTT) second near-infrared(NIR-Ⅱ)imaging organic molecule

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Estimate pose deviation of on-orbit deployable mechanisms based on cross-ratio invariability

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Chinese Journal of Aeronautics 2024年第10期37卷 483-492页

作者： Peiran ZHANG Fuqiang ZHOU Zhipeng SONG Wentao GUO Haishu tan School of Instrumentation and Optoelectronic Engineering Beihang UniversityBeijing 100191China School of Physics and Optoelectronic Engineering Foshan UniversityFoshan 528225China

With the rapid development of space science projects,large deployable mechanisms have been widely ***,due to the effects of mechanical friction and gravitational acceleration,on-orbit mechanisms cannot be always deployed to the expected *** some precision optical mechanisms,even a minor deviation can result in significant error,so it needs to be measured and *** this paper,the deployment process was modeled and simplified as rotation under single-rotation-axis constraint and translation under single-direction *** solve the problem,a method based on cross-ratio invariability was *** proposed method does not rely on camera calibration techniques,as well as artificial marking points,both of which are necessary in ***,only three calibration images before launch and a measurement image on orbit were *** and experiments demonstrated that the proposed method is more accurate than *** addition,experiments also proved that the feasibility of the proposed method under dark conditions with the aid of a light source and some reflective marking points.

关键词： Cross-ratio invariability Deployable mechanism Pose deviation estimation Single-DOF constraint Vision measurement

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Three-dimensional numerical manifold method for heat conduction problems with a simplex integral on the boundary

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Science China(Technological Sciences) 2024年第4期67卷 1007-1022页

作者： TONG DeFu YI XiongWei tan Fei JIAO YuYong LIANG JiaWei Faculty of Engineering China University of GeoscienceWuhan 430074China Department of Civil Engineering Monash UniversityMelbourne VIC 3800Australia Badong National Observation and Research Station of Geohazards China University of GeoscienceWuhan 430074China

The three-dimensional numerical manifold method(3D-NMM),which is based on the derivation of Galerkin's variation,is a powerful calculation tool that uses two cover *** 3D-NMM can be used to handle continue-discontinue problems and extend to THM *** this study,we extended the 3D-NMM to simulate both steady-state and transient heat conduction *** modelling was carried out using the raster methods(RSM).For the system equation,a variational method was employed to drive the discrete equations,and the crucial boundary conditions were solved using the penalty *** solve the boundary integral problem,the face integral of scalar fields and two-dimensional simplex integration were used to accurately describe the integral on polygonal *** numerical examples were used to verify the results of 3D steady-state and transient heat-conduction *** numerical results indicated that the 3D-NMM is effective for handling 3D both steadystate and transient heat conduction problems with high solution accuracy.

关键词： three-dimensional numerical manifold method transient analysis heat conduction problem Galerkin variation simplex integration

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Surface roughness classification using light scattering matrix and deep learning

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Science China(Technological Sciences) 2024年第2期67卷 520-535页

作者： SUN Hao tan Wei RUAN YiXiao BAI Long XU JianFeng State Key Laboratory of Intelligent Manufacturing Equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China Wuhan Digital Design and Manufacturing Innovation Center Co. LtdWuhan 430074China

High-quality optical components have been widely used in various applications;thus,extremely high beam quality is ***,surface roughness is a key indicator of the surface *** this study,the angular distribution of light scattering field intensity was obtained for surfaces having different roughness profiles based on the finite difference time domain(FDTD)method,and the results were compared with those obtained using the generalized Harvey-Shack(GHS)*** was shown that the FDTD approach can be used for an accurate simulation of the scattered field of a rough surface,and the superposition of results obtained from many surfaces that have the same roughness level was in good agreement with the result given by the analytic GHS model.A light scattering matrix(LSM)method was proposed based on the FDTD simulation results that could obtain rich surface roughness *** classification effect of LSM was compared with that of the single-incidence scattering distribution(SISD)based on a ResNet-50 deep learning *** classification accuracy of the model trained with the LSM dataset was obtained as 95.74%,which was 23.40%higher than that trained using the SISD ***,the effects of different noise types and filtering methods on the classification performance were analyzed,and the LSM was also shown to improve the robustness and generalizability of the trained surface roughness ***,the proposed LSM method has important implications for improving the data acquisition scheme of current light scattering measurement systems,and it also has the potential to be used for detection and characterization of surface defects of optical components.

关键词： surface roughness FDTD simulation GHS theory deep learning light scattering matrix

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岩质隧道深浅埋划分方法及判别标准探讨

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现代隧道技术 2019年第1期56卷 14-21页

作者：邱陈瑜郑颖人张艳涛谭万鹏赵尚毅陆军勤务学院重庆401311 福建省闽武长城岩土工程有限公司福州350012 中建隧道建设有限公司重庆401147 空军工程大学西安710038

传统的深埋与浅埋隧道划分方法以普氏压力拱理论为基础,由于普氏理论的局限性,这种划分方法不尽合理。鉴于此,文章将有限元极限分析法应用于隧道深浅埋划分中,提出了隧道深浅埋划分的三条原则。对于Ⅳ级、Ⅴ级围岩的岩质隧道,根据隧道... 详细信息

传统的深埋与浅埋隧道划分方法以普氏压力拱理论为基础,由于普氏理论的局限性,这种划分方法不尽合理。鉴于此,文章将有限元极限分析法应用于隧道深浅埋划分中,提出了隧道深浅埋划分的三条原则。对于Ⅳ级、Ⅴ级围岩的岩质隧道,根据隧道的破坏模式划分深埋与浅埋,破裂面贯通至地表即为浅埋隧道,破裂面没有贯通至地表即为深埋隧道,并利用有限元强度折减法求出浅埋隧道压力拱高度,以此作为深浅埋分界线;对于围岩等级高的岩质隧道,以无衬砌隧道稳定安全系数来划分深浅埋,安全系数大于等于1.5时为深埋隧道,安全系数小于1.5时还要根据破坏模式进行深浅埋判断。此外,深浅埋隧道划分还应考虑环境、施工、地质构造、不稳定块体等因素的影响,由此可能造成围岩整体塌落,形成松散压力。最后,文章建议对于深埋隧道可按弹塑性数值分析计算,而对浅埋隧道除按弹塑性数值分析外,还需按浅埋松散荷载依据荷载-结构模式分析,以确保安全。

关键词：深埋隧道浅埋隧道划分标准普氏压力拱有限元强度折减法浅埋压力拱高度稳定安全系数

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Simulation of urban expansion using geographical similarity transition rules and neighbourhood sizes

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Journal of Geographical Sciences 2024年第7期34卷 1394-1414页

作者： LI Yinqi AN Yue ZHOU Zhou REN Hui tan Xuelan College of Resources Hunan Agricultural UniversityChangsha410128China College of Geographical Sciences Hunan Normal UniversityChangsha410081China

Most existing cellular automata(CA)models impose strict requirements on the number and spatial distribution of *** makes it a challenge to capture spatial heterogeneity in urban dynamics and meet the modeling needs of large and complex geographic *** paper presents a CA model based on geographically optimal similarity(GOS)transition rules and similarly sized neighborhoods(SSN).By comparing the similarity in geographical configuration between samples and predicted points,the model enables a comprehensive characterization of the driving mechanism behind urban expansion and its self-organizing *** helps to mitigate the impact of sample selection and assumptions about spatial stationarity on simulation *** performance of GOS-SSN-CA simulation was tested by taking the urban expansion in the Changsha-Zhuzhou-Xiangtan urban agglomeration in China as an *** results show that GOS can derive more accurate and reliable urban transition rules with fewer samples,thereby significantly reducing spatial prediction errors compared with logistic ***,SSN selects different neighborhood sizes to represent the difference between the local self-organizing range and surrounding cells,thus further improving the simulation accuracy and restricting urban expansion ***,GOS-SSN-CA effectively characterizes the geographical similarity of urban expansion,improves simulation accuracy while constraining the urban expansion form,and enhances the practical application value of CA.

关键词： urban growth cellular automata geographic similarity model optimization spatial nonstationarity

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A review of MXene-derived quantum dots:Synthesis,characterization,properties,and applications

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Particuology 2024年第8期91卷 50-71页

作者： Chunhe Zhou Kar Ban tan Wenjuan Han Li Wang Ming Lu The Joint Laboratory of MXene Materials Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of EducationJilin Normal UniversityChangchunJilin 130103China Department of Chemistry Faculty of ScienceUniversiti Putra MalaysiaSerdangSelangor 43400Malaysia

Cutting MXene to a minimum size and forming the derived two-dimensional MXene quantum dots(MQDs),which possess a unique intrinsic layered geometry structure,restricts exciton due to their novel spatial *** gives rise to a broad spectrum of fascinating properties,rendering them for various ***,the correlation between composition,structure,and processing control of MQDs is investigated systematically,giving further insight into the intrinsic and extrinsic *** review also provides an opportunity to explore new compositions,modify the properties,and tailor MQDs into the guided architectural design before any prospective applications.

关键词： MXene Quantum dots Characterization Properties Applications

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Review on laser directed energy deposited aluminum alloys

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International Journal of Extreme Manufacturing 2024年第2期6卷 84-131页

作者： Tian-Shu Liu Peng Chen Feng Qiu Hong-Yu Yang Nicholas tan Yew Jin Youxiang Chew Di Wang Ruidi Li Qi-Chuan Jiang Chaolin tan Singapore Institute of Manufacturing Technology(SIMTech) Agency for ScienceTechnology and Research(A∗STAR)5 Cleantech LoopSingapore 636732Singapore State Key Laboratory of Automotive Simulation and Control Jilin UniversityChangchun 130025People’s Republic of China Key Laboratory of Automobile Materials Ministry of Education and Department of Materials Science and EngineeringJilin UniversityChangchun 130025People’s Republic of China School of Mechanical&Automotive Engineering South China University of TechnologyGuangzhou 510640People’s Republic of China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083People’s Republic of China

Lightweight aluminum(Al)alloys have been widely used in frontier fields like aerospace and automotive industries,which attracts great interest in additive manufacturing(AM)to process high-value Al *** a mainstream AM technique,laser-directed energy deposition(LDED)shows good scalability to meet the requirements for large-format component manufacturing and ***,LDED Al alloys are highly challenging due to their inherent poor printability(*** laser absorption,high oxidation sensitivity and cracking tendency).To further promote the development of LDED high-performance Al alloys,this review offers a deep understanding of the challenges and strategies to improve printability in LDED Al *** porosity,cracking,distortion,inclusions,element evaporation and resultant inferior mechanical properties(worse than laser powder bed fusion)are the key challenges in LDED Al *** parameter optimizations,in-situ alloy design,reinforcing particle addition and field assistance are the efficient approaches to improving the printability and performance of LDED Al *** underlying correlations between processes,alloy innovation,characteristic microstructures,and achievable performances in LDED Al alloys are *** benchmark mechanical properties and primary strengthening mechanism of LDED Al alloys are *** review aims to provide a critical and in-depth evaluation of current progress in LDED Al *** opportunities and perspectives in LDED high-performance Al alloys are also outlined.

关键词： additive manufacturing laser directed energy deposition(LDED) aluminum alloys printability aluminum matrix composite auxiliary fields mechanical properties

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