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Experimental study on the size effect on the equation of state of concretes under shock loading

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Defence Technology（防务技术） 2024年第3期33卷 160-167页

作者： Mei Li Jian cui Yanchao Shi Baijian Tang Xin Chen Key Laboratory of Coast Civil Structural Safety of the Ministry of Education Tianjin UniversityTianjin 300072China School of Civil Engineering Suzhou University of Science and Technology1701 Binhe RoadSuzhou 215011JiangsuChina School of Civil Engineering Tianjin UniversityTianjin 300072China

Adopting the classical theory of hydrocodes,the constitutive relations of concretes are separated into an equation of state(EoS)which describes the volumetric behavior of concrete material and a strength model which depicts the shear properties of *** experiments on the EoS of concrete is always challenging due to the technical difficulties and equipment limitations,especially for the specimen size effect on the *** some researchers investigate the shock properties of concretes by fly-plate impact tests,the specimens used in their tests are usually in one *** this paper,the fly-plate impact tests on concrete specimens with different sizes are performed to investigate the size effect on the shock properties of concrete *** mechanical background of the size effect on the shock properties are revealed,which is related to the lateral rarefaction effect and the deviatoric stress produced in the *** to the tests results,the modified EoS considering the size effect on the shock properties of concrete are proposed,which the bulk modulus of concrete is unpredicted by up to 20% if size effects are not accounted for.

关键词： Concrete Equation of state Size effect Shock wave Fly-plate impact test

A Piezoelectrically Driven Microrobot Using a Novel Monolithic Spatial Parallel Mechanism as Its Hip Joint

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Journal of Bionic Engineering 2024年第2期21卷 803-820页

作者： Guangping Wu Ziyang Wang Jiaxin Zhao Feng cui Xinghan Cai National Key Laboratory of Advanced Micro and Nano Manufacture Technology Shanghai Jiao Tong UniversityShanghai200240China Department of Micro-Nano Electronics School of Electronic Information and Electrical EngineeringShanghai Jiao Tong UniversityShanghai200240China

Inspired by the fast,agile movements of insects,we present a 1.9 g,4.5 cm in length,piezoelectrically driven,quadrupedal *** microrobot uses a novel spatial parallel mechanism as its hip joint,which consists of two spatially orthogonal slider-crank *** mechanism maps two inputs of two independent actuators to the decoupled swing and lift outputs of a leg,and each leg can produce the closed trajectories in the sagittal plane necessary for robot ***,the kinematics of the transmission are analyzed,and the parameters of the flexure hinges are designed based on geometrical constraints and yield *** hip joints,legs and exoskeletons are integrated into a five-layer standard laminate for monolithic fabrication which is composed of two layers of carbon fiber,two layers of acrylic adhesive and a polyimide *** measured output force(15.97 mN)of each leg is enough to carry half of the robot’s weight,which is necessary for the robot to move *** has been proven that the robot can successfully perform forward and turning *** to the microrobot fabricated with discrete components,the monolithically fabricated microrobot is more capable of maintaining the original direction of locomotion when driven by a forward signal and has a greater speed,whose maximum speed is 25.05 cm/s.

关键词： Insect-like Crawling microrobot Piezoelectric drive Parallel mechanism Monolithic fabrication

Hot-exciton effects on exciton diffusion and circular polarization dynamics in a single PbI_(2)nanoflake

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Science China(Technological Sciences) 2024年第1期67卷 83-90页

作者： XU ChenYu WANG Lei cui Lin GAO BingRong WANG HaiYu State Key Laboratory of Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun 130012China

As one of the emerging two-dimensional lead halide materials,lead iodide(PbI_(2))nanosheets have proven to possess strong application potential in the fields of high-energy radiation detection and highly efficient perovskite solar ***,the underlying photophysical properties such as hot-exciton-related carrier dynamics remain unclear for PbI_(2)***,we report the exciton dynamics of a single PbI_(2)nanoflake prepared by an aqueous solution *** a three-dimensional(3D)diffusion model,we obtain the exciton annihilation radius and diffusion coefficient of a single PbI_(2)nanoflake under nonresonant and resonant excitation conditions of band-edge exciton *** initial exciton densities increase,we find the carrier recombination mechanism for a single PbI_(2)nanoflake gradually changes from exciton-exciton annihilation to free-carrier ***,we reveal the room-temperature circular polarization of a single PbI_(2)nanoflake is due to free-carrier recombination with a band-edge exciton dissociation time of~120 fs under the resonant excitation condition.

关键词： single PbI_(2)nanoflake exciton diffusion room-temperature circular polarization ultrafast spectroscopy

Dynamic Characteristics of Functionally Graded Timoshenko Beams by Improved Differential Quadrature Method

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 1647-1668页

作者： Xiaojun Huang Liaojun Zhang Hanbo cui Gaoxing Hu School of Architecture and Civil Engineering Anhui Polytechnic UniversityWuhu241000China College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing210098China

This study proposes an effective method to enhance the accuracy of the Differential Quadrature Method(DQM)for calculating the dynamic characteristics of functionally graded beams by improving the form of discrete node ***,based on the first-order shear deformation theory,the governing equation of free vibration of a functionally graded beam is transformed into the eigenvalue problem of ordinary differential equations with respect to beam axial displacement,transverse displacement,and cross-sectional rotation angle by considering the effects of shear deformation and rotational inertia of the beam ***,ignoring the shear deformation of the beam section and only considering the effect of the rotational inertia of the section,the governing equation of the beam is transformed into the eigenvalue problem of ordinary differential equations with respect to beam transverse *** on the differential quadrature method theory,the eigenvalue problem of ordinary differential equations is transformed into the eigenvalue problem of standard generalized algebraic ***,the first several natural frequencies of the beam can be *** feasibility and accuracy of the improved DQM are verified using the finite element method(FEM)and combined with the results of relevant literature.

关键词： Timoshenko beams functionally graded materials dynamic characteristics natural frequency improved differential quadrature method

Damage Characteristics Analysis and Fractal Study of Shale With Prefabricated Fractures under Thermal-mechanical Coupling

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Journal of Wuhan University of Technology(Materials Science) 2024年第3期39卷 570-586页

作者：张辉邬忠虎 SONG Huailei WANG Wentao TANG Motian cui Hengtao College of Civil Engineering Guizhou UniversityGuiyang 550025China

To study the damage and failure of shale with different fracture inclination angles under uniaxial compression loading,in this work,RFPA2D-Thermal,a two-dimensional real failure process analysis software,was used for numerical *** simulation results show that quartz in shale mainly affects the tensile and compressive strength of shale by increasing rock *** coupling of temperature and pressure will cause lateral and volume destruction of shale,which enables the shale body to be more easily *** inclination is the key factor affecting shale damage *** failure mode of shale with low-and high-angle fractures is mainly shear failure,and the compressive strength does not vary with crack *** damage mode of obliquely intersecting fractured shale is slip damage along the fracture face,the compressive strength decreases and then increases with the fracture inclination,and a minimum value *** acoustic emission simulation results of the damage process effectively reflect the accumulated internal damage and macroscopic crack appearance until fracture instability when the prefabricated fractured shale is subjected to uniaxial compressive *** crack inclinations of 0°and 120℃ corresponds to the most complex"N"shape damage *** crack inclinations of 30°and 60°,and the damage mode is an inverted"λ"shape.

关键词： shale temperature and pressure numerical simulation fracture dip angle fractal dimension

The impact of Internet access on household dietary quality:Evidence from rural China

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Journal of Integrative Agriculture 2024年第2期23卷 374-383页

作者： Yi cui Qiran Zhao Thomas Glauben Wei Si College of Economics and Management China Agricultural UniversityBeijing 100083China Academy of Global Food Economics and Policy China Agricultural UniversityBeijing 100083China Leibniz Institute of Agricultural Development in Transition Economies(IAMO) Halle(Saale)06120Germany

Over the past few decades,the Internet has rapidly diffused across *** spread of the Internet has had a profound economic and social impact on Chinese rural *** research shows that Internet access significantly impacts agricultural production and improves smallholder farmers’*** these,the Internet can affect other dimensions of social ***,research about the impact of Internet access on dietary quality in rural China remains *** study utilizes multi-period panel data from Fixed Observation Point in rural China from 2009 to 2015 to estimate the impact of Internet access on dietary quality and food consumption of rural households and conducts a causal *** models with time and household fixed effects allow robust estimation while reducing potential issues of unobserved *** estimates show that Internet access has significantly increased rural household dietary quality(measured by the Chinese Diet Balance Index).Further research finds that Internet access has increased the consumption of animal products,such as aquatic and dairy *** also examine the underlying *** access improves dietary quality and food consumption mainly through increasing household income and food *** results encourage the promotion of Internet access as a valuable tool for nutritional improvements,especially in rural areas.

关键词： dietary quality fixed effect model Internet access rural China

A Joint Entity Relation Extraction Model Based on Relation Semantic Template Automatically Constructed

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Computers, Materials & Continua 2024年第1期78卷 975-997页

作者： Wei Liu Meijuan Yin Jialong Zhang Lunchong cui Key Laboratory of Cyberspace Situation Awareness of Henan Province Zhengzhou450001China

The joint entity relation extraction model which integrates the semantic information of relation is favored by relevant researchers because of its effectiveness in solving the overlapping of entities,and the method of defining the semantic template of relation manually is particularly prominent in the extraction effect because it can obtain the deep semantic information of ***,this method has some problems,such as relying on expert experience and poor *** by the rule-based entity relation extraction method,this paper proposes a joint entity relation extraction model based on a relation semantic template automatically constructed,which is abbreviated as *** model refines the extraction rules of relation semantic templates from relation corpus through dependency parsing and realizes the automatic construction of relation semantic *** on the relation semantic template,the process of relation classification and triplet extraction is constrained,and finally,the entity relation triplet is *** experimental results on the three major Chinese datasets of DuIE,SanWen,and FinRE showthat the RSTAC model successfully obtains rich deep semantics of relation,improves the extraction effect of entity relation triples,and the F1 scores are increased by an average of 0.96% compared with classical joint extraction models such as CasRel,TPLinker,and RFBFN.

关键词： Natural language processing deep learning information extraction relation extraction relation semantic template

Transient features of graphitization and nitrogen-vacancy color centers in a diamond fabricated by localization femtosecond laser direct writing

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Science China Technological Sciences 2024年第8期67卷 2530-2536页

作者： cui Lin YIN SiYu HU ZiFan WANG Lei State Key Laboratory of Integrated Optoelectronics College of Electronic Science and Engineering Jilin University

Femtosecond laser direct writing provides an efficient approach to fabricating single nitrogen vacancy(NV) color centers with a relatively high yield. Different from previously reported NV color centers with a random distribution in a bulk diamond or nanocrystals, this gives an opportunity to study the photophysical properties of single NV color centers with precise numbers and positions. However, ultrafast studies on single NV color centers prepared by localization femtosecond laser direct writing are still rare, especially for the graphitization inside a diamond and its relationship with single NV color centers. Here, we report the broadband transient absorption(TA) spectroscopic features of the graphitization and NV color centers in a diamond fabricated by localization femtosecond laser direct writing at room temperature under 400 nm excitation. In comparison with the graphene oxide film, the bleaching features of the graphitization point array in a diamond are similar to reduced graphene oxide,accompanied by excited state absorption signals from local carbon atom vacancy defects in graphene-like structures induced by laser writing. On the other hand, transient features of laser processing array containing single NV color centers with a yield of～50% are different from those of the graphitization point array. Our findings suggest that for ultrashort pulse processing of diamonds, broadband TA spectral signals are sensitive to the surrounding atomic environment of processing sites, which could be applied to laser writing point defects in other materials used as solid-state single photon sources.

关键词： nitrogen-vacancy color center graphitization diamond femtosecond laser direct writing ultrafast spectroscopy

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Discriminatively Constrained Semi-Supervised Multi-View Nonnegative Matrix Factorization with Graph Regularization

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Big Data Mining and Analytics 2024年第1期7卷 55-74页

作者： Guosheng cui Ye Li Jianzhong Li Jianping Fan Shenzhen Institute of Advanced Technology Chinese Academy of SciencesShenzhen 518055China Joint Engineering Research Center for Health Big Data Intelligent Analysis Technology Shenzhen 518055China University of Chinese Academy of Sciences Beijing 100049China School of Computer Science and Control Engineering Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China

Nonnegative Matrix Factorization(NMF)is one of the most popular feature learning technologies in the field of machine learning and pattern *** has been widely used and studied in the multi-view clustering tasks because of its *** study proposes a general semi-supervised multi-view nonnegative matrix factorization *** algorithm incorporates discriminative and geometric information on data to learn a better-fused representation,and adopts a feature normalizing strategy to align the different *** specific implementations of this algorithm are developed to validate the effectiveness of the proposed framework:Graph regularization based Discriminatively Constrained Multi-View Nonnegative Matrix Factorization(GDCMVNMF)and Extended Multi-View Constrained Nonnegative Matrix Factorization(ExMVCNMF).The intrinsic connection between these two specific implementations is discussed,and the optimization based on multiply update rules is *** on six datasets show that the effectiveness of GDCMVNMF and ExMVCNMF outperforms several representative unsupervised and semi-supervised multi-view NMF approaches.

关键词： multi-view semi-supervised clustering discriminative information geometric information feature normalizing strategy