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Cyclic shear behavior of en-echelon joints under constant normal stiffness conditions

Journal of Rock Mechanics and Geotechnical Engineering 2024年第9期16卷 3419-3436页

作者： Bin Wang Yujing Jiang Qiangyong Zhang Hongbin Chen Richeng liu Yuanchao Zhang Graduate School of Engineering Nagasaki UniversityNagasaki852-8521Japan Research Center of Geotechnical and Structural Engineering Shandong UniversityJi’nan250061China State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyXuzhou221116China College of Civil Engineering Fuzhou UniversityFuzhou350108China

To reveal the mechanism of shear failure of en-echelon joints under cyclic loading,such as during earthquakes,we conducted a series of cyclic shear tests of en-echelon joints under constant normal stiffness(CNS)*** analyzed the evolution of shear stress,normal stress,stress path,dilatancy characteristics,and friction coefficient and revealed the failure mechanisms of en-echelon joints at different *** results show that the cyclic shear behavior of the en-echelon joints is closely related to the joint angle,with the shear strength at a positive angle exceeding that at a negative angle during shear *** the number of cycles increases,the shear strength decreases rapidly,and the difference between the varying angles gradually *** occurs in the early shear cycles(1 and 2),while contraction is the main feature in later cycles(310).The friction coefficient decreases with the number of cycles and exhibits a more significant sensitivity to joint angles than shear *** joint angle determines the asperities on the rupture surfaces and the block size,and thus determines the subsequent shear failure mode(block crushing and asperity degradation).At positive angles,block size is more greater and asperities on the rupture surface are smaller than at nonpositive ***,the cyclic shear behavior is controlled by block crushing at positive angles and asperity degradation at negative angles.

关键词： En-echelon joint Cyclic shear tests Shear stress Normal displacement Constant normal stiffness(CNS)

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Analysis on influencing factors of detecting chemical oxygen demand in water by three-dimensional spectroscopy

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Optoelectronics Letters 2024年第1期20卷 42-47页

作者： ZHOU Kunpeng liu Zhiyang CONG Menglong MAN Shanxin Inner Mongolia Autonomous Region Joint Laboratory of Nuclear and Radiation Detection College of Physics and Electronic InformationInner Mongolia Minzu UniversityTongliao 028000China College of Information Engineering Jingzhou UniversityJingzhou 434000China Alxa League Meteorological Bureau Alxa 750300China

This paper focuses on the standard chemical oxygen demand(COD)liquid and studies the impact of pH,nitrite nitrogen,nitrate nitrogen,heavy metals,salinity,and other factors on fluorescence intensity and fluorescence peak positions during the detection of COD in water using fluorescence *** influence mechanisms of different environmental factors on fluorescence spectra are also *** indicate that pH value affects the fluorescence emission wavelength(Em),resulting in a red shift from 1.5 to 7.2,and a blue shift from 7.2 to *** nitrogen can react with organic matter in water to form nitro compounds,leading to a decrease in fluorescence *** has a negligible effect on T1 peak but a relatively large effect on T2 *** metal ion concentration has a significant impact on T2 peak,while T1 peak position shifts with an increase in heavy metal *** study aims to explore the factors that can impact the detection of COD in water using three-dimensional fluorescence spectrometry,providing references to improve accuracy and practicability for COD detection based on three-dimensional fluorescence spectrometry.

关键词： chemical negligible nitrate

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Intestinal flora: New perspective of type 2 diabetes

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World Journal of Clinical Cases 2024年第11期12卷 1996-1999页

作者： Yan liu Jun Chang Li-Ding Bai Department of Gastroenterology Hospital of Integrated Chinese and Western MedicineTianjinTianjin 300100China First Teaching Hospital of Tianjin University of Traditional Chinese Medicine Tianjin 300381China Academy of Traditional Chinese Medicine Tianjin University of Traditional Chinese MedicineTianjin 300193China

Diabetes comprises a group of metabolic diseases characterized by hyperglycemia stemming from various *** diabetes management primarily focuses on blood glucose control,yet it is inherently progressive,necessitating increased reliance on exogenous blood glucose control methods over ***,there is an urgent need to explore novel intervention strategies addressing both diabetes and its *** human intestinal microbiota,often referred to as the"second genome",exhibits significant diversity and plays a pivotal role in insulin resistance,glucose and lipid metabolism,and inflammatory ***,Li and Guo have elucidated the involvement of intestinal flora in the pathogenesis of type 2 diabetes mellitus(T2DM)and proposed a novel therapeutic approach targeting intestinal *** advancement enhances our comprehension of the multifaceted and multi-target regulation of T2DM by intestinal microflora,thereby offering fresh avenues for understanding its pathogenesis and clinical *** letter briefly summarizes the role of intestinal flora in T2DM based on findings from animal experiments and clinical ***,it discusses the potential clinical applications and challenges associated with targeting intestinal flora as therapeutic interventions.

关键词： Microbial metabolites Intestinal flora Probiotics Insulin resistance Type 2 diabetes

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Construction of an engineered Escherichia coli for effective synthesis of 2'-fucosyllactose via the salvage pathway

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Synthetic and Systems Biotechnology 2024年第1期9卷 108-114页

作者： Shanquan Liang Zi He Dan liu Shaoqing Yang Qiaojuan Yan zhengqiang Jiang College of Food Science and Nutritional Engineering China Agricultural UniversityBeijing100083China Food Laboratory of Zhongyuan Luohe462300HenanChina College of Engineering China Agricultural UniversityBeijing100083China

2'-Fucosyllactose(2'-FL)is one of the important functional oligosaccharides in breast *** far,few attempts on biosynthesis of 2'-FL by the salvage pathway have been ***,the salvage pathway enzyme genes were introduced into the *** BL21star(DE3)for synthesis of 2'-*** 2'-FL titer increased from 1.56 to 2.13 g/L by deleting several endogenous genes on competitive ***α-1,2-fucosyltransferase(WbgL)was selected,and improved the 2'-FL titer to 2.88 g/***,the expression level of pathway enzyme genes was tuned through optimizing the plasmid copy ***,the spatial distribution of WbgL was enhanced by fusing with the MinD *** optimizing the fermentation conditions,the 2'-FL titer reached to 7.13 g/*** final strain produced 59.22 g/L of 2'-FL with 95%molar conversion rate of lactose and 92% molar conversion rate of fucose in a 5 L *** findings will contribute to construct a highly efficient microbial cell factory to produce 2'-FL or other HMOs.

关键词： 2'-fucosyllactose Human milk oligosaccharides Escherichia coli Fed-batch fermentation Salvage pathway

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DGConv: A Novel Convolutional Neural Network Approach for Weld Seam Depth Image Detection

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Computers, Materials & Continua 2024年第2期78卷 1755-1771页

作者： Pengchao Li Fang Xu Jintao Wang Haibing Guo Mingmin liu zhenjun Du State Key Laboratory of Robotics Shenyang Institute of AutomationChinese Academy of SciencesShenyang110016China Institutes for Robotics and Intelligent Manufacturing Chinese Academy of SciencesShenyang110169China University of Chinese Academy of Sciences Beijing100049China Shenyang SIASUN Robot&Automation Co. Ltd.Shenyang110168China

We propose a novel image segmentation algorithm to tackle the challenge of limited recognition and segmentation performance in identifying welding seam images during robotic intelligent ***,to enhance the capability of deep neural networks in extracting geometric attributes from depth images,we developed a novel deep geometric convolution operator(DGConv).DGConv is utilized to construct a deep local geometric feature extraction module,facilitating a more comprehensive exploration of the intrinsic geometric information within depth ***,we integrate the newly proposed deep geometric feature module with the Fully Convolutional Network(FCN8)to establish a high-performance deep neural network algorithm tailored for depth image ***,we enhance the FCN8 detection head by separating the segmentation and classification *** enhancement significantly boosts the network’s overall detection ***,for a comprehensive assessment of our proposed algorithm and its applicability in real-world industrial settings,we curated a line-scan image dataset featuring weld *** dataset,named the Standardized Linear Depth Profile(SLDP)dataset,was collected from actual industrial sites where autonomous robots are in ***,we conducted experiments utilizing the SLDP dataset,achieving an average accuracy of 92.7%.Our proposed approach exhibited a remarkable performance improvement over the prior method on the identical ***,we have successfully deployed the proposed algorithm in genuine industrial environments,fulfilling the prerequisites of unmanned robot operations.

关键词： Weld image detection deep learning semantic segmentation depth map geometric feature extraction

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多相催化氧化伯醇制备羧酸的研究进展

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精细化工 2024年第7期41卷 1393-1403页

作者：薛飞刘梦力廖敏李臻夏春谷王金棒中国科学院兰州化学物理研究所羰基合成与选择氧化国家重点实验室甘肃兰州730000 江西省烟草公司赣州市公司江西赣州341000 中国烟草总公司郑州烟草研究院河南郑州450001

伯醇催化氧化制羧酸是有机合成中极为重要的转化过程,具有广泛的应用前景。对于多相催化体系,高效催化剂的制备一直是研究的热点和难点。该文对近年来涉及多相催化氧化伯醇制备羧酸的文献进行了全面的梳理。从单金属及其氧化物和双金属... 详细信息

伯醇催化氧化制羧酸是有机合成中极为重要的转化过程,具有广泛的应用前景。对于多相催化体系,高效催化剂的制备一直是研究的热点和难点。该文对近年来涉及多相催化氧化伯醇制备羧酸的文献进行了全面的梳理。从单金属及其氧化物和双金属及其氧化物基催化剂,以及是否采用载体等角度系统评估了伯醇氧化多相催化剂的发展现状和趋势;介绍了杂多酸催化和绿色催化的研究进展;展望了多相催化在工业应用中的发展前景和挑战。

关键词：伯醇催化氧化多相催化羧酸金属催化剂金属氧化物催化剂

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Unidirectional transport of both wettable and nonwettable liquids on an asymmetrically concave structured surface

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Fundamental Research 2024年第3期4卷 557-562页

作者： Zhongxue Tang Kang Luan Bojie Xu Huan liu Research Institute for Frontier Science School of PhysicsBeihang UniversityBeijing 100191China Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education School of ChemistryBeihang UniversityHaidian DistrictBeijing 100191China

Unidirectional liquid transport(UDLT)has been widely used in various fields as an important process for transferring both mass and ***,UDLT driven by a structural gradient has been witnessed for a long time only in wettable *** nonwettable liquids,UDLT can hardly proceed merely by a structural ***,we propose an asymmetrically concave structured surface(AMC-surface),featuring tip-to-base periodically arranged pyramid-shaped concave structures with a certain degree of overlap,which enables the UDLT of both wettable and nonwettable *** wettable liquids,the capillary force along each corner leads to the UDLT pointing toward the base side of the concave pyramid,while for nonwettable liquids,the UDLT is attributable to the static liquid pressure overwhelming the repulsive Laplace pressure induced by the asymmetric grooves and overlapping *** a result,both wettable and nonwettable liquids transport spontaneously and unidirectionally on the AMC-surface with no energy ***,the concave structure endows good mechanical stability and can be easily prepared using a facile nail-punching approach over a large *** also demonstrated its application in a continuous chemical reaction in a confined *** envision that the unique UDLT behavior on the as-developed AMC-surface will shed new light on the programmable manipulation of various liquids.

关键词： Unidirectional liquidtransport Asymmetrically concave structure Capillary force Laplace pressure Wettability

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Field testing of shear strength of granite residual soils

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第9期16卷 3718-3732页

作者： Song Yin Pengfei liu Xianwei Zhang Wenyuan He Pan Yan Yuzhou Sun School of Civil Engineering and Architecture Zhongyuan University of TechnologyZhengzhou450007China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China

The characteristics of residual soils are very different from those of sedimentary *** the strength characteristics of sedimentary soils have been studied extensively,the shear strength characteristics of granitic residual soils(GRS)subjected to the weathering of parent rocks have rarely been *** this study,the shear strength characteristics of GRS in the Taishan area of southeast China(TSGRS)were studied by field and laboratory *** field tests consisted of a cone penetration test(CPT),borehole shear test(BST),self-boring pressuremeter test(SBPT),and seismic dilatometer Marchetti test(SDMT).The shortcomings of laboratory testing are obvious,with potential disturbances arising through the sampling,transportation,and preparation of soil *** to the special structure of GRS samples and the ease of disturbance,the results obtained from laboratory tests were generally lower than those obtained from situ *** CPT and scanning electron microscopy(SEM)results indicated significant weathering and crustal hardening in the shallow *** resulted in significant differences in the strength and strength parameters of shallow soil obtained by the *** on the SDMT and SBPT results,a comprehensive evaluation method of shear strength for TSGRS was *** SBPT was suitable for evaluating the strength of shallow *** material index(ID)and horizontal stress index(KD)values obtained by the SDMT satisfied the empirical relationship proposed by Marchetti based on the ID index,and were therefore considered suitable for the evaluation of the shear strength of deep GRS.

关键词： Granite residual soils Shear strength Field tests Self-boring pressuremeter Seismic dilatometer Borehole shear test

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Dynamic Resistance and Energy Absorption of Sandwich Beam via a Micro-Topology Optimization

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Chinese Journal of Mechanical Engineering 2024年第4期37卷 146-162页

作者： Shiqiang Li Yuwei Li Xiaomin Ma Jianguang Fang Zhifang liu Zhihua Wang Institute of Applied Mechanics Taiyuan University of TechnologyTaiyuan 030024China Shanxi Key Laboratory of Material Strength and Structural Impact Taiyuan University of TechnologyTaiyuan 030024China School of Civil and Environmental Engineering University of Technology SydneySydneyNSW 2007Australia

The current research of sandwich structures under dynamic loading mainly focus on the response characteristic of *** micro-topology of core layers would sufficiently influence the property of sandwich ***,the micro deformation and topology mechanism of structural deformation and energy absorption are *** this paper,based on the bi-directional evolutionary structural optimization method and periodic base cell(PBC)technology,a topology optimization frame work is proposed to optimize the core layer of sandwich *** objective of the present optimization problem is to maximize shear stiffness of PBC with a volume *** effects of the volume fraction,filter radius,and initial PBC aspect ratio on the micro-topology of the core were *** dynamic response process,core compression,and energy absorption capacity of the sandwich beams under blast impact loading were analyzed by the finite element *** results demonstrated that the overpressure action stage was coupled with the core compression *** the same loading and mass per unit area,the sandwich beam with a 20%volume fraction core layer had the best blast *** filter radius has a slight effect on the shear stiffness and blast resistances of the sandwich *** increasing the filter radius could slightly improve the bending *** changing the initial PBC aspect ratio,there are three ways for PBC evolution:The first is to change the angle between the adjacent bars,the second is to further form holes in the bars,and the third is to combine the first two ***,not all three ways can improve the energy absorption capacity of the *** the aspect ratio of the PBC arbitrarily may lead to worse *** studies are necessary for further detailed *** research proposes a new topology sandwich beam structure by micro-topology optimization,which has sufficient shear *** micro mechanism of structural

关键词： Topology optimization Sandwich beam Impact loading Dynamic resistance Energy absorption Micro mechanism

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Audio-visual keyword transformer for unconstrained sentence-level keyword spotting

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CAAI Transactions on Intelligence Technology 2024年第1期9卷 142-152页

作者： Yidi Li Jiale Ren Yawei Wang Guoquan Wang Xia Li Hong liu Key Laboratory of Machine Perception Peking UniversityShenzhen Graduate SchoolShenzhenChina College of Electronics and Information Engineering Sichuan UniversityChengduChina Department of Computer Science ETH ZurichZurichSwitzerland

As one of the most effective methods to improve the accuracy and robustness of speech tasks,the audio-visual fusion approach has recently been introduced into the field of Keyword Spotting(KWS).However,existing audio-visual keyword spotting models are limited to detecting isolated words,while keyword spotting for unconstrained speech is still a challenging *** this end,an Audio-Visual Keyword Transformer(AVKT)network is proposed to spot keywords in unconstrained video *** authors present a transformer classifier with learnable CLS tokens to extract distinctive keyword features from the variable-length audio and visual *** outputs of audio and visual branches are combined in a decision fusion *** humans can easily notice whether a keyword appears in a sentence or not,our AVKT network can detect whether a video clip with a spoken sentence contains a pre-specified ***,the position of the keyword is localised in the attention map without additional position ***-imental results on the LRS2-KWS dataset and our newly collected PKU-KWS dataset show that the accuracy of AVKT exceeded 99%in clean scenes and 85%in extremely noisy *** code is available at https://***/jialeren/AVKT.

关键词： artificial intelligence multimodal approaches natural language processing neural network speech processing

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