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车致拱桥短吊杆弯曲效应及疲劳体系可靠性评估方法研究

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价值工程 2024年第3期43卷 143-145页

作者：肖新辉张智丰张海萍曹原湖南工业大学株洲412007

拱桥短吊杆疲劳脆断是引起桥梁垮塌的主要原因,吊杆中平行钢丝的体系失效机制尚不明确。为解决这一问题,本文采用瞬态分析法分析了车载作用下拱桥短吊杆的“弯拉”作用,研究了吊杆中平行高强钢丝的应力分布特征,讨论了平行钢丝的疲劳失... 详细信息

拱桥短吊杆疲劳脆断是引起桥梁垮塌的主要原因,吊杆中平行钢丝的体系失效机制尚不明确。为解决这一问题,本文采用瞬态分析法分析了车载作用下拱桥短吊杆的“弯拉”作用,研究了吊杆中平行高强钢丝的应力分布特征,讨论了平行钢丝的疲劳失效路径。研究表明:短吊杆疲劳破坏失效时弯曲受拉侧的高强丝应力最大,平行钢丝由受拉侧向受压侧进行疲劳断裂传递。以国内系杆拱桥芙蓉镇大桥为例,计算其短吊杆体系可靠指标,吊杆运营25年后其可靠度指标进入预警区间。

关键词：短吊杆系杆拱桥平行钢丝体系可靠性

维普期刊数据库博看期刊

Intermittent disturbance mechanical behavior and fractional deterioration mechanical model of rock under complex true triaxial stress paths

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International Journal of Mining Science and Technology 2024年第1期34卷 117-136页

作者： zhi Zheng Hongyu Xu Kai zhang Guangliang feng Qiang zhang Yufei Zhao State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures Key Laboratory of Disaster Prevention and Structural Safety of Ministry of EducationCollege of Civil Engineering and ArchitectureGuangxi UniversityNanning 530004China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower ResearchBeijing 100080China State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116China

Mechanical excavation,blasting,adjacent rockburst and fracture slip that occur during mining excavation impose dynamic loads on the rock mass,leading to further fracture of damaged surrounding rock in three-dimensional high-stress and even causing ***,a novel complex true triaxial static-dynamic combined loading method reflecting underground excavation damage and then frequent intermittent disturbance failure is *** triaxial static compression and intermittent disturbance tests are carried out on *** effects of intermediate principal stress and amplitude on the strength characteristics,deformation characteristics,failure characteristics,and precursors of monzogabbro are analyzed,intermediate principal stress and amplitude increase monzogabbro strength and tensile fracture *** increases in microseismic parameters during rock loading can be precursors for intermittent rock *** on the experimental result,the new damage fractional elements and method with considering crack initiation stress and crack unstable stress as initiation and acceleration condition of intermittent disturbance irreversible deformation are proposed.A novel three-dimensional disturbance fractional deterioration model considering the intermediate principal stress effect and intermittent disturbance damage effect is established,and the model predicted results align well with the experimental *** sensitivity of stress states and model parameters is further explored,and the intermittent disturbance behaviors at different f are *** study provides valuable theoretical bases for the stability analysis of deep mining engineering under dynamic loads.

关键词： True triaxial static and disturbance test Mechanical properties Failure mechanism and precursor Intermittent disturbance effect Fractional mechanical model

维普期刊数据库

Multi-scale hash encoding based neural geometry representation

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Computational Visual Media 2024年第3期10卷 453-470页

作者： zhi Deng Haoyao Xiao Yining Lang Hao feng Juyong zhang School of Mathematical Sciences University of Science and Technology of ChinaHefei 230026China Alibaba Artiﬁcial Intelligence Governance Laboratory Alibaba GroupHangzhou 310017China

Recently, neural implicit function-basedrepresentation has attracted more and more attention,and has been widely used to represent surfacesusing differentiable neural networks. However, surfacereconstruction from point clouds or multi-view imagesusing existing neural geometry representations stillsuffer from slow computation and poor accuracy. Toalleviate these issues, we propose a multi-scale hashencoding-based neural geometry representation whicheffectively and efficiently represents the surface asa signed distance ﬁeld. Our novel neural networkstructure carefully combines low-frequency Fourierposition encoding with multi-scale hash encoding. Theinitialization of the geometry network and geometryfeatures of the rendering module are accordinglyredesigned. Our experiments demonstrate that theproposed representation is at least 10 times faster forreconstructing point clouds with millions of *** also signiﬁcantly improves speed and accuracyof multi-view reconstruction. Our code and modelsare available at https://***/Dengzhi-USTC/Neural-Geometry-Reconstruction.

关键词： neural geometry representation hash encoding point cloud reconstruction multi-view reconstruction

Effect of lanthanum on inclusions in non-oriented electrical steel slabs

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Journal of Iron and Steel Research(International) 2024年第7期31卷 1680-1691页

作者： Qiang Ren zhi-yuan Hu Yun-xia Liu Wei-cheng zhang Zi-qi Gao Li-feng zhang School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004HebeiChina School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China Research and Development Department Shougang Zhixin Qian'an Electromagnetic Material Co.Ltd.Qian'an 064400HebeiChina School of Mechanical and Materials Engineering North China University of TechnologyBeijing 100144China

The effect of lanthanum on the characteristics of inclusions in the slab of non-oriented electrical steels was investigated through industrial trials and thermodynamic *** number,size,and chemical composition of inclusions in the surface,one-quarter of thickness and the center of slabs with and without lanthanum addition were statistically analyzed using an automatic inclusion analysis *** the lanthanum-free slab,inclusions were predominately ***_(2)O_(3),MgO,and AlN as well as a small number of Al_(2)O_(3)-MgO-CaO and *** number densities of oxide inclusions and AlN decreased from the surface to the center of the slab,which was ascribed to the difference in cooling intensity during the continuous *** the steel with lanthanum addition,inclusions were modified into LaAlO_(3) and La_(2)O_(2)S and gradually transformed into dual-phase MgO-La_(2)S3 with an increasing distance from the slab surface due to the reaction between the lanthanum-containing inclusion and the steel *** uneven distribution of oxide inclusions along the thickness of the slab was eliminated in the lanthanum-bearing slab because the dissolved oxygen was remarkably decreased by ***-bearing inclusions were more likely to agglomerate AlN by inducing the heterogeneous nucleation of AlN on their surface,while small-size ***_(2)O_(3) inclusions hardly showed a coarsening effect on the size of AlN.

关键词： Lanthanum-Inclusion Non-oriented electrical steel Aluminum nitride Heterogenous nucleation

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中药元宝草镇痛的代谢组学研究

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实验室检测 2024年第1期2卷 129-135页

作者：杨代晓申健张志烽梁旭霞梁晓艳广东省生物制品与药物研究所广州510440 广西中医药大学附属瑞康医院南宁530011

目的基于气相色谱-质谱(GC-MS)技术和偏最小二乘分析(PLS-DA)代谢组学方法,观察给予元宝草后小鼠血清代谢物组变化,并对镇痛机制进行初步解释。方法建立小鼠热板法以及醋酸扭体法两种镇痛模型,借助GC/MS对小鼠血清进行代谢物检测分析,... 详细信息

目的基于气相色谱-质谱(GC-MS)技术和偏最小二乘分析(PLS-DA)代谢组学方法,观察给予元宝草后小鼠血清代谢物组变化,并对镇痛机制进行初步解释。方法建立小鼠热板法以及醋酸扭体法两种镇痛模型,借助GC/MS对小鼠血清进行代谢物检测分析,收集数据后,采用PLS-DA方法对样品中内源性小分子代谢产物进行检测和分类处理。结果热板法镇痛实验表明阿司匹林组、元宝草组、中剂量组小鼠和模型组比较,在30 min和60 min时舔足时间均有极显著性差异(P<0.01),随着给药时间的延长,元宝草对痛症的抑制作用表现出不同的效果,推断与血药浓度的高低有关;和空白组相比,元宝草组小鼠的扭体次数有降低,差异显著(P<0.01),表明元宝草在一定程度上起到镇痛作用;小鼠血清代谢特征有显著差异,进一步筛选对数据分类存在较大影响的代谢通路,鉴别得到牛磺酸、谷胱甘肽、精氨酸和脯氨酸、抗坏血酸5代谢途径与疼痛的代谢情况有关。结论元宝草组在一定程度上可以逆转异常改变,具有镇痛作用。

关键词：元宝草镇痛代谢组学气相色谱-质谱(GC-MS)

维普期刊数据库

Prediction for permeability index of blast furnace based on VMD-PSO-BP model

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Journal of Iron and Steel Research(International) 2024年第3期31卷 573-583页

作者： Xiao-jie Liu Yu-jie zhang Xin Li zhi-feng zhang Hong-yang Li Ran Liu Shu-jun Chen School of Metallurgy and Energy North China University of Science and TechnologyTangshan 063210HebeiChina Chengde Branch HBIS Group Co.Ltd.Chengde 067000HebeiChina

The permeability index is one of the important production indicators to monitor the operation of blast *** is crucial to grasp the trends of changes in the new permeability index in *** the complex vibration spectrum of the permeability index,a prediction model of the permeability index based on the VMD-PSO-BP(variational mode decomposition-particle swarm optimization-back propagation)method was ***,the key factors that affect the permeability index of blast furnace were studied from multiple ***,the permeability index was divided into multiple sub-modes based on the difference of frequency bands by the VMD algorithm,and a PSO-BP prediction model was established for each ***,the prediction results of each sub-mode were summed to obtain the final *** results show that the composite prediction accuracy by using the VMD algorithm is 3%higher than that of the traditional prediction method,which has better applicability.

关键词： Big data-Blast furnace Air permeability Variational mode decomposition Particle swarm optimization Back propagation Model prediction

Metallurgy and Solidification Microstructure Control of Fusion-Based Additive Manufacturing Fabricated Metallic Alloys:A Review

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Acta Metallurgica Sinica(English Letters) 2024年第1期37卷 29-53页

作者： Qiang Li Xing-Ran Li Bai-Xin Dong Xiao-Long zhang Shi-Li Shu feng Qiu Lai-Chang zhang zhi-Hui zhang Key Laboratory of Bionic Engineering(Ministry of Education) and College of Bionic Science and EngineeringJilin UniversityChangchun130022China Institute of Structured and Architected Materials Liaoning Academy of MaterialsShenyang110167China Key Laboratory of Automobile Materials Ministry of Education and Department of Materials Science and EngineeringJilin UniversityChangchun130025China School of Mechanical and Aerospace Engineering Jilin UniversityChangchun130025China School of Engineering Edith Cowan University270 Joondalup DriveJoondalupPerthWA6027Australia

The metal-based additive manufacturing(AM),also referred to as metal 3D printing,has drawn particular interest because it enables direct creation,aided by computationally-directed path design,of intricate components with site-specific compositions and geometrical requirements as well as low buy-to-fly *** the last two decades,the objective of this revolutionary technology has been shifting from only“rapid prototyping”to advanced manufacturing of special high-end products or devices,which,in many aspects,outperform conventional manufacturing *** fusion-based AM,significant progress has been achieved in understanding the processing window of macroscopic scales,non-equilibrium metallurgy of mesoscale scales,and grain evolution of microscopic *** the versatile capacity of AM facilitates new avenues for discovering advanced materials and structures,their potential has still not been fully *** the unique non-equilibrium solidification during the AM process,coarse columnar grains with strong textures are usually developed along the build direction,which downgrades the mechanical *** push the limits of this digital manufacturing,this review attempts to provide in-depth and comprehensive overviews of the recent progress in understanding the evolution and control of the as-built microstructure that has been made recently and the challenges encountered during the AM process.

关键词： Additive manufacturing Temperature field Microstructure control Nanoparticles Functionally graded materials

Perforated gastric ulcer causing mediastinal emphysema: A case report

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World Journal of Clinical Cases 2024年第4期12卷 859-864页

作者： zhi-Cheng Dai Xun-Wu Gui feng-He Yang Hao-Yuan zhang Wen-feng zhang Department of General Surgery Mengcheng County First People's HospitalMengcheng 233500Anhui ProvinceChina Department of Medical Imaging Mengcheng County First People's HospitalMengcheng 233500Anhui ProvinceChina

BACKGROUND Mediastinal emphysema is a condition in which air enters the mediastinum between the connective tissue spaces within the pleura for a variety of *** can be spontaneous or secondary to chest trauma,esophageal perforation,medi-cally induced factors,*** common symptoms are chest pain,tightness in the chest,and respiratory *** mediastinal emphysema patients have mild symptoms,but severe mediastinal emphysema can cause respiratory and circulatory failure,resulting in serious *** SUMMARY A 75-year-old man,living alone,presented with sudden onset of severe epigastric pain with chest tightness after drinking *** to the remoteness of his residence and lack of neighbors,the patient was found by his nephew and brought to the hospital the next morning after the disease *** tomography(CT)showed free gas in the abdominal cavity,mediastinal emph-ysema,and subcutaneous *** gastrointestinal angiography showed that the esophageal mucosa was intact and the gastric antrum was ***,we chose to perform open gastric perforation repair on the patient under thoracic epidural anesthesia combined with intravenous *** operative incision of the muscle layer of the patient's abdominal wall was made,and a large amount of subperitoneal gas was *** a continued incision of the peritoneum revealed the presence of a perforation of approx-imately 0.5 cm in the gastric antrum,which we repaired after pathological ***,the patient received high-flow oxygen and cough *** CT was performed on the first and sixth postoperative days,and the mediastinal and subcutaneous gas was gradually *** After gastric perforation,a large amount of free gas in the abdominal cavity can reach the mediastinum through the loose connective tissue at the esophageal hiatus of the diaphragm,and upper gastrointestinal angiography can clarify the site of *** pat

关键词： Gastric ulcer Perforated Mediastinal emphysema Case report

Spatial Structure of Peer Networks and Academic Achievement Based on a Random Control Trial Experiment

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China & World Economy 2024年第3期32卷 67-97页

作者： Shilan feng Ya Tan zhi Wang Qinghua zhang School of Marxism Peking UniversityChina School of International Trade and Economics University of International Business and EconomicsChina China Center for Economic Studies Fudan Universityand Shanghai Institute of International Finance and EconomicsChina Guanghua School of Management Peking UniversityChina

This paper investigates whether changing the seating arrangement in a classroom can facilitate positive spillovers from top-performing students to others,using a field experiment conducted in a Chinese high *** study groups with balanced abilities,the treatment altered the spatial distribution by assigning the two top students to seats in the spatial center of each *** the reference groups where students were allowed to choose their own seating arrangements,the lowest performing were significantly less likely to sit next to a top student than they would be under a random *** results suggest that,in the treated groups,there could be enhanced academic spillovers from the top *** treatment especially benefited the two lowest performing students in science *** contrast,the treatment exerted negative effects on the test scores of the two middle-performing students,due to a disruption *** results suggest that the spatial layout of a peer network can have a significant impact on learning outcomes.

关键词： field experiment peer effects social interactions spatial structure test scores