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Lightweight Si_(3)N_(4)@SiO_(2. ceramic foam for thermal insulation and electromagnetic wave transparency

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Nano Research 2024年第5期17卷 4298-4306页

作者： Zongwei Tong Xiangjie Yan Yuexiang Wang Kexun Li weihai Ma China-Blarus Belt and Road Joint Laboratory on Electromagnetic Environment Effect the 33rd Research Institute of ChinaElectronics Technology Group CorporationTaiyuan 030032China Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education School of Material Science and EngineeringTianjin UniversityTianjin 300072China Department of Materials Science and Engineering Jinzhong UniversityJinzhong 030619China

Increasing porosity is one of the most direct ways to improve the thermal insulation and dielectric properties of *** now,many wet methods for preparing Si_(3)N_(4) ceramic foams usually face the problems of complex rheology,long period,and expensive cost,and the reported pore sizes of Si_(3)N_(4) ceramic foams are typically micron-grade,resulting in a lack of competitiveness in thermal insulation and wave-transparent *** this paper,the Si_(3)N_(4)@SiO_(2. ceramic foams were prepared using an efficient dry-method,which combined three processes of low temperature chemical vapor deposition(LTCVD),template,and isostatic *** method has the advantages of simple operation and short preparation period,and can realize near-net size molding and mass *** addition,the evolution mechanisms of honeycomb microstructure and composition of Si_(3)N_(4)@SiO_(2. ceramic foam during sintering were studied by chemical reaction *** as-prepared Si_(3)N_(4)@SiO_(2. ceramic foam possesses low density(0.377 g·cm^(-3)),high compressive strength(7.5 MPa),low thermal conductivity(0.0808 W·m^(-1)·K^(-1)),and excellent dielectric properties(ε2.tanδ<0.009)in the frequency range of 8-18 GHz,and its maximum working temperature in air can reach up to 1100℃.It will be recommended to be applied in the interlayer of Si_(3)N_(4) ceramic radome to improve its thermal insulation and electromagnetic wave transparency performances.

关键词： silicon nitride ceramic foam honeycomb microstructure dielectric properties thermal insulation

Application Analysis of Multiple Neurons Connected with Fast Inhibitory Synapses

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Journal of Bionic Engineering 2024年第4期21卷 1905-1918页

作者： Wen Duan weihai Chen Jianhua Wang Zhongcai Pei Jingmeng Liu Jianer Chen School of Automation Science and Electrical Engineering Beihang UniversityXueyuan RoadBeijing100191China Hangzhou Innovation Institute Beihang UniversityChuanghui StreetHangzhou310051ZhejiangChina School of Electrical Engineering and Automation Anhui UniversityAnhui230601ZhejiangChina Zhejiang Rehabilitation Medical Center Binsheng RoadHangzhou310052ZhejiangChina

Almost all living organisms exhibit autonomic oscillatory activities,which are primarily generated by the rhythmic activities of their neural *** nonlinear oscillator models have been proposed to elucidate these neural behaviors and subsequently applied to the domain of robot ***,the oscillation patterns generated by these models are often unpredictable and need to be obtained through parameter *** study introduces a mathematical model that can be used to analyze multiple neurons connected through fast inhibitory *** characteristic of this oscillator is that its stationary point is stable,but the location of the stationary point changes with the system *** through reasonable topology and threshold parameter selection can the oscillation be *** study analyzed the conditions for stable oscillation in two-neuron networks and three-neuron networks,and obtained the basic rules of the phase relationship of the oscillator network established by this *** addition,this study also introduces synchronization mechanisms into the model to enable it to be synchronized with the sensing ***,this study used these theories to establish a robot single leg joint angle generation *** experimental results showed that the simulated robot could achieve synchronization with human motion,and had better control effects compared to traditional oscillators.

关键词： Oscillator Phase trajectory Synaptic threshold Synchronization Motion generation

Design,Simulation and Kinematic Validation of a Hip Prosthetic Mechanism with a Multimotor Function

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Journal of Bionic Engineering 2024年第3期21卷 1321-1333页

作者： Majun Song Zhongyi Li Jingjing Jiang weihai Chen Sheng Guo Hao Zheng Lianzheng Niu Hangzhou Innovation Institute Beihang UniversityHangzhou310051China Hangzhou Huacheng Software Technology Co.Ltd. Hangzhou310051China School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing100044China

We previously developed a powered hip prosthetic mechanism with kinematic functions of hip flexion-extension and abduction-adduction,and its theoretical and simulation-based kinematics were *** internal-external hip rotation has a positive effect on the movements of human lower limbs according to medical research,we developed a novel hip prosthetic mechanism based on a previous hip prosthesis that possesses motion characteristics similar to those of a human bionic hip,and the motion characteristics of multiple Degrees-of-Freedom(DoFs)were analyzed after kinematic ***,a walking model of the human‒machine model was established,and the walking stability of an amputee,which reflects the rehabilitation effect,was explored while the hip prosthetic mechanism considered the internal-external rotation of the ***,a prototype and its verification platform were built,and kinematic validation of the hip prosthetic mechanism was carried *** results showed that the designed Parallel Mechanism(PM)possesses human-like motion characteristics similar to those of a human bionic hip and can be used as a hip ***,the existing motion characteristic of internal-external hip rotation can enhance the walking stability of an amputee via this hip prosthetic mechanism.

关键词： Hip prosthetic mechanism Parallel mechanism Walking stability Kinematic validation

High-Speed Rubbing Behavior of Abrasive Coating Coated on Titanium Alloy Blade Tips

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Acta Metallurgica Sinica(English Letters) 2024年第4期37卷 749-762页

作者： Wenshuang Gu Shuai Yang Shiyi Zhang Zhiliang Pei weihai Xue Deli Duan Jun Gong Chao Sun Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang110016China

In aero-engines, abrasive coatings are typically utilized to protect the blade tip from excessive wear caused by the harder abradable sealing coating and thereby improve the sealing performance of engines. Therefore, a Ni/cBN abrasive coating was prepared on titanium alloy using electrodeposition. The high-speed rubbing tests with a linear velocity of 350 m/s and different incursion rates were performed to investigate the effect of the Ni/cBN abrasive coating on the wear behavior against NiCrAl/diatomite seal coating. Results showed that melting wear and adhesive transfer occurred on the bare blades, causing the bare blade to suffer excessive wear. While the Ni/cBN abrasive coating exhibited superior wear resistance and cutting performance. The cBN grits pullout, the abrasion of Ni matrix and transfer of seal coating to the cBN grits were the main wear mechanism of the Ni/cBN abrasive coating. Additionally, it was found that the relationship between the incursion rate and high-speed rubbing behavior is quite different for the bare blade and Ni/cBN coating. The reason for the difference in wear behavior of bare blade and Ni/cBN coating at different incursion rates was discussed in detail.

关键词： Gas turbine sealing Abrasive coating High-speed rubbing Material transfer Abradable coating

Magmatic-tectonic response of the South China Craton to the Paleo-Pacific subduction during the Triassic:a new viewpoint based on Well NK-1

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Journal of Oceanology and Limnology 2024年第1期42卷 58-89页

作者： Chan WANG Hao LIU Gang LI Zhen SUN Tingting GONG Li MIAO Xiaowei ZHU Yunying ZHANG weihai XU Wen YAN Key Laboratory of Ocean and Marginal Sea Geology South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou) Guangzhou 511458China Key Laboratory of Tectonic Controlled Mineralization and Oil Reservoir of Ministry of Natural Resources Chengdu University of TechnologyChengdu 610059China School of Earth Sciences and Resources China University of Geosciences(Beijing)Beijing 100083China College of Earth Science Chengdu University of TechnologyChengdu 610059China University of Chinese Academy of Sciences Beijing 100049China

The Nansha Block(NB)is one of the blocks separated from the southern margin of the South China Craton(SCC)by the western Pacific subduction,which contains rich information of geodynamic and tectonic *** reveal the essence of western Paleo-Pacific subduction during the Triassic period,Well NK-1 in this block was selected for petrographic study,and published research data from other cooperative teams were compared.A double-cycle pattern of basic to neutral magmatic volcanism was established,and 36 lithological rhythmic layers and representative cryptoexplosive breccia facies and welded tuff bands were *** with a reanalysis of published geochronological data,geochemical elements,and isotope geochemistry,we found that the rock assemblages could be divided into an intermediate-acid dacite(DA)series(SiO_(2.>65%)and basaltic(BA)series(Co2.8.6±3.2.–(2.7.9±3.5)Ma).BA exhibits obvious calc-alkaline island-arc magmatic properties:(^(87)Sr/^(86)Sr)_i ratio ranging 0.70377–0.71118(average:0.70645),^(147)Sm/^(144)Nd ratio ranging 0.119–0.193(average:0.168),and chondrite-normalized rare earth element(REE)curves being flat,while DA exhibits remarkable characteristics of subducted island-arc andesitic magma:(^(87)Sr/^(86)Sr)_i ratio(0.70939–0.7112.;average:0.71035),εNd(t)value(-6.2.-4.8;average:-5.6)andε_(Hf)(t)value(-2.9–-1.7,average:-2.2.show obvious crust-mantle mixing *** and DA reveal typical characteristics of island-arc magma systems and typeⅡenriched mantle(EM-Ⅱ)*** magma was likely resulted from the process whereby the continental crust frontal accretionary wedge was driven by the Paleo-Pacific slab subduction into the deep and began to melt,resulting in a large amount of melt(fluid)joined the asthenosphere on the side of the continental *** contrast,DA magma was likely resulted from the process whereby the plate front was forced to bend with increasing subducti

关键词： Paleo-Pacific tectonic domain tectonic evolution rift volcanic rock Nansha Block South China Craton

维普期刊数据库

Wear-resistant Ag-MAX phase 3D interpenetrating-phase composites:Processing,structure,and properties

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Nano Research 2024年第2期17卷 806-819页

作者： Yu Guo Xi Xie Zengqian Liu Longchao Zhuo Jian Zhang Shaogang Wang Qiqiang Duan Qing Jia Dake Xu weihai Xue Deli Duan Filippo Berto Zhefeng Zhang Rui Yang Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China School of Materials Science and Engineering Xi’an University of TechnologyXi’an 710048China Electrobiomaterials Institute Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education)Northeastern UniversityShenyang 110819China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Department of Chemical Engineering Materials and EnvironmentSapienza University of RomeRoma 00185Italy

Electrical contact materials are generally Ag-or Cu-based composites and play a critical role in ensuring the reliability and efficiency of electrical equipments and electronic *** MAX(M is an early transition metal,A is an element from III or IV main groups,and X is carbon or/and nitrogen)phase ceramics display a unique combination of properties and may serve as an ideal reinforcement phase for electrical contact *** biological materials evolved in nature generally exhibit three-dimensional(3D)interpenetrating-phase architectures,which may offer useful inspiration for the architectural design of electrical contact ***,a series of bi-continuous Ag-Ti_(3)SiC_(2. MAX phase composites with high ceramic contents exceeding 50 vol.%and having micron-and ultrafine-scaled 3D interpenetrating-phase architectures,wherein both constituents were continuous and mutually interspersed,were exploited by pressureless infiltration of Ag melt into partially sintered Ti_(3)SiC_(2. *** mechanical and electrical properties as well as the friction and wear performance of the composites were investigated and revealed to be closely dependent on the ceramic contents and characteristic structural *** composites exhibited a good combination of properties with high hardness over 2.3 GPa,high flexural strength exceeding 530 MPa,decent fracture toughness over 10 MPa·m^(1/2.,and good wear resistance with low wear rate at an order of 10^(-5)mm^(3)/(N·m),which were much superior compared to the counterparts made by powder metallurgy *** particular,the hardness,electrical conductivity,strength,and fracture toughness of the composites demonstrated a simultaneous improvement as the structure was refined from micron-to ultrafine-scales at equivalent ceramic *** good combination of properties along with the facile processing route makes the Ag-Ti_(3)SiC_(2.3D interpenetrating-phase composites appealing for electrical contact applicatio

关键词： three-dimensional(3D)interpenetrating-phase architecture Ag-MAX(M=early transition metal A=element from III or IV main groups and X=carbon or/and nitrogen)phase composites melt infiltration electrical contact materials mechanical

当前美国共产主义运动评析——从美国革命共产党人党的成立说起

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当代世界社会主义问题 2024年第3期 69-78,166页

作者：余维海华中师范大学政治与国际关系学院广东省社会科学研究基地世界政党研究中心武汉430079

2.2.年美国革命共产党人党高调成立,成为美国共产主义运动的发展之“新现象”。美国革命共产党人党是当代托洛茨基主义的政党,是美国众多共产主义政党中的一员。系统研究该党的历史出场,有助于从整体上把握美国共产主义运动的新特征:在... 详细信息

2.2.年美国革命共产党人党高调成立,成为美国共产主义运动的发展之“新现象”。美国革命共产党人党是当代托洛茨基主义的政党,是美国众多共产主义政党中的一员。系统研究该党的历史出场,有助于从整体上把握美国共产主义运动的新特征:在影响力上,新冠疫情暴发后社会主义的吸引力和新因素在美国有所增长;在党的工作方式上,践行群众路线收效甚微,网络化“草根运动”成为“新宠”;在党的斗争特点上,激进化和革命化成为许多共产主义政党亮眼的标签;在党际关系上,同质政党较量与竞争更加激烈。美国革命共产党人党的成立表明美国共产主义运动仍在前行,但从整体态势和前景上看,制约美国共产主义运动发展的组合性障碍依然存在,美国共产主义运动在可以预见的未来还是难以形成破局之力。

关键词：美国革命共产党人党美国共产党美国共产主义运动

维普期刊数据库博看期刊

拔尖创新博士生的识别、选拔与培养——基于优秀学位论文作者群体画像研究

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教育发展研究 2024年第3期44卷 38-45页

作者：黄维海李树岳南京农业大学公共管理学院南京210095

通过人工神经网络技术识别优秀博士学位论文作者的共同、典型特征构建群体画像模型,是甄选具有拔尖创新潜质人才、服务有效教与学的新手段。基于1500份毕业博士样本,本研究构建出理工农医和人文社科优秀博士学位论文作者的群体画像,党... 详细信息

通过人工神经网络技术识别优秀博士学位论文作者的共同、典型特征构建群体画像模型,是甄选具有拔尖创新潜质人才、服务有效教与学的新手段。基于1500份毕业博士样本,本研究构建出理工农医和人文社科优秀博士学位论文作者的群体画像,党员身份、父母高学历、高学习投入、高能力素养、学科竞赛获奖或获得综合性奖励是两类群体画像的共有特征,体育锻炼习惯、前置学校双一流、实习实践的经历是人文社科类优秀学位论文作者画像的独有特征,较好的家庭经济水平、高课堂投入、高协作解决问题能力和学习能力则是理工农医类优秀学位论文作者画像的独有特征。基于画像模型的发现,选拔优秀博士生需要认识到党员身份、获奖的信号作用和家庭资本、高学习投入的支持作用,培养中要重视非认知能力与认知能力的统整融合,将课堂开设在广阔的大地上加强实践锻炼。

关键词：优秀博士学位论文群体画像拔尖创新人才培养人工神经网络

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Single-cell transcriptomic Atlas of aging macaque ocular outflow tissues

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Protein & Cell 2024年第8期15卷 594-611页

作者： Jian Wu Chaoye Wang Shuhui Sun Tianmin Ren Lijie Pan Hongyi Liu Simeng Hou Shen Wu Xuejing Yan Jingxue Zhang Xiaofang Zhao weihai Liu Sirui Zhu Shuwen Wei Chi Zhang Xu Jia Qi Zhang Ziyu Yu Yehong Zhuo Qi Zhao Chenlong Yang Ningli Wang Beijing Institute of Ophthalmology Beijing Tongren Eye CenterBeijing Tongren HospitalCapital Medical UniversityBeijing Key Laboratory of Ophthalmology and Visual SciencesBeijing 100730China State Key Laboratory of Ophthalmology Zhongshan Ophthalmic CenterSun Yat-sen UniversityGuangzhou 510060China State Key Laboratory of Oncology in South China Collaborative Innovation Center for Cancer MedicineSun Yat-sen University Cancer CenterGuangzhou 510060China State Key Laboratory of Membrane Biology Institute of ZoologyChinese Academy of SciencesBeijing 100101China Beijing Institute for Stem Cell and Regenerative Medicine Beijing 100101China Institute for Stem Cell and Regeneration Chinese Academy of SciencesBeijing 100101China Department of Neurosurgery Peking University Third HospitalCenter for Precision Neurosurgery and Oncology of Peking University Health Science CenterBeijing 100191China Spencer Center for Vision Research Byers Eye InstituteSchool of MedicineStanford UniversityPalo AltoCA 94304USA

The progressive degradation in the trabecular meshwork(TM)is related to age-related ocular diseases like primary open-angle ***,the molecular basis and biological significance of the aging process in TM have not been fully ***,we established a dynamic single-cell transcriptomic landscape of aged macaque TM,wherein we classified the outflow tissue into 12.cell subtypes and identified mitochondrial dysfunction as a prominent feature of TM ***,we divided TM cells into 13 clusters and performed an in-depth analysis on cluster O,which had the highest aging score and the most significant changes in cell proportions between the two ***,we found that the APOE gene was an important differentially expressed gene in cluster O during the aging process,highlighting the close relationship between cell migration and extracellular matrix regulation,and TM *** work further demonstrated that silencing the APOE gene could increase migration and reduce apoptosis by releasing the inhibition on the PI3K-AKT pathway and downregulating the expression of extracellular matrix components,thereby increasing the aqueous outflow rate and maintaining intraocular pressure within the normal *** work provides valuable insights for future clinical diagnosis and treatment of glaucoma.

关键词： single-cell transcriptomic atlas macaque trabecular meshwork ocular outflow tissue aging