检索结果-南通市图书馆

A low-frequency and broadband wave-insulating vibration isolator based on plate-shaped metastructures

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2024年第7期45卷 1171-1188页

作者： Wei WEI feng GUAN Xin fang College of Intelligent Science National University of Defense TechnologyChangsha410073China Naval Research Academy Beijing100161China

A metamaterial vibration isolator,termed as wave-insulating isolator,is proposed,which preserves enough load-bearing capability and offers ultra-low and broad bandgaps for greatly enhanced wave *** consists of plate-shaped metacells,whose symmetric and antisymmetric local resonant modes offer several low and broad mode bandgaps although the complete bandgap remains high and *** bandgap mechanisms,vibration isolation properties,effects of key parameters,and robustness to complex conditions are *** experimentally demonstrated,the wave-insulating isolator can improve the vibration insulation in the ranges of[50 Hz,180 Hz]and[260 Hz,400 Hz]by 15 dB and 25 dB,respectively,in contrast to the conventional isolator with the same first resonant frequency.

关键词： metamaterial and metastructure vibration isolation bandgap wave insulation plate

Enantioselective Synthesis of Benzimidazole Atropisomers Featuring a N-N Axis

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2024年第7期42卷 711-718页

作者： fang-Bei Ge Qi-Kun Yin Chuan-jun Lu Xuan Xuan Jia feng Ren-Rong Liu College of Chemistry and Chemical Engineering Qingdao UniversityQingdaoShandong 266071China School of Pharmacy Key Laboratory of Molecular Pharmacology and Drug EvaluationMinistry of EducationYantai UniversityYantaiShandong 264005China

Atroposelective synthesis of N-N atropisomers is an emerging area but remains underexplored;in particular,the synthesis of N-N benzimidazole atropisomers is still ***,the first enantioselective synthesis of N-N benzimidazole atropisomers via the palladium-catalyzed de novo construction of benzimidazole skeleton is *** readily available palladium catalyst and biphosphine ligand,a broad range of nonbiaryl benzimidazole and indole-benzimidazole atropisomers were conveniently ac-cessed in high yields and with excellent ***,these N-N benzimidazole atropisomers showed great anti-tumor activity and selectivity to breast cancer MCF-7 *** simple catalytic system,broad substrate scope,high enantioselectivi-ty,and good bioactivity make this approach highly attractive.

关键词： Asymmetric synthesis Atropisomerism Palladium Benzimidazole Antitumor

A disk I/O optimized system for concurrent graph processing jobs

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2024年第3期18卷 13-29页

作者： Xianghao XU fang WANG Hong JIANG Yongli CHENG Dan feng Peng fang School of Computer Science and Engineering Nanjing University of Science and TechnologyNanjing 210094China Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China Department of Computer Science&Engineering University of Texas at ArlingtonArlingtonTX 76019USA College of Computer and Data Science Fuzhou UniversityFuzhou 350108China Zhejiang Lab Hangzhou 311121China

In order to analyze and process the large graphs with high cost efficiency,researchers have developed a number of out-of-core graph processing systems in recent years based on just one commodity *** the other hand,with the rapidly growing need of analyzing graphs in the real-world,graph processing systems have to efficiently handle massive concurrent graph processing(CGP)***,due to the inherent design for single graph processing job,existing out-of-core graph processing systems usually incur unnecessary data accesses and severe competition of I/O bandwidth when handling the CGP *** this paper,we propose GraphCP,a disk I/O optimized out-of-core graph processing system that efficiently supports the processing of CGP *** proposes a benefit-aware sharing execution model to share the I/O access and processing of graph data among the CGP jobs and adaptively schedule the graph data loading based on the states of vertices,which efficiently overcomes above challenges faced by existing out-of-core graph processing ***,GraphCP adopts a dependency-based future-vertex updating model so as to reduce disk I/Os in the future *** addition,GraphCP organizes the graph data with a Source-Sorted Sub-Block graph representation for better processing capacity and I/O access *** evaluation results show that GraphCP is 20.5×and 8.9×faster than two out-of-core graph processing systems GridGraph and GraphZ,and 3.5×and 1.7×faster than two state-of-art concurrent graph processing systems Seraph and GraphSO.

关键词： graph processing disk I/O concurrent jobs

Recent Advances in Deciphering the Mechanisms and Biological Functions of DNA Demethylation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2024年第6期42卷 645-651页

作者： Yang feng Sheng-jun Chen Bi-feng Yuan Key Laboratory of Aquatic Product Processing Ministry of Agriculture and Rural AffairsNational R&D Center for Aquatic Product ProcessingSouth China Sea Fisheries Research InstituteChinese Academy of Fishery SciencesGuangzhouGuangdong510300 China School of Public Health Research Center of Public HealthRenmin Hospital of Wuhan UniversityWuhan UniversityWuhanHubei430071 China

5-Methylcytosine (5mC) is a dynamic and reversible epigenetic modification in genomic DNA of higher *** has been well-established that the demethylation of 5mC occurs through the ten-eleven translocation (TET)-mediated oxidation of 5mC followed by thymine DNA glycosylase (TDG)-initiated base excision repair (BER).Recent findings also have identified an alternative pathway of DNA *** this pathway,TET enzymes directly oxidize 5mC to form 5-formylcytosine (5fC) or 5-carboxylcytosine (5caC).These modified bases can undergo direct deformylation or decarboxylation,***,DNA demethylation can also occur through the deamination of 5mC and 5hmC,resulting in the production of thymine and 5-hydroxymethyluracil (5hmU),*** DNA demethylation pathways possess critical functional implications and roles in biological *** Recent Advances article will focus on the studies of mechanisms and biological functions of DNA demethylation,shedding light on the reversible nature of the epigenetic modification of 5mC.

关键词： Epigenetics DNA DNA methylation 5-Methylcytosine Demethylation Mechanisms Biological functions C—C bond cleavage Mass spectrometry

Self-Triggered Set Stabilization of Boolean Control Networks and Its Applications

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2024年第7期11卷 1631-1642页

作者： Rong Zhao jun-e feng Dawei Zhang the School of Mathematics Shandong UniversityShandong UniversityJinan 250100China

Set stabilization is one of the essential problems in engineering systems, and self-triggered control(STC) can save the storage space for interactive information, and can be successfully applied in networked control systems with limited communication resources. In this study, the set stabilization problem and STC design of Boolean control networks are investigated via the semi-tensor product technique. On the one hand, the largest control invariant subset is calculated in terms of the strongly connected components of the state transition graph, by which a graph-theoretical condition for set stabilization is derived. On the other hand, a characteristic function is exploited to determine the triggering mechanism and feasible controls. Based on this, the minimum-time and minimum-triggering open-loop, state-feedback and output-feedback STCs for set stabilization are designed,respectively. As classic applications of self-triggered set stabilization, self-triggered synchronization, self-triggered output tracking and self-triggered output regulation are discussed as well. Additionally, several practical examples are given to illustrate the effectiveness of theoretical results.

关键词： Boolean control networks(BCNs) output regulation self-triggered control semi-tensor product of matrices set stabilization synchronization

Total flavonoids of Astragalus membranaceus protect against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced neurotoxicity in mice by inhibiting ferroptosis through SLC7A11/GPX-4 signaling pathway

在线全文

学校读者我要写书评

暂无评论

Food Science and Human Wellness 2024年第1期13卷 414-420页

作者： Zitian Gao Gaorui Wang Yujie Chen Wuke Yuan jun Cai Aiping feng Jie fang Qi Xu Xiaojun Wu School of Public Health Shanghai University of Traditional Chinese MedicineShanghai 201203China Shanghai Key Laboratory of Compound Chinese Medicines The Ministry of Education(MOE)Key Laboratory for Standardization of Chinese MedicineInstitute of Chinese Materia MedicaShanghai University of Traditional Chinese MedicineShanghai 201203China Longhua Hospital affiliated to Shanghai University of Traditional Chinese Medicine Shanghai University of Traditional Chinese MedicineShanghai 201203China

Parkinson’s disease(PD)is a common neurodegenerative disorder with no *** membranaceus is used in Chinese culture as a food supplement to boost *** present study aimed to explore the neuroprotective effects of total flavonoids extracted from ***(TFA)and their protective *** offered neuroprotection against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP)in the mouse model of Parkinsonism,by improving behavior performance in the gait analysis and pole test,and inhibiting the decline of tyrosine hydroxylase(TH)positive neurons and TH protein expression in substantia nigra of *** also prevented 1-methyl-4-phenylpyridinium(MPP+)induced neurotoxicity in SHSY5Y cells,by increasing GSH and GSH/GSSG ratio,and reducing reactive oxygen *** addition,the neuroprotective effects of TFA were associated with its ability to restore MPTP/MPP+induced downregulation of SLC7A11 and glutathione peroxidase 4(GPX-4).In conclusion,we demonstrated that TFA exerted significant neuroprotection against MPTP/MPP+induced neurodegeneration by inhibiting ferroptosis through the regulation of SLC7A11/GPX-4 axis,suggesting the use of TFA as a possible food supplement in the prevention of PD.

关键词： Parkinson’s disease Total fl avonoids of Astragalus membranaceus Ferroptosis SLC7A11

Grain size effect on the assembly quality of micro-scaled barrel formed by microforming

在线全文

学校读者我要写书评

暂无评论

Advances in Manufacturing 2024年第1期12卷 19-32页

作者： Dien Hu Jieyichen fang feng Zeng Ming-Wang Fu Department of Mechanical Engineering Research Institute of Advanced ManufacturingThe Hong Kong Polytechnic UniversityHung HomKowloonHong KongPeople’s Republic of China Xiamen Yulong Machinery Co.Ltd. Xiamen361023FujianPeople’s Republic of China

In this research,a method employing micro-extrusion was designed to produce the micro-scaled barrel-shaped parts with complex geometrical features to study the feasibility of the proposed microforming method and its grain size effect on the formability of the complicated internal features in terms of deformation behavior,material evolution,accuracy of dimensions and final components *** results reveal that the deformation behavior is highly affected by grain size and becomes unpredictable with increased grain *** addition,assembly parameters including feature dimension,tolerance and coaxiality also vary with grain size,and the variation of grain size needs to be accommodated by different assembly types,viz.,clearance fit or transition *** the microstructural evolution aspect,it was identified there were two dead zones and four shear bands,and the formation of these deformation zones was barely affected by the variation in grain *** bulges,cracks,and fracture induced voids were observed on the surface of the final components,tailoring the microstructure of the working material with finer grains could significantly avoid these *** study advances the understanding of forming microparts by extrusion processes and provides guidance for microforming of similar microparts.

关键词： Microformed part Size effect Extrusion Microstructural evolution Dimensions Assembly accuracy

Effects of retained dry material on the impact,overflow and landing dynamics

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2024年第9期16卷 3629-3640页

作者： jun fang Yifei Cui Haiming Liu State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijingChina Department of Civil and Environmental Engineering The Hong Kong University of Science and TechnologyHong KongChina

During long-term operation,the performance of obstacles would be changed due to the material accumulating upslope the ***,the effects of retained material on impact,overflow and landing dynamics of granular flow have not yet been *** address this gap,physical flume tests and discrete element simulations are conducted considering a range of normalized deposition height h0/H from 0 to 1,where h0 and H represent the deposition height and obstacle height,*** analytical model is modified to evaluate the flow velocity and flow depth after interacting with the retained materials,which further serve to calculate the peak impact force on the ***,the computed impact forces successfully predict the experimental results when a≥25°.In addition,the results indicate that a higher h0/H leads to a lower dynamic impact force,a greater landing distance L,and a larger landing coefficient Cr,where Cr is the ratio of slope-parallel component of landing velocity to flow velocity just before *** to the existing overflow model,the measured landing distance L is underestimated by up to 30%,and therefore it is insufficient for obstacle design when there is retained ***,the recommended Cr in current design practice is found to be nonconservative for estimating the landing velocity of geophysical *** study provides insightful scientific basis for designing obstacles with deposition.

关键词： Granular flow Obstacle deposition Impact Overflow Landing

Unstructured Road Extraction in UAV Images based on Lightweight Model

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2024年第2期37卷 372-384页

作者： Di Zhang Qichao An Xiaoxue feng Ronghua Liu jun Han feng Pan School of Automation Beijing Institute of TechnologyBeijing 100081China Tianjin Institute of Maritime Navigation Instruments Tianjin 300130China The 716th Research Institute of China Shipbuilding Group Co. LtdJiangsu 222061China

There is no unified planning standard for unstructured roads,and the morphological structures of these roads are complex and *** is important to maintain a balance between accuracy and speed for unstructured road extraction *** road extraction algorithms based on deep learning have problems such as high model complexity,high computational cost,and the inability to adapt to current edge computing ***,it is best to use lightweight network *** the need for lightweight models and the characteristics of unstructured roads with different pattern shapes,such as blocks and strips,a TMB(Triple Multi-Block)feature extraction module is proposed,and the overall structure of the TMBNet network is *** TMB module was compared with SS-nbt,Non-bottleneck-1D,and other modules via *** feasibility and effectiveness of the TMB module design were proven through experiments and *** comparison experiment,using multiple convolution kernel categories,proved that the TMB module can improve the segmentation accuracy of the *** comparison with different semantic segmentation networks demonstrates that the TMBNet network has advantages in terms of unstructured road extraction.

关键词： Unstructured road Lightweight model Triple Multi-Block(TMB) Semantic segmentation net