检索结果-南通市图书馆

Microstructure evolution,mechanical properties and fracture behavior of Al-xSi/AZ91D bimetallic composites prepared by a compound casting

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 Magnesium and Alloys 2024年第5期12卷 1944-1964页

作者： Guangyu li Wenming Jiang Feng Guan Junwen Zhu Yang Yu Zitian fan State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

In this paper,the effect of the Si content on microstructure evolution,mechanical properties,and fracture behavior of the Al-xSi/AZ91D bimetallic composites prepared by compound casting was investigated *** obtained results showed that all the Al-xSi/AZ91D bimetallic composites had a metallurgical reaction layer(MRL),whose thickness increased with increasing Si content for the hypoeutectic Al-Si/AZ91D composites,while the hypereutectic Al-Si/AZ91D composites were *** MRL included eutectic layer(E layer),intermetallic compound layer(IMC layer)and transition region layer(T layer).In the IMC layer,the hypereutectic Al-Si/AZ91D composites contained some Si solid solution and flocculent Mg_(2)Si+Al-Mg IMCs phases not presented in the hypoeutectic Al-Si/AZ91D ***,increasing Si content,the thickness proportion of the T layer increased,forming an inconsistent preferred orientation of the *** shear strengths of the Al-xSi/AZ91D bimetallic composites enhanced with increasing Si content,and the Al-15Si/AZ91D composite obtained a maximum shear strength of 58.6 MPa,which was 73.4% higher than the Al-6Si/AZ91D *** fractures of the Al-xSi/AZ91D bimetallic composites transformed from the T layer into the E layer with the increase of the Si *** improvement of the shear strength of the Al-xSi/AZ91D bimetallic composites was attributed to the synergistic action of the Mg_(2)Si particle reinforcement,the reduction of oxidizing inclusions and the ratio of Al-Mg IMCs as well as the orientation change of the MRL.

关键词： Al/Mg bimetallic composites Si content Mg_(2)Si reinforcement Microstructure Mechanical properties Fracture behavior

Deployment Dynamic Modeling and Driving Schemes for a Ring-Truss Deployable Antenna

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2024年第4期37卷 163-182页

作者： Baiyan He lijun Jia Kangkang li Rui Nie Yesen fan Guobiao Wang Key Laboratory of Mechanism Theory and Equipment Design Ministry of EducationTianjin UniversityTianjin 300350China Xi’an Institute of Space Radio Technology Xi’an 710000China International Institute for Innovative Design and Intelligent Manufacturing of Tianjin University in Zhejiang Shaoxing 312077China

Mesh reflector antennas are widely used in space tasks owing to their light weight,high surface accuracy,and large folding *** are stowed during launch and then fully deployed in orbit to form a mesh reflector that transmits *** deployment is essential for duty services;therefore,accurate and efficient dynamic modeling and analysis of the deployment process are *** major challenge is depicting time-varying resistance of the cable network and capturing the cable-truss coupling behavior during the deployment *** paper proposes a general dynamic analysis methodology for cable-truss *** the topological diversity and geometric nonlinearity,the cable network's equilibrium equation is derived,and an explicit expression of the time-varying tension of the boundary cables,which provides the main resistance in truss deployment,is *** deployment dynamic model is established,which considers the coupling effect between the soft cables and deployable *** effects of the antenna's driving modes and parameters on the dynamic deployment performance were investigated.A scaled prototype was manufactured,and the deployment experiment was conducted to verify the accuracy of the proposed modeling *** proposed methodology is suitable for general cable antennas with arbitrary topologies and parameters,providing theoretical guidance for the dynamic performance evaluation of antenna driving schemes.

关键词： Cable antenna Deployment dynamics Performance evaluation Driving scheme Deployable structure

Research on Performance Optimization of Spark Distributed Computing Platform

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2024年第5期79卷 2833-2850页

作者： Qinlu He fan Zhang Genqing Bian Weiqi Zhang Zhen li School of Information and Control Engineering Xi’an University of Architecture and TechnologyXi’an710054China Shaanxi Institute of Metrology Science Xi’an710043China

Spark,a distributed computing platform,has rapidly developed in the field of big *** in-memory computing feature reduces disk read overhead and shortens data processing time,making it have broad application prospects in large-scale computing applications such as machine learning and image ***,the performance of the Spark platform still needs to be *** a large number of tasks are processed simultaneously,Spark’s cache replacementmechanismcannot identify high-value data partitions,resulting inmemory resources not being fully utilized and affecting the performance of the Spark *** address the problem that Spark’s default cache replacement algorithm cannot accurately evaluate high-value data partitions,firstly the weight influence factors of data partitions are modeled and ***,based on this weighted model,a cache replacement algorithm based on dynamic weighted data value is proposed,which takes into account hit rate and data *** integration and usage strategies are implemented based on LRU(LeastRecentlyUsed).Theweight update algorithm updates the weight value when the data partition information changes,accurately measuring the importance of the partition in the current job;the cache removal algorithm clears partitions without useful values in the cache to releasememory resources;the weight replacement algorithm combines partition weights and partition information to replace RDD partitions when memory remaining space is ***,by setting up a Spark cluster environment,the algorithm proposed in this paper is experimentally *** have shown that this algorithmcan effectively improve cache hit rate,enhance the performance of the platform,and reduce job execution time by 7.61%compared to existing improved algorithms.

关键词： Spark memory optimization memory replacement strategy

Responses of osteoblasts under varied tensile stress types induced by stretching basement materials

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Smart and Nano Materials 2024年第2期15卷 279-295页

作者： Xuezheng Geng Qiao li Yan Yao lizhen Wang Yubo fan Beijing Advanced Innovation Center for Biomedical Engineering School of Biological Science and Medical EngineeringKey Laboratory of Biomechanics and Mechanobiology(Beihang University)Ministry of EducationBeijingChina School of Engineering Medicine Beihang UniversityBeijingChina

Osteoblasts are mechanosensitive *** stress with different conditions,including loading time,frequency,magnitude,*** cause varied responses in ***,it was not clarified that the effect of the loading types on the *** this study,we focused on the effect of varied tensile stress types on osteoblasts,including isotropic stretch,biaxial stretch,and uniaxial stretch with the negative ratio of transverse strain to axial strain(NR)-1,0,and 0.2 *** proliferation was determined to be most efficient when stimulated by 6%strain at a frequency of 1 Hz and a negative value of 0 for 1 h/*** varied strain resulted in a thickening of the F-actin cytoskeleton and a thinning of the *** flattening caused Yes-associated protein(YAP)to be transported to the *** was suggested that the influence of loading types on the mechanobiology responses must be *** mechanism of cell mechanical sensitivity under varied loading types was explored,which would provide good sugges-tions for designing microstructures to control deformation patterns in bone tissue engineering.

关键词： MC3T3-E1 tensile stress negative poisson’s ratio cell proliferation YAP

Unlocking supercapacitive energy storage potential:Catalyzing electrochemically inactive manganese oxides to active MnO_(2)via heterostructure reconstruction

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2024年第7期17卷 5897-5906页

作者： Baohong Zhang Tao Jiang Xinyan Zhou Xiaoyu fan Binbin Jia lidong li School of Chemistry Beihang UniversityBeijing 100191China College of Materials and Chemical Engineering Key Laboratory of Inorganic Nonmetallic Crystalline and Energy Conversion MaterialsChinaThree Gorges UniversityYichang 443002China Chinese Academy of Sciences(CAS)Key Laboratory of Nanosystem and Hierarchy Fabrication CAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyBeijing 100190China Shanghai GTX Semiconductor Co. Ltd.Shanghai 201806China

Advancing supercapacitor system performance hinges on the innovation of novel electrode materials seamlessly integrated within distinct ***,we introduce a direct approach for crafting nanorod arrays featuring crystalline/amorphous CuO/MnO_(2)−*** reconfigured heterostructure results in an elevated content of electrochemically active MnO_(2).The nanorod arrays serve as efficient capacitive anodes and are easily prepared via low-potential electrochemical *** resulting structure spontaneously forms a p–n heterojunction,developing a built-in electric field that dramatically facilitates the charge transport *** intrinsic electric field,in conjunction with the crystalline/amorphous architecture,enables a large capacitance of 1.0 F·cm^(−2)at 1.0 mA·cm^(−2),an ultrahigh rate capability of approximately 85.4%at 15 mA·cm^(−2),and stable cycling performance with 92.4%retention after 10,000 *** calculations reveal that the presence of heterojunctions allows for the optimization of the electronic structure of this composite,leading to improved conductivity and optimized OH−adsorption *** work provides new insights into the rational design of heterogeneous nanostructures,which hold great potential in energy storage applications.

关键词： reconfiguration active MnO_(2) crystalline/amorphous structure p-n heterojunction supercapacitor

Numerical investigation of the photo-thermal characteristics of a direct absorption solar collector using Monte Carlo and finite volume methods

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2024年第8期67卷 2436-2448页

作者： ZHU YanLong li SuNing fan JianHua KONG WeiQiang YUAN Yuan TAN HePing School of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001China Department of Civil Engineering and Mechanical Engineering Technical University of DenmarkKoppels AlléBuilding 4042800 Kgs.LyngbyDenmark School of Vehicle and Energy Yanshan UniversityQinhuangdao 066004China

In this study, a novel model of photothermal conversion in a direct absorption solar collector based on the Monte Carlo and finite volume methods was built and validated and the temperatures of the novel and traditional solar collectors were compared. The sensitivity of the parameters to the radiative heat loss was investigated. Finally, the radiative heat transfer characteristics were discussed using the radiative exchange factor. The results of this study validated the advantages of the novel solar collector at both the surface and fluid temperatures. Under the conditions used in this study, the maximum temperature difference of the novel solar collector was 30 K, compared with 193 K for the traditional solar collector. Furthermore, the collector was divided into several units along the flow direction. The radiative exchange factor indicated that with an increase in the attenuation coefficient, the percentage of radiation intensity in the total solar radiation absorbed by the corresponding unit ***, it decreased with an increase in the incident angle and scattering albedo. These results provide a reference for addressing the low efficiency and thermal damage caused by traditional solar collectors at high temperatures.

关键词： direct absorption solar collector radiative heat transfer Monte Carlo

Self-doping active sites in microbe-derived carbonaceous electrocatalysts for the oxygen reduction reaction performance

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第8期17卷 6803-6819页

作者： Xiaofeng Xiao Xiaochun Tian Junpeng li fan Yang Rui Bai Feng Zhao Key Laboratory of Urban Pollutant Conversion Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China University of Chinese Academy of Sciences Beijing 100049China

Microorganisms are rich in heteroatoms,which can be self-doped to form active sites during pyrolysis and loaded on microbederived carbonaceous *** recent years,microbe-derived carbonaceous materials,characterized with abundant selfdoping sites,have been continuously developed as cost-effective electrocatalysts for oxygen reduction reaction(ORR).To fully unlock the catalytic potential of microbe-derived carbonaceous materials,a comprehensive analysis of catalytic sites and mechanisms for ORR is *** paper provides a summary of the ORR catalytic performance of microbe-derived carbonaceous materials reported to date,with a specific focus on the self-doping sites introduced during their pyrolytic *** highlights the mono-or co-doping sites involving nonmetallic elements such as oxygen(O),nitrogen(N),phosphorus(P),and sulfur(S)atoms,as well as covers the doping of metallic iron(Fe)atoms with various coordination configurations in microbe-derived carbonaceous *** the impact of these self-doping sites on ORR catalytic performance can guide the design of doping sites in microbe-derived carbonaceous *** approach has the potential to maximize electrocatalytic activity of microbe-derived carbonaceous materials and contributes to the development of more efficient and cost-effective carbonaceous electrocatalysts.

关键词： electrocatalysis heteroatoms self-doped single atom catalyst microbe-derived carbonaceous material

Transforming Adolescent Smiles:Correcting Skeletal Mandibular Retrusion and Bimaxillary Protrusion with Clear Aligners

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Current Medical Science 2024年第3期44卷 657-666页

作者： Wen-jie fan Jia-qi ZHANG Jia-qi ZHAN li HU li-li CHEN Department of Stomatology Union HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430022China School of Stomatology Tongji Medical CollegeHuazhong University of Science and TechnologyWuhan430030China Wuhan National High Magnetic Field Center Wuhan430074China The Affiliated lianyungang Hospital of Xuzhou Medical University/The First People’s Hospital of lianyungang Lianyungang222000China The First Affiliated Hospital of Kangda College of Nanjing Medical University/The First People’s Hospital of lianyungang Lianyungang222000China

Maxillary protrusion combined with mandibular retraction is a highly prevalent but extremely complex maxillofacial deformity that can have a serious negative impact on patients’facial aesthetics and mental *** traditional orthodontic treatment strategy often involves extracting 4 first premolars and conventional fixed techniques,combined with mini-implant screws,to retract the anterior teeth and improve facial *** recent years,an invisible orthodontic technique,without brackets,has become increasingly ***,while an invisible aligner has been used in some cases with reasonable results,there remain significant challenges in achieving a perfect *** case report presents an adolescent patient with bimaxillary protrusion and mandibular *** on the characteristics of the invisible aligners and the growth characteristics of the adolescent’s teeth and jawbone,we designed precise three-dimensional tooth movement and corresponding resistance/over-correction for each tooth,while utilizing the patient’s jawbone growth potential to promote rapid development of the mandible,accurately and efficiently correcting bimaxillary protrusion and skeletal mandibular *** patient’s facial aesthetics,especially the lateral morphology,have been greatly improved,and various aesthetic indicators have also shown significant changes,and to the patient’s great benefit,invasive mini-implant screws were not used during the *** case highlights the advantages of using invisible aligners in adolescent maxillary protrusion combined with mandibular retraction ***,comprehensive and accurate design combined with good application of growth potential can also enable invisible orthodontic technology to achieve perfect treatment effects in tooth extractions,providing clinical guidance for orthodontists.

关键词： mandibular retrusion esthetic orthodontic treatment clear aligners growth potential

Analytical Modeling of Disaster-induced Load Loss for Preventive Allocation of Mobile Power Sources in Urban Power Networks

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 Modern Power Systems and Clean Energy 2024年第4期12卷 1063-1073页

作者： Zhuorong Wang Qingxin Shi Ke fan Haiteng Han Wenxia liu fangxing li School of Electrical&Electronics Engineering North China Electric Power UniversityBeijing 102206China College of Energy and Electrical Engineering Hohai UniversityNanjing 211100China The University of Tennessee Knoxville TN 37996USA

Continuous power supply of urban power networks(UPNs)is quite essential for the public security of a city be-cause the UPN acts as the basis for other infrastructure *** recent years,UPN is threatened by extreme weather *** accurate modeling of load loss risk under extreme weather is quite essential for the preventive action of ***-sidering the forecast intensity of a typhoon disaster,this paper proposes analytical modeling of disaster-induced load loss for preventive allocation of mobile power sources(MPSs)in ***,based on the topological structure and fragility model of overhead lines and substations,we establish an analytical load loss model of multi-voltage-level UPN to quantify the spatial dis-tribution of disaster-induced load loss at the substation ***,according to the projected load loss distribution,a pre-ventive allocation method of MPS is proposed,which makes the best use of MPS and dispatches the limited power supply to most vulnerable areas in the ***,the proposed meth-od is validated by the case study of a practical UPN in China.

关键词： Load loss fragility model pre-disaster allocation mobile power source urban power network