检索结果-南通市图书馆

Analysis of bending and buckling of pre-twisted beams:A bioinspired study

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2014年第4期30卷 507-515页

作者： zi-Long Zhao Hong-Ping Zhao Zheng Chang Xi-qiao Feng Institute of Biomechanics and Medical Engineering AML Department of Engineering MechanicsTsinghua University Center for Nano and Micro Mechanics Tsinghua University

Twisting chirality is widely observed in artificial and natural materials and structures at different length scales. In this paper, we theoretically investigate the effect of twisting chiral morphology on the mechanical properties of elas- tic beams by using the Timoshenko beam model. Particular attention is paid to the transverse bending and axial buckling of a pre-twisted rectangular beam. The analytical solution is first derived for the deflection of a clamped-free beam under a uniformly or periodically distributed transverse force. The critical buckling condition of the beam subjected to its self- weight and an axial compressive force is further solved. The results show that the twisting morphology can significantly improve the resistance of beams to both transverse bending and axial buckling. This study helps understand some phenomena associated with twisting chirality in nature and provides inspirations for the design of novel devices and structures.

关键词： Twisting chirality. Timoshenko beam. Bending.Euler buckling · Bionics

Potential use of large language models for mitigating students’problematic social media use:ChatGPT as an example

在线全文

学校读者我要写书评

暂无评论

World Journal of Psychiatry 2024年第3期14卷 334-341页

作者： Xin-qiao Liu zi-Ru Zhang School of Education Tianjin UniversityTianjin 300350China

The problematic use of social media has numerous negative impacts on individuals'daily lives,interpersonal relationships,physical and mental health,and ***,there are few methods and tools to alleviate problematic social media,and their potential is yet to be fully *** large language models(LLMs)are becoming increasingly popular for providing information and assistance to people and are being applied in many aspects of *** mitigating problematic social media use,LLMs such as ChatGPT can play a positive role by serving as conversational partners and outlets for users,providing personalized information and resources,monitoring and intervening in problematic social media use,and *** this process,we should recognize both the enormous potential and endless possibilities of LLMs such as ChatGPT,leveraging their advantages to better address problematic social media use,while also acknowledging the limitations and potential pitfalls of ChatGPT technology,such as errors,limitations in issue resolution,privacy and security concerns,and potential *** we leverage the advantages of LLMs to address issues in social media usage,we must adopt a cautious and ethical approach,being vigilant of the potential adverse effects that LLMs may have in addressing problematic social media use to better harness technology to serve individuals and society.

关键词： Problematic use of social media Social media Large language models ChatGPT Chatbots

Carbon nanofibers embedded with Fe-Co alloy nanoparticles via electrospinning as lightweight high-performance electromagnetic wave absorbers

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2024年第6期43卷 2769-2783页

作者： Wen-Jun Cai Jian-Guo Jiang zi-Dong Zhang zi-xuan Liu Lu-JieZhang Zhen-Kun Long Ke Bi Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials(Ministry of Education) Shandong UniversityJinan 250061China School of Materials Science and Engineering Shandong UniversityJinan 250061China Energy Institute Qilu University of Technology(Shandong Academy of Sciences)Jinan 250014China State Key Laboratory of Information Photonics and Optical Communications School of ScienceBeijing University of Posts and TelecommunicationsBeijing 100876China

As a lot of electromagnetic pollution and interference issues have emerged,to overcome electromagnetic interference,prevent electromagnetic hazards,and develop new high-performance electromagnetic wave(EMW)absorbers have become a significant task in the field of materials *** this paper,a three-dimensional(3D)carbon nanofibers network with core-shell structure,embedded with varied molar ratios of iron and cobalt(4:0,3:1,2:2,1:3,0:4),was effectively synthesized(Fe/Co@C-CNFs)via *** phase,microstructure,magnetic and EMW absorption properties were *** is discovered that Fe/Co@C-CNFs doped with iron:cobalt=1:1 have excellent EMW absorption *** the matching thickness is 1.08 mm,the minimum reflection loss(RL)value is-18.66 dB,while the maximum effective absorption bandwidth(EAB)reaches 4.2 GHz(13.9-18 GHz)at a thickness of 1.22 *** is owing to the absorbers'superior impedance matching and multiple reflections as well as the conductivity,dielectric,and magnetic losses of carbon nanofibers embedded with Fe-Co alloy *** addition,the radar cross section(RCS)of the absorbers has been calculated by CST Studio Suite,showing that the absorbing coating can effectively reduce the RCS at various angles,especially for Fe/Co@C-CNFs doped with iron:cobalt=1:*** findings not only provide new insights for the preparation of light-weight and high-performance electromagnetic wave absorbers,but also contribute to energy storage and conversion.

关键词： Electromagnetic wave(EMW)absorbers Fe/Co@C-CNFs Core-shell structure EMW absorbing mechanism Radar cross section(RCS)

Fabrication and sintering behavior of high-nitrogen nickel-free stainless steels by metal injection molding

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2010年第4期17卷 423-428页

作者： zi-wei Xu Cheng-chang Jia Chun-jiang Kuang xuan-hui Qu School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Powder Metallurgy Division Advanced Technology ＆ Materials Co. Ltd. Beijing 100081 China

High-nitrogen nickel-free stainless steels were fabricated by the metal injection molding technique using high nitrogen alloying powders and a mixture of three polymers as *** of metal powders and binders with various proportions were also investigated, and an optimum powder loading capacity was determined as 64vol%.Intact injection molded compacts were successfully obtained by regulating the processing *** debinding process for molded compacts was optimized with a combination of thermo-gravimetric analysis and differential scanning calorimetry *** optimum relative density and nitrogen content of the specimens are obtained at 1360℃,which are 97.8%and 0.79wt%,respectively.

关键词： metal injection molding debinding stainless steel sintering behavior sintered density nitrogen content

Preternatural Hexagonal High-Entropy Alloys: A Review

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2020年第8期33卷 1033-1045页

作者： Rui-xuan Li Jun-Wei qiao Peter K. Liaw Yong Zhang Beijing Advanced Innovation Center of Materials Genome Engineering State Key Laboratory for Advanced Metals and MaterialsUniversity of Science and Technology Beijing30 Xueyuan RoadBeijing 100083China Research Center for High-Entropy Alloys College of Materials Science and EngineeringTaiyuan University of TechnologyTaiyuan 030024China Department of Materials Science and Engineering The University of TennesseeKnoxvilleTN 37996USA

Recently,various topics on high-entropy alloys have been reported and great amounts of excellent properties have been investigated,including high strength,great corrosion resistance,great thermal stability,good fatigue and fracture properties,*** all these research activities,high-entropy alloys tend to form face-centered-cubic(FCC)or body-centeredcubic(BCC)solid solutions due to their high-entropy stabilization effect,while the hexagonal structures are rarely *** to now,the reported hexagonal high-entropy alloys are mainly composed of rare-earth elements and transitional *** phase transformation and magnetic properties have also aroused wide *** study summarizes the above results and provides the forecast to the future.

关键词： High-entropy alloys Hexagonal close-packed structure Phase formation rules Rare-earth elements Multiple-based-element(MBE)alloys

Forecast of cosmological constraints with superluminous supernovae from the Chinese Space Station Telescope

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年第10期67卷 128-138页

作者： xuan-Dong Jia Jian-Ping Hu Fa-Yin Wang zi-Gao Dai School of Astronomy and Space Science Nanjing UniversityNanjing 210093China Key Laboratory of Modern Astronomy and Astrophysics(Nanjing University) Ministry of EducationNanjing 210093China Department of Astronomy University of Science and Technology of ChinaHefei 230026China

Superluminous supernovae(SLSNe)are a class of intense celestial events that can be standardized for measuring cosmological parameters,bridging the gap between type Ia supernovae and the cosmic microwave *** this work,we discuss the cosmological applications of SLSNe from the Chinese Space Station Telescope(CSST).Our estimation suggests that SLSNe rate is biased tracing the cosmic star formation rate,exhibiting a factor of(1+z)^(1.2).We futher predict that CSST is poised to observe~360 SLSNe in the 10 square degrees ultra-deep field survey within a span of 2.5 years.A stringent constraint on cosmological parameters can be derived from their peak-color *** is anticipated to uncover a substantial number of SLSNe,contributing to a deeper understanding of their central engines and shedding light on the nature of dark energy at high redshifts.

关键词： supernovae cosmology cosmological constant

Sequence structure controllable polymerization-induced self-assembly

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第1期67卷 390-397页

作者： zi-xuan Chang Ren-Man Zhu Chun-Yan Hong Wen-Jian Zhang Department of Polymer Science and Engineering University of Science and Technology of ChinaHefei 230026China Institute of Physical Science and Information Technology Anhui UniversityHefei 230601China Key Laboratory of Environment-Friendly Polymeric Materials of Anhui Province Anhui UniversityHefei 230601China

Polymerization-induced self-assembly(PISA)combines synthesis and self-assembly of artificial polymers in one-pot,which brings us one step closer to emulating ***,the reported PISA formulations primarily focus on developing nano-objects with new chemical compositions and rarely on structural regulation of polymers with specific ***,sequence structure controllable polymerization-induced self-assembly(SCPISA)is reported by using 7-(2-methacryloyloxyethoxy)-4-methylcoumarin(CMA)as a *** the copolymerization of 2-hydroxyethyl methacrylate(HEMA)and CMA,controlled incorporation of CMA units into the polymer chains can be realized by programmable light/heat ***-based P(HEMA-co-CMA)copolymers with the same composition but different sequence structures generate a range of ***,the morphologies of the resultant nano-objects can also be controlled by regulating the feed molar ratio of CMA and HEMA,which is similar to the conventional PISA,but the synthesis procedure is obviously simplified in *** versatility of the methodology is further demonstrated by the fabrication of different functional nano-objects with sequence structure-dependent morphologies in SCPISA systems with different functional monomers.

关键词： polymerization-induced self-assembly sequence-controlled polymers PET-RAFT polymerization

Climate change,ambient air pollution,and students'mental health

在线全文

学校读者我要写书评

暂无评论

World Journal of Psychiatry 2024年第2期14卷 204-209页

作者： Jing-xuan Wang Xin-qiao Liu School of Education Tianjin UniversityTianjin 300350China

The impact of global climate change and air pollution on mental health has become a crucial public health *** public awareness of health,advancements in medical diagnosis and treatment,the way media outlets report environmental changes and the variation in social resources affect psychological responses and adaptation methods to climate change and air *** the context of climate change,extreme weather events seriously disrupt people's living environments,and unstable educational environments lead to an increase in mental health issues for *** pollution affects students'mental health by increasing the incidence of diseases while decreasing contact with nature,leading to problems such as anxiety,depression,and decreased cognitive *** call for joint efforts to reduce pollutant emissions at the source,improve energy structures,strengthen environmental monitoring and governance,increase attention to the mental health issues of students,and help student groups build resilience;by establishing public policies,enhancing social support and adjusting lifestyles and habits,we can help students cope with the constantly changing environment and maintain a good level of mental *** these comprehensive measures,we can more effectively address the challenges of global climate change and air pollution and promote the achievement of the United Nations Sustainable Development Goals.

关键词： Climate change Ambient air pollution Mental health Energy structure Public policy Sustainable development

Fast quantum state transfer and entanglement for cavity-coupled many qubits via dark pathways

维普期刊数据库评论

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 physics 2022年第4期17卷 91-98页

作者： Yi-xuan Wu zi-Yan Guan Sai Li Zheng-Yuan Xue Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials and School of Physics and Telecommunication EngineeringSouth China Normal UniversityGuangzhou 510006China Guangdong–Hong Kong Joint Laboratory of Quantum Matter and Frontier Research Institute for PhysicsSouth China Normal UniversityGuangzhou 510006China

Quantum state transfer(QST)and entangled state generation(ESG)are important building blocks for modern quantum information *** achieve these tasks,convention wisdom is to consult the quantum adiabatic evolution,which is time-consuming,and thus is of low ***,using the shortcut to adiabaticity technique,we propose a general method to realize high-fidelity fast QST and ESG in a cavity-coupled many qubits system via its dark pathways,which can be further designed for high-fidelity quantum tasks with different optimization ***,with a proper dark pathway,QST and ESG between any two qubits can be achieved without decoupling the others,which simplifies experimental ***,ESG among all qubits can also be realized in a single *** addition,our scheme can be implemented in many quantum systems,and we illustrate its implementation on superconducting quantum ***,we propose a powerful strategy for selective quantum manipulation,which is promising in cavity coupled quantum systems and could find many convenient applications in quantum information processing.

关键词： entanglement generation quantum information processing cavity QED