检索结果-南通市图书馆

Structural and elastic properties of Ce2O3 under pressure from LDA+U method

在线全文

学校读者我要写书评

暂无评论

Frontiers of Physics 2013年第4期8卷 405-411页

作者： yuan-yuan Qi Zhen-Wei Niu Cai cheng Yan cheng Institute of Atomic and Molecular Physics Sichuan University

We investigate the structural and elastic properties of hexagonal Ce2O3 under pressure using LDA+U scheme in the frame of density functional theory(DFT).The obtained lattice constants and bulk modulus agree well with the available experimental and other theoretical *** pressure dependences of normalized lattice parameters a/a0 and c/c0,ratio c/a,and normalized primitive volume V /V0 of Ce2O3 are ***,the pressure dependences of elastic properties and three anisotropies of elastic waves of Ce2O3 are investigated for the frst *** fnd that the negative value of C44 is indicative of the structural instability of the hexagonal structure Ce2O3 at zero temperature and 30 ***,the density of states(DOS) of Ce2O3 under pressure is investigated.

关键词： elastic properties high pressure density functional theory Ce2O3

Exfoliation Corrosion of As‑Extruded Mg–1Li–1Ca:the Influence of the Superficial Layer

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2024年第8期37卷 1339-1353页

作者： Ze‑Song Wei Zi‑You Ding Lei Cai Shao‑Xia Ma Dong‑Qing Zhao Lan‑yue Cui cheng‑Bao Liu yuan‑Sheng Yang yuan‑Ding Huang Rong‑Chang Zeng Corrosion Laboratory for Light Metals College of Materials Science and EngineeringShandong University of Science and TechnologyQingdao 266590China Engineering Research Center for Magnesium‑Based New Materials Center for Advancing Materials Performance from the Nanoscale(CAMP‑Nano)State Key Laboratory for Mechanical Behavior of MaterialsXi’an Jiaotong UniversityXi’an 710049China Shandong Provincial Key Laboratory of High Strength Lightweight Metallic Materials Advanced Materials InstituteQilu University of Technology(Shandong Academy of Sciences)Jinan 250014China Institute of Metals Research Chinese Academy of SciencesShenyang 110016China Institute of Metallic Biomaterials Helmholtz-Zentrum HereonMax‑Planck‑Str.121502 GeesthachtGermany

Exfoliation corrosion(EFC)has rarely been reported for wrought magnesium *** EFC of the as-extruded Mg–1Li–1Ca alloy was observed after the removal of outermost fine-grained *** microstructure and corrosion products were investigated using optical microscopy,scanning electron microscopy,electron backscattered diffraction,X-ray diffraction,and Fourier transform infrared *** corrosion behavior was analyzed using electrochemical polarization,electrochemical impedance spectroscopy,and scanning Kelvin probe *** results indicated that the surface of Mg–1Li–1Ca,with the superficial layer removed,was more susceptible to EFC.A linear correlation between grain boundary density and corrosion resistance was ***,the influence of factors such as grain size,intermetallic compounds,different alloy surfaces,and corrosion products on EFC were discussed,and the corresponding EFC mechanism was clarified.

关键词： Magnesium alloys Exfoliation corrosion Microstructure Intermetallic compound Metamorphic skin

The effect of COVID-19 vaccines on sperm parameters: a systematic review and meta-analysis

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Asian Journal of Andrology 2023年第4期25卷 468-473页

作者： Yu-cheng Ma Chao cheng Chi yuan Li-yuan Xiang Jun Wen Xi Jin Department of Urology Institute of Urology(Laboratory of Reconstructive Urology)West China HospitalSichuan UniversityChengdu 610000China

Published data were gathered for a meta-analysis to determine the difference in sperm parameters before and after administration of different types of coronavirus disease 2019(COVID-19)vaccines,because the reproductive toxicity of COVID-19 vaccines has not yet been evaluated in clinical trials and COVID-19 has been associated with decreases in sperm *** preferred procedures for systematic reviews and meta-analyses were followed in the conduct and reporting of this *** average sperm parameters of all sperm donors’multiple sperm donations were compared before and after receiving various COVID-19 *** volume,total sperm motility,total sperm count,morphological change,and sperm concentration were the primary outcome *** compiled and analyzed the results of six studies on total sperm motility,six studies on semen volume,six studies on sperm concentration,two studies on morphological change,and two studies on total sperm *** comparisons with patients who had and had not been vaccinated were only reported in one of the included *** different types of COVID-19 vaccine injections were compared,no discernible differences in parameters were *** to the available data,the parameters of semen are unaffected by inactivated or messenger RNA(mRNA)COVID-19 *** support these findings,additional prospectively designed research is required.

关键词： COVID-19 mRNA vaccine sperm parameters sperm quality vaccine safety

Vertical graphene-coated Cu wire for enhanced tolerance to high current density in power transmission

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 2022年第11期15卷 9727-9733页

作者： Kun Wang Shuting cheng Qingmei Hu Feng Yu Yi cheng Kewen Huang Hao yuan Jun Jiang Wenjuan Li Junliang Li Shichen Xu Jianbo Yin yue Qi Zhongfan Liu Center for Nanochemistry(CNC) Beijing Science and Engineering Center for NanocarbonsBeijing National Laboratory for Molecular SciencesCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China Beijing Graphene Institute(BGI) Beijing 100095China State Key Laboratory of Heavy Oil Processing College of ScienceChina University of PetroleumBeijing 102249China

Cu wires(CuWs)are widely used as electric transmission ***,their limited thermal and chemical stabilities become challenges under the high-power and harsh *** is regarded as an ideal protective barrier for CuW benefiting from its impermeability to all atoms and ***,the excellent hydrophobicity of vertical graphene(VG)will strengthen its protective capability as a corrosion and oxidation ***,VG is directly synthesized on CuW by plasmaenhanced chemical vapor deposition *** hydrophobic VG coating with a high water contact angle can effectively exclude the corrosive liquid and moisture from CuW surface and prevent their further ***,the electrochemical corrosion rate of VG-CuW is reduced by~13,8,and 2 times,compared with bare CuW,VG-CuW with hydrophilic treatment,and CuW coated with thick horizontal graphene layers,*** oxidation occurs on VGCuW after the long-time exposure to humid air at~200℃ along with the largely enhanced tolerance under high-current operating *** study reveals the impressive potentials of hydrophobic VG as a robust corrosion and oxidation barrier for metal wires used in high-power cables and electronic devices in harsh environment.

关键词： vertical graphene Cu wire oxidation and corrosion plasma-enhanced chemical vapor deposition

Effects of quenching and partitioning process on mechanical properties of TRIP780 steel

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 Iron and Steel Research International 2019年第9期26卷 991-999页

作者： Xian-hong Han cheng-long Wang yuan-yuan Li Gang Liu National Engineering Research Center of Die and Mold CAD School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200030China Shanghai Marine Equipment Research Institute Shanghai 200031China

A transformation-induced plasticity (TRIP) steel was applied to test its mechanical properties in quenching and partitioning (Q&P) process. A series of Q&P experiments followed by tensile tests, Charpy impact tests, fracture morphology analyses and microstructure observations were conducted. The experimental results showed that the Q&P treatment could increase the mechanical properties of TRIP steel evidently. The strength of tested TRIP780 after Q&P process reaches more than 1500 MPa with elongation of 17.8%, which is obviously greater than that of 22MnB5 after hot stamping. The microstructure observations indicate that the good combination of high strength and plasticity of TRIP steel after Q&P process is attributed to the multi-phase microstructure of hard martensite matrix and soft retained austenite.

关键词： Transformation-induced plasticity steel Quenching and partitioning process Hot stamping Mechanical property

Linear fractional composition operators on the Dirichlet space in the unit ball

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 Mathematics 2009年第8期52卷 1661-1670页

作者： ZHOU ZeHua yuan cheng Department of Mathematics Tianjin UniversityTianjin 300072China

We investigate the adjoints of linear fractional composition operators C ? acting on classical Dirichlet space D(B N ) in the unit ball B N of ? N , and characterize the normality and essential normality of C ? on D(B N ) and the Dirichlet space modulo constant function D 0(B N ), where ? is a linear fractional map ? of B N . In addition, we also show that for any non-elliptic linear fractional map ? of B N , the composition maps σ o ? and ? o σ are elliptic or parabolic linear fractional maps of B N .

关键词： linear fractional composition operators Dirichlet space adjoints essential normality 47B38 46E15 32A37

Single-atom catalysts for CO oxidation,CO_(2) reduction,and O_(2) electrochemistry

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2022年第2期31卷 254-279页

作者： Wenyu yuan Yiyuan Ma Heng Wu Laifei cheng Department of Physics Tokyo Metropolitan UniversityHachiojiTokyo 192-0397Japan Science and Technology on Thermostructural Composite Materials Laboratory Northwestern Polytechnical UniversityXi’an 710072ShaanxiChina

CO_(x)(x=1,2)and O_(2) chemistry play key roles in tackling global severe environmental challenges and energy *** date,the efficient selective electrocatalytic transformations of COx-carbon chemicals,and O_(2)-hydrogenated products are still huge ***-atom catalysts(SACs)as atomic-scale novel catalysts in which only isolated metal atoms are dispersed on supports shed new insights in overcome these obstacles in CO_(x) and O_(2) chemistry,including CO oxidation,CO_(2) reduction reaction(CO_(2)RR),oxygen reduction reaction(ORR),and oxygen evolution reaction(OER).In this review,the unique features and advanced synthesis strategies of SACs from a viewpoint of fundamental synthesis design are first highlighted to guide future strategy design for controllable SAC ***,the to-date reported CO_(2)RR,CO oxidation,OER,and ORR mechanism are included and *** importantly,the design principles and design strategies of improving the intrinsic activity,selectivity,and stability are extensively discussed and the engineering strategy is classified as neighbor coordination engineering,metal-atom engineering,and substrate *** the comprehensive review and summary of state-of-the-art SACs,the synthesis–structure–property–mechanism–design principle relation can be revealed to shed lights into the structural construction of ***,we present an outlook on current challenges and future directions for SACs in CO_(x) and O_(2) chemistry.

关键词： Single-atom catalysts CO_(2)reduction reaction CO oxidation Oxygen reduction reaction Oxygen evolution reaction

Reinforcement learning-based scheduling of multi-battery energy storage system

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2023年第1期34卷 117-128页

作者： cheng Guangran DONG Lu yuan Xin SUN Changyin School of Automation Southeast UniversityNanjing 210096China Peng cheng Laboratory Shenzhen 518066China School of Cyber Science and Engineering Southeast UniversityNanjing 211189China

In this paper, a reinforcement learning-based multibattery energy storage system(MBESS) scheduling policy is proposed to minimize the consumers ’ electricity cost. The MBESS scheduling problem is modeled as a Markov decision process(MDP) with unknown transition probability. However, the optimal value function is time-dependent and difficult to obtain because of the periodicity of the electricity price and residential load. Therefore, a series of time-independent action-value functions are proposed to describe every period of a day. To approximate every action-value function, a corresponding critic network is established, which is cascaded with other critic networks according to the time sequence. Then, the continuous management strategy is obtained from the related action network. Moreover, a two-stage learning protocol including offline and online learning stages is provided for detailed implementation in real-time battery management. Numerical experimental examples are given to demonstrate the effectiveness of the developed algorithm.

关键词： multi-battery energy storage system(MBESS) reinforcement learning periodic value iteration data-driven

Non-tensorial gravitational wave background in NANOGrav 12.5-year data set

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2021年第12期64卷 84-89页

作者： Zu-cheng Chen Chen yuan Qing-Guo Huang CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUCASHangzhou 310024China Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China

We perform the first search for an isotropic non-tensorial gravitational-wave background(GWB) allowed in general metric theories of gravity in the North American Nanohertz Observatory for Gravitational Waves(NANOGrav) 12.5-year data set. By modeling the GWB as a power-law spectrum, we find strong Bayesian indication for a spatially correlated process with scalar transverse(ST) correlations whose Bayes factor versus the spatially uncorrelated common-spectrum process is 107 ± 7, but no statistically significant evidence for the tensor transverse, vector longitudinal, and scalar longitudinal polarization modes. The median and the 90% equal-tail amplitudes of ST mode are ■ , or equivalently the energy density parameter per logarithm frequency is ■, at frequency of 1/year.

关键词： gravitational wave scalar transverse polarization pulsar timing array