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Self-assembly of perovskite nanocrystals:From driving forces to applications

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Journal of Energy Chemistry 2024年第1期88卷 561-578,I0013页

作者： Yi Li fei zhang School of Chemical Engineering and Technology Tianjin UniversityTianjin 300072China Collaborative Innovation Center of Chemical Science and Engineering(Tianjin) Tianjin 300072China

Self-assembly of metal halide perovskite nanocrystals(NCs)into superlattices can exhibit unique collective properties,which have significant application values in the display,detector,and solar cell *** review discusses the driving forces behind the self-assembly process of perovskite NCs,and the commonly used self-assembly methods and different self-assembly structures are ***,we summarize the collective optoelectronic properties and application areas of perovskite superlattice ***,we conclude with an outlook on the potential issues and future challenges in developing perovskite NCs.

关键词： Self-assembly Metal halide perovskite Nanocrystals Driving forces

Forecast for weighing neutrinos in cosmology with SKA

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Science China(Physics,Mechanics & Astronomy) 2020年第8期63卷 53-60页

作者： Jing-fei zhang Bo Wang Xin zhang Department of Physics College of SciencesNortheastern UniversityShenyang 110819China Ministry of Education’s Key Laboratory of Data Analytics and Optimization for Smart Industry Northeastern UniversityShenyang 110819China Center for High Energy Physics Peking UniversityBeijing 100080China

We investigate what role the SKA neutral hydrogen(HI)intensity mapping(IM)and galaxy sky surveys will play in weighing neutrinos in *** use the simulated data of the baryon acoustic oscillation(BAO)measurements from the HI surveys based on SKA1(IM)and SKA2(galaxy)to do the *** the current observations,we use the Planck 2015 cosmic microwave background(CMB)anisotropies observation,the optical BAO measurements,the type Ia supernovae(SN)observation(Pantheon compilation),and the latest H0 *** consider three mass ordering cases for massive neutrinos,i.e.,the normal hierarchy(NH),inverted hierarchy(IH),and degenerate hierarchy(DH)*** is found that the SKA observation can significantly improve the constraints on?m and *** to the current observation,the SKA1 data can improve the constraints on?m by about 33%,and on H0 by about 36%;the SKA2 data can improve the constraints on?m by about 58%,and on H0 by about 66%.It is also found that the SKA observation can only slightly improve the constraints on∑mν.Compared to the current observation,the SKA1 data can improve the constraints on∑mνby about 4%,3%,and 10%,for the NH,IH,and DH cases,respectively;the SKA2 data can improve the constraints on∑mνby about 7%,7%,and 16%,for the NH,IH,and DH cases,respectively.

关键词： 21 cm observation intensity mapping survey Square Kilometre Array baryon acoustic oscillations neutrino mass

Global Well-posedness for gKdV-3 in Sobolev Spaces of Negative Index

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Acta Mathematica Sinica,English Series 2008年第5期24卷 857-866页

作者： Zhi fei zhang School of Mathematical Science Peking University Beijing 100871 P. R. China

The initial value problem for the generalized Korteweg-deVries equation of order three on the line is shown to be globally well posed for rough data. Our proof is based on the multilinear estimate and the I-method int... 详细信息

关键词： KdV equation Global well posedness I-method Multilinear estimate

Searching for sterile neutrinos in dynamical dark energy cosmologies

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Science China(Physics,Mechanics & Astronomy) 2018年第5期61卷 10-19页

作者： Lu Feng Jing-fei zhang Xin zhang Department of Physics College of Sciences Northeastern University Center for High Energy Physics Peking University

We investigate how the dark energy properties change the cosmological limits on sterile neutrino parameters by using recent cosmological observations. We consider the simplest dynamical dark energy models, the wCDM model and the holographic dark energy（HDE） model, to make an analysis. The cosmological observations used in this work include the Planck 2015 CMB temperature and polarization data, the baryon acoustic oscillation data, the type Ia supernova data, the Hubble constant direct measurement data, and the Planck CMB lensing data. We find that, mν,sterileff〈 0.2675 eV and Neff〈 3.5718 for ΛCDM cosmology, mν,sterileff〈 0.5313 eV and Neff〈 3.5008 for wCDM cosmology, and mν,sterileff〈 0.1989 eV and Neff〈 3.6701 for HDE cosmology, from the constraints of the combination of these data. Thus, without the addition of measurements of growth of structure, only upper limits on both mν,sterileff and Neff can be derived, indicating that no evidence of the existence of a sterile neutrino species with e V-scale mass is found in this analysis. Moreover, compared to the ΛCDM model, in the wCDM model the limit on mν,sterileff becomes much looser, but in the HDE model the limit becomes much tighter. Therefore, the dark energy properties could significantly influence the constraint limits of sterile neutrino parameters.

关键词： sterile neutrino dynamical dark energy cosmological observations

Elliptical encirclement control capable of reinforcing performances for UAVs around a dynamic target

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Defence Technology（防务技术） 2024年第2期32卷 104-119页

作者： fei zhang Xingling Shao Yi Xia Wendong zhang National Key Laboratory for Electronic Measurement Technology School of Instrument and ElectronicsNorth University of ChinaTaiyuan030051China

Most researches associated with target encircling control are focused on moving along a circular orbit under an ideal environment free from external ***,elliptical encirclement with a time-varying observation radius,may permit a more flexible and high-efficacy enclosing solution,whilst the non-orthogonal property between axial and tangential speed components,non-ignorable environmental perturbations,and strict assignment requirements empower elliptical encircling control to be more challenging,and the relevant investigations are still *** this line,an appointed-time elliptical encircling control rule capable of reinforcing circumnavigation performances is developed to enable Unmanned Aerial Vehicles(UAVs)to move along a specified elliptical path within a predetermined reaching *** remarkable merits of the designed strategy are that the relative distance controlling error can be guaranteed to evolve within specified regions with a designer-specified convergence ***,wind perturbations can be online counteracted based on an unknown system dynamics estimator(USDE)with only one regulating parameter and high computational *** tool demonstrates that all involved error variables are ultimately limited,and simulations are implemented to confirm the usability of the suggested control algorithm.

关键词： Elliptical encirclement Reinforced performances Wind perturbations UAVs

Impacts of dark energy on constraining neutrino mass after Planck 2018

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Communications in Theoretical Physics 2020年第12期72卷 163-170页

作者： Ming zhang Jing-fei zhang Xin zhang Department of Physics College of SciencesNortheastern UniversityShenyang 110819China Key Laboratory of Data Analytics and Optimization for Smart Industry(Northeastern University) Ministry of EducationShenyang 110819China Center for Gravitation and Cosmology Yangzhou UniversityYangzhou 225009China

Considering the mass splittings of three active neutrinos,we investigate how the properties of dark energy affect the cosmological constraints on the total neutrino mass∑mv using the latest cosmological *** this paper,several typical dark energy models,including ACDM,wCDM,CPL,and HDE models,are *** the analysis,we also consider the effects from the neutrino mass hierarchies,*** degenerate hierarchy(DH),the normal hierarchy(NH),and the inverted hierarchy(IH).We employ the current cosmological observations to do the analysis,including the Planck 2018 temperature and polarization power spectra,the baryon acoustic oscillations(BAO),the type Ia supernovae(SNe),and the Hubble constant H0 *** the ACDM+∑mv model,we obtain the upper limits of the neutrino mass∑mv<0.123 eV(DH),∑mv<0.156 eV(NH),and∑mv<0.185 eV(IH)at the 95%C.L.,using the Planck+BAO+SNe data *** the wCDM+∑mv model and the CPL+∑mv model,larger upper limits of∑mv are obtained compared to those of the ACDM+∑mv *** most stringent constraint on the neutrino mass,∑mv<0.080 eV(DH),is derived in the HDE+∑mv *** addition,we find that the inclusion of the local measurement of the Hubble constant in the data combination leads to tighter constraints on the total neutrino mass in all these dark energy models.

关键词： neutrino mass mass hierarchies of neutrinos dark energy cosmological constraints Planck 2018

Stability analysis of layered slopes in unsaturated soils

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Frontiers of Structural and Civil Engineering 2022年第3期16卷 378-387页

作者： Guangyu DAI fei zhang Yuke WANG Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering Hohai UniversityNanjing 210098China Jiangsu Province's Geotechnical Research Center Nanjing 210098China College of Water Conservancy Engineering Zhengzhou UniversityZhengzhou 450001China

This study presents stability analyses of layered soil slopes in unsaturated conditions and uses a limit equilibrium method to determine the factor of safety involving suction stress of unsaturated ***-dimensional steady infiltration and evaporation conditions are considered in the stability *** example of a two-layered slope in clay and silt is selected to verify the used method by comparing with the results of other *** analyses are conducted to explore the influences of the matric suction on the stability of layered soil *** obtained results show that larger suction stress provided in unsaturated clay dominates the stability of the layered ***,the location and thickness of the clay layer have significant influences on slope *** the water level decreases,the factor of safety reduces and then increases gradually in most ***/evaporation can obviously affect the stability of unsaturated layered slopes,but their influences depend on the soil property and thickness of the lower soil layer.

关键词： slope stability suction stress unsaturated soil layered slope limit equilibrium

A note on near-field site amplification effects of ground motion from a radially inhomogeneous valley

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Earthquake Engineering and Engineering Vibration 2018年第4期17卷 707-718页

作者： zhang Ning Gao Yufeng Wu Yongxin zhang fei Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering Hohai University College of Civil and Transportation Engineering Hohai University

To improve the understanding of the near-field soil and topographic amplification effects, an analytical solution by the authors for the scattering of plane SH waves by a radially inhomogeneous semi-cylindrical valley is extended to the case of a line source of cylindrical SH waves. Upon confirmation of its accuracy with past exact solutions for a homogeneous and an inhomogeneous semi-cylindrical valley under far-field plane SH waves, the extended solution is used to calculate the ground motion amplification factors for both the homogeneous and inhomogeneous valleys subjected to near-field waves. A comprehensive parametric study is conducted with respect to the location of the wave source, the dimensionless frequency of the incident waves, and the inhomogeneity degree of the covering soil layer. It is found that more amplifications and reductions of ground motions will occur within a certain range in and around the valley as the sources are located further. Consistent with the far-field case, it is confirmed that an increase of the degree of inhomogeneity of the covering soil layer generally amplifies the ground motions significantly.

关键词： elastic SH-waves wave scattering and diffraction ground motion amplification valley canyon

Redshift drift constraints on holographic dark energy

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Science China(Physics,Mechanics & Astronomy) 2017年第3期60卷 80-86页

作者： Dong-Ze He Jing-fei zhang Xin zhang Department of Physics College of Sciences Northeastern University Center for High Energy Physics Peking University

The Sandage-Loeb （SL） test is a promising method for probing dark energy because it measures the redshift drift in the spectra of Lyman-o： forest of distant quasars, covering the ＂redshift desert＂ of 2 ≤ z ≤ 5, which is not covered by existing cosmological observations. Therefore, it could provide an important supplement to current cosmological observations. In this paper, we explore the impact of SL test on the precision of cosmological constraints for two typical holographic dark energy models, i.e., the original holographic dark energy （HDE） model and the Ricci holographic dark energy （RDE） model. To avoid data inconsistency, we use the best-fit models based on current combined observational data as the fiducial models to simulate 30 mock SL test data. The results show that SL test can effectively break the existing strong degeneracy between the present-day matter density Ωm0 and the Hubble constant 1-1o in other cosmological observations. For the considered two typical dark energy models, not only can a 30-year observation of SL test improve the constraint precision of Ωm0 and h dramatically, but can also enhance the constraint precision of the model parameters c and α significantly.

关键词： redshift drift Sandage-Loeb test holographic dark energy Ricci dark energy cosmological constraints