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Dark Energy Accretion onto a Black Hole in an Expanding Universe

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Communications in Theoretical Physics 2009年第9期52卷 441-444页

作者： SUN cheng-yi Institute of Modern Physics Northwest University Xi＇an 710069 China

By using the solution describing a black hole embedded in the FLRW universe,we obtain the evolvingequation of the black hole mass expressed in terms of the cosmological *** evolving equation indicates thatin the phant... 详细信息

关键词： black hole dark energy accretion FRW universe

Effect of Reduction and Carburization Pretreatment on Iron Catalyst for Synthesis of Light Olefins from CO Hydrogenation

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Chemical Research in Chinese Universities 2017年第4期33卷 672-677页

作者： AN Tong DANG Dan cheng yi Department of Chemical Engineering Tsinghua University Beijing 100084 P. R. China

Effect of reduction and carburization pretreatment on iron catalyst for CO hydrogenation to light olefins was investigated. The bulk structure and surface composition of the catalysts during pretreatment were characterized by means of X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS） and high-resolution transmission elec- tron microscopy（HRTEM）. The results indicated that phase transformation of iron phases involved a-Fe203---~Fe304 --,a-Fe both in the bulk and on the surface layers in hydrogen atmosphere. However, a-Fe203 was firstly transformed to Fe3C and then to Fe5C2 in CO atmosphere, while in syngas atmosphere directly to Fe5C2. As carburization pretreatment time was prolonged, the degree of carburization on the surface increased, and the increase degree of iron catalyst carburization in CO pretreatment was stronger than that in syngas pretreatment. It inferred that surface carbon species was more easily formed in syngas pretreatment instead of iron carbide in CO pretreatment. After hydrogen pretreatment, when the catalyst was reduced to a mixture of magnetite and metallic iron, the selectivity to light olefins was relatively low. Under the joint effects of the active sites from surface iron carbide and surface carbon layers blocking the active sites, longer CO pretreatment time resulted in higher methane selectivity and less light olefins. The selectivity to methane on H2-pretreated catalyst was lower than that of CO-pretreated catalyst.

关键词： Light olefin Fischer-Tropsch synthesis CO hydrogenation Iron catalyst Pretreatment

Advances in electrocatalysts for oxygen evolution reaction of water electrolysis-from metal oxides to carbon nanotubes

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Progress in Natural Science:Materials International 2015年第6期25卷 545-553页

作者： yi cheng San Ping Jiang Fuels and Energy Technology Institute & Department of Chemical Engineering Curtin University

The water electrolysis for hydrogen production is constrained by the thermodynamically unfavorable oxygen evolution reaction(OER),which requires input of a large amount of energy to drive the *** of the key challenges to increase the efficiency of the water electrolysis system is to develop highly effective and robust electrocatalysts for the *** the past 20–30 years,significant progresses have been made in the development of efficient electrocatalysts,including metal oxides,metal oxide-carbon nanotubes(CNTs) hybrid and metal-free CNTs based materials for the *** this critical review,the overall progress of metal oxides catalysts and the role of CNTs in the development of OER catalyst are summarized,and the latest development of new metal free CNTs-based OER catalyst is discussed.

关键词： Water electrolysis Oxygen reduction reaction Metal oxide Hybrid metal oxide/CNTs CNTs

Radar false alarm plots elimination based on multi-feature extraction and classification

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The Journal of China Universities of Posts and Telecommunications 2024年第1期31卷 83-92页

作者： cheng yi Zhao Yan yin Peiwen School of Control Science and Engineering Tiangong UniversityTianjin 300387China Tianjin Key Laboratory of Intelligent Control of Electrical Equipment Tianjin 300387China

Caused by the environment clutter,the radar false alarm plots are *** false alarm points has always been a key issue in Radar plots *** this paper,a radar false alarm plots elimination method based on multi-feature extraction and classification is proposed to effectively eliminate false alarm ***,the density based spatial clustering of applications with noise(DBSCAN)algorithm is used to cluster the radar echo data processed by constant false-alarm rate(CFAR).The multi-features including the scale features,time domain features and transform domain features are ***,a feature evaluation method combining pearson correlation coefficient(PCC)and entropy weight method(EWM)is proposed to evaluate interrelation among features,effective feature combination sets are selected as inputs of the ***,False alarm plots classified as clutters are *** experimental results show that proposed method can eliminate about 90%false alarm plots with less target loss rate.

关键词： radar plots elimination density based spatial clustering of applications with noise multi-feature extraction classifier

Relationship Between Oct agonal Quasicrystal and β-Mn Type Crystal in Cut Description

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Chinese Physics Letters 1996年第3期13卷 199-202页

作者： LI Fang-hua cheng yi-fan Institute of Physics Chinese Academy of SciencesBeijing 1000801 Max-Planck-Institut fur Metallforschung Institut fur Werkstoff-WeissenschaftSeestrasse 9270147 StuttgartGermany

The transformation from the octagonal lattice to a square lattice is demonstrated straightforward under the cut description by introducing a peculiar linear phason *** calculated lattice parameter of the ft-Mn structure from the edge length of squares and rhombi forming the octagonal quasilattice is in agreement with experimental results.

关键词： strain. agonal lattice

Robust tracking control of a piezodriven monolithic flexure-hinge stage

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Science China(Physics,Mechanics & Astronomy) 2009年第6期52卷 926-934页

作者： HUANG yi-cheng cheng Chih-Hao Department Mechatronics Engineering National Changhua University of Education500 Chinde Rd.ChanghuaTaiwanChina

This study presents the controller design and tests of a new piezodriven two degree-of freedom (DOF) monolithic stage for precision motion. The computer-controlled system is developed, designed and employed for better displacement error compensation by proportional-integral-derivative (PID) controller based on Internal Model Control (IMC), Iterative Learning Control (ILC) and Disturbance Observer (DO). Experimental results show that stage positioning is precisely controlled (error ≈ 1.42%) for tracking sinusoidal waveforms by IMC and P-type ILC with repeatable disturbance. With additional DO, experiment tests perform error ≈ 0.5% with non-repeatable disturbance up to 16% of the maximum traveling length in roughly 5 iterations. This is close to the hardware reproducibility level. Experimental results show the piezo-stage controlled system can be potentially used for nano technology applications for precision engineering in industrial systems.

关键词： iterative learning control internal model control disturbance observer piezoelectric actuator monolithic motion stage

3D-Printed Janus Piezoelectric Patchesfor Sonodynamic Bacteria Elimination and Wound Healing

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Research 2023年第3期6卷 335-344页

作者： Danqing Huang yi cheng Guopu Chen Yuanjin Zhao Institute of Translational Medicine the Affiliated Drum Tower Hospital of Nanjing University Medical SchoolNanjing 210002China State Key Laboratory of Bioelectronics School of Biological Science and Medical EngineeringSoutheast UniversityNanjing 210096China Oujang Laboratory(Zhejiang Lab for Regenerative Medicine Vision and Brain Health)Wenzhou InstituteUniversity of Chinese Academy of SciencesWenzhouZhejiang 325001China

Management of infected wounds has raised worldwide *** in this field focus on the development of intelligent patches for improving the wound ***,inspired by the cocktail treatment and combinational therapy stratagem,we present a novel Janus piezoelectric hydrogel patch via 3-dimensional printing for sonodynamic bacteria elimination and wound *** top layer of the printed patch was poly(ethylene glycol)diacrylate hydrogel with gold-nanoparticle-decorated tetragonal barium titanate encapsulation,which realizes the ultrasound-triggered release of reactive oxygen species without leaking *** bottom layer is fabricated with methacrylate gelatin and carries growth factors for the cell proliferation and tissue *** on these features,we have demonstrated invivo that the Janus piezoelectric hydrogel patch can exert substantial infection elimination activity under the excitation of ultrasound,and its sustained release of growth factors can promote tissue regeneration during wound *** results indicated that the proposed Janus piezoelectric hydrogel patch had practical significance in sonodynamic infection alleviation and programmable wound healing for treating different clinical diseases.

关键词： patch dynamic piezoelectric

Compact asymmetric sound absorber at the exceptional point

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Science China(Physics,Mechanics & Astronomy) 2021年第4期64卷 10-16页

作者： DongTing Li SiBo Huang yi cheng Yong Li Institute of Acoustics School of Physics Science and EngineeringTongji UniversityShanghai 200092China

We present an asymmetric absorber at an exceptional point(EP) with a compact configuration and deep-subwavelength *** conventional side-branched sound absorbers in dual-port systems, the proposed asymmetric absorber exhibits a compact shape that is coaxial with the waveguide. By tuning the loss and geometric parameters of the non-Hermitian system to reach an EP, we observe extreme asymmetric absorption. This phenomenon is theoretically and experimentally validated by observing a quasi-perfect absorption and a near-total reflection for opposite incidences at the ultra-thin(1/28 th of the operating wavelength)neck-embedded tube employed in this study. Furthermore, we demonstrate an EP-induced tunable asymmetric absorption. Our study proposes novel approaches to manipulate the EP-induced wave phenomena, paving the way for the development of novel acoustic absorbers, sensors, isolators, and directional devices.

关键词： asymmetric sound absorber acoustic metamaterial non-Hermitian system exceptional point

Plasma treated M1 MoVNbTeO_(x)-CeO_(2) composite catalyst for improved performance of oxidative dehydrogenation of ethane

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Green Energy & Environment 2023年第3期8卷 904-914页

作者： Shuairen Qian Yuxin Chen Binhang Yan yi cheng Department of Chemical Engineering Tsinghua UniversityBeijing100084China

High activity and productivity of MoVNbTeO_(x) catalyst are challenging tasks in oxidative dehydrogenation of ethane(ODHE)for industrial *** this work,phase-pure M1 with 30 wt%CeO_(2) composite catalyst was treated by oxygen plasma to further enhance catalyst *** results show that the oxygen vacancies generated by the solid-state redox reaction between M1 and CeO_(2) capture active oxygen species in gas and transform V^(4+)to V^(5+)without damage to M1 *** space-time yield of ethylene of the plasma-treated catalyst was significantly increased,in which the catalyst shows an enhancement near~100% than that of phase-pure M1 at 400℃ for ODHE *** treatment for catalysts demonstrates an effective way to convert electrical energy into chemical energy in catalyst *** conversion is achieved by using the catalyst as a medium.

关键词： Oxidative dehydrogenation of ethane(ODHE) MoVNbTeO_(x) Composite catalyst Oxygen plasma Energy conversion