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Preparation and catalytic effect of porous Co3O4 on the hydrogen storage properties of a li-B-N-H system

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Progress in Natural Science:Materials International 2017年第1期27卷 132-138页

作者： you li Yi Zhang Mingxia Gao Hongge Pan Yongfeng liu State Key Laboratory of Silicon Materials Key Laboratory of Advanced Materials and Applications for Batteries of Zhejiang Province and School of Materials Science and Engineering Zhejiang University Center of Material Science National University of Defense Technology Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education) Nankai University

A porous Co3O4with a particle size of 1–3 μm was successfully prepared by heating Co-based metal organic frameworks MOF-74（Co） up to 500 °C in air atmospheric conditions. The as-prepared porous Co3O4significantly reduced the dehydrogenation temperatures of the liBH4-2liNH2system and improved the purity of the released hydrogen. The liBH4-2liNH2-0.05/3Co3O4sample started to release hydrogen at 140 °C and released hydrogen levels of approximately 9.7 wt% at 225 °C. The end temperature for hydrogen release was lowered by 125 °C relative to that of the pristine sample. Structural analyses revealed that the as-prepared porous Co3O4is in-situ reduced to metallic Co, which functions as an active catalyst, reducing the kinetic barriers and lowering the dehydrogenation temperatures of the liBH4-2liNH2system. More importantly, the porous Co3O4-containing sample exhibited partially improved reversibility for hydrogen storage in the liBH4-2liNH2system.

关键词： Hydrogen storage Complex hydrides Borohydrides Amides Dehydrogenation

Viewpoint on optical frequency divider with 10–21 precision

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National Science Review 2016年第4期3卷 394-395页

作者： li you Department of Physics Tsinghua University

A frequency divider slaves the frequency(f)of an output at an arbitrary set ratio(R)with respect to the frequency(f)of an input wave:f=f/R,maintaining phase coherence,frequency stability and *** its wide appearance in modern electronics for radio waves and microwaves,frequency division in the optical domain,which requires two lasers(input+output),remains to be

关键词： precision Viewpoint on optical frequency divider with 10

Global regularity for a class of Monge-Ampère type equations

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Science China Mathematics 2022年第3期65卷 501-516页

作者： Mengni li you li Department of Mathematical Sciences Tsinghua UniversityBeijing 100084China Yau Mathematical Sciences Center Tsinghua UniversityBeijing 100084China

In this paper we are concerned with the global regularity of solutions to the Dirichlet problem for a class of Monge-Ampère type *** employing the concept of(a,η) type domain,we emphasize that the boundary regularity depends on the convexity of the domain in *** key idea of our proof is to provide more effective global H?lder estimates of convex solutions to the problem based on carefully choosing auxiliary functions and constructing sub-solutions.

关键词： Dirichlet problem Monge-Ampère type equation H?lder estimate

Optimal global regularity for minimal graphs over convex domains in hyperbolic space

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Frontiers of Mathematics in China 2022年第5期17卷 905-914页

作者： you li Yannan liU School of Mathematics and Statistics Beijing Technology and Business UniversityBeijing 100048China

We use the concept of the inside-(a,η,h)domain to construct a subsolution to the Dirichlet problem for minimal graphs over convex domains in hyperbolic *** an application,we prove that the Hölder exponent max{1/a,1/(... 详细信息

关键词： Minimal graph equation optimal regularity global regularity

PD-like finite time controller with simple structure for satellite attitude control

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Defence Technology（防务技术） 2023年第8期26卷 123-133页

作者： li you Ye Dong Xiao Bing Xidian University Xi'an710126China Harbin Institute of Technology Harbin 150090China Northwestern Polytechnical University Xi'an710072China

A finite time controller with PD-like structure for satellite attitude control is proposed in this *** controller is constructed with simple structure based on standard PD *** fractional order term is designed hence system could both have strong robustness and finite time convergence rate,and the advantage of finite time control and PD control is combined in this *** convergence rate is discussed by Lyapunov method,and the constraint on control parameters is given by implementing the coupled term of angular velocity and attitude ***,the accuracy at steady stage depending on control parameters is given hence system could converge to this field within finite *** stability and performance is demonstrated by numerical simulation results.

关键词： Finite time control PD-like Simple structure Attitude control

Coordinated multicast and unicast transmission in V2V underlay massive MIMO

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Science China(Information Sciences) 2022年第3期65卷 235-245页

作者： Xinxin NIU li you Xiqi GAO National Mobile Communications Research Laboratory Southeast University Purple Mountain Laboratories

This paper investigates coordinated multicast and unicast transmission for vehicle-to-vehicle(V2 V) underlay massive multiple-input multiple-output(MIMO). First, the achievable ergodic multicast rate for the cellular link and the achievable ergodic unicast rate for all the V2 V links are summed with weight to formulate the rate optimization problem, with the assumption that the statistical channel state information(CSI) is known at the base station and the transmitters of the V2 V communication pairs. We then derive the optimal transmitting directions in closed-form for the cellular link and all the V2 V links,respectively, which converts the original optimal problem to a simpler power allocation problem in the beam domain. Via invoking the concave-convex procedure, an efficient iterative algorithm with guaranteed convergence is proposed for the power allocation problem. Furthermore, we replace the objectives which contain high-complex expectation operations with their deterministic equivalents in each iteration of the proposed algorithm to achieve lower algorithm complexity. Simulation results show the fast convergence speed of the proposed power allocation algorithm and the significant performance gains of the proposed transmission design for V2 V underlay massive MIMO.

关键词： coordinated multicast and unicast transmission V2V underlay massive MIMO statistical CSI

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A divergent volume for black holes calls for no ‘firewall’

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Communications in Theoretical Physics 2020年第2期72卷 83-87页

作者： Baocheng Zhang li you School of Mathematics and Physics China University of GeosciencesWuhan 430074China State Key Laboratory of Low Dimensional Quantum Physics Department of PhysicsTsinghua UniversityBeijing 100084China Frontier Science Center for Quantum Information BeijingChina

The presumption that Hawking radiations are thermally distributed can be considered to result from their entanglement with the internal degrees of freedom for a black *** leads to the‘firewall’paradox if unitary evolution continues into Page’s time when a black hole evaporates away half of its initial ***,if the interior of a black hole houses sufficient degrees of freedom to maintain entanglement with the outside at all times,unitarity can be preserved during the complete radiation process and no firewall will be *** paper proposes a scenario that rescinds the firewall by introducing the concept of volume for a black *** on the operational definition by Christodoulou and Rovelli(Christodoulou and Rovelli 2015 ***.D 91064046),we show that the volume and its associated entropy for a collapsed black hole diverges if the final evaporation stage is treated using noncommutative *** implicates the interior of a black hole possesses adequate space to store information for a black hole of any mass,like the inside of a‘magician’s bag’.

关键词： volume entropy black hole thermodynamics firewall

A singular Monge-Ampère equation on unbounded domains

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Science China Mathematics 2018年第8期61卷 1473-1480页

作者： Huaiyu Jian you li Department of Mathematical Sciences Tsinghua University

In this paper, we study the Dirichlet problem for a singular Monge-Amp`ere type equation on unbounded domains. For a few special kinds of unbounded convex domains, we find the explicit formulas of the solutions to the problem. For general unbounded convex domain ?, we prove the existence for solutions to the problem in the space C∞(?) ∩ C(?). We also obtain the local C1/2-estimate up to the ?? and the estimate for the lower bound of the solutions.

关键词： Dirichlet problem singular Monge-Ampere equation unbounded domain

Observing second sound in ultracold Fermi gases

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National Science Review 2014年第1期1卷 2-3页

作者： li you Department of Physics Tsinghua University

Water lowing down a pipe experiences viscous drag that causes it to lose energy and slow down.A superluid,such as liquid helium(3He and4He)or electrons in a superconductor,can low without friction when in contact with a *** fascinating phenomenon,or superluidity,was discovered by Kapitza[1],Allen and Misener[2]in *** formation of a superluid is related to the formation of a Bose–Einstein condensate(BEC).4He is a boson

关键词： Observing second sound in ultracold Fermi gases