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Dynamic transport characteristics of side-coupled double-quantum-impurity systems

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Chinese Physics B 2022年第9期31卷 493-501页

作者： Yi-Jie Wang jian-hua wei Department of Physics Renmin University of ChinaBeijing 100872China

A systematic study is performed on time-dependent dynamic transport characteristics of a side-coupled double-quantum-impurity system based on the hierarchical equations of *** is found that the transport current behaves like a single quantum dot when the coupling strength is low during tunneling or Coulomb *** the case of only tunneling transition,the dynamic current oscillates due to the temporal coherence of the electron tunneling *** oscillation frequency of the transport current is related to the step voltage applied by the lead,while temperature T,electron-electron interaction U and the bandwidth W have little *** amplitude of the current oscillation exists in positive correlation with W and negative correlation with *** the increase in coupling t_(12) between impurities,the ground state of the system changes from a Kondo singlet of one impurity to a spin singlet of two ***,lowering the temperature could promote the Kondo effect to intensify the oscillation of the dynamic *** only the Coulomb transition is coupled,it is found that the two split-off Hubbard peaks move upward and have different interference effects on the Kondo peak at the Fermi surface with the increase in U_(12),from the dynamics point of view.

关键词： quantum dots tunneling transition capacitive type

Asymptotic energy efficiency analysis for the state-of-the-art relaying protocols

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The Journal of China Universities of Posts and Telecommunications 2011年第6期18卷 8-13页

作者： WANG Yu-ning ZHANG jian-hua XU wei Key Lab of Universal Wireless Communications Ministry of Education Wireless Technology Innovation Institute Beijing University of Posts and Telecommunications Beijing 100876 China

This article analyzes the energy-efficiency performances of fixed relaying schemes, selection relaying schemes and incremental relaying schemes in the three-node relay network. The closed-form asymptotic energy per good-bit （EPG） expressions for the state-of-the-art relaying protocols at high signal-to-noise ratio （SNR） regime are derived. In the formulation of the energy consumption model, the transmission, circuit and retransmission energies are all taken into account. To facilitate the comparison of energy-efficiency performances between different relaying protocols, the link reliabilities and retransmission probabilities are determined by the asymptotic outage probabilities at high SNR regime under the Rayleigh fading assumption. Computer simulations are carried out in both symmetric and asymmetric relay networks. The simulation results show the differences of system energy expenditure between these state-of-the-art relaying protocols. Finally some practical implications can be made from the observation.

关键词： green communication EPG relay energy-efficiency outage probability

ON NECESSITY OF PLACING AN AERATOR IN THE BOTTOM DISCHARGE TUNNEL AT THE LONGTAN HYDROPOWER STATION

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Journal of Hydrodynamics 2006年第6期18卷 698-701页

作者： WU jian-hua WU wei-wei RUAN Shi-ping College of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210098 China

The air entrainment for avoiding cavitation damage has been widely used in long free flow tunnels. It is crucial to determine whether an aerator is needed for shorter tunnels. In this article, the bottom discharge tunnel at the Longtan Hydropower Station was involved, for which the free flow tunnel section was only 50.00 m long. The cavitation in the tunnel with and without the aerator was investigated using the physical models of the scale 1/30, through the measurements of cavitation noise. The experimental results show that it is necessary to place the aerator at the inlet of the free flow section for higher reservoir level to protect this tunnel from cavitation damage.

关键词： aerator bottom discharge tunnel cavitation damage cavitation noise Longtan Hydropower Station

Adaptive fuzzy integral sliding mode velocity control for the cutting system of a trench cutter

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Frontiers of Information Technology & Electronic Engineering 2016年第1期17卷 55-66页

作者： Qi-yan TIAN jian-hua wei Jin-hui FANG Kai GUO State Key Laboratory of Fluid Power&Mechatronic Systems Zhejiang UniversityHangzhou 310027China

This paper presents a velocity controller for the cutting system of a trench cutter(TC). The cutting velocity of a cutting system is affected by the unknown load characteristics of rock and soil. In addition, geological conditions vary with time. Due to the complex load characteristics of rock and soil, the cutting load torque of a cutter is related to the geological conditions and the feeding velocity of the cutter. Moreover, a cutter's dynamic model is subjected to uncertainties with unknown effects on its function. In this study, to deal with the particular characteristics of a cutting system, a novel adaptive fuzzy integral sliding mode control(AFISMC) is designed for controlling cutting velocity. The model combines the robust characteristics of an integral sliding mode controller with the adaptive adjusting characteristics of an adaptive fuzzy controller. The AFISMC cutting velocity controller is synthesized using the backstepping technique. The stability of the whole system including the fuzzy inference system, integral sliding mode controller, and the cutting system is proven using the Lyapunov theory. Experiments have been conducted on a TC test bench with the AFISMC under different operating conditions. The experimental results demonstrate that the proposed AFISMC cutting velocity controller gives a superior and robust velocity tracking performance.

关键词： Cutting system, Electro-hydraulic system, Cutting velocity control, Adaptive fuzzy integral sliding mode control

Zero-energy modes in serially coupled double quantum dots

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Chinese Physics B 2020年第6期29卷 441-445页

作者： Fu-Li Sun Zhen-hua Li jian-hua wei Department of Physics&Beijing Key Laboratory of Optoelectronic Functional Materials and Micro-nano Devices Renmin University of ChinaBeijing 100872China School of Physical Science and Technology&Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education Lanzhou UniversityLanzhou 730000China

We investigate symmetrically coupled double quantum dots via the hierarchical equations of motion method and propose a novel zero-energy mode(ZEM) at a temperature above the spin singlet–triplet transition temperature. Owing to the resonance of electron quasi-particle and hole quasi-particle, ZEM has a peak at ω = 0 in the spectral density *** further examine the effect of the magnetic field on the ZEM, where an entanglement of spin and charge has been determined;therefore, the magnetic field can split the ZEM in the spectra.

关键词： zero-energy mode quantum dot temperature

Theoretical study on the exciton dynamics of coherent excitation energy transfer in the phycoerythrin 545 light-harvesting complex

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Chinese Physics B 2022年第1期31卷 631-641页

作者： Xue-Yan Cui Yi-Jing Yan jian-hua wei Department of Physics&Beijing Key Laboratory of Optoelectronic Functional Materials and Micro-nano Devices Renmin University of ChinaBeijing 100872China Hefei National Laboratory for Physical Sciences at the Microscale&Department of Chemical Physics University of Science and Technology of ChinaHefei 230026China

The experimental observation of long-lived quantum coherence in the excitation energy transfer(EET)process of the several photosynthetic light-harvesting complexes at low and room temperatures has aroused hot *** challenges the common perception in the field of complicated pigment molecular systems and evokes considerable theoretical efforts to seek reasonable *** this work,we investigate the coherent exciton dynamics of the phycoerythrin 545(PE545)*** use the dissipation equation of motion to theoretically investigate the effect of the local pigment vibrations on the population transfer *** result indicates that the realistic local pigment vibrations do assist the energy *** demonstrate the coherence between different pigment molecules in the PE545 system is an essential ingredient in the EET process among various *** coherence makes the excitation energy delocalized,which leads to the redistribution of the excitation among all the chromophores in the steady ***,we investigate the effects of the complex high-frequency spectral density function on the exciton dynamics and find that the high-frequency Brownian oscillator model contributes most to the exciton dynamic *** discussions on the local pigment vibrations of the Brownian oscillator model suggest that the local heterogeneous protein environments and the effects of active vibration modes play a significant role in coherent energy transport.

关键词： exciton dynamics light-harvesting complex quantum coherence

Chiral splitting of Kondo peak in triangular triple quantum dot

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Chinese Physics B 2022年第5期31卷 593-601页

作者： Yi-Ming Liu Yuan-Dong Wang jian-hua wei Department of Physics Renmin University of ChinaBeijing 100872China School of Electronic Electrical and Communication EngineeringUniversity of Chinese Academy of SciencesBeijing 100049China

New characteristics of the Kondo effect,arising from spin chirality induced by the Berry phase in the equilibrium state,are *** analysis is based on the hierarchical equations of motion(HEOM)approach in a triangular triple quantum-dot(TTQD)*** the absence of magnetic field,TTQD has four-fold degenerate chiral ground states with degenerate spin *** a perpendicular magnetic field is applied,the chiral interaction is induced by the magnetic flux threading through TTQD and the four-fold degenerate states split into two chiral state *** chiral excited states manifest as chiral splitting of the Kondo peak in the spectral *** theoretical analysis is confirmed by the numerical ***,under a Zeeman magnetic field B,the chiral Kondo peak splits into four peaks,owing to the splitting of spin *** influence of spin chirality on the Kondo effect signifies an important role of the phase *** work provides insight into the quantum transport of strongly correlated electronic systems.

关键词： Kondo effect quantum dot chiral splitting

Synthesis of 9-Arylpolyhydroacridine Promoted by Ionic Liquid Under Solvent-free Condition

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Chinese Chemical Letters 2006年第7期17卷 874-876页

作者： jian hua wei Yi Qun LI Xi Zhong LIAN Mei Yun ZHOU Department of Chemistry Jinan University Guangzhou 510632

The condensation reactions of aromatic aldehydes, 5,5-dimethyl-1,3-cyclohexanedione and ammonium acetate efficiently promoted by several ionic liquids under solvent-free condition to afford corresponding 3, 3, 6, 6-te... 详细信息

关键词： 9-Arylpolyhydroacridine ionic liquid synthesis.

Manipulation of internal blockage in triangular triple quantum dot

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Chinese Physics B 2024年第5期33卷 588-593页

作者：齐月魏建华 Department of Physics Renmin UniversityBeijing 100876China

We utilize the calculation of hierarchical equations of motion to demonstrate that the spin-dependent properties between adjacent quantum dots(QDs)can be changed by breaking the internal symmetry configuration,corresponding to the inversion of dominant chiral *** the linear triple quantum dots(LTQDs)connected to two electron reservoirs,we can observe that the blockage appears at the triangle triple quantum dots(TTQDs)by gradually increasing the coupling strength between next-nearest double *** the initial coupling between LTQDs has altered,the internal chiral circulation also undergoes the corresponding transform,thus achieving qualitative regulation and detection of the blocking *** also investigate the response of the chiral circulation to the dot–lead coupling strength,indicating the overall robust chiral circulation of the TTQDs frustration.

关键词： quantum dots chiral topology blocking