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high frequency Communication Network with Diversity: System Structure and Key Enabling Techniques

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China Communications 2018年第9期15卷 46-59页

作者： Kun Xu Bin Jiang Zeyou Su Shengqing Wang Makun Guo Xiao Li Zhiyong Du College of Information and Communication National University of Defense Technology

high frequency sky wave communication suffers from poor performance including poor link quality and low link success rate. To enhance performance, diversity technology is proposed in the high frequency communication network(HFCN) in this ***, we present the benefits and the challenges by introducing diversity technology into the existing HFCN. Secondly, to exploit the benefits fully and overcome the challenges, we propose a system structure suitable for deploying diversity technology in HFCN in large scale,based on the cloud radio access network and software defined network. Moreover, we present a general structure for the real-time updating frequency management system that plays a more important role especially when resource consuming(e.g., frequency) diversity technology is deployed. Thirdly, we investigate the key techniques enabling diversity technology deployment. Finally, we point out the future research directions to help the HFCN with diversity work more efficiently and intelligently.

关键词： high frequency high frequency communication network diversity technology access layer and core layer frequency management system

high frequency performance of nano-scale ultra-thin-body Schottky-barrier n-MOSFETs

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Science China(Information Sciences) 2011年第8期54卷 1756-1761页

作者： DU Gang,LIU XiaoYan & HAN RuQi Institute of Microelectronics,Peking University,Beijing 100871,China 1. Institute of Microelectronics Peking University Beijing 100871 China

The high frequency performances of nano-scale ultra-thin-body (UTB) Schottky-barrier n-MOSFETs (SB-nMOSFETs) are investigated using 2D full-band self-consistent ensemble Monte Carlo method. The UTB SB-nMOSFET devices offer excellent RF performance with high values of f T and f *** significant dependence of f T and f max on gate voltage and weak dependence on barrier height are ***,the significant dependence of g m and g ds on both gate voltage and SB height are shown. Moreover,the scalability of f T is outstanding and close to the ideal case (f T ∝ 1/L2g ). The high frequency performances of 45 nm channel length SB-nMOSFETs at ballistic transport limit are also investigated. Results show that scattering strongly affects the capacitances C gs,C gd and C *** ballistic transport limit the f T and f max are almost 10 times *** Scattering effects in nano-scale SB-nMOSFETs cannot be neglected.

关键词： Monte Carlo ultra thin body (UTB) Schottky-barrier MOSFETs (SB-MOSFETs) high frequency

A review of high frequency resonant DC-DC power converters:Topologies and planar magnetic technologies

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Science China(Technological Sciences) 2020年第8期63卷 1335-1347页

作者： XU DianGuo GUAN YueShi WANG YiJie WANG Wei School of Electrical Engineering and Automation Harbin Institute of TechnologyHarbin 150001China

With the development of high frequency resonant DC-DC power converters,the system efficiency,power density and dynamic characteristics have been significantly *** frequency resonant DC-DC converters have been applied in DC grid,renewable energy,transportation,aerospace,point-of-load(POL)power supply and many other *** high switching frequencies,switching loss and magnetic loss are the main concerns;thus,the resonant topology and planar magnetic are two key technologies to reduce *** review compares different resonant topologies and analyzes the advantages and disadvantages respectively,such as LLC circuit,dual active bridge(DAB)circuit,and other high order resonant *** planar magnetic components,optimal winding structures,modeling methods and integration methods are thoroughly *** corresponding topics,the opportunities and challenges in the future development are summarized,which mainly focus on the characteristics of wide bandgap devices,such as the dynamic resistance,output capacitance loss and also the integrated *** review can be a helpful guidance when designing high frequency resonant DC-DC converters.

关键词： high frequency resonant DC-DC power converter planar magnetic components

Dispersive behavior of high frequency Rayleigh waves propagating on an elastic half space

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Acta Mechanica Sinica 2021年第4期37卷 562-569,I0001页

作者： Ning Jia Zhilong Peng Jianjun Li Yin Yao Shaohua Chen Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China Beijing Key Laboratory of Lightweight Multi-Functional Composite Materials and Structures Beijing Institute of TechnologyBeijing 100081China School of Mechanical and Electrical Engineering Central South UniversityChangsha 410083China

When the wavelength of Rayleigh wave is comparable with nanometers,Rayleigh wave will become *** an interesting phenomenon cannot be predicted by the classical theory of *** order to reveal the internal mechanism and influencing factors of the dispersion,a model of Rayleigh wave propagating on an elastic half space is established and analyzed by a new theory of surface elastodynamics,in which the surface effect characterized by both the surface energy density and surface inertia is *** intrinsic nano-length scales,including the ratio of bulk surface energy density to bulk shear modulus and the ratio of surface mass density to bulk mass density,are *** is found that when the wavelength of Rayleigh wave is comparable with the two intrinsic nano-lengths,the surface effect becomes *** a result,dispersion of Rayleigh wave happens and even two Rayleigh waves with different wave speeds may ***,it is found that the effect of surface energy density would enhance the wave speed,while that of surface inertia would reduce *** the increase of wavelength,both effects gradually disappear and the Rayleigh wave speed degenerates to the classical *** results of this paper are not only helpful to understand the dispersive mechanism of elastic waves,but also helpful for the fine design and measurement of nanowave devices.

关键词： Rayleigh wave high frequency Dispersion Elastodynamics Surface effect

Gate-structure optimization for high frequency power AlGaN/GaN HEMTs

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Journal of Semiconductors 2010年第5期31卷 51-54页

作者：王东方袁婷婷魏珂陈晓娟刘新宇 Institute of Microelectronics Chinese Academy of Sciences Graduated University of the Chinese Academy of Sciences

The influence of gate-head and gate-source-spacing on the performance of AlGaN/GaN HEMTs was studied. Suggestions are then made to improve the performance of high frequency power AlGaN/GaN HEMTs by optimizing the *** the field-plate length can effectively enhance gain,current gain cutoff frequency and maximum frequency of *** reducing the field-plate length,devices with 0.35μm gate length have exhibited a current gain cutoff frequency of 30 GHz and a maximum frequency of oscillation of 80 *** maximum frequency of oscillation can be further optimized either by increasing the gate-metal thickness,or by using aτ-shape gate （the gate where the gate-head tends to the source side）.Reducing the gate-source spacing can enhance the maximum drain-current and breakdown voltage,which is beneficial in enhancing the maximum output power of AlGaN/GaN HEMTs.

关键词： AlGaN/GaN HEMT high frequency gate structure power

Magnitude and rupture duration from high frequency teleseismic P wave with projected landweber deconvolution

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Science China Earth Sciences 2013年第1期56卷 13-21页

作者： ZHENG Yong NI SiDao CHEN Yong TAN Ying Don HELMBERGER State Key Laboratory of Geodesy and Earth's Dynamics Institute of Geodesy and Geophysics Chinese Academy of Sciences Institute of Geophysics Chinese Earthquake Administration Seismological Laboratory California Institute of Technology

Earthquake magnitude and rupture duration are among the most important parameters characterizing an earthquake for the purpose of early tsunami warning. While they can be routinely determined from broadband P waveforms with iterative inver- sion procedures, the inversion procedures may fail when the rupture either lasts longer than the interval between P and later ar- rivals or requires too much time or human intervention. Little contaminated by later arrivals, high frequency P waves are useful for modeling earthquake source processes, though the envelope waveform is affected by strong scattering in lithosphere. With high frequency envelopes from aftershocks as Empirical Green＇s Function （EGF）, the coda effects can be removed and more accurate relative source time function （RSTF） of the main shock can be obtained. Assuming that RSTFs cannot be negative, we use the projected Landweber deconvolution method （PLD） to obtain high frequency RSTFs because PLD method has the ad- vantage of non-negativity, causality, and compactness （finite duration）. We are able to determine rupture durations of four large earthquakes： the 2004 Sumatra-Andaman earthquake, the 2005 Nias event, the 2006 Java event, and the 2011 Tokuko earthquake. The rupture durations of the Sumatra-Andaman, Nias, and Tohuko events are found to be around 550, 1 i0, and 120 s respectively, consistent with previous studies. The rupture duration of the Java event is about 130 s, supporting that the Java event is a tsunami earthquake. The magnitudes of these earthquakes are found to depend on both the amplitude and the duration of the deconvolved waveforms, and can be approximated by integrating these waveforms.

关键词： high frequency deconvolution rupture duration magnitude

Flocking of multi-agent system with high frequency feedback robust control

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The Journal of China Universities of Posts and Telecommunications 2019年第4期26卷 43-50页

作者： Zhang Qing Wang Jie Yang Zhengquan Chen Zengqiang College of Science Civil Aviation University of ChinaTianjin 300300China Department of Automation Nankai UniversityTianjin 300071China

Flocking of multi-agent system with high-frequency feedback robust control is put forward in *** controller that has high-frequency feedback robust control is designed;it is proved that the velocity error is bounded and no collision occurs between the multi-agent under the action of the high-frequency feedback robust control by employing the boundedness theorem and the Lyapunov stability *** of multi-agent system can be formed under the action of the high-frequency feedback robust *** of multi-agent system with high-frequency feedback robust control is realized in numerical *** with the state diagram and velocity error diagram of the original flocking of multi-agent system in the simulation,flocking of multi-agent system with high-frequency feedback robust control has better stability.

关键词： flocking multi-agent system high frequency robust control

high frequency behaviours and Mssbauer study of field annealed FeCuNbSiB alloy ribbons

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Chinese Physics B 2010年第9期19卷 570-575页

作者：马小明李志伟位建强王涛李发伸 Institute of Applied Magnetics Key Laboratory for Magnetism and Magnetic Materials of the Ministry of EducationLanzhou University

This paper investigates the high frequency behaviours and magnetic anisotropy of rapidly solidified FINEMET （***3Cul） alloy ribbons annealed in an applied magnetic field. It finds that the ribbons annealed with the applied magnetic field show much higher resonance frequencies and have even higher permeability at higher frequencies than the samples annealed without the magnetic field and the non-annealed ribbons. MSssbauer spectroscopy had been employed to study the spatial distribution of the magnetic moments of five selected FINEMET alloy ribbons in different heat-treated conditions. The results show that an easy plane has been established after annealling in the magnetic field, while for the other ribbons this effect is not significant. Hence, the relationship between magnetic field annealing and high frequency property has been bridged by the bianisotropic theory.

关键词： FINEMET field annealing MSssbauer spectrum high frequency

An innovative detection method of high frequency BPSK signal with low signal-to-noise ratio

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Journal of Harbin Institute of Technology(New Series) 2012年第6期19卷 93-99页

作者：石硕徐立振顾学迈张宏莉 National Key Laboratory of Communication System and Information Control Technology Harbin Institute of Technology

Based on chaotic oscillator system, this paper proposes a novel method on high frequency low signal- to-noise ratio BPSK（ Binary Phase Shift Keying） signal detection. Chaotic oscillator system is a typical non-lin- ear system which is sensitive to periodic signals and immune to noise at the same time. Those properties make it possible to detect low signal-to-noise ratio signals. The BPSK signal is a common signal type which is widely used in modern communication. Starting from the analysis of advantages of chaotic, os~.illator system and signal features of the BPSK signal, we put forward a unique method that can detect low signar-to-noise ratio BPSK sig- nals with high frequency. The simulation results show that the novel method can dclct.t low signal-to-noise ratio BPSK signals with frequency in an order of magnitude of l0s Hz, and the input Signal-to-Noise Ratio threshold can be -20 dB.

关键词： low signal-to-noise ratio signal detection chaotic oscillator system Binary Phase Shift Keying high frequency