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Fine Doppler shift acquisition algorithm for BeiDou software receiver by a look-up table

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Journal of Systems Engineering and Electronics 2020年第3期31卷 612-625页

作者： QIU Wenqi ZENG Qingxi gao chang LYU Chade State Key Laboratory of Automotive Simulation and Control Jilin UniversityChangchun 130012China Non-destructive Detection and Monitoring Technology for High-speed Transportation Facilities Key Laboratory of Ministry of Industry and Information Technology Nanjing 211106China College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China

The BeiDou software receiver uses the fast Fourier transform(FFT)to perform the *** Doppler shift estimation accuracy should be less than 500 Hz to ensure satellite signals to enter a locked state in the tracking *** the frequency step is usually 500 Hz or larger,the Doppler shift estimation accuracy cannot guarantee that satellite signals are brought into a stable tracking *** straightforward solutions consist in increasing the sampling time and using zero-padding to improve the frequency resolution of the ***,these solutions intensify the complexity and amount of *** contradiction between the acquisition accuracy and the computational load leads us to research for a more simple and effective algorithm,which achieves fine acquisition by a look-up *** coarse acquisition using the parallel frequency acquisition(PFA)algorithm,the proposed algorithm optimizes the Doppler shift estimation through the look-up table method based on the FFT results to improve the acquisition accuracy of the Doppler shift with a minimal additional computing *** the Doppler shift is within the queryable range of the table,the proposed algorithm can improve the Doppler shift estimation accuracy to 50 Hz for the BeiDou B1I signal.

关键词： fine acquisition fast Fourier transform(FFT) table look-up parallel frequency acquisition(PFA) BeiDou

Fermion Entropy of Vaidya-Bonner Black Hole

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Chinese Physics Letters 2001年第9期18卷 1167-1169页

作者： gao chang-Jun SHEN You-Gen Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030 National Astronomical Observatories Chinese Academy of SciencesBeijing 100012 Institute of Theoretical Physics Chinese Academy of SciencesBeijing 100080

Using the membrane model which is based on the brick-wall model, we have calculated the free energy and entropy of the Vaidya-Bonner black hole due to fermion fields. The result shows that the entropy of the Vaidya-Bonner black hole is exactly proportional to the area of its event horizon. The relationship between the entropy and event horizon in such a non-static case is just the same as that in a static or stationary cases.

关键词： horizon entropy Vaidya

Experimental and computational studies on flow behavior of gas-solid fluidized bed with disparately sized binary particles

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Particuology 2008年第2期6卷 59-71页

作者： Jinsen gao Jian chang Chunxi Lu Chunming Xu State Key Laboratory of Heavy Oil Processing China University of Petroleum Changping Beijing 102249 China

This paper presents experimental and computational studies on the flow behavior of a gas-solid fluidized bed with disparately sized binary particle mixtures. The mixing/segregation behavior and segregation efficiency of the small and large particles are investigated experimentally. Particle composition and operating conditions that influence the fluidization behavior of mixing/segregation are examined. Based on the granular kinetics theory, a multi-fluid CFD model has been developed and verified against the experimental results. The simulation results are in reasonable agreement with experimental data. The results showed that the smaller particles are found near the bed surface while the larger particles tend to settle down to the bed bottom in turbulent fluidized bed. However, complete segregation of the binary particles does not occur in the gas velocity range of 0.695-0.904 m/s. Segregation efficiency increases with increasing gas velocity and mean residence time of the binary particles, but decreases with increasing the small particle concentration. The calculated results also show that the small particles move downward in the wall region and upward in the core. Due to the effect of large particles on the movement of small particles, the small particles present a more turbulent velocity profile in the dense phase than that in the dilute phase.

关键词： Binary particles Distinct size difference Mixing Segregation Fluidized bed CFD

Ag^(+)、Zn^(2+)、Cr^(3+)改性Y型分子筛吸附脱除喹啉的模拟计算研究

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原子与分子物理学报 2025年第1期42卷 61-68页

作者：孙潇镝唐克高畅富添王聚财洪新辽宁工业大学化学与环境工程学院锦州121001 葫芦岛市应急管理局葫芦岛125000

首先考察了吸附时间对三种改性Y型分子筛AgY、ZnY、CrY吸附脱除模拟燃料中喹啉的影响,结果发现三种分子筛对喹啉的吸附容量和去除率大小顺序均为:AgY>CrY>ZnY.运用Materials Studio软件,采用巨正则蒙特卡洛(GCMC)和密度泛函理论(DFT)对... 详细信息

首先考察了吸附时间对三种改性Y型分子筛AgY、ZnY、CrY吸附脱除模拟燃料中喹啉的影响,结果发现三种分子筛对喹啉的吸附容量和去除率大小顺序均为:AgY>CrY>ZnY.运用Materials Studio软件,采用巨正则蒙特卡洛(GCMC)和密度泛函理论(DFT)对改性Y型分子筛吸附喹啉机理进行了模拟计算研究,得出以下结论:模拟计算AgY、ZnY、CrY的比表面积和孔体积与其低温N2吸附-脱附表征结果基本一致,并且发现改性Y型分子筛的吸附脱氮能力与比表面积和孔体积关系不大;以Fukui函数为基础,采用Mulliken和Hirshfeld两种布局数分析方法模拟计算了三种改性Y型分子筛的相对亲电性并分析Lewis酸强弱,其Lewis酸大小顺序为:AgY>CrY>ZnY;对三种改性分子筛进行了前线轨道分析,其化学吸附活性大小为AgYCrY>ZnY,模拟计算所得各种结果与实验结果顺序完全一致.

关键词： Y型分子筛改性吸附喹啉模拟

Multi-Mode Guided Waves Based Reference-Free Damage Diagnostic Imaging in Plates

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Structural Durability & Health Monitoring 2019年第1期13卷 41-59页

作者： Jiaqi Zhang Kehai Liu chang gao Zhanjun Wu Yuebin Zheng Dongyue gao State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian116024China School of Civil Engineering Dalian University of TechnologyDalian116024China School of Aeronautics and Astronautics Sun Yat-sen UniversityGuangzhou510275China

Probability-based diagnostic imaging(PDI)is one of the most well-known damage identification methods using guided *** is usually applied to diagnose damage in *** previous studies were dependent on the certain damage index(DI)which is always calculated from the guided wave *** conventional methods,DI is simply defined by comparing the real-time data with the baseline data as ***,the baseline signal is easily affected by varying environmental conditions of *** this paper,a reference-free diagnostic imaging method is developed to avoid the influence of environmental factors,such as temperature and load *** DI is defined based on the mode conversion of multi-mode guided waves with realtime signals without baseline *** improve the accuracy of diagnosis,two terms are included in the reference-free *** is called energy DI,which is defined based on the feature of signal *** other is called correlation DI and is defined based on the correlation *** the PDI algorithm can be carried out instantaneously according to the reference-free *** real-time signals which are used to calculate DI are collected by the piezoelectric lead zirconate titanate(PZT)transducers placed on both sides of a *** numerical simulations by the finite element(FE)method on aluminum plates with PZT arrays are performed to validate the effectiveness of the reference-free damage diagnostic *** approach is validated by two different arrays:a circle network and a square *** results of diagnostic imaging are demonstrated and discussed in this ***,the advantage of reference-free DI is investigated by comparing the accuracy of defined reference-free DI and energy DI.

关键词： Multi-mode guided waves probability-based diagnostic imaging referencefree mode conversion

Recent Development of Integrated Systems of Microsupercapacitors

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Energy Material Advances 2022年第1期2022卷 132-146页

作者： chang gao Yuyang Gu Yang Zhao Liangti Qu Key Laboratory of Cluster Science Ministry of Education of ChinaBeijing Key Laboratory of Photoelectronic/Electrophotonic Conversion MaterialsSchool of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 100081China School of Electronic and Information Engineering Beijing Jiaotong UniversityBeijing 100044China Key Laboratory of Organic Optoelectronics&Molecular Engineering of Ministry of Education Department of ChemistryTsinghua UniversityBeijing 100084China

Development of wearable and portable electronics promotes the miniaturization of energy storage ***(MSC)featuring in fast charging and discharging rates,long cycle life,and high-power density stands out from miniaturized energy storage devices,particularly for its small size and adjustable structure which is easily processed to integrate with other on-chip *** this review,we systematically analyzed the MSC integration with other electronics from the perspective of structures and *** the beginning,we briefly introduced typical MSCs with unique ***,applications and integrations of MSCs with energy-consuming or energy-generating electronics were ***,compatible materials and designed structure of the all-in-one device were also ***,challenges and future development of MSC-integrated systems were put forward.

关键词： consuming generating electronics

Determination of Critical Parameters of Carbon Dioxide+Butyraldehyde System with Different Compositions

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Chemical Research in Chinese Universities 2005年第6期21卷 687-691页

作者： ZHANG Jing-chang gao Xi-xin CAO Wei-liang Key Laboratory of Science and Technology of Controllable Chemical Reactions of Ministry of Education Institute of Modern Catalysis Beijing University of Chemical Technology Beijing 100029 P. R. China

Supercritical carbon dioxide（SC-CO2 ） is considered in green chemistry as a substitute for conventional solvents in chemical reactions due to its environmentally benign character. Recently we have reported the homogeneous hydroformylation of propylene in supercritical carbon dioxide（ SC-CO2 ） , which is an example of this kind of application of carbon dioxide. The determination for the critical parameters of carbon dioxide ＋ butyraldehyde mixtures is necessary for this reaction design which is the focus of the present paper. The critical parameters of the binary systems were determined via the static visual method at a constant volume with the molar fraction of butyraldehyde ranging from 1.0% to 2. 2% and the pressure ranging from 5 to 10 MPa. The experimental results show that the critical pressure and temperature increased with increasing the molar fraction of butyraldehyde. The bubble（dew） temperatures and the bubble （dew） pressures for the binary systems were also determined experimentally. The p-T Figures at different compositions of the binary systems were described. In addition, the critical compressibility factors Zc of the binary systems at different concentrations of n-butyraldehyde were calculated. It was found that the critical compressibility factor values of the binary systems decreased with increasing the molar fraction of n-butyraldehyde in the experimental range.

关键词： Carbon dioxide + butyraldehyde binary system Critical temperature Critical pressure p-T Figure Critical compressibility factor

BeiDou B1I/B3I Signals Joint Tracking Algorithm Based on Kalman Filter

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第6期36卷 879-888页

作者： LYU Chade ZENG Qingzi XU Rui gao chang QIU Wenqi College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106P.R.China Key Laboratory of Nuclear Technology Application and Radiation Protection in Astronautics(Nanjing University of Aeronautics and Astronautics) Ministry of Industry and Information TechnologyNanjing 211106P.R.China

Dual-frequency satellite positioning receivers are widely used because they can eliminate ionospheric delay and solve the full-circumference ambiguity ***,in traditional dual-frequency receivers,the relevance of dual-frequency signals are not considered,and,with no improvement imposed to the tracking loop,two independent tracking loops are used to achieve the tracking of dual-frequency *** this paper,the Bei Dou dual-frequency signals joint tracking algorithm based on Kalman filter is proposed for the tracking of Bei Dou B1I and B3I dual-frequency *** the relevance of B1I and B3I signals into consideration,the algorithm adds a Kalman filter between the phase detector and carrier loop filter of the traditional dual-frequency independent tracking *** output results of the phase detectors of the B1I and B3I branches are then combined and filtered by the Kalman filter,and the results are input to the carrier loop filters of the corresponding *** by experiments,the algorithm not only enables the loop to enter a stable tracking state quickly,but also reduces the noise bandwidth of the two loop filters by about 10 Hz with the same tracking performance obtained.

关键词： BeiDou B1I/B3I dual-frequency signals joint tracking Kalman filter

Fabrication of Porous Silica Microspheres Under the Assistance of Solid Template

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Chemical Research in Chinese Universities 2012年第3期28卷 546-554页

作者： MAO Zheng-wei HU Ling ZHAO Qing-he gao chang-you Key Laboratory of Macromolecular Synthesis and Functionalization Ministry of EducationDepartment of Polymer Science and EngineeringZhejiang UniversityHangzhou 310027P.R.China

Spherical porous silica microparticles were synthesized by a sol-gel process in the presence of porous CaCO3 particles, followed by removal of the carbonate templates. The resulting silica particles had very high porosity and wide pore size distribution, whose surface area and pore volume reached up to 367.3 m2/g and 0.72 mL/g, re- spectively. With a larger amount of the tetraethyl orthosilicate used, hollow silica microspheres were further obtained. Characterization was made to confirm the chemical and physical structures and purity of the silica microspheres. Spontaneous deposition of tetramethyl rhodamine isothiocyanate labeled dextran into the microspheres was also ob- served due to the charge attraction.

关键词： Porosity Deposition Sol-gel preparation Silicone dioxide Microsphere