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Almost perfect sequences based on cyclic difference sets

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Journal of Systems Engineering and Electronics 2007年第1期18卷 155-159页

作者： Chen Gang zhao zhengyu Ionosphere Lab Wuhan Univ. Wuhan 430070 E R. China

The perfect sequences are so ideal that all out-of-phase autocorrelation coefficients are zero, and if the sequences are used as the coding modulating signal for the phase-modulated radar, there will be no interference of side lobes theoretically. However, it has been proved that there are no binary perfect sequences of period 4 〈 n ≤ 12100. Hence, the almost perfect sequences with all out-of-phase autocorrelation coefficients as zero except one are of great practice in engineering. Currently, the cyclic difference set is one of most effective tools to analyze the binary sequences with perfect periodic autocorrelation function. In this article, two characteristic formulas corresponding to the autocorrelation and symmetric structure of almost perfect sequences are calculated respectively. All almost perfect sequences with period n, which is a multiple of 4, can be figured out by the two formulas. Several almost perfect sequences with different periods have been hunted by the program based on the two formulas and then applied to the simulation program and practical application for ionospheric sounding.

关键词： Perfect sequence Almost perfect sequence Cyclic difference sets Autocorrelation coefficients Side lobes Ionospheric sounding

Numerical study of radio wave propagation in clear air acoustic scatterer

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Journal of Systems Engineering and Electronics 2018年第4期29卷 684-692页

作者： WANG Panpan ZHOU Chen zhao zhengyu Department of Space Physics School of Electronic Information Wuhan University

This paper numerically investigates the radio wave scattering by the artificial acoustic disturbance in the atmospheric boundary layer. The numerical model is based on the finitedifference time-domain（FDTD） method for radio wave propagation and fluid simulation for atmospheric disturbance by acoustics waves. The characteristics of radio wave scattering propagation in the artificial acoustic perturbations are investigated by this numerical model. The numerical simulation results demonstrate that the radio wave propagation scattered by acoustic scatterer has the characteristic of forward tropospheric scatter. When the radio waves are scattered, they distribute in all directions; a majority of radio waves continues to propagate along the original direction, and only a small part of the energy is scattered. For the same acoustic scatterer, if we merely change the radio wave emission elevation, the horizontal spans of forward scattering radio wave packets centers gradually decrease with the increasing of emission elevations; and the energy of wave packets increases firstly and then decreases with launching elevation, reaching the maximum at a certain angle. If we merely change the wave emitting position, the horizontal spans decrease with the increasing of emission positions, and the energy of wave packets also increases firstly and then decreases with launch position, reaching the maximum at a certain position. This approach can be very promising for atmospheric scatter communications.

关键词： radio waves scattering propagation clear air atmo-sphere acoustic scatterer scatter communication.

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《针灸秘验》刺血疗法特色探析

光明中医 2024年第4期39卷 660-663页

作者：吴俊郿赵征宇成都中医药大学针灸推拿学院四川成都610075

通过研习彭静山《针灸秘验》刺血医案归纳总结刺血疗法的规律及特点。彭氏运用刺血疗法灵活多变,广泛用于泻热解毒、镇静止痛、化瘀消癥、急救研究、消肿利水等方面。个人特色鲜明,方式方法独特。此文拟从刺血工具、刺血部位、刺血出血... 详细信息

通过研习彭静山《针灸秘验》刺血医案归纳总结刺血疗法的规律及特点。彭氏运用刺血疗法灵活多变,广泛用于泻热解毒、镇静止痛、化瘀消癥、急救研究、消肿利水等方面。个人特色鲜明,方式方法独特。此文拟从刺血工具、刺血部位、刺血出血量、刺血适应证以及刺血特色5个方面进行阐发,力图挖掘《针灸秘验》刺血疗法运用规律,加深对彭静山传统刺血疗法的认识与理解,加强临床运用水平,以期更好地传承其学术思想。

关键词：《针灸秘验》刺血疗法彭静山

Construction of Fe/Ag galvanic couple by mechanochemical in-situ reduced Ag to accelerate the degradation of Fe-based implant

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中国科学:技术科学英文版 2023年第10期66卷 2824-2836页

作者： YANG WenJing SONG Hao zhao zhengyu SHUAI CiJun PAN Hao Institute of Bioadditive Manufacturing Jiangxi University of Science and TechnologyNanchang 330013China Shenzhen Institute of Information Technology School of Sino-German RoboticsShenzhen 518172China State Key Laboratory of Precision Manufacturing for Extreme Service Performance College of Mechanical and Electrical EngineeringCentral South UniversityChangsha 410083China Department of Periodontics&Oral Mucosal Section Xiangya Stomatological HospitalCentral South UniversityChangsha 410013China

Orthopedic applications of Fe have been hindered by the insufficient degradation *** with noble elements(such as Ag,Au,and Pt)to generate galvanic couples is a feasible ***,the direct preparation of homogenous alloys by mechanical alloying or metallurgy is difficult because of the differences in strength,density,and *** this study,Ag_(2)O was selected as the precursor phase for incorporation into Fe to achieve a homogeneous distribution of Ag,which was then reduced in situ to Ag via a mechanochemical reduction reaction during mechanical *** composite powders were printed as implants by selective laser melting,where a fast cooling rate contributed to the retention of the phase distribution of the obtained *** electrochemical tests showed that the Fe-Ag_(2)O implant had a high corrosion current density(21.88±0.12μA/cm^(2))and instantaneous corrosion rate(0.23±0.05 mm/year).Moreover,the implant exhibited a faster degradation rate(0.22 mm/year)than Fe(0.15 mm/year)and Fe-Ag(0.21 mm/year)after immersion for 28 *** acceleration mechanism of the implant could be attributed to the uniformly distributed Ag particles triggering many galvanic couples with the Fe grains,which was confirmed by the observation of the corrosion *** addition,the composite implants exhibited good biocompatibility and antibacterial properties.

关键词： biodegradable implant mechanochemical reduction uniform dispersion galvanic corrosion

Inertia gravity wave activity in the troposphere and lower stratosphere observed by Wuhan MST radar

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Science China Earth Sciences 2016年第5期59卷 1066-1073页

作者： QING HaiYin ZHOU Chen zhao zhengyu NI BinBin ZHANG YuanNong Department of Space Physics School of Electronic Information Wuhan University

The troposphere and lower stratosphere(TLS) is a region with active atmospheric fluctuations. The Wuhan Mesosphere-Stratosphere-Troposphere(MST) radar is the first MST radar to have become operational in China's Mainland. It is dedicated to real-time atmospheric observations. In this paper, two case studies about inertia gravity waves(IGWs) derived from three-dimensional wind field data collected with the Wuhan MST radar are presented. The intrinsic frequencies, vertical wavelengths, horizontal wavelengths, vertical wavenumber spectra, and energy density are calculated and analyzed. In this paper, we also report on multiple waves existing in the lower stratosphere observed by the Wuhan MST radar. Lomb-Scargle spectral analysis and the hodograph method were used to derive the vertical wavenumber and propagation direction. Meanwhile, an identical IGW is observed by Wuhan MST radar both in troposphere and lower stratosphere regions. Combining the observations, the source of the latter IGW detected in the TLS would be the jet streams located in the tropopause region, which also produced wind shear above and below the tropopause.

关键词： Wuhan MST radar TLS Inertia gravity waves Brunt-Vaisala frequency Richardson number

针刺对失眠大鼠自发活动节律周期及丘脑网状核内γ-氨基丁酸能神经元的影响

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中华中医药杂志 2024年第6期39卷 3063-3067页

作者：舒治钧黎明蔡定均张全怡徐义鹏赵征宇成都中医药大学针灸推拿学院成都610075 长宁县中医医院四川长宁644317

目的:观察针刺对失眠大鼠自发活动近日节律周期、丘脑网状核(TRN)内γ-氨基丁酸(GABA)能神经元、神经元上α7烟碱型乙酰胆碱受体(α7-nAChRs)和神经元突触可塑性的影响,探讨针刺治疗失眠的中枢调节机制。方法:将24只SPF级雄性SD大鼠随... 详细信息

目的:观察针刺对失眠大鼠自发活动近日节律周期、丘脑网状核(TRN)内γ-氨基丁酸(GABA)能神经元、神经元上α7烟碱型乙酰胆碱受体(α7-nAChRs)和神经元突触可塑性的影响,探讨针刺治疗失眠的中枢调节机制。方法:将24只SPF级雄性SD大鼠随机分为空白组、模型组、针刺组,每组8只,采用对氯苯丙氨酸(PCPA)腹腔注射法建立失眠大鼠模型。针刺组于每日ZT授时因子时间(ZT4)(11:00)针刺单侧内关、足三里,每日1次,每次15 min,每5分钟行平补平泻的捻转手法1 min,共5 d。观察大鼠24 h自发活动昼夜节律周期及TRN内小清蛋白阳性神经元(PV)/α7-nAChRs、PV/突触后致密蛋白-95(PSD-95)的共表达情况。结果:造模后,模型组及针刺组自发活动近日节律周期显著缩短(P<0.01,P<0.05);针刺治疗后,针刺组自发活动近日节律周期延长,恢复至正常状态(P<0.05)。免疫荧光结果显示,模型组TRN内PV/α7-nAChRs、PV/PSD-95共表达水平均显著降低(P<0.01,P<0.05);针刺组TRN内PV/α7-nAChRs、PV/PSD-95的共表达水平均显著增加(P<0.05)。结论:针刺可能通过上调PV阳性神经元上α7-nAChRs的表达,激活TRN内GABA能神经元并改善神经元突触可塑性,恢复失眠大鼠自发活动近日节律周期,从而发挥治疗失眠的作用。

关键词：针刺失眠节律周期小清蛋白阳性神经元 α7烟碱型乙酰胆碱受体突触后致密蛋白-95 内关足三里

Higher-Order Statistics and Nonlinear Processes in Space Plasmas

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Wuhan University Journal of Natural Sciences 1998年第2期3卷 181-186页

作者： zhao zhengyu Dai Honggang Shi Xianqing Wuhan University College of Electronic Information Wuhan China (GRID:grid.49470.3e) (ISNI:***)

Statistics of order 2 (variance, auto and cross-correlation functions, auto and cross-power spectra) and 3 (skewness, auto and cross-bicorrelation functions, auto and cross-bispectra) are used to analyze the wave-particle interaction in space plasmas. The signals considered here are medium scale electron density irregularities and ELF/ULF electrostatic turbulence. Nonlinearities are mainly observed in the ELF range. They are independently pointed out in time series associated with fluctuations in electronic density and in time series associated with the measurement of one electric field component. Peaks in cross-bicorrelation function and in mutual information clearly show that, in well delimited frequency bands, the wave-particle interactions are nonlinear above a certain level of fluctuations. The way the energy is transferred within the frequencies of density fluctuations is indicated by a bi-spectra analysis.

关键词： higher-order statistics nonlinear processes space plasmas

Evidence of X-mode heating suppressing O-mode heating

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Earth and Planetary Physics 2020年第6期4卷 588-597页

作者： Ting Feng Chen Zhou Xiang Wang MoRan Liu zhengyu zhao Department of Space Physics School of Electronic InformationWuhan UniversityWuhan 430072China

In this study,we present three experiments carried out at the EISCAT(European Incoherent Scatter Scientific Association)heating facility on October 29 and 30,*** results from the first experiment showed overshoot during the O-mode heating *** second experiment,which used cold-start X-mode heating,showed the generation of parametric decay instability,whereas overshoot was not *** third experiment used power-stepped X-mode heating with noticeable O-mode wave *** decay instability and oscillating two-stream instability were generated at the O-mode reflection height without the overshoot effect,which implies suppression of the thermal parametric instability with X-mode *** propose that the electron temperature increased because X-mode heating below the upper hybrid height decreased the growth rate of the thermal parametric instability.

关键词： ionospheric heating parametric decay instability thermal parametric instability overshoot suppression

An atmospheric backscatter model on wind measurements using far-field approximation method

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Frontiers of Electrical and Electronic Engineering in China 2007年第2期2卷 248-254页

作者： SHU Weiping zhao zhengyu Geomagnetism Laboratory School of Electronic InformationWuhan UniversityWuhan 430079China

A backscatter model was developed for measur-ing wind field with the far-field approximation *** theoretical computation and computer simulations with one spatial dimension show that this model can realistically describe the physical meaning and process of the three methods in wind measurements including the spaced antenna(SA)method,Doppler beam swing(DBS)method,and spaced interferometry(SI).The computational difficulties of the traditional theoretical model cannot only be smoothed away,but common characteristics and differences of the three methods can be compared *** comparison of the numerical results between the Wuhan medium frequency(MF)radar(30°N,114°E)observation and the computer simulation of the full correlation analysis(FCA)of the SA method indicates that the two results agree very well and this model has practical application.

关键词： far-field approximation wind measurement backscatter model simulation