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research on fiber optic gyro signal de-noising based on wavelet packet soft-threshold

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Journal of Systems Engineering and Electronics 2009年第3期20卷 607-612页

作者： Qian Huaming & ma Jichen Coll.of Automation,Harbin Engineering Univ.,Harbin 150001,P.r.China Coll. of Automation Harbin Engineering Univ. Harbin 150001 P. R. China

Gyro＇s drift is not only the main drift error which influences gyro＇s precision but also the primary factor that affects gyro＇s reliability. reducing zero drift and random drift is a key problem to the output of a gyro signal. A three-layer de-nosing threshold algorithm is proposed based on the wavelet decomposition to dispose the signal which is collected from a running fiber optic gyro （FOG）. The coefficients are obtained from the three-layer wavelet packet decomposition. By setting the high frequency part which is greater than wavelet packet threshold as zero, then reconstructing the nodes which have been filtered out noise and interruption, the soft threshold function is constructed by the coefficients of the third nodes. Compared wavelet packet de-noise with forced de-noising method, the proposed method is more effective. Simulation results show that the random drift compensation is enhanced by 13.1%, and reduces zero drift by 0.052 6°/h.

关键词： wavelet transform drift fiber optic gyro soft-threshold signal de-noising

Evolution of microstructure and phase composition of Ti-3Al-5Mo-4.5V alloy with varied β phase stability

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Journal of materials Science & Technology 2018年第12期34卷 2325-2330页

作者： Q.Xue Y.J.ma J.F.Lei r.Yang C.Wang School of Metallurgy Northeastern University Institute of Metal research Chinese Academy of Sciences

The microstructure evolution and phase composition of an α+β titanium alloy, Ti-3Al-5Mo-4.5V(wt.%),have been investigated. Electron probe micro analysis(EPma) quantitative results manifest that the stability of β phase decreases with increasing quenching temperature, which is influenced by the significant variation of β-stabilizing elements concentration. Detailed microstructure analysis shows that the β→ωphase transformation does occur when quenching at 750℃ and 800 ℃. The ω-reflections change from incommensurate ω-spots(750 ℃) to ideal ω-spots(800 ℃) as the β stability of the alloy decreases. Further the decrease of β phase stability encourages the formation of athermal α " martensite, which has the following orientation relationships: [111]β//[110]α",[100]p//[100]α " and [-110]p//[00-1]α" with respect to the β matrix.

关键词： Dual-phase titanium alloy β phase stability ω phase α" martensite Microstructure

Mechanical properties and deformation mechanisms of Ti-3Al-5Mo-4.5V alloy with varied β phase stability

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Journal of materials Science & Technology 2018年第12期34卷 2507-2514页

作者： Q.Xue Y.J.ma J.F.Lei r.Yang C.Wang Institute of Metal research Chinese Academy of Sciences School of Metallurgy Northeastern University

Evolution of deformation mechanisms and mechanical properties of Ti-3Al-5Mo-4.5V alloy with different β phase stability have been systematically investigated. β phase stability alteration is achieved through quenching temperature variation from dual α+β field(700℃) to single β field(880℃). Tensile tests at ambient temperature show that apparent yield strength of the alloy experiences an abrupt decrease followed by a significant increase from 700℃ to 880℃. Work hardening behavior is characterized by transition from the initial two-regime feature to the three-stage outlook. Concurrently, the maximum working hardening rate drops from 14000 MPa to 3000 MPa, which is concurrent with the shrinking volume fraction of primary a phase. Detailed discussion about the relationship between deformation mechanisms and β phase stability has been outlined.

关键词： Dual-phase titanium alloy β phase stability Work hardening behavior Deformation mechanisms

Numerical Analysis of the Nonlinear Parameterization of Waves in Currents over a Submerged Sill with a Non-Hydrostatic Model

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Journal of Ocean University of China 2017年第4期16卷 689-696页

作者： ma Xlaozhou ma Yuxiang GAO Yunpeng DONG Guohai State key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116024 P. R. China

An investigation of the effects of a uniform current strength direction(following or opposing wave propagation) on the nonlinear transformation of irregular waves over a submerged trapezoidal sill is carried out using SWASH,a non-hydrostatic numerical wave *** nonlinear parameters(i.e.,asymmetry,skewness,and kurtosis) are calculated,and the empirical formulas for these parameters are presented as a function of the local Ursell number based on the present numerical data *** the shoaling area of the submerged sill,the nonlinear characteristics of waves are more obvious when waves propagate in the same direction as the currents than when waves propagate in the opposite *** nonlinear parameters grow with the strengthening of the following currents over the crest,they tend to decrease as the adverse current velocity increases over the crest area of the submerged sill.

关键词： wave-current interaction shallow water nonlinear characteristic parameters non-hydrostatic water-current model

DrA Audio Coding Standard

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Chinese Journal of Electronics 2014年第3期23卷 521-526页

作者： ma Wenhua XU Jing ma Yuanzhe YOU Yuli Department of Computers Cisco School of InformaticsGuangdong University of Foreign Studies Department of Science and Technology Guangdong Rising Assets Management Co. Department of Biomedical Science and Technology South China University of Technology Guangdong Provincial key Laboratary for Digital Audio Technology

DrA(Dynamic resolution adaptation)audio coding standard was shown to deploy transientlocalized MDCT to effectively suppress pre-echo artifacts and statistic allocation of codebooks to improve the compression efficiency of Huffman coding. Its quantizers and Huffman codebooks are designed in such a way that a signal path of 24 bits is provided throughout the codec so that high audio quality can be delivered if bit rate *** simple, it delivers state-of-the-arts compression efficiency as shown by five rounds of ITU-r BS.11116 compliant subjective listening tests.

关键词： Audio coding Standard Listening test Modified discrete cosine transform(MDCT) Huffman coding

Ground-Based In Situ Measurements of Near-Surface Aerosol mass Concentration over Anantapur:Heterogeneity in Source Impacts

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Advances in Atmospheric Sciences 2013年第1期30卷 235-246页

作者： B.S.k.rEDDY k.r.kUmar G.BALAkrISHNAIAH k.r.GOPAL r.r.rEDDY V.SIVAkUmar S.Md.ArAFATH A.P.LINGASWAMY S.PAVANkUmarI k.UmaDEVI Y.N.AHAMMED Aerosol and Atmospheric research Laboratory Department of PhysicsSri Krishnadevaraya UniversityAnantapur 515003Andhra PradeshIndia Institute of Low Temperature Science Hokkoido UniversitySapporo 0600819Japan School of Physics University of KwaZulu-NatalDurban 4000South Africa Institute of Environmental Engineering National Chiao Tung UniversityHsinchuTaiwan Department of Physics Yogi Vemana UniversityKadapa 516003India

Surface measurements of aerosol physical properties were made at Anantapur （14.62°N, 77.65°E, 331 m a.s.l）, a semiarid rural site in India, during August 2008-July 2009. Measurements included the segregated sizes of aerosolsas as well as total mass concentration and size distributions of aerosols measured at low relative humidity （rH〈75%） using a Quartz Crystal Microbalance （QCM） in the 25-0.05 um aerodynamic diameter range. The hourly average total surface aerosol mass concentration in a day varied from 15 to 70 ug m-3, with a mean value of 34.02±9.05 ug m-3 for the entire study period. A clear diurnal pattern appeared in coarse, accumulation and nucleation-mode particle concentrations, with two local maxima occurring in early morning and late evening hours. The concentration of coarse-mode particles was high during the summer season, with a maximum concentration of 11.81±0.98 ug m-3 in the month of April, whereas accumulationmode concentration was observed to be high in the winter period contributed 〉68% to the total aerosol mass concentration. Accumulation aerosol mass fraction, Af （= ma/Mt） was highest during winter （mean value of Af -0.80） and lowest （Af - 0.64） during the monsoon season. The regression analysis shows that both reff and rm are dependent on coarse-mode aerosols. The relationship between the simultaneous measurements of daily mean aerosol optical depth at 500 nm （AOD500） and PM2.5 mass concentration （[PM2.5]） shows that surface-level aerosol mass concentration increases with the increase in columnar aerosol optical depth over the observation period.

关键词： aerosols mass concentration size distribution effective radius backward trajectories

Improved Hrmander’s Theorem and New Methods for Oscillatory Integral Operators

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Acta mathematica Sinica,English Series 2009年第11期25卷 1865-1874页

作者： Sheng-Ming ma LMIB and School of mathematics and System Sciences Beihang University Beijing 100083 P. R. China

This paper proves a theorem on the decay rate of the oscillatory integral operator with a degenerate C^∞ phase function, thus improving a classical theorem of HSrmander. The proof invokes two new methods to resolve the singularity of such kind of operators： a delicate method to decompose the operator and balance the L^2 norm estimates; and a method for resolution of singularity of the convolution type. The operator is decomposed into four major pieces instead of infinite dyadic pieces, which reveals that Cotlar＇s Lemma is not essential for the L^2 estimate of the operator. In the end the conclusion is further improved from the degenerate C^∞ phase function to the degenerate C^4 phase function.

关键词： oscillatory integral operators decay rate Fourier integral operators degenerate phase resolution of singularity

On Minimal Graph Evolutions in the Hyperbolic Space

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Acta mathematica Sinica,English Series 1999年第3期15卷 371-374页

作者： Li ma Department of Applied mathematics, Tsinghua University, Beijing 100084, P. r. China Department of Applied mathematics Tsinghua University Beijing P. R. China

We study here minmal graph evolutions in the hyperbolic space and prove that there exists a unique smooth solution.

关键词： Minimal graph evolution Apriori estimate

Flow Characteristics of a refrigerant-Oil Mixture in a Vapor Compression Heat Pump Heat Exchanger for Space Applications

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Journal of Thermal Science 2022年第2期31卷 407-416页

作者： ma rui YE Yilin ma Xudong WU Yuting YAN Suying WANG Feng College of Energy and Power Engineering Inner Mongolia University of TechnologyHohhot 010051China key Laboratory of Wind and Solar Energy Utilization Mechanism and Optimization in Inner Mongolia Inner Mongolia University of TechnologyHohhot 010051China key Laboratory of Enhanced Heat Transfer and Energy Conservation Ministry of EducationBeijing 100124China

The vapor compression heat pump is considered as the best option for aerospace thermal control *** heat exchanger in vapor compression heat pump is a component that is greatly influenced by the cosmic *** oil enters heat pump system with a refrigerant under microgravity,and the entrance of the lubricant increases the complexity of the *** this work,FLUENT software was used to study the flow and lubricant deposition of a two-phase mixture of lubricant POE rL 68H and refrigerant r134a in a heat exchanger without the consideration of phase-change heat *** functional relationships between the oil film thickness and the proportion of lubricating oil,the gravitational acceleration,the inlet flow velocity,and the placement directions of the two phases of oil in the heat exchanger were *** results demonstrate that with the increase of the gravitational acceleration and the lubricating oil content,the thickness of the oil film will exhibit an S-type change in line with the Boltzmann function,and the amount of lubricating oil deposition will *** the increase of the flow velocity,the thickness of the oil film will exhibit an exponential decline.

关键词： heat exchanger two-phase flow microgravity numerical simulation vapor compression heat pump