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Interference-Driven Designs of Nonlinear-Phase FIR Filter with Application in FBMC System

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China Communications 2016年第12期13卷 15-24页

作者： Jiangang Wen Jingyu Hua Sunan Li kai Zhou Dongming Wang College of Information Engineering Zhejiang University of Technology Zhejiang Key Lab.Commun.Network&Appl. Zhejiang Univ.Tech. National Mobile Communication Research Laboratory Southeast University

In the forthcoming 5G systems, new technologies, such as amorphous networks and non-orthogonal filter bank multicarriers(FBMC), provide an effective way to accommodate high-rate transmissions. Meanwhile, the prototype filter affects the adjacent channel interference, and therefore is important for FBMC systems. Besides, once the amorphous network is taken into account, the requirement for interference controlmust be much stricter. Accordingly, this paper focuses on the design of prototype filter with better ability of interference controlling, where we exploit the nonlinear phase FIR filter(NLPFF) instead of traditional linear phase FIR filter(LPFF) to achieve more optimization spaces under a small sacrifice of linear phase. In ourdesigns, both the amplitude and phase responsesare handled independently to approach the stopband performance enhancements, in while the nearly perfect reconstruction(NPR) conditionsare relaxed by pre-specified thresholds. Computer simulations confirm the effectiveness of the NLPFF designs, and demonstrate the advantages of the proposed NLPFF in FBMC applications.

关键词： constrained minimax constrained least-square FBMC nonlinear-phase filter interference

Geochemical Characteristics and Genesis of the Metallogenic Rocks in the Chagande'ersi Molybdenum Deposit in Wulatehouqi,Inner Mongolia

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Acta Geologica Sinica(English Edition) 2013年第1期87卷 148-157页

作者： YAN kai XIAO Rongge HE Zhongyin FENG Gang WANG Shuli China University of Geosciences CITIC Mining Technology Development Co. Ltd The 8th Institute of Geology and Mineral Exploration of Inner Mongolia Chinese Academy of Geological Sciences

Geochemical characteristics of the Chagande＇ersi molybdenum deposit in Inner Mongolia and its genesis were analyzed in this study using rock mineralography and rock geochemical testing. The mineralized country rocks of the Chagande＇ersi molybdenum deposit consist mainly of medium- to fine-grained monzogranite, medium-to fine-grained rich-K granite, with minor fine-grained K- feldspar granite veins and quartz veins. The rocks are characterized by high silica, rich alkali, high potassium, which are favorable factors for molybdenum mineralization. The rocks have the Rittmann index ranging from 1.329 to 1.961, an average Na20＋K20 value of 7.41, and AI2Oa/（CaO＋Na20＋K^O）〉1, suggesting that the rocks belong to the high-K calc-alkaline peraluminous granite. The typical rock samples are enriched in Rb, Th, K and light rare earth elements, depleted in Sr, Ba, Nb, P and Ti, and these features are similar to that of the melt granite resulting from collision of plate margins. The JEu of the rocks falls the zone between the crust granite and crust-mantle granite, and are close to that of the crust granite; （La/LU）N indicates the formation environment of granite is a continental margin setting. The Nb/Ta ratios are close to that of the average crust （10）; the Zr/Hf ratios of monzogranite are partly below the mean mantle （34-60）, while the Zr/Hf ratio of K-feldspar granite are close to the mean value in the crust. Comprehensive analyses show that the granite in this area formed during the transition period between tectonic collision and post-collision. During the plate collision and orogeny, the crust and mantle material were mixed physically, remelting into lava and then crystal fractionation, finally gave rise to the formation of the rock body in this area. This has close spatial and temporal relation with the molybdenum mineralization.

关键词： Chagande'ersi Mo ore deposit rock mineralographical characteristics rock geochemistry,granite genesis tectonic setting

Particle filter based automatic frequency control scheme by combining the two-step structure

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The Journal of China Universities of Posts and Telecommunications 2012年第2期19卷 9-14页

作者： CHEN Peng LI Ju-hu NIU kai WU Wei-ling Key Laboratory of Universal Wireless Communications(Minislry of Education) Beijing University of Posts and TelecommunicationsBeijing 100876China

In this paper a new automatic frequency control （AFC） scheme was proposed, which could be used for the receiver of low earth orbit （LEO） satellite communication system in continuous transmitting scenario. By employing the time varying characteristic of particle filter technique, the new scheme combined the preamble based estimating step and data based estimating step to provide initial probability density recursively. Theoretical analysis proved that the proposed AFC scheme could provide better performance than the two-step scheme. The same conclusion was achieved by computer simulations with the criteria of root-mean square （RMS） frequency estimating performance and bit error rate performance.

关键词： satellite communication Doppler effect automatic frequency control particle filter

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超燃冲压发动机尾喷管进口气流角畸变研究

推进技术 2021年第12期42卷 2694-2702页

作者：陈以勒俞凯凯徐惊雷南京航空航天大学能源与动力学院江苏南京210016

为探索气流角畸变对超燃冲压发动机尾喷管性能的影响,开展了喷管在单一气流角畸变和耦合畸变进口条件下的数值模拟研究。首先简要介绍采用的数值模拟方法,并根据实验结果校核数值方法的有效性。同时为得到准确的数值结果,进行了网格无... 详细信息

为探索气流角畸变对超燃冲压发动机尾喷管性能的影响,开展了喷管在单一气流角畸变和耦合畸变进口条件下的数值模拟研究。首先简要介绍采用的数值模拟方法,并根据实验结果校核数值方法的有效性。同时为得到准确的数值结果,进行了网格无关性验证。然后,通过数值模拟获取超燃冲压发动机燃烧室出口气流参数,用于研究气流角畸变对喷管性能的影响并讨论了其影响规律。在此基础上,进一步研究了气流角畸变与马赫数畸变相互耦合对喷管气动性能的影响。结果表明,气流角畸变对推力影响很小:推力系数变化仅为0.37%;但对升力和俯仰力矩影响显著,相应增幅分别可达51.84%和12.11%。此外发现气流角畸变和马赫数畸变对喷管气动性能的影响是相互独立的。因此在超燃冲压发动机喷管的相关研究过程中,有必要对气流角畸变加以考虑。另外还需要关注由于气流角畸变导致的喷管升力和俯仰力矩变化对飞行器整体稳定性的影响。

关键词：超燃冲压发动机单边膨胀喷管气流角畸变马赫数畸变数值模拟气动性能

Numerical simulation of the Moon's rotation in a rigorous relativistic framework

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Research in Astronomy and Astrophysics 2016年第6期16卷 59-68页

作者： Zai Wang Wen-Biao Han kai Tang Jin-He Tao Department of Physics Shanghai University Shanghai Astronomical Observatory Chinese Academy of Sciences

This paper describes a numerical simulation of the rigid rotation of the Moon in a relativis- tic framework. Following a resolution passed by the International Astronomical Union （IAU） in 2000, we construct a kinematieally non-rotating reference system named the Selenocentric Celestial Reference System （SCRS） and give the time transformation between the Selenocentric Coordinate Time （TCS） and Barycentric Coordinate Time （TCB）. The post-Newtonian equations of the Moon＇s rotation are written in the SCRS, and they are integrated numerically. We calculate the correction to the rotation of the Moon due to total relativistic torque which includes post-Newtonian and gravitomagnetic torques as well as geodetic precession. We find two dominant periods associated with this correction： 18.6 yr and 80.1 yr. In addition, the precession of the rotating axes caused by fourth-degree and fifth-degree harmonics of the Moon is also analyzed, and we have found that the main periods of this precession are 27.3 d, 2.9 yr, 18.6 yr and 80.1 yr.

关键词： lunar libration -- Selenocentric Celestial Reference System -- geodetic precession -- general relativity

In situ observation of austenite grain growth behavior in the simulated coarse-grained heat-affected zone of Ti-microalloyed steels

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International Journal of Minerals,Metallurgy and Materials 2014年第9期21卷 878-885页

作者： Xiang-liang Wan kai-ming Wu Gang Huang Ran Wei Lin Cheng The State Key Laboratory of Refractories and Metallurgy Hubei Collaborative Innovation Center for Advanced Steels Wuhan University of Science and Technology

The austenite grain growth behavior in a simulated coarse-grained heat-affected zone during thermal cycling was investigated via in situ observation. Austenite grains nucleated at ferrite grain boundaries and then grew in different directions through movement of grain boundaries into the ferrite phase. Subsequently, the adjacent austenite grains impinged against each other during the α→γtransformation. After the α→γ transformation, austenite grains coarsened via the coalescence of small grains and via boundary migration between grains. The growth process of austenite grains was a continuous process during heating, isothermal holding, and cooling in simulated thermal cycling. Abundant finely dispersed nanoscale TiN particles in a steel specimen containing 0.012wt% Ti effectively retarded the grain boundary migration, which resulted in refined austenite grains. When the Ti concentration in the steel was increased, the number of TiN particles de- creased and their size coarsened. The big particles were not effective in pinning the austenite grain boundary movement and resulted in coarse austenite grains.

关键词： alloy steel austenite grain growth heat-affected zone coarsening titanium nitride

High-Precision Direct Method for the Radiative Transfer Problems

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Communications in Theoretical Physics 2013年第6期59卷 782-788页

作者： ZHANG Yan HOU Su-Qing YANG Ping WU kai-Su beijing University of Chemical Technology Beijing 100029 China Institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China University of Chinese Academy of Sciences Beijing 100049 China

It is the main aim of this paper to investigate the numerical methods of the radiative transfer equation. Using the five-point formula to approximate the differential part and the Simpson formula to substitute for integral part respectively, a new high-precision numerical scheme, which has 4-order local truncation error, is obtained. Subsequently, a numerical example for radiative transfer equation is carried out, and the calculation results show that the new numerical scheme is more accurate.

关键词： radiative transfer equation direct method five-point numerical formula truncation error

Investigation on sampling artifacts of particle associated PAHs using ozone denuder systems

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Frontiers of Environmental Science & Engineering 2014年第2期8卷 284-292页

作者： kai LIU Fengkui DUAN Kebin HE Yongliang MA yuan CHENG State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University Beijing 100084 China

Polycyclic aromatic hydrocarbons （PAHs） are complex organic compounds which are identified as significant carcinogenic to human health. PAHs （mainly in particle phase） are susceptible to atmospheric oxidant gases, especially ozone, nitrogen oxides （NOx）, hydroxyl radical （OH）, and could be degraded on filters during sampling process, leading to an underestimation of ambient PAH concentrations. The goal of this work was to investigate particle associated PAHs sampling artifacts caused by ozone in summer of beijing. Comparative sampling systems were operated simultaneously during the whole campaign, one with activated carbon ozone denuder, the other being set as conventional sampling system. Activated carbon denuder was testified to be highly efficient to eliminate ozone from air stream. In general, nine particle-bound PAHs observed from conventional sampler were all lower than those from ozone denuder system. The total PAHs （particle phase） concentration was averagely underestimated by 35.9% in conventional sampling procedure. Benzo[a]pyrene （BaP） had the highest percentage of mass loss. founded to have influences Ambient temperature was on PAHs sampling artifacts. High temperature can increase loss of particle associated PAHs during sampling.

关键词： particle associated polycyclic aromatic hydro- carbons (PAHs) ozone denuder sampling artifacts

A Non-invasive Method of Tracing Spiral Tips

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Chinese Physics Letters 2001年第6期18卷 834-836页

作者： WANG kai MAO Xiao-Ming OU-YANG Qi Department of Physics and Mesoscopic Physics Laboratory Peking UniversityBeijing 100871

A new method is developed to trace the tip of spiral waves in an excitable *** information of a spiral tip movement is obtained from only six *** method can trace the tip of a simple rotating spiral as well as a complex spiral tip *** importantly,it can be used to distinguish between a spiral and a target *** method is checked with data by experiments and numerical simulations,and found to be successful.

关键词： checked rotating Spiral