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Performance analysis of DFT spread generalized multi-carrier systems

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Science in China(Series F) 2009年第12期52卷 2385-2396页

作者： li mingqi ZHANG XiaoDong Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 China

Discrete Fourier transform-spread generalized multi-carrier （DFT-S-GMC） based single carrier-frequency division multiple access （SC-FDMA） scheme is a promising solution for uplink transmission of broadband wireless communication. In this paper, the impact of non-perfect orthogonal prototype filter to the performance of the DFT-S-GMC system is discussed. Single sub-band frequency-domain equalization （FDE） method is presented and the performance loss caused by FDE-tone discarding is analyzed. Moreover, the post-processing signal to interference plus noise ratio （SINR） of DFT-S-GMC receiver over multi-path channel is addressed. The theoretical analysis illustrates that the non-perfect orthogonal prototype filter results in inter-symbol interference （ISI） and inter-sub-band interference （IBI）, and the variance of the ISI is still less than le-4 and much larger than that of IBI. By designing proper system parameters, the reconstruction error due to FDE-tones discarding can be controlled under -40 dB; the post-processing SINR of the DFT-S-GMC receiver with minimum mean square error （MMSE） equalization is higher than that with zero forcing （ZF） equalization. The theoretical performances are verified by extensive simulation results.

关键词： filter-bank single carrier-frequency division multiple access generalized multi-carrier frequency domain equalization performance analysis

Generating Virtual Images for Multi-view Video

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Chinese Journal of Electronics 2017年第4期26卷 810-813页

作者： ZHANG lijun li Yue ZHU Qiuyu li mingqi New Media Wireless Research Center Shanghai Advanced Research Institute Chinese Academy of Sciences School of Communication and Information Engineering Shanghai University

As for the research in the Free view television(FTV) and stereo video areas, the accurate multi-view video capture is a expensive precondition. We present a virtual multi-view video capture system based on Open GL programming. By using this system, a researcher may create arbitrary 3D scenes, and capture images with depth maps by setting up multiple virtual cameras, whose intrinsic and extrinsic parameters can be imported from or exported to the outside. We conducted several experiments within it to perform camera calibration, depth estimation and view-points synthesis. The system has been demonstrated to be a powerful tool for evaluation of stereo video algorithms.

关键词： Multi-view video Virtual realistic Com puter vision Sterio video Free view television(FTV)

Parameter analysis for the coexistence of cognitive LTE and spectrum authorized systems

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High Technology Letters 2013年第1期19卷 42-47页

作者：杨程 Rui Yun li mingqi Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai Advanced Research Institute Chinese Academy of Sciences The State Key Laboratory of Integrated Services Networks Xidian University Key Laboratory of Information Coding and Transmission Southwest Jiaotong University

In order to realize the coexistence between the LTE system and the spectrum authorized systems over 700MHz frequency band,the geographical position and operation band location between long term evolution(LTE)base stations and digital tevevision transmission tower should satisfy certain constraints,which are analyzed and deduced in this *** the concluded constraints,the interference to each other is lower than their interference tolerances,so that the coexistance between the two types of systems is *** on the constraints for both LTE and spectrum authorized systems,numerical results of the geographical position interval and operation band location interval are obtained,which have significant practical value for the LTE base station placement,network planning and operation band selection.

关键词： cognitive long term evolution LTE) coexistence operation band location geographical position

Effects of grain's shape-and size-polydispersities,orientation,and area fraction on tortuosity and permeability of 2D granular media

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Particuology 2024年第7期90卷 535-557页

作者： Ke Cao Huisu Chen Mohammad Iqbal Khan mingqi li lin liu Jiangsu Key Laboratory of Construction Materials School of Materials Science and EngineeringSoutheast UniversityNanjing 211189China Department of Civil Engineering College of EngineeringKing Saud UniversityP.O.Box 800Riyadh 11421Saudi Arabia School of Civil and Transportation Engineering Hebei University of TechnologyTianjin 300401China College of Civil and Transportation Engineering Hohai UniversityNanjing210098China

The microstructure of granular media, including grain's shape- and size-polydispersities, orientation, and area fraction can potentially affect its permeability. However, few studies consider the coupling effects of these features. This work employs geometrical probability and stereology to establish quantitative relationships between the above microstructural features and the geometric tortuosity of the two-dimensional granular media containing superellipse, superoval, and polygon grains. Then the lattice Boltzmann method (LBM) is used to determine the permeabilities of these granular media. By combining the tortuosity model and the LBM-derived permeabilities, modified K–C equations are formulated to predict the permeability and the shape factor, considering the grain's shape- and size-polydispersities, orientation, and area fraction. The reliability of these methods can be verified by comparing them with both our simulations and available experimental, theoretical, and numerical data reported in the literature. The findings implicate that the tortuosity and permeability of the granular media are strongly correlated with the grain's shape, orientation, and area fraction but unaffected by the size polydispersity and spatial arrangement of grains. Only circularity is not enough to derive a unified formula for considering the impact of grain shape on tortuosity and permeability, other shape parameters need to be explored in the future.

关键词： Geometric tortuosity Konzey-Carman equation Shape and size ploydispersities Grain orientation Lattice Boltzmann method Granular media

V-BLAST-based demodulate-and-forward two-way relaying:protocol design and the detection

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High Technology Letters 2009年第4期15卷 388-393页

作者：贠超 Xiong Haitao Wang Ping li mingqi Bu Zhiyong Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 P.R. China Shanghai Jushri Technologies Inc. Shanghai 201112 P.R.China

We propose a novel vertical Bell Laboratories layered space-time （V-BLAST） based two-way relaying protocol that comprises two user terminals and one multi-antenna demodulate-and-forward （DMF） relay station. We consider the situation when these two user temainals employ different modulation types and investigate its detection techniques. The key feature of the detection techniques is that we quantify decision reliability at the relay station by introducing a so-called normalized correlation coefficient （CORR）, rather than having full confidence in demodulation at the relay station. With the assistance of the normalized correlation coefficient, we develop detection methods at both the relay station and user terminals. In particular, we propose a CORR-based ordering algorithm at the relay station which can be applied to detection for general V-BLAST architectures. Simulation results demonstrate the superiority of the CORR- based ordering algorithm over the conventional signal-to-noise based ordering algorithm. Finally, we demonstrate overall error-performance of the V-BLAST-based DMF two-way relaying protocol via simulations.

关键词： Relaying demodulate-and-forward (DMF) vertical Bell Laboratories layered space-

Starch grains from dental calculus reveal ancient plant foodstuffs at Chenqimogou site, Gansu Province

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Science China Earth Sciences 2010年第5期53卷 694-699页

作者： li mingqi YANG XiaoYan WANG Hui WANG Qiang JIA Xin GE QuanSheng Institute of Geographical Sciences and Natural Resources Research Chinese Academy of SciencesBeijing 100101China Graduate School of the Chinese Academy of Sciences Beijing 100049China Gansu Provincial Institute of Cultural Relics and Archaeology Lanzhou 730000China Key Laboratory of Western China’s Environmental Systems MOELanzhou UniversityLanzhou 730000China

Chenqimogou site, located at the south bank of Tao River, is comprised of a large group of graves dated to ~4000 a BP. For its large scale, unique mortuary system, and abundant of typical artifacts, the site was named one of 'Top Ten Archaeological Discoveries of 2008 in China'. Many intact human skeletons have been excavated from the graves. Three teeth from two adult skeletons excavated from graves M187 and M194 were examined. Forty-eight starch grains were retrieved from dental calculus of three teeth. Six of those starch grains could not be identified because of damage. The others were classified into seven groups. Most of them were from wheat (Triticum aestivum) and/or barley (Hordeum vulgare). Remains possibly from foxtail millet (Setaria italica), buckwheat (Fagopyrum esculentum), gingkgo (Ginkgo biloba), acorn (Quercus spp.), bean, roots or tubers were identified. Ancient starch grains from dental calculus indicate that human foodstuffs primarily sourced from wheat, buckwheat, and foxtail millet. Acorn, beans, tubers or roots were supplements. A variety of starch grains retrieved from dental calculus revealed that diverse crops were cultivated in the Chenqimogou site 4000 years ago, and both dry-land farming and gathering were engaged.

关键词： Chenqimogou site Qijia Culture starch grain analysis dental calculus ancient plant diet

Variations of the temperature and solar activity in China

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Research in Cold and Arid Regions 2014年第6期6卷 531-539页

作者： mingqi li QuanSheng Ge ZhiXin Hao JingYun Zheng Key Laboratory of Land Surface Pattern and Simulation Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences

In this paper we analyze daily mean, minimum, and maximum temperature data collected at 119 meteorological stations over five regions of China during the period 1951-2010. The series of minimum, maximum, and mean temperatures from each climatic region have similar signatures, but there are differences among the five regions and the countrywide average. The results indicate that the periods of faster warming were not synchronous across the regions studied： warming in northeast China and Tibet began in 1986, while in central-east, southeast, and northwest China the warming emerged in 1995. Furthermore, central-east and northwest China, and Tibet, have warmed continuously since 2000, but the temperature has decreased during this period in southeast China. We evaluated the evolution of these temperature series using a novel nonlinear filtering technique based on the concept of the lifetime of temperature curves. The decadal to secular evolution of solar activity and temperature variation had similar signatures in the northeast, southeast, and northwest re- gions and the average across the whole country, indicating that solar activity is a significant control on climate change over secular time scales in these regions. In comparison with these regions, the signatures were different in central-east China and Tibet because of regional differences （e.g., landforms and elevation） and indirect effects （e.g., cloud cover influencing the radiation balance, thereby inducing climate change）. Furthermore, the results of wavelet analysis indicated that the El Nino Southem Oscillation （ENSO） has had a significant impact on climate change, but at different times among the regions, and these changes were most probably induced by differing responses of the atmospheric system to solar forcing.

关键词： temperature variation solar activity lifetime wavelet analysis China

Projecting Spatial Patterns of Flood Hazard: Recent Climate and Future Changes over Yangtze River Basin

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Chinese Journal of Population,Resources and Environment 2010年第3期8卷 83-88页

作者： He Shanfeng Ge Quansheng Wu Shaohong Dai Erfu Shi Chunjian li mingqi Institute of Geographic Sciences and Natural Resources Research CAS Beijing 100101 China Henan Polytechnic University Jiaozuo Henan 454000 China Graduate School of Chinese Academy of Sciences Beijing 100049 China Environmental and Water Resources Engineering University of Delaware Newark DE 19716 USA

Projection of hazard changes in climate extremes is critical to assessing the potential impacts of climate change on human and natural systems. Using simulations of providing regional climates for impacts studies, five indicators (rainstorm days, maximum 3-day precipitation, elevation, gradient and distance from river or lake) were selected to project the spatial patterns of flood hazard over Yangtze River Basin for the baseline period (1961– 1990) and future (2011–2100) under SRES B2 scenario. The results showed the mean annual rainstorm days over the basin by the near-term, mid-term and long-term would increase from 3.9 days to 4.7, 4.9 and 5.1 days, and the mean annual maximum 3-day precipitation from 122 mm to 143, 146 and 149 mm, respectively. The flood hazard of the basin would become more severe, especially in the middle and lower reaches. Flood hazard grade 5 by the nearterm, mid-term and long-term would extend from 10.99% to 25.46, 28.14 and 29.75%, respectively.

关键词： climate change extreme weather event SRES B2 scenario PRECIS synthetic weighted mark method

H_(3)Se in the Imˉ3m Phase:High-Pressure Superconductor with T_(c) Reaching 200K at 64GPa Mediated by Anharmonic Phonons

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Chinese Physics Letters 2024年第12期41卷 159-165页

作者： Yao Ma mingqi li Wenjia Shi Vei Wang Pugeng Hou Mi Pang Department of Applied Physics School of SciencesXi’an University of TechnologyXi’an 710054China College of Science Northeast Electric Power UniversityChangchun Road 169Jilin 132012China

Hydrogen-based compounds have attracted significant attention in recent years due to the discovery of conventional superconductivity with high critical temperature under high pressure,rekindling hopes for finding roomtemperature *** this study,we investigated the vibrational and superconducting properties of H_(3)Sein the Im￣3m phase under pressures of *** approach combines the stochastic self-consistent harmonic approximation and first-principles calculations to account for the quantum and anharmonic effects of *** to the results,these effects significantly modify the crystal structure,increasing the inner pressure by approximately 8GPa compared to situations in which they are *** phonon spectra suggest that when these effects are considered,the crystal stabilizes at pressures as low as approximately 61GPa,which is significantly lower than the previously predicted value of over *** calculations also highlight the critical role of quantum and anharmonic effects on the electron-phonon coupling *** these factors can result in a significant overestimation of the superconducting critical temperature(T_(c))by approximately 4K(200GPa)to 25K(125GPa).With anharmonic phonons,the T_(c) calculated from the Migdal-Eliashberg equations reaches 200K(μ⋆=0.1,λ=4.1)as the pressure decreases to 64GPa,indicating that the crystal is a rare high-Tc superconductor at moderate pressures.

关键词： harmonic critical Superconductor