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M-BCJR Algorithm with Channel Shortening Based on Ungerboeck Observation Model for Faster-than-Nyquist Signaling

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China Communications 2021年第4期18卷 88-98页

作者： Hui Che yong bai School of Information and Communication Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China School of Information and Communication Engineering Hainan UniversityHaikou 570228China

The M-BCJR algorithm based on the Ungerboeck observation model is a recent study to reduce the computational complexity for faster-than-Nyquist(FTN)signaling[1].In this paper,we propose a method that can further reduce the complexity with the approximately same or better bit error rate(BER)performance compared to[1].The information rate(IR)loss for the proposed method is less than 1%compared to the true achievable IR(AIR).The proposed improvement is mainly by introducing channel shortening(CS)before the M-BCJR *** our proposal,the Ungerboeck M-BCJR algorithm and CS can work together to defeat severe inter-symbol interference(ISI)introduced by FTN *** ISI length for the M-BCJR algorithm with CS is optimized based on the criterion of the IR *** the two cases=0.5 and=0.35,compared to Ungerboeck M-BCJR without CS benchmark[1],the computational complexities of Ungerboeck M-BCJR with CS are reduced by 75%.Moreover,for the case=0.35,the BER performance of Ungerboeck M-BCJR with CS outperforms that of the conventional M-BCJR in[1]at the low signal to noise ratio region.

关键词： M-BCJR Ungerboeck model channel shortening FTN reduced-complexity turbo equalization

Coded Modulation Faster-than-Nyquist Transmission with Precoder and Channel Shortening Optimization

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China Communications 2021年第2期18卷 49-64页

Faster-than-Nyquist(FTN)signaling can improve the spectrum efficiency(SE)of the transmission *** this paper,we propose a coded modulation FTN(CM-FTN)transmission scheme with precoder and channel shortening(CS)optimization to improve bit error rate(BER)performance and reduce the complexity of FTN *** our proposal,the information rate(IR)or spectral efficiency(SE)is employed and verified as a better performance metric for CM-FTN than the minimum Euclidian distance(MED).The precoder of CM-FTN is optimized for maximizing the IR criterion using the bare-bones particle swarm optimization(BB-PSO)***,a three-carrier CM-FTN system model is used to capture the broadening effect of *** targeting for the IR maximization,the inter-symbol interference(ISI)length for CS is optimized to reduce the receiver complexity without performance *** results demonstrate that our method has a 0.6dB precoding gain compared with the nonprecoding scheme and a maximum of 87.5%of the complexity of FTN equalizer is reduced without BER loss.

关键词： faster-than-Nyquist coded modulation information rate minimum Euclidian distance precoder channel shortening

Subduction zone geochemistry

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Geoscience Frontiers 2019年第4期10卷 1223-1254页

作者： yong-fei Zheng CAS Key Labaratory of Crust-Mantle Materials and Environments School of Earth and Space Sciences University of Science and Technology of China

Crustal recycling at convergent plate boundaries is essential to mantle ***,crustal signatures in the mantle source of basaltic rocks above subduction zones were primarily incorporated in the form of liquid rather than solid *** physicochemical property of liquid phases is determined by the dehydration behavior of crustal rocks at the slab-mantle interface in subduction *** of the significant fractionation in incompatible trace elements but the full inheritance in radiogenic isotopes relative to their crustal sources,the production of liquid phases is crucial to the geochemical transfer from the subducting crust into the *** this process,the stability of specific minerals in subducting crustal rocks exerts a primary control on the enrichment of given trace elements in the liquid *** this reason,geochemically enriched oceanic basalts can be categorized into two types in terms of their trace element distribution patterns in the primitive mantle-normalized *** is island arc basalts(IAB),showing enrichment in LILE,Pb and LREE but depletion in HFSE such as Nb and Ta relative to HREE,The other is ocean island basalts(OIB),exhibiting enrichment in LILE and LREE,enrichment or non-depletion in HFSE but depletion in Pb relative to *** either types,these basalts show the enhanced enrichment of LILE and LREE with increasing their incompatibility relative to normal mid-ocean ridge basalts(MORB).The thermal regime of subduction zones can be categorized into two stages in both time and space,The first stage is characterized by compressional tectonism at low thermal *** a consequence,metamorphic dehydration of the subducting crust prevails at forearc to subarc depths due to the breakdown of hydrous minerals such as mica and amphibole in the stability field of garnet and rutile,resulting in the liberation of aqueous solutions with the trace element composition that is considerably enriched in LILE,Pb and LREE bu

关键词： Subduction zone Basalts Element mobility Geochemical differentiation Crustal metasomatism Mantle geochemistry

Application of land use regression for estimating concentrations of major outdoor air pollutants in Jinan, China

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第11期11卷 857-867页

作者： Li CHEN Shi-yong DU Zhi-peng bai Shao-fei KONG Yan YOU Bin HAN Dao-wen HAN Zhi-yong LI College of Environmental Science and Engineering Nankai University Tianjin 300071 China State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution and Control Tianjin 300071 China College of Urban and Environmental Science Tianjin Normal University Tianjin 300387 China Jinan Institute of Environmental Sciences Jinan 250014 China

SO2, NO2, and PM10 are the major outdoor air pollutants in China, and most of the cities in China have regulatory monitoring sites for these three air pollutants. In this study, we developed a land use regression (LUR) model using regulatory monitoring data to predict the spatial distribution of air pollutant concentrations in Jinan, China. Traffic, land use and census data, and meteorological and physical conditions were included as candidate independent variables, and were tabulated for buffers of varying radii. SO2, NO2, and PM10 concentrations were most highly correlated with the area of industrial land within a buffer of 0.5 km (R2=0.34), the distance from an expressway (R2=0.45), and the area of residential land within a buffer of 1.5 km (R2=0.25), respectively. Three multiple linear regression (MLR) equations were established based on the most significant variables (p<0.05) for SO2, NO2, and PM10, and R2 values obtained were 0.617, 0.640, and 0.600, respectively. An LUR model can be applied to an area with complex terrain. The buffer radii of independent variables for SO2, NO2, and PM10 were chosen to be 0.5, 2, and 1.5 km, respectively based on univariate models. Intercepts of MLR equations can reflect the background concentrations in a certain area, but in this study the intercept values seemed to be higher than background concentrations. Most of the cities in China have a network of regulatory monitoring sites. However, the number of sites has been limited by the level of financial support available. The results of this study could be helpful in promoting the application of LUR models for monitoring pollutants in Chinese cities.

关键词： Land use regression (LUR) Air pollution Background concentration Geographic information system (GIS)

Methods for Detection of Subsurface Damage:A Review

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Chinese Journal of Mechanical Engineering 2018年第3期31卷 23-36页

作者： Jing-fei Yin Qian bai Bi Zhang Key Laboratory for Precision and Non-traditional Machining of Ministry of Education Dalian University of Technology Department of Mechanical and Energy Engineering South University of Science and Technology

Subsurface damage is easily induced in machining of hard and brittle materials because of their particular mechani?cal and physical properties. It is detrimental to the strength,performance and lifetime of a machined part. To manu?facture a high quality part,it is necessary to detect and remove the machining induced subsurface damage by the subsequent processes. However,subsurface damage is often covered with a smearing layer generated in a machining process,it is rather di cult to directly observe and detect by optical microscopy. An e cient detection of subsur?face damage directly leads to quality improvement and time saving for machining of hard and brittle materials. This paper presents a review of the methods for detection of subsurface damage,both destructive and non?destructive. Although more reliable,destructive methods are typically time?consuming and confined to local damage infor?mation. Non?destructive methods usually su er from uncertainty factors,but may provide global information on subsurface damage distribution. These methods are promising because they can provide a capacity of rapid scan and detection of subsurface damage in spatial distribution.

关键词： Subsurface damage Hard and brittle material Taper polishing Measurement Laser scattering

Time-varying parameter auto-regressive models for autocovariance nonstationary time series

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Science China Mathematics 2009年第3期52卷 577-584页

作者： fei WanChun bai Lun College of Textile and Clothing Engineering Suzhou UniversitySuzhou 215021China

In this paper, autocovariance nonstationary time series is clearly defined on a family of time series. We propose three types of TVPAR (time-varying parameter auto-regressive) models: the full order TVPAR model, the time-unvarying order TVPAR model and the time-varying order TV-PAR model for autocovariance nonstationary time series. Related minimum AIC (Akaike information criterion) estimations are carried out.

关键词： autocovariance nonstationary time series time-varying parameter time-varying order auto-regressive model minimum AIC estimation 37M10 68Q10

Effect of cooling rate on the magnetic properties of Fe_(53)Nd_(37)Al_(10) alloy

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International Journal of Minerals,Metallurgy and Materials 2013年第5期20卷 440-444页

作者： Qin bai Yan-fei Hao Jiao Wang Hua Man yong-jun Tang Hui Xu Shuang Xia Key Laboratory for Microstructures Shanghai University

The effect of cooling rate on the magnetic properties of the Fe53Nd37Al10 alloy prepared by different methods, i.e., suction casting and melt spinning at different rates, was investigated. The Fe53Nd37Al10 ribbon at the wheel speed of 5 m.s-1 exhibits the highest coercivity in the samples. Two hard magnetic phases are detected from the hysteresis loops of the 5 m.s-1 ribbon at all temperatures below room temperature. Their appearance is associated with different exchange coupling interactions, which are between the two kinds of hard magnetic phases or between the hard magnetic phase and the soft magnetic phase.

关键词： amorphous materials magnetization anisotropy cooling

A confinement strategy to in-situ prepare a peanut-like N-doped, C-wrapped TiO_(2) electrode with an enhanced desalination capacity and rate for capacitive deionization

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Nano Research 2021年第3期14卷 684-691页

作者： Mingxing Liang Xueting bai fei Yu Jie Ma College of Marine Ecology and Environment Shanghai Ocean UniversityShanghai201306China State Key Laboratory of Pollution Control and Resource Reuse College of Environmental Science and EngineeringTongji UniversityShanghai200092China Research Center for Environmental Functional Materials College of Environmental Science and EngineeringTongji University1239 Siping RoadShanghai200092China Shanghai Institute of Pollution Control and Ecological Security Shanghai200092China

Capacitive deionization(CDI)technology has been considered a promising desalination technique,especially for brackish water,because of its relatively low energy consumption,facile operation,and easy regeneration of ***,the desalination capacity,cost,fabrication method,electrochemical stability,and environmental unfriendliness of the electrodes have restricted the practical application of the CDI ***,we reported the one-step in situ preparation of nitrogen-doped and carbon-decorated MXene-derived TiO_(2)(termed N-TiO_(2−x)/C)through the confinement-growth *** small particle size(∼25 nm)and uniform distribution of a peanut-like N-TiO_(2−x)/C material could be ascribed to the confined growth space created by the nanoporous structure of melamine *** defects produced by N doping provide an enhanced electrical conductivity and more adsorption sites,while wrapping with a carbon shell layer increases the conductivity and offers protection for N-TiO_(2−x) to achieve an excellent electrochemical *** prepared N-TiO_(2−x)/C electrode is hydrophilic due to the abundant oxygen-containing functional groups(e.g.,C-O,N-Ti-O,-NO_(x),and-OH)and exhibits a high salt removal capacity(33.4 mg·g^(−1)),desalination rate(1.5 mg·g^(−1)·min^(−1)),and remarkable cycling stability(without declining after 100 cycles),which might be ascribed to the synergistic effects of the short ion diffusion path,more active adsorption sites,enhanced conductivity,pseudocapacitive behavior,and protection of the carbon shell *** work provides a confined-growth strategy to develop MXene-derived oxide electrodes for electrochemical desalination.

关键词： capacitive deionization confinement growth MXene-derived N-doped pseudocapacitive behavior

A Revised Graduated Cylindrical Shell Model and its Application to a Prominence Eruption

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Research in Astronomy and Astrophysics 2023年第12期23卷 63-72页

作者： Qing-Min Zhang Zhen-yong Hou Xian-yong bai Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryNanjing 210023China Yunnan Key Laboratory of the Solar Physics and Space Science Kunming 650216China School of Earth and Space Sciences Peking UniversityBeijing 100871China National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Solar Activity and Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China

In this paper,the well-known graduated cylindrical shell(GCS)model is slightly revised by introducing longitudinal and latitudinal deflections of prominences originating from active regions(ARs).Subsequently,it is applied to the three-dimensional(3D)reconstruction of an eruptive prominence in AR 13110,which produced an M1.7 class flare and a fast coronal mass ejection(CME)on 2022 September *** is revealed that the prominence undergoes acceleration from~246 to~708 km s^(-1).Meanwhile,the prominence experiences southward deflection by 15°±1°without longitudinal deflection,suggesting that the prominence erupts *** deflections of the prominence and associated CME are consistent,validating the results of fitting using the revised GCS ***,the true speed of the CME is calculated to be 1637±15 km s^(-1),which is~2.3 times higher than that of *** is indicative of continuing acceleration of the prominence during which flare magnetic reconnection reaches maximum beneath the erupting ***,the reconstruction using the revised GCS model could successfully track a prominence in its early phase of evolution,including acceleration and deflection.

关键词： Sun flares-Sun filaments-prominences-Sun coronal mass ejections(CMEs)