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Wideband Channel Estimation for THz Massive MIMO

China Communications 2021年第5期18卷 66-80页

作者： Jingbo Tan Linglong dai Beijing National Research Center for Information Science and Technology(BNRist)as well as the Department of Electronic Engineering Tsinghua UniversityBeijing 100084China

Terahertz(THz)communication is considered to be a promising technology for future 6G *** overcome the severe attenuation and relieve the high power consumption,massive multipleinput multiple-output(MIMO)with hybrid precoding has been widely considered for THz ***,accurate wideband channel estimation,which is essential for hybrid precoding,is challenging in THz massive MIMO *** existing wideband channel estimation schemes based on the ideal assumption of common sparse channel support will suffer from a severe performance loss due to the beam split *** this paper,we propose a beam split pattern detection based channel estimation scheme to realize reliable wideband channel estimation in THz massive MIMO ***,a comprehensive analysis on the angle-domain sparse structure of the wideband channel is provided by considering the beam split *** on the analysis,we define a series of index sets called as beam split patterns,which are proved to have a one-to-one match to different physical channel *** by this one-to-one match,we propose to estimate the physical channel direction by exploiting beam split patterns at ***,the sparse channel supports at different subcarriers can be obtained by utilizing a support detection *** support detection window is generated by expanding the beam split pattern which is determined by the obtained physical channel *** above estimation procedure will be repeated path by path until all path components are ***,the wideband channel can be recovered by calculating the elements on the total sparse channel support at all *** proposed scheme exploits the wideband channel property implied by the beam split effect,i.e.,beam split pattern,which can significantly improve the channel estimation *** results show that the proposed scheme is able to achieve higher accuracy than existing schemes.

关键词： THz communication massive MIMO hybrid precoding beam split wideband channel estimation

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A review of experimental and theoretical research on the deformation and failure behavior of rocks subjected to cyclic loading

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第5期13卷 1203-1230页

作者： Yi Liu Feng dai State Key Laboratory of Hydraulics and Mountain River Engineering College of Water Resource and HydropowerSichuan UniversityChengdu610065China

Rock engineering is highly susceptible to cyclic loads resulting from earthquakes,quarrying or *** the fatigue properties and failure mechanism of rocks is pivotal for long-term stability assessment of rock engineering *** far,significant progress has been gained on the mechanical characteristics of rocks subjected to cyclic *** providing a global insight of typical results and main features of rocks under cyclic loading conditions,this study comprehensively reviews the state-ofthe-art of deformation and failure mechanism and fatigue constitutive relationship of rocks subjected to cyclic loading in the past 60 ***,cyclic tests on rocks are classified into different types based on loading paths,loading parameters,loading types and environment ***,representative results are summarized and highlighted in terms of the fatigue response of rocks,including the deformation degradation,energy dissipation,damage evolution and failure characteristics;both laboratory testing and numerical results are presented,and various measurement techniques such as X-ray microcomputed tomography(micro-CT)and digital image correlation(DIC)are ***,the influences of cyclic loads on the mechanical characteristics of rocks are discussed,including the cyclic stress,frequency,amplitude and ***,constitutive relationships for rocks subjected to cyclic loading are outlined,in which typical fatigue constitutive models are compared and analyzed,regarding the elastoplastic model,the internal variable model,the energy-based damage model and the discrete element-based ***,some ambiguous questions and prospective research are interpreted and discussed.

关键词： Cyclic loads Mechanical properties Damage evolution Fatigue failure Constitutive relationship

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Flag-Transitive 3-(v,k,3)Designs and PSL(2,q)Groups

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Algebra Colloquium 2021年第1期28卷 33-38页

作者： Shaojun dai Shangzhao Li School of Mathematical Sciences Tiangong UniversityTianjin 300387China School of Mathematics and Statistics Changshu Institute of Technology ChangshuJiangsu 215500China

This article is a contribution to the study of the automorphism groups of 3-(v,k,3)*** S=(P,B)be a non-trivial 3-(q+1,k,3)*** a two-dimensional projective linear group PSL(2,q)acts flag-transitively on S,then S is a 3... 详细信息

关键词： flag-transitive 3-designs PSL(2,q)groups

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Impacts of external forcing and internal variability on the North Atlantic multidecadal variations since 1950

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Science China Earth Sciences 2024年第8期67卷 2699-2701页

作者： Wenjian HUA Aiguo dai Key Laboratory of Meteorological Disaster Ministry of Education/Collaborative Innovation Center on Forecast and Evaluation of Meteorological DisastersNanjing University of Information Science and TechnologyNanjing 210044China Department of Atmospheric and Environmental Sciences University at AlbanyState University of New YorkAlbany 12222USA

The physical formation mechanisms of the Atlantic Multidecadal Variability(AMV)in the context of global warming have been a key research topic(Vecchi et al.,2017).The conventional view is that the AMV is mainly driven by internal dynamics within the climate system,especially in the Atlantic Ocean(Zhang et al.,2019).However,some studies suggest that decadal to multidecadal variations in North Atlantic sea surface temperature(SST)since around 1950 are related to anthropogenic and natural aerosol emissions(Otter?et al.,2010;Booth et al.,2012;Hua et al.,2019).

关键词： Atlantic decadal forcing

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A new process to improve short-chain fatty acids and bio-methane generation from waste activated sludge

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Journal of Environmental Sciences 2016年第5期28卷 159-168页

作者： Bin Dong Peng Gao Dong Zhang Yinguang Chen Lingling dai Xiaohu dai State Key Laboratory of Pollution Control and Resources Reuse School of Environmental Science and Engineering Tongji University

As an important intermediate product, short-chain fatty acids（SCFAs） can be generated after hydrolysis and acidification from waste activated sludge, and then can be transformed to methane during anaerobic digestion process. In order to obtain more SCFA and methane,most studies in literatures were centered on enhancing the hydrolysis of sludge anaerobic digestion which was proved as un-efficient. Though the alkaline pretreatment in our previous study increased both the hydrolysis and acidification processes, it had a vast chemical cost which was considered uneconomical. In this paper, a low energy consumption pretreatment method, i.e. enhanced the whole three stages of the anaerobic fermentation processes at the same time, was reported, by which hydrolysis and acidification were both enhanced, and the SCFA and methane generation can be significantly improved with a small quantity of chemical input. Firstly, the effect of different pretreated temperatures and pretreatment time on sludge hydrolyzation was compared. It was found that sludge pretreated at 100°C for 60 min can achieve the maximal hydrolyzation. Further, effects of different initial p Hs on acidification of the thermal pretreated sludge were investigated and the highest SCFA was observed at initial p H 9.0with fermentation time of 6 d, the production of which was 348.63 mg COD/g VSS（6.8 times higher than the blank test） and the acetic acid was dominant acid. Then, the mechanisms for this new pretreatment significantly improving SCFA production were discussed. Finally,the effect of this low energy consumption pretreatment on methane generation was investigated.

关键词： Low energy consumption process Short-chain fatty acids Waste activated sludge Methane generation

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Estimation of IIR Systems with Binary-Valued Observations

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Chinese Annals of Mathematics,Series B 2023年第5期44卷 687-702页

作者： Ruifen dai Lei GUO Data Science Institute Shandong UniversityJinan 250100China Key Laboratory of Systems and Control Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China

Estimation and control problems with binary-valued observations exist widely in practical ***,most of the related works are devoted to finite impulse response(FIR for short)systems,and the theoretical problem of infinite impulse response(IIR for short)systems has been less *** study the estimation problems of IIR systems with binary-valued observations,the authors introduce a projected recursive estimation algorithm and analyse its global convergence properties,by using the stochastic Lyapunov function methods and the limit theory on double array *** is shown that the estimation algorithm has similar convergence results as those for FIR systems under a weakest possible non-persistent excitation ***,the upper bound for the accumulated regret of adaptive prediction is also established without resorting to any excitation condition.

关键词： Binary-valued observations Infinite impulse response Adaptive estimation Double array martingales Adaptive prediction

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Identification of Secondary Dislocations by Singular Value Decomposition of the Nye Tensor

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Acta Metallurgica Sinica(English Letters) 2014年第6期27卷 1078-1082页

作者： Fuzhi dai Wenzheng Zhang Key Laboratory of Advanced Materials (MOE) School of Materials Science and Engineering Tsinghua University

Recently, we proposed the use of singular values and singular vectors of the Nye tensor to specify the features of dislocations. To further validate the method in identifying dislocations, the algorithm is applied to detect secondary dislocations in this paper. Different from the perfect and partial dislocations where the reference state is a single crystal, the reference state for detecting secondary dislocations should be a bi-crystal in a coincident coherent state. It is demonstrated that the secondary dislocations in an interface can be correctly identified when the reference state is appropriately selected.

关键词： Nye tensor Singular value decomposition Secondary dislocation

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On-demand molecular design for efficient blue phosphorescence

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Science China Chemistry 2024年第7期67卷 2124-2126页

作者： Meiqi dai Dongpeng Yan Beijing Key Laboratory of Energy Conversion and Storage Materials Key Laboratory of RadiopharmaceuticalsMinistry of EducationCollege of ChemistryBeijing Normal UniversityBeijing 100875China

Blue luminescence(including both fluorescence and phosphorescence)is one of the core elements in solid-state lighting and full-color *** to now,ultralong room temperature phosphorescence(RTP)with a long lifetime over 0.1 s has been continuously *** ultralong phosphorescence emission bands are in the region of 500 to600 ***,high-energy blue phosphorescence remains an immense challenge[1].

关键词： blue lifetime bands

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Environmental Protection and Energy Color Changing Clothing Design under the Background of Sustainable Development

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Journal of Renewable Materials 2022年第11期10卷 2717-2728页

作者： Jingyu dai Hongyu dai Yutong Xie T.Indumathi College of Art Design and Media Sanda UniversityShanghai201209China Data science institute Vanderbilt UniversityNashville37212USA Center of Art Education Shanghai University of Medicine&Health SciencesShanghai201318China PSG College of Technology Coimbatore641004India

In order to promote the application of clean energy technology in clothing and promote the integration of industrial development and artificial intelligence wearable technology,this study elaborates the energy application characteristics of intelligent wearable products at home and abroad and its application in different fields,aiming at the current research status of wearable technology in the field of textile and *** wearable distributed generation technology is classified,and a creative clothing design for detecting climate temperature is *** on the monitoring of body temperature,the changes in clothing pattern color can reflect people’s health and emotional *** the same time,it can also be applied to the screening of abnormal body temperature during the COVID-19.

关键词： Clean energy temperature variable materials wearable clothing design

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Neighborhood predictors of short sleep duration and bedtime irregularity among children in the United States: results from the 2019-2020 National Surveyof Children's Health

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World Journal of Pediatrics 2024年第1期20卷 73-81页

作者： Ying dai Jianghong Liu School of Nursing University of Pennsylvania418 Curie Blvd.Room 426Claire M.Fagin HallPhiladelphiaPA19104-6096USA

Background Environmental factors may contribute to short sleep duration and irregular bedtime in *** factors and children's sleep duration and bedtime regularity remain a less investigated *** aim of this study was to investigate the national and state-level proportions of children with short sleep duration and irregular bedtime and their neighborhood *** A total of 67,598 children whose parents completed the National Survey of Children's Health in 2019-2020 were included in the ***-weighted Poisson regression was used to explore the neighborhood predictors of children's short sleep duration and irregular *** The prevalence of short sleep duration and irregular bedtime among children in the United States(US)was 34.6%[95%confidence interval(CI)=33.8%-35.4%]and 16.4%(95%CI=15.6%-17.2%)in 2019-2020,*** neighborhoods,supportive neighborhoods,and neighborhoods with amenities were found to be protective factors against children's short sleep duration,with risk ratios ranging between 0.92 and 0.94,P<*** with detracting elements were associated with an increased risk of short sleep duration[risk ratio(RR)=1.06,95%CI=1.00-1.12]and irregular bedtime(RR=1.15,95%CI=1.03-1.28).Child race/ethnicity moderated the relationship between neighborhood with amenities and short *** Insufficient sleep duration and irregular bedtime were highly prevalent among US children.A favorable neighborhood environment can decrease children's risk of short sleep duration and irregular *** the neighborhood environment has implications for children's sleep health,especially for children from minority racial/ethnic groups.

关键词： Child National Survey of Children's Health Neighborhood.Sleep Social determinants of health

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