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Advance of research on modern soil phytolith

Science China Earth Sciences 2018年第9期61卷 1169-1182页

作者： Changhui WEN Houyuan lu Xinxin ZUO Yong ge Key Laboratory of Cenozoic geology and Environment Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China University of Chinese Academy of Sciences Beijing 100049 China Center for Excellence in Tibetan Plateau Earth Science Chinese Academy of Sciences Beijing 100101 China School of geography Science Fujian Normal University Fuzhou 350007 China Key Laboratory of Vertebrate Evolution and Human Origins Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences Beijing 100044 China CAS Center for Excellence in Life and Paleoenvironment Beijing 100044 China

Phytolith study is a new branch of micropaleontology with an increasingly important role in geology, archaeology, and plant taxonomy. Phytoliths have several advantages considering their characteristics of small particle size, high production, wide distribution, anti-decomposition, in situ deposition, distinctive morphologies, and element sequestrating capacity. Phytolith assemblages in modem soil have been found to be closely related to modem vegetation types and climate conditions, which forms the basis for the quantitative study of paleoecology, paleoclimate, and bio-geochemical cycles. At present, phytolith studies generally focus on the following four aspects：（1） Morphology： about 260 unduplicated types of phytoliths have been identified in modem soil, of which 110 types are from grasses, 50 types from ferns, woody plants and other angiosperms, whereas the origin plants of the remaining 100 types are still under investigation. （2） Soil phytolith assemblages and vegetation： phytolith assemblages from the topsoil have been used to distinguish surface vegetation types including different forests and grasslands over a typical region. This model has been applied to restore past vegetation conditions and monitor the dynamic evolution of specific vegetation types at different temporal and spatial scales. （3） Soil phytolith assemblages and climate： quantitative and semi-quantitative relationships between phytolith assemblages and a series of climate parameters, such as annual mean temperature, annual mean precipitation and altitude, have been established through mathematical analysis. In this manner, quantitative reconstruction of paleoclimatic parameters has been achieved through the phytolith-climate transfer function model. （4） Soil phytolith and its sequestered elements： in this topic, the content of soil PhytOC （Phytolith-occluded Organic Carbon） and the importance of PhytOC in the bio-geochemical cycle have been the focus. The study of modem soil phytoliths has

关键词： Modem soil Phytolith Morphology Paleoenvironment Quantification

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A Representation of the Lorentz Spin Group and Its Application

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Acta Mathematica Sinica,English Series 2007年第4期23卷 577-598页

作者： qi Keng lu Ke WU Institute of Mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 P. R. China School of Mathematical Science Capital Normal University Beijing 100037 P. R. China

For an integer m ≥ 4, we define a set of 2[m/2] × 2[m/2] matrices γj （m）, （j = 0, 1,..., m - 1） which satisfy γj （m）γk （m）＋γk （m）γj （m） = 2ηjk （m）I[m/2], where （ηjk （m）） 0≤j,k≤m-1 is a d... 详细信息

For an integer m ≥ 4, we define a set of 2[m/2] × 2[m/2] matrices γj （m）, （j = 0, 1,..., m - 1） which satisfy γj （m）γk （m）＋γk （m）γj （m） = 2ηjk （m）I[m/2], where （ηjk （m）） 0≤j,k≤m-1 is a diagonal matrix, the first diagonal element of which is 1 and the others are -1, I[m/2] is a 2[m/1] × 2[m/2] identity matrix with [m/2] being the integer part of m/2. For m = 4 and 5, the representation （m） of the Lorentz Spin group is known. For m≥ 6, we prove that （i） when m = 2n, （n ≥ 3）, （m） is the group generated by the set of matrices {T｜T=1/√ξ（（I＋k） 0 ＋ 0 I-K）（ U 0 0 U）, （ii） when m = 2n ＋ 1 （n≥ 3）, （m） is generated by the set of matrices {T｜T=1/√ξ（I -k^- k I）U,U∈ （m-1）,ξ=1-m-2 ∑k,j=0 ηkja^k a^j〉0, K=i[m-3 ∑j=0 a^j γj（m-2）＋a^（m-2） In],K^-=i[m-3∑j=0 a^j γj（m-2）-a^（m-2） In]}

关键词： Lorentz spin group representation Yang-Mills equation

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Designing highly transparent cerium doped Y_(2)O_(3) ceramics with high mechanical and thermal properties for UV-shielding in extreme conditions

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Journal of Advanced Ceramics 2024年第7期13卷 1032-1042页

作者： Cong Zhang Jianqi qi Xiaolan Zhou Zhonghua lu Tiecheng lu College of Physics Sichuan UniversityChengdu 610064China Key Laboratory of High Energy Density Physics of Ministry of Education Sichuan UniversityChengdu 610064China Key Laboratory of Radiation Physics and Technology of the Ministry of Education Sichuan UniversityChengdu 610064China

Ultraviolet(UV)radiation poses risks to both human health and *** response to the urgent demand for UV-shielding across various applications,extensive endeavors have been dedicated to developing UV-shielding materials spanning from wide-bandgap semiconductors to organo-inorganic composite ***,existing UV shielding materials,though suitable for daily use,cannot meet the demands of extreme *** this work,we incorporated CeO_(2)as a UV absorber into Y_(2)O_(3)transparent ceramics for *** effect of CeO_(2)concentration on the optical,mechanical,and thermal properties of Y_(2)O_(3)ceramics was systematically *** findings indicate that CeO_(2)serves not only as a UV absorber but also as an effective sintering aid for Y_(2)O_(3)transparent *** 5 at%Ce-doped Y_(2)O_(3)transparent ceramics exhibit the optimal optical quality,with in-line transmittance of~77%at 800 *** introduction of Ce shifted the UV cutoff edge of Y_(2)O_(3)transparent ceramics from 250 to 375 nm,which was attributed to the visible band absorption of Ce^(4+).This shift grants UV shielding capabilities to Y_(2)O_(3)transparent ceramics,resulting in 100%shielding for ultraviolet C(UVC,100-280 nm)and ultraviolet B(UVB,280-320 nm)and~95%shielding for ultraviolet A(UVA,320-400 nm).The service stability(optical properties)under various corrosive conditions(acid,alkali,UV irradiation,and high temperature)was investigated,confirming the excellent stability of this transparent ceramic UV-shielding material.A comparison of the performance parameters of transparent ceramics with those of traditional UV shielding materials such as glasses,films,and coatings was *** work provides innovative design concepts and an effective solution for UVshielding materials for extreme conditions.

关键词： ultraviolet(UV)-shielding transparent ceramics bandgap engineering thermal properties optical properties

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A Robust UWB Array Localization Scheme through Passive Anchor Assistance

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China Communications 2021年第4期18卷 1-13页

作者： Haipeng lu TianyuWang Feng ge Yuan Shen Electronic Engineering Department Tsinghua UniversityBeijing 100084China Beijing National Research Center for Information Science and Technology Beijing 100084China

Ultra-Wide Bandwidth(UWB)localization based on time of arrival(TOA)and angle of arrival(AOA)has attracted increasing interest owing to its high accuracy and low ***,existing localization methods often fail to achieve satisfactory accuracy in realistic environments due to multipath effects and non-line-of-sight(NLOS)*** this paper,we propose a passive anchor assisted localization(PAAL)scheme,where the active anchor obtains TOA/AOA measurements to the agent while the passive anchors capture the signals from the active anchor and *** proposed method fully exploits the time-difference-of-arrival(TDOA)information from the measurements at the passive anchors to complement single-anchor joint TOA/AOA *** performance limits of the PAAL system are derived as a benchmark via the information ***,we implement the PAAL system on a low-cost UWB platform,which can achieve 20 cm localization accuracy in NLOS environments.

关键词： ultra-wideband localization NLOS environments passive listening adaptive unscented Kalman filter(UKF)

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Technical methods of national security supervision:Grain storage security as an example

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Journal of Safety Science and Resilience 2023年第1期4卷 61-74页

作者： Yudie Jianyao qi Zhang Liang ge Jianguo Chen Department of Engineering Physics Tsinghua UniversityBeijing 100084China Institute of Public Safety Research Tsinghua UniversityBeijing 100084China Tsinghua Shenzhen International Graduate School Tsinghua UniversityShenzhen 518055China National Food and Strategic Reserves Administration Beijing 100084China

Grain security guarantees national *** has many widely distributed grain depots to supervise grain storage ***,this has led to a lack of regulatory capacity and *** the development of reserve-level information technology,big data supervision of grain storage security should be *** study proposes big data research architecture and an analysis model for grain storage security;as an example,it illustrates the supervision of the grain loss problem in storage *** statistical analysis model and the prediction and clustering-based model for grain loss supervision were used to mine abnormal data.A combination of feature extraction and feature selection reduction methods were chosen for dimensionality.A comparative analysis showed that the nonlinear prediction model performed better on the grain loss data set,with R2 of 87.21%,87.83%,91.97%,and 89.40%for Gradient Boosting Regressor(GBR),Random Forest,Decision Tree,XGBoost regression on test sets,*** abnormal data were filtered out by GBR combined with residuals as an *** deep learning model had the best performance on the mean absolute error,with an R2 of 85.14%on the test set and only one abnormal data *** is contrary to the original intention of finding as many anomalies as possible for supervisory *** classes were generated using principal component analysis dimensionality reduction combined with Density-Based Spatial Clustering of Applications with Noise(DBSCAN)clustering,with 11 anomalous data points screened by adding the amount of normalized grain *** on the existing grain information system,this paper provides a supervision model for grain storage that can help mine abnormal *** the current post-event supervision model,this study proposes a pre-event supervision *** study provides a framework of ideas for subsequent scholarly research;the addition of big data technology will help improve efficien

关键词： Grain storage security Supervision model Abnormal data mining

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Cobalt(Ⅲ)hydride HAT mediated enantioselective intramolecular hydroamination access to chiral pyrrolidines

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Science China Chemistry 2024年第6期67卷 2002-2008页

作者： qi Meng Tao qin Huanran Miao ge Zhang qian Zhang Jilin Province Key Laboratory of Organic Functional Molecular Design&Synthesis Department of ChemistryNortheast Normal UniversityChangchun130024China State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai200032China

Enantioenriched pyrrolidines and derivatives are ubiquitous substructures in compounds of importance to medicinal and biological ***,we report an efficient cobalt-catalyzed intramolecular asymmetric hydroamination reaction that produces chiral pyrrolidines with good to excellent yield and *** with previously reported radicalinvolved methodologies for enantioenriched pyrrolidines,these conditions feature two elegant versatilities,enabling(1)the use of cobalt-catalyzed hydrogen atom transfer(HAT)to generate organocobalt intermediates that bring radical reaction to organometallic chemistry,and(2)enantioselective intramolecular C-N bond forging through an S_(N)2-like displacement involving dynamic kinetic resolution(DKR).This approach provides a new alternative and efficient methodology for enantioselective radical-involved C-N bond construction that can be used in the synthesis of both chiral pyrrolidines and homologous nitrogen heterocycles.

关键词： asymmetric catalysis radical hydroamination cobalt catalysis hydrogen atom transfer

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Unseen head pose prediction using dense multivariate label distribution

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Frontiers of Information Technology & Electronic Engineering 2016年第6期17卷 516-526页

作者： Gao-li SANG Hu CHEN ge HUANG qi-jun ZHAO State Key Laboratory of Fundamental Science on Synthetic Vision College of Computer ScienceSichuan University College of Mathematics and Information Engineering Jiaxing University

Accurate head poses are useful for many face-related tasks such as face recognition, gaze estimation,and emotion analysis. Most existing methods estimate head poses that are included in the training data(i.e.,previously seen head poses). To predict head poses that are not seen in the training data, some regression-based methods have been proposed. However, they focus on estimating continuous head pose angles, and thus do not systematically evaluate the performance on predicting unseen head poses. In this paper, we use a dense multivariate label distribution(MLD) to represent the pose angle of a face image. By incorporating both seen and unseen pose angles into MLD, the head pose predictor can estimate unseen head poses with an accuracy comparable to that of estimating seen head poses. On the Pointing'04 database, the mean absolute errors of results for yaw and pitch are 4.01?and 2.13?, respectively. In addition, experiments on the CAS-PEAL and CMU Multi-PIE databases show that the proposed dense MLD-based head pose estimation method can obtain the state-of-the-art performance when compared to some existing methods.

关键词： Head pose estimation Dense multivariate label distribution Sampling intervals Inconsistent labels

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Experimental study on sulfur removal from ladle furnace refining slag in hot state by blowing Air

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International Journal of Minerals,Metallurgy and Materials 2016年第1期23卷 33-39页

作者： Li-huaZhao lu Lin qi-fan Wu School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing Beijing 100083 China

In view of the present problem of sulfur enrichment in the metallurgical recycling process of ladle furnace （LF） refining slag, a simple and efficient method of removing sulfur from this slag was proposed. The proposed method is compatible with current steelmaking processes. Sulfur removal from LF refining slag for SPHC steel （manufactured at a certain steel plant in China） by blowing air in the hot state was studied by using hot-state experiments in a laboratory. The FactSage software, a carbon/sulfur analyzer, and scanning electron micros- copy in conjunction with energy-dispersive X-ray spectroscopy were used to test and analyze the sulfur removal effect and to investigate factors influencing sulfur removal rate. The results show that sulfur ions in LF refining slag can be oxidized into SO2 by O2 at high tempera- ture by blowing air into molten slag; SO2 production was observed to reach a maximum with a small amount of blown O2 when the tem- perature exceeded 1350℃. At 1370℃ and 1400℃, experimental LF refining slag is in the liquid state and exhibits good fluidity; under these conditions, the sulfur removal effect by blowing air is greater than 90wt% after 60 min. High temperature and large air flow rate are benefi- cial for removing sulfur from LF refining slag; compared with air flow rate, temperature has a greater strongly influences on the sulfur re- moval.

关键词： steelmaking refining slag sulfur removal oxidation resource utilization

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Clustering by data competition

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Science China(Information Sciences) 2013年第1期56卷 65-77页

作者： lu ZhiMao ZHANG qi Pattern Recognition and Natural Computation Laboratory Harbin Engineering University

Clustering analysis is an unsupervised method to find out hidden structures in *** partitional clustering algorithms are sensitive to the selection of initial exemplars,the outliers and *** this paper,a novel technique called data competition algorithm is proposed to solve the *** the concept of aggregation field model is defined to describe the partitional clustering ***,the exemplars are identified according to the data ***,the members will be assigned to the suitable *** competition algorithm is able to avoid poor solutions caused by unlucky initializations,outliers and noise,and can be used to detect the coexpression gene,cluster the image,diagnose the disease,distinguish the variety,*** provided experimental results validate the feasibility and effectiveness of the proposed schemes and show that the proposed approach of data competition algorithm is simple,stable and *** experimental results also show that the proposed approach of data competition clustering outperforms three of the most well known clustering algorithms K-means clustering,affinity propagation clustering,hierarchical clustering.

关键词： data mining clustering analysis partitional clustering data competition

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A novel compilation method of comprehensive mission spectrum of aero-engine maneuvering load based on use-related mission segment

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Chinese Journal of Aeronautics 2023年第3期36卷 161-170页

作者： Xuming NIU qi lu Zhigang SUN Yingdong SONG Jiangsu Province Key Laboratory of Aerospace Power System and College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Laboratory of Aero-Engine Thermal Environment and Structure Ministry of Industry and Information Technology College of Energy and Power EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210016China College of Energy and Power Engineering and State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Comprehensive Mission Spectrum(CMS)of an aero-engine can reflect the usage characteristics of the *** can provide load input for engine life prediction and accelerated mission *** this paper,a novel compilation method of CMS of aero-engine maneuvering load based on mission segment is ***,the use-related Typical Mission Segment(TMS)of maneuvering load is divided and identified according to spectral ***,the mathematical model of different kinds of TMS are established based on stochastic process ***,the CMS of maneuvering load is compiled based on *** proposed method can accurately quantify the compilation of *** compiled CMS shows good agreement with the original load *** to damage consistency inspection,the compiled CMS is consistent with the damage caused by the original load spectrum in terms of low cycle fatigue.

关键词： Aero-engine Comprehensive mission spectrum Maneuvering load Spectrum compilation Typical mission segment

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