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An inorganic liquid crystalline dispersion with 2D ferroelectric moieties

National Science Review 2024年第05期 254-263页

作者： Ziyang Huang Zehao Zhang Rongjie Zhang Baofu Ding Liu Yang Keyou Wu Youan Xu Gaokuo Zhong Chuanlai Ren Jiarong Liu Yugan Hao Menghao Wu Teng Ma Bilu Liu Shenzhen Graphene Centre Shenzhen Key Laboratory of Advanced Layered Materials for Value-added ApplicationsTsinghua-Berkeley Shenzhen Institute and Institute of Materials ResearchTsinghua Shenzhen International Graduate School Tsinghua University institute of Technology for Carbon Neutrality Faculty of Materials Science and Engineering Shenzhen Institute of Advanced Technology Chinese Academy of Sciences School of Physics and institute for Quantum Science and Engineering School of Chemistry and Institute of Theoretical ChemistryHuazhong University of Science and Technology Xi'an Research institute of High Technology Shenzhen institute of Advanced Technology Chinese Academy of Sciences Department of Applied Physics Hong Kong Polytechnic University

Electro-optical effect-based liquid crystal devices have been extensively used in optical modulation techniques, in which the Kerr coefficient reflects the sensitivity of the liquid crystals and determines the strength of the device's operational electric field. The Peterlin–Stuart theory and the O'Konski model jointly indicate that a giant Kerr coefficient could be obtained in a material with both a large geometrical anisotropy and an intrinsic polarization, but such a material is not yet reported. Here we reveal a ferroelectric effect in a monolayer two-dimensional mineral vermiculite. A large geometrical anisotropy factor and a large inherent electric dipole together raise the record value of Kerr coefficient by an order of magnitude, till 3.0 × 10-4mV-2. This finding enables an ultra-low operational electric field of10～2–10～4V m-1and the fabrication of electro-optical devices with an inch-level electrode separation, which has not previously been practical. Because of its high ultraviolet stability（decay <1% under ultraviolet exposure for 1000 hours）, large-scale production, and energy efficiency, prototypical displayable billboards have been fabricated for outdoor interactive scenes. This work provides new insights for both liquid crystal optics and two-dimensional ferroelectrics.

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Spatial pattern of impervious surfaces and their impacts on land surface temperature in Beijing,China

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Journal of Environmental Sciences 2007年第2期19卷 250-256页

作者： XIAO Rong-bo OUYANG Zhi-yun ZHENG Hua LI Wei-feng SCHIENKE Erich W WANG Xiao-ke State Key Lab of Urban and Regional Ecology Environmental Sciences Chinese Academy of Sciences Belting 100085 China Department of Science and Technology Studies Rensselaer Polytechnic Institute Troy NY 12180 USA

Land surface temperature （LST）, which is heavily influenced by urban surface structures, is a significant parameter in urban environmental analysis. This study examined the effect impervious surfaces （IS） spatial patterns have on LST in Beijing, China. A classification and regression tree model （CART） was adopted to estimate IS as a continuous variable using Landsat images from two seasons combined with QuickBird. LST was retrieved from the Landsat Thematic Mapper （TM） image to examine the relationships between IS and LST. The results revealed that CART was capable of consistently predicting LST with acceptable accuracy （correlation coefficient of 0.94 and the average error of 8.59%）. Spatial patterns of IS exhibited changing gradients across the various urban-rural transects, with LST values showing a concentric shape that increased as you moved from the outskirts towards the downtown areas. Transect analysis also indicated that the changes in both IS and LST patterns were similar at various resolution levels, which suggests a distinct linear relationship between them. Results of correlation analysis further showed that IS tended to be positively correlated with LST, and that the correlation coefficients increased from 0.807 to 0.925 with increases in IS pixel size. The findings identified in this study provide a theoretical basis for improving urban planning efforts to lessen urban temperatures and thus dampen urban heat island effects.

关键词： urban heat islands urban land cover normalized difference vegetation index (NDVI) climate mitigation regression tree

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Hybrid hard-/soft-decision LDPC decoding strategy for NAND flash memory

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Chinese Science Bulletin 2014年第28期59卷 3554-3561页

作者： Wenzhe Zhao Guiqiang Dong Hongbin Sun Tong Zhang Nanning Zheng institute of Artificial Intelligence and Robots Xi’an Jiaotong University Skyera Inc. 1704 Automation pkwy San Jose CA 95131 USA rensselaer polytechnic institute Troy NY 12180 USA

This paper concerns a decoding strategy to improve the throughput in NAND flash memory using lowdensity parity-check(LDPC) codes. As the reliability of NAND flash memory continues degrading, conventional error correction codes have become increasingly *** code is highly desirable, due to its powerful correction strength. However, in order to maximize the correction strength, LDPC codes demand fine-grained memory sensing,leading to a significant read latency penalty. To address the drawbacks caused by soft-decision LDPC decoding, this paper proposes a hybrid hard-/soft-decision LDPC decoding strategy. Simulation results show that the proposed approach could reduce the read latency penalty and hence improve the decoding throughput up to 30 %, especially in early lifetime of NAND flash memory, compared with the conventional decoding with equivalent area.

关键词： NAND闪存 LDPC码解码策略软判决混合型快闪存储器低密度奇偶校验闪速存储器

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A Journal for Human and Machine

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Data Intelligence 2019年第1期1卷 1-5页

作者： James Hendler Ying Ding Barend Mons rensselaer institute for Data Exploration and Applications Rensselaer Polytechnic InstituteTroyNY12180USA School of Informatics Computingand EngineeringIndiana UniversityBloomingtonIN 47408USA Leiden University Medical Centre The NetherlandsPoortgebouw N-01Rijnsburgerweg 102333 AA LeidenThe Netherlands

It is with great pride to bring you this new journal of Data *** journal has at least two major purposes that we hope ***,it will embrace the traditional role of a journal in helping to facilitate the communication of research and best practices in scientific data sharing,especially across disciplines,an area that is continually growing in importance for the modern practice of ***,we will be experimenting with new methods of enhancing the sharing of this communication,and examples of the field,by utilizing the increasing power of intelligent computing systems to further facilitate the growth of the *** journal’s title,combining“data,”the field we will support,and“intelligence,”a means to that end,is meant to connote this growing interaction.

关键词： interaction. journal utilizing

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Enhanced valley splitting of WSe_(2)in twisted van der Waals WSe_(2)/CrI_(3)heterostructures

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npj Computational Materials 2022年第1期8卷 277-283页

作者： Mei Ge Han Wang Jizheng Wu Chen Si Junfeng Zhang Shengbai Zhang School of Physics and Information Engineering Shanxi Normal UniversityTaiyuanChina Chemical Sciences Division Lawrence Berkeley National LaboratoryBerkeleyCAUSA School of Materials Science and Engineering Beihang UniversityBeijingChina Department of Physics Applied Physicsand AstronomyRensselaer Polytechnic InstituteTroyNYUSA

Van der Waals(vdW)heterostructures composed of different two-dimensional(2D)materials offer an easily accessible way to combine properties of individual materials for *** to the discovery of a set of unanticipated physical phenomena,the twisted 2D vdW heterostructures have gained considerable attention ***,we report enhanced valley splitting in twisted 2D vdW WSe_(2)/CrI_(3)*** particular,the splitting can be 1200%(or 5.18 meV)of the value for a non-twisted *** to the k·p model,this value is equivalent to a~20 T external magnetic field applied perpendicular to the 2D *** thermodynamic stability of 2D vdW WSe_(2)/CrI_(3)heterostructures,on the other hand,depends linearly on the interlayer twisting angle.

关键词： twisted splitting gained

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Overcoming the fundamental light-extraction efficiency limitations of deep ultraviolet light-emitting diodes by utilizing transverse-magnetic-dominant emission

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Light(Science & Applications) 2015年第1期4卷 422-429页

作者： Dong Yeong Kim Jun Hyuk Park Jong Won Lee Sunyong Hwang Seung Jae Oh Jungsub Kim Cheolsoo Sone EFred Schubert Jong Kyu Kim Department of Materials Science and Engineering Pohang University of Science and TechnologyPohang 790-784Korea LED Business Samsung ElectronicsYongin 446-920Korea Future Chips Constellation Department of ElectricalComputerand Systems EngineeringRensselaer Polytechnic InstituteTroyNY 12180USA

While the demand for deep ultraviolet(DUV)light sources is rapidly growing,the efficiency of current AlGaN-based DUV light-emitting diodes(LEDs)remains very low due to their fundamentally limited light-extraction efficiency(LEE),calling for a novel LEE-enhancing approach to deliver a real ***,we propose sidewall emission-enhanced(SEE)DUV LEDs having multiple light-emitting mesa stripes to utilize inherently strong transverse-magnetic polarized light from the AlGaN active region and three-dimensional reflectors between the *** SEE DUV LEDs show much enhanced light output power with a strongly upward-directed emission due to the exposed sidewall of the active region and Al-coated selective-area-grown n-type GaN *** devices also show reduced operating voltage due to better n-type ohmic contact formed on the regrown n-GaN stripes when compared with conventional ***,the proposed approach simultaneously improves optical and electrical *** addition,strategies to further enhance the LEE up to the theoretical optimum value and control emission directionality are discussed.

关键词： deep ultraviolet light-emitting diodes light-extraction efficiency

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Sinogram denoising via attention residual dense convolutional neural network for low-dose computed tomography

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Nuclear Science and Techniques 2021年第4期32卷 70-83页

作者： Yin-Jin Ma Yong Ren Peng Feng Peng He Xiao-Dong Guo Biao Wei Key Laboratory of Optoelectronic Technology and Systems Ministry of EducationChongqing UniversityChongqing 400044China School of Data Science Tongren UniversityTongren 554300China School of Microelectronics and Communication Engineering Chongqing UniversityChongqing 400044China Department of Biomedical Engineering Rensselaer Polytechnic InstituteTroyNY 12180USA

The widespread use of computed tomography(CT)in clinical practice has made the public focus on the cumulative radiation dose delivered to ***-dose CT(LDCT)reduces the X-ray radiation dose,yet compromises quality and decreases diagnostic *** have made great efforts to develop various algorithms for LDCT and introduced deep-learning techniques,which have achieved impressive ***,most of these methods are directly performed on reconstructed LDCT images,in which some subtle structures and details are readily lost during the reconstruction procedure,and convolutional neural network(CNN)-based methods for raw LDCT projection data are rarely *** address this problem,we adopted an attention residual dense CNN,referred to as AttRDN,for LDCT sinogram ***,it was aided by the attention mechanism,in which the advantages of both feature fusion and global residual learning were used to extract noise from the contaminated LDCT ***,the denoised sinogram was restored by subtracting the noise obtained from the input noisy ***,the CT image was reconstructed using filtered *** experimental results qualitatively and quantitatively demonstrate that the proposed AttRDN can achieve a better performance than state-of-the-art ***,it can prevent the loss of detailed information and has the potential for clinical application.

关键词： Low-dose CT Sinogram denoising Deep learning Attention mechanism

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Online Pattern Recognition and Data Correction of PMU Data Under GPS Spoofing Attack

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Journal of Modern Power Systems and Clean Energy 2020年第6期8卷 1240-1249页

作者： Ancheng Xue Feiyang Xu Jingsong Xu Joe H.Chow Shuang Leng Tianshu Bi State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China State Grid Ningxia Yinchuan Electric Power Company Yinchuan 750001China the Department of Electrical Computerand Systems EngineeringRensselaer Polytechnic Institute(RPI)TroyNY 12180USA

Smart grids are increasingly dependent on data with the rapid development of communication and *** one of the important data sources of smart grids,phasor measurement unit(PMU)is facing the high risk from *** with cyber attacks,global position system(GPS)spoofing attacks(GSAs)are easier to implement because they can be exploited by portable devices,without the need to access the physical ***,this paper proposes a novel method for pattern recognition of GSA and an additional function of the proposed method is the data correction to the phase angle difference(PAD)***,this paper analyzes the effect of GSA on PMU measurement and gives two common patterns of GSA,i.e.,the step attack and the ramp ***,the method of estimating the PAD deviation across a transmission line introduced by GSA is proposed,which does not require the line *** obtaining the estimated PAD deviations,the pattern of GSA can be recognized by hypothesis tests and correlation coefficients according to the statistical characteristics of the estimated PAD ***,with the case studies,the effectiveness of the proposed method is demonstrated,and the success rate of the pattern recognition and the online performance of the proposed method are analyzed.

关键词： global position system(GPS) GPS spoofing attack(GSA),phasor measurement,pattern recognition,data correction,line parameter

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Bacteria Adherence Properties of Nitrided Layer on Ti6Al4V by the Plasma Nitriding Technique

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Journal of Wuhan University of Technology(Materials Science) 2013年第6期28卷 1223-1226页

作者： FAN Ailan ZHANG Huiqiao MA Yong ZHANG Xiangyu ZHANG Jianqiang TANG Bin Research institute of Surface Engineering Taiyuan University of Technology College of Environmental Engineering Taiyuan University of Technology Department of architectural Engineering Shanxi Polytechnic College

The nitrided layer on Ti6A14V substrate was prepared by the plasma nitriding technique. The sample was characterized by X-ray diffraction （XRD）, glow discharge optical emission spectroscopy （GDOES）, X-ray photoelectron spectroscopy （XPS）, and rough-meter. X- ray diffraction analysis reveals that TiN, Ti2N and Ti phase exist in the nitrided layer subsurface. GDOES analysis shows the thickness of the nitrided layer is about 3 ~tm. XPS analysis shows that there is higher N, lower A1 and lower V in the nitrided layer surface than in the Ti6A14V surface. Rough-meter analysis results show the roughness of the nitrided layer is greater than that of Ti6A14V alloy base. The bacteria adherence property of the nitrided layer on Ti6A14V substrate on the Streptococcus mutans was investigated and compared with that of Ti6A14V alloy by fluorescence microscope. It shows that the nitrided layer inhibits the bacteria adherence.

关键词： Ti6A14V plasma nitriding technique nitrided layer bacteria adherence property

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Spatial and Temporal Patterns of Soil Nitrogen Distribution under Different Land Uses in a Watershed in the Hilly Area of Purple Soil,China

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Journal of Mountain Science 2013年第3期10卷 410-417页

作者： YANG Xiao-lin ZHU Bo LI Yi-ling institute of Mountain Hazards and Environment Chinese Academy of Sciences Henan polytechnic University graduate University of the Chinese Academy of Sciences

Quantification of soil spatial and temporal variability at watershed scale is important in ecological modeling, precision agriculture, and natural resources management. The spatio-temporal variations of soil nitrogen under different land uses in a small watershed （12.10 km^2） in the hilly area of purple soil at the upper reaches of the Yangtze River in southwestern China were investigated by using conventional statistics, geostatistics, and a geographical information system in order to provide information for land management and control of environmental issues. A total of 552 soil samples （o to 15 cm） from 276 sites within the watershed were collected in April and August of 2o11, and analyzed for soil total nitrogen （STN） and nitrate nitrogen （NO3-N）. We compared spatial variations of STN and NO3-N under different land uses as well as the temporal variations in April （dry season） and August （rainy season）. Results showed that STN contents were deeply affected by land-use types; median STN values ranged from 0.94to ***-I, and STN contents decreased in the following order： paddy field 〉 foresfland 〉 sloping cropland. No significant difference was found for STN contents between April and August under the same land use. However, NO3- N contents were 23.26, 10.58, and 26.19 mg·kg^-1 in April, and 1.34, 8.51, and 3.00 mg·kg^-1 in August for the paddy field, sloping cropland and forestland, respectively. Nugget ratios for STN indicatedmoderate spatial dependence in the paddy field and sloping cropland, and a strong spatial dependence in forestland. The processes of nitrogen movement, transformation, absorption of plant were deeply influenced by land use types; as a result, great changes of soil nitrogen levels at spatial and temporal scales were demonstrated in the studied watershed.

关键词： Land use Soil nitrogen Spatial variation Temporal variation Watershed scale

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