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An Initial Perturbation Method for the Multiscale Singular Vector in Global Ensemble Prediction

Advances in Atmospheric Sciences 2024年第3期41卷 545-563页

作者： Xin LIU Jing CHEN Yongzhu LIU Zhenhua HUO Zhizhen XU Fajing CHEN Jing WANG Yanan MA yumeng han School of Atmospheric Sciences Nanjing University of Information Science&TechnologyNanjing 210044China Chinese Academy of Meteorological Sciences Beijing 100081China CMA Earth System Modeling and Prediction Centre(CEMC) Beijing 100081China Key Laboratory of Earth System Modeling and Prediction of China Meteorological Administration Beijing 100081China Tianjin Meteorological Observatory Tianjin 300074China China Meteorological Administration Xiong’an Atmospheric Boundary Layer Key Laboratory Hebei 071799China

Ensemble prediction is widely used to represent the uncertainty of single deterministic Numerical Weather Prediction(NWP) caused by errors in initial conditions(ICs). The traditional Singular Vector(SV) initial perturbation method tends only to capture synoptic scale initial uncertainty rather than mesoscale uncertainty in global ensemble prediction. To address this issue, a multiscale SV initial perturbation method based on the China Meteorological Administration Global Ensemble Prediction System(CMA-GEPS) is proposed to quantify multiscale initial uncertainty. The multiscale SV initial perturbation approach entails calculating multiscale SVs at different resolutions with multiple linearized physical processes to capture fast-growing perturbations from mesoscale to synoptic scale in target areas and combining these SVs by using a Gaussian sampling method with amplitude coefficients to generate initial perturbations. Following that, the energy norm,energy spectrum, and structure of multiscale SVs and their impact on GEPS are analyzed based on a batch experiment in different seasons. The results show that the multiscale SV initial perturbations can possess more energy and capture more mesoscale uncertainties than the traditional single-SV method. Meanwhile, multiscale SV initial perturbations can reflect the strongest dynamical instability in target areas. Their performances in global ensemble prediction when compared to single-scale SVs are shown to(i) improve the relationship between the ensemble spread and the root-mean-square error and(ii) provide a better probability forecast skill for atmospheric circulation during the late forecast period and for short-to medium-range precipitation. This study provides scientific evidence and application foundations for the design and development of a multiscale SV initial perturbation method for the GEPS.

关键词： multiscale uncertainty singular vector initial perturbation global ensemble prediction system

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Optimizing 2D-metal contact in layered Tin-selenide via native oxide modulation

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Nano Research 2024年第4期17卷 3014-3020页

作者： Yue Zheng Qi You Zhentian Yin Jian Tang Ke Jiang Zihao Xie Henan Li Cheng han yumeng Shi International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education Institute of Microscale OptoelectronicsShenzhen UniversityShenzhen 518060China College of Electronics and Information Engineering Shenzhen UniversityShenzhen 518060China

The discovery of two-dimensional(2D)semiconductor has opened up new avenues for the development of short-channel field-effect transistors(FETs)with desired electrical *** them,orthorhombic tin-selenide(SnSe)has garnered increasing attention due to its potential applications in a variety of electronic,optoelectronic,and thermoelectric ***,the realization of high-performance SnSe FETs with low contact resistance(Rc)remains a ***,we systematically investigate the contact of few-layer SnSe FETs through the modulation of native oxide on SnSe by using different *** is found that chromium(Cr)-contacted devices possess the best FET performance,such as electron mobility up to 606 cm^(2)/(V·s)at 78 K,current on/off ratio exceeding 1010,and saturation current of~550μA/μm,where a negligible Schottky barrier(SB)of~30 meV and a low contact resistance of~425Ωμm are achieved.X-ray photoelectron spectroscopy(XPS)and cross-sectional electron dispersive X-ray spectroscopy(EDX)results further reveal that the improved contact arises from the Cr-induced reduction of native oxide(SnOx)to Sn,which thins the tunneling barrier for efficient electron *** findings provide a deep insight into the 2D-metal contact of SnSe and pave the way for its applications in future nanoelectronics.

关键词： few-layer SnSe field-effect transistors(FETs) Cr contact native oxide contact resistance(Rc) Schottky barrier(SB)

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Interlayer exciton dynamics of transition metal dichalcogenide heterostructures under electric fields

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Nano Research 2024年第5期17卷 4555-4572页

作者： Jian Tang Yue Zheng Ke Jiang Qi You Zhentian Yin Zihao Xie Henan Li Cheng han Xiaoxian Zhang yumeng Shi International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education Institute of Microscale OptoelectronicsShenzhen UniversityShenzhen 518060China College of Electronics and Information Engineering Shenzhen UniversityShenzhen 518060China Key Laboratory of Luminescence and Optical Information Ministry of EducationInstitute of Optoelectronic TechnologyBeijing Jiaotong UniversityBeijing 100044China

Stacking single layers of atoms on top of each other provides a fundamental way to achieve novel material systems and engineer their physical properties,which offers opportunities for exploring fundamental physics and realizing next-generation optoelectronic *** the two-dimensional(2D)-stacked systems,transition metal dichalcogenide(TMDC)heterostructures are particularly attractive because they host tightly-bonded interlayer excitons which possess various novel and appealing *** interlayer excitons have drawn significant research attention and hold high potential for the application in unique optoelectronic devices,such as polarization-and wavelength-tunable single photon emitters,valley Hall transistors,and possible high-temperature *** development of these devices requires a comprehensive understanding of the fundamental properties of these interlayer excitons and the impact of electric fields on their *** this review,we summarize the recent advances on the understanding of interlayer exciton dynamics under electric fields in TMDC *** put emphasis on the electrical modulation of interlayer excitons’emission,the valley Hall transport of charge carriers after the separation of interlayer excitons by an electric field,and the correlation physics of interlayer excitons and charges under electrical doping and *** and perspectives are finally discussed for the application of TMDC heterostructures in future optoelectronics.

关键词： interlayer exciton transition metal dichalcogenide(TMDC)heterostructures circular polarization valley Hall effect strong coupling

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Enhancing low-resource cross-lingual summarization from noisy data with fine-grained reinforcement learning

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Frontiers of Information Technology & Electronic Engineering 2024年第1期25卷 121-134页

作者： Yuxin HUANG Huailing GU Zhengtao YU yumeng GAO Tong PAN Jialong XU Faculty of Information Engineering and Automation Kunming University of Science and TechnologyKunming 650504China Yunnan Key Laboratory of Artificial Intelligence Kunming University of Science and TechnologyKunming 650504China

Cross-lingual summarization(CLS)is the task of generating a summary in a target language from a document in a source ***,end-to-end CLS models have achieved impressive results using large-scale,high-quality datasets typically constructed by translating monolingual summary corpora into CLS ***,due to the limited performance of low-resource language translation models,translation noise can seriously degrade the performance of these *** this paper,we propose a fine-grained reinforcement learning approach to address low-resource CLS based on noisy *** introduce the source language summary as a gold signal to alleviate the impact of the translated noisy target ***,we design a reinforcement reward by calculating the word correlation and word missing degree between the source language summary and the generated target language summary,and combine it with cross-entropy loss to optimize the CLS *** validate the performance of our proposed model,we construct Chinese-Vietnamese and Vietnamese-Chinese CLS *** results show that our proposed model outperforms the baselines in terms of both the ROUGE score and BERTScore.

关键词： Cross-lingual summarization Low-resource language Noisy data Fine-grained reinforcement learning Word correlation Word missing degree

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Spatial-temporal differentiation and influencing factors of rural settlements in mountainous areas: an example of Liangshan Yi Autonomous Prefecture, Southwestern China

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Journal of Mountain Science 2024年第1期21卷 218-235页

作者： WANG yumeng DENG Qingchun YANG Haiqing LIU Hui YANG Feng ZHAO Yakai School of Geographical Sciences China West Normal UniversityNanchong 637009China Sichuan Provincial Engineering Laboratory of Monitoring and Control for Soil Erosion in Dry Valleys China West Normal UniversityNanchong 637009China Liangshan Soil Erosion and Ecological Restoration in Dry Valleys Observation and Research Station Xide 616753China

Rural settlement is the basic spatial unit for compact communities in rural area. Scientific exploration of spatial-temporal differentiation and its influencing factors is the premise of spatial layout rationalization. Based on land use data of Liangshan Yi Autonomous Prefecture(hereinafter referred to as Liangshan Prefecture) in Sichuan Province, China from 1980 to 2020, compactness index, fractal dimension, imbalance index, location entropy and the optimal parameters-based geographical detector(OPGD) model are used to analyze the spatial-temporal evolution of the morphological characteristics of rural settlements, and to explore the influence of natural geographical factors, socioeconomic factors, and policy factors on the spatial differentiation of rural settlements. The results show that:(1) From 1980 to 2020, the rural settlements area in Liangshan Prefecture increased by 15.96 km^(2). In space, the rural settlements are generally distributed in a local aggregation, dense in the middle and sparse around the periphery. In 2015, the spatial density and expansion index of rural settlements reached the peak.(2) From 1980 to 2020, the compactness index decreased from 0.7636 to 0.7496, the fractal dimension increased from 1.0283 to 1.0314, and the fragmentation index decreased from 0.1183 to 0.1047. The spatial morphological structure of rural settlements tended to be loose, the shape contour tended to be complex, the degree of fragmentation decreased, and the spatial distribution was significantly imbalanced.(3) The results of OPGD detection in 2015 show that the influence of each factor is slope(0.2371) > traffic accessibility(0.2098) > population(0.1403) > regional GDP(0.1325) > elevation(0.0987) > poverty alleviation(0). The results of OPGD detection in 2020 show that the influence of each factor is slope(0.2339) > traffic accessibility(0.2198) > population(0.1432) > regional GDP(0.1219) > poverty alleviation(0.0992) > elevation(0.093). Natural geographical facto

关键词： Rural settlements Location entropy Geographical detector Spatiotemporal differentiation Influencing factors

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改进TOPSIS法的武汉城市轨道交通节点重要度评估

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重庆交通大学学报:自然科学版 2023年第9期42卷 113-121页

作者：涂敏韩雨濛武汉理工大学交通与物流工程学院湖北武汉430063

随着城市轨道交通规模的不断发展,如何快速有效地挖掘重要站点对轨道交通的安全运营具有重要意义。以2021年底武汉城市轨道交通为研究对象,运用Space-L方法构建武汉地铁网络拓扑结构;考虑节点所处的局部环境和节点在网络中的全局属性,... 详细信息

随着城市轨道交通规模的不断发展,如何快速有效地挖掘重要站点对轨道交通的安全运营具有重要意义。以2021年底武汉城市轨道交通为研究对象,运用Space-L方法构建武汉地铁网络拓扑结构;考虑节点所处的局部环境和节点在网络中的全局属性,引入进行网页排名的PageRank算法,分析了客流量对地铁站点的影响;最后通过基于余弦相似性TOPSIS法代替传统TOPSIS法来解决节点重要度排序的问题。研究结果表明:武汉城市轨道交通网络为无标度网络,整个线路呈现出小环线、长放射线的模式,放射线过长会造成长距离通勤放射线过分依赖市中心的换乘,易造成客流的不均衡;重要度排名靠前的车站在轨道交通网络中拥有着较多的邻居节点、位置相对中心化、客流量较大且具有较高的局部重要性和全局重要性;与单一指标评估结果相比,笔者方法更加全面客观并赋予了不同属性指标权重,使得评价更加全面,且能在一定程度上改善因欧式距离失效而产生的逆序现象。

关键词：交通工程复杂网络轨道交通复杂网络余弦相似性 TOPSIS模型节点重要度

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High-temperature elemental segregation induced structure degradation in high-entropy fluorite oxide

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Journal of Advanced Ceramics 2024年第3期13卷 310-322页

作者： Yixuan Hu Mariappan Anandkumar yumeng Zhang Joydip Joardar Atul Suresh Deshpande Xiaodong Wang Kolan Madhav Reddy School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Department of Materials Science and Metallurgical Engineering Indian Institute of Technology HyderabadSangareddy 502285India International Advanced Research Centre for Powder Metallurgy and New Materials(ARCI) Hyderabad 500005India

Fluorite-structured oxides constitute an important category of oxides with a wide range of high-temperature *** the concept of high entropy,high-entropy fluorite oxides(HEFOs)have showcased intriguing high-temperature application ***,unlocking this potential necessitates an assessment of their long-term stability under high-temperature *** this study,we conducted a prolonged heat treatment at 1000℃on typical HEFO,specifically(CeHfZrGdLa)O_(x).After 100 h,high-intensity X-ray diffraction(XRD)revealed a transition from a single-phase fluorite to a multi-phase *** investigation by analytical electron microscoy(AEM)demonstrated that this degradation resulted from facilitated element diffusion and consequent escalating chemical fluctuation at high temperatures,leading to spontaneous segregation and separation of Ce and La elements,forming Ce-rich,La-poor,and La-rich ***,the La-rich phase spontaneously transformed from a fluorite structure(space group Fm3m)to a bixbyite structure(space group Ia3)at elevated temperatures,resulting in the appearance of superstructure reflection in XRD profiles and electron diffraction *** the intricate phase decomposition,the energy band gap showed minimal variation,suggesting potential property stability of(CeHfZrGdLa)O_(x)across a broad range of *** findings offer valuable insights into the future applications of HEFOs.

关键词： phase transition high-temperature stability elemental segregation high-entropy fluorite oxides(HEFOs)

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Cryptic divergences and repeated hybridizations within the endangered “living fossil” dove tree(Davidia involucrata) revealed by whole genome resequencing

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Plant Diversity 2024年第2期46卷 169-180页

作者： yumeng Ren Lushui Zhang Xuchen Yang Hao Lin Yupeng Sang Landi Feng Jianquan Liu Minghui Kang Key Laboratory of Bio-resource and Eco-environment of Ministry of Education College of Life SciencesSichuan UniversityChengdu 610065China State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystem College of EcologyLanzhou UniversityLanzhou 730000China Guangdong Provincial Key Laboratory of Plant Adaptation and Molecular Design Guangzhou Key Laboratory of Crop Gene EditingInnovative Center of Molecular Genetics and EvolutionSchool of Life SciencesGuangzhou UniversityGuangzhou 510006China

The identification and understanding of cryptic intraspecific evolutionary units(lineages) are crucial for planning effective conservation strategies aimed at preserving genetic diversity in endangered ***, the factors driving the evolution and maintenance of these intraspecific lineages in most endangered species remain poorly understood. In this study, we conducted resequencing of 77 individuals from 22 natural populations of Davidia involucrata, a “living fossil” dove tree endemic to central and southwest China. Our analysis revealed the presence of three distinct local lineages within this endangered species, which emerged approximately 3.09 and 0.32 million years ago. These divergence events align well with the geographic and climatic oscillations that occurred across the distributional ***, we observed frequent hybridization events between the three lineages, resulting in the formation of hybrid populations in their adjacent as well as disjunct regions. These hybridizations likely arose from climate-driven population expansion and/or long-distance gene flow. Furthermore, we identified numerous environment-correlated gene variants across the total and many other genes that exhibited signals of positive evolution during the maintenance of two major local lineages. Our findings shed light on the highly dynamic evolution underlying the remarkably similar phenotype of this endangered species. Importantly, these results not only provide guidance for the development of conservation plans but also enhance our understanding of evolutionary past for this and other endangered species with similar histories.

关键词： Davidia involucrata Cryptic lineage Hybridization Population genomics Positive evolution

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New findings of Changxingaspis(Xiushuiaspidae,Galeaspida)from the Silurian of Tarim Basin and Zhejiang Province,China

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Acta Geologica Sinica(English Edition) 2024年第3期98卷 531-540页

作者： LI Xutong ZhanG yumeng LIN Xianghong ZHU Min ZHAO Wenjin TANG Lizhou Shan Xianren GAI Zhikun Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences Institute of Vertebrate Paleontology and PaleoanthropologyChinese Academy of SciencesBeijing 100044China College of Life Sciences Jiangxi Normal UniversityNanchang 330022China Yunnan Key Laboratory for Palaeobiology Institute of PalaeontologyYunnan UniversityKunming 650500China University of Chinese Academy of Sciences Beijing 100044China

New discovery of the early Silurian fossil fish Changxingaspis(Xiushuiaspidae,Galeaspida),Changxingaspis nianzhongi *** ***,are described from the Tataertag Formation in Tarim Basin and the Kangshan Formation in Zhejiang Province,*** mainly differs from *** in the shape of the median dorsal opening that is transverse elliptic with a width/length ratio of about 3.0,the long lateral transverse canals extending to the lateral margin of the headshield,and the second lateral transverse canal with dichotomous *** of *** from the Tataertag Formation and *** from the Kangshan Formation provide direct evidence on the specific level for the correlation between these two formations,which further supports the Silurian fish-bearing red beds in northwest Zhejiang belonging to the Silurian Lower Red Beds(LRBs)rather than the Upper Red Beds(URBs).Additionally,as the first record of the Changxingaspis in Tarim Basin,it extends the paleogeographical distribution of this genus from the South China Block to the Tarim Block,providing new evidence to support faunal exchanges between these two blocks and the hypothesis of a united Tarim-South China Block during the early Silurian.

关键词： vertebrate paleontology Galeaspids Changxingaspis new taxon Tataertag Formation Kangshan Formation Aeronian-Telychian Tarim Zhejiang

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Reorganization of 3D genome architecture provides insights into pathogenesis of early fatty liver disease in laying hens

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Journal of Animal Science and Biotechnology 2024年第3期15卷 1086-1100页

作者： Yanli Liu Zhuqing Zheng Chaohui Wang yumeng Wang Xi Sun Zhouzheng Ren Xin Yang Xiaojun Yang College of Animal Science and Technology Northwest A&F UniversityYangling 712100China Institute of Agricultural Biotechnology Jingchu University of TechnologyJingmen 448000China

Background Fatty liver disease causes huge economic losses in the poultry industry due to its high occurrence and lethality ***-dimensional(3D)chromatin architecture takes part in disease processing by regulating tran-scriptional *** study is carried out to investigate the alterations of hepatic 3D genome and H3K27ac profiling in early fatty liver(FLS)and reveal their effect on hepatic transcriptional reprogramming in laying *** Results show that FLS model is constructed with obvious phenotypes including hepatic visible lipid deposi-tion as well as higher total triglyceride and cholesterol in serum.A/B compartment switching,topologically associat-ing domain(TAD)and chromatin loop changes are identified by high-throughput/resolution chromosome conforma-tion capture(HiC)*** genes of these alternations in hepatic 3D genome organization significantly enrich pathways related to lipid metabolism and hepatic damage.H3K27ac differential peaks and differential expres-sion genes(DEGs)identified through RNA-seq analysis are also enriched in these ***,certain DEGs are found to correspond with changes in 3D chromatin structure and H3K27ac binding in their *** motif analysis reveals that candidate transcription factors are implicated in regulating transcriptional ***,disturbed folate metabolism is observed,as evidenced by lower folate levels and altered enzyme *** Our findings establish a link between transcriptional reprogramming changes and 3D chromatin struc-ture variations during early FLS formation,which provides candidate transcription factors and folate as targets for FLS prevention or treatment.

关键词： 3D chromatin architecture Fatty liver disease Folate H3K27ac profiling Transcription reprogramming

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