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机器学习中的特征选择方法研究及展望

北京邮电大学学报 2018年第1期41卷 1-12页

作者：崔鸿雁徐帅张利锋 roy e.welsch Berthold K.P.Horn 北京邮电大学网络与交换技术国家重点实验室北京100876 北京邮电大学网络体系构建与融合北京市重点实验室北京100876 先进信息网络北京实验室北京100876 Sloan School of Management Massachusetts Institute of Technology MA 02139 USA Csail Laboratory Massachusetts Institute of Technology MA 02139 USA

任何领域的大数据研究都离不开用机器学习方法提取特征.为了探求满足海量大数据分析需求的特征选择方法,笔者对利用机器学习进行特征选择的常用方法做了深入分析,归纳总结出特征选择的五大类方法：相关性度量方法、Lasso稀疏选择方法、... 详细信息

任何领域的大数据研究都离不开用机器学习方法提取特征.为了探求满足海量大数据分析需求的特征选择方法,笔者对利用机器学习进行特征选择的常用方法做了深入分析,归纳总结出特征选择的五大类方法：相关性度量方法、Lasso稀疏选择方法、集成方法、神经网络方法、主成分分析方法.通过对比不同特征选择方法的原理、实现过程以及应用场景,给出了不同算法下进行特征选择时的适用范围、优缺点和关键点,为研究者提供参考.

关键词：机器学习特征选择迁移学习对抗神经网络人工智能

Structural,optical,electrical,and dielectric relaxation properties of rare earth containing sodium bismuth titanate Na_(0.5)Bi_(0.5)TiO_(3) perovskite:effect of ionic radius

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Journal of Rare earths 2024年第2期42卷 383-391,I0006页

作者： Rajdip roy Abhigyan Dutta Department of Physics The University of BurdwanBurdwan713104India

The main focus of this work is to study the effect of the ionic radius of different rare earth dopant cations Re^(3+)(Re=La,Sm,Dy,and Ho) on structural and various physical properties of sodium bismuth titanate(Na_(0.5)B_(0.5)TiO_(3),NBT) based perovskite *** X-ray diffraction data indicate the successful formation of the rhombohedral phase(space group R3c) of NBT nano perovskite incorporated with various rare earth ions in *** lattice parameters were found to increase linearly with the ionic radius of the dopant *** ionic radii and atomic mass of rare earth dopants appear to be essential factors in the grain growth of the prepared *** grain growth results in better crystallinity of the sample by reducing the microstrain with the increase of dopant ionic *** emission scanning electron microscopy and energy-dispersive X-ray spectra confirm the prepared compositions' phase purity and *** UV-Vis spectra reveal that La-doped NBT composition exhibits the lowest optical band gap,which unfolds the application of NBT-based perovskite as photoactive *** ac conductivity and complex impedance spectra unveil that the composition with the largest ionic radius,i.e.,La-doped NBT compound,exhibits the highest dc and bulk conductivity with the lowest activation *** frequency-dependent dielectric data follows Havriliak-Negami(HN) formalism and non-Debye type relaxation *** also indicate that La-doped NBT composition exhibits the highest dielectric strength ***,this study first elaborates that the increasing ionic radius of the rare earth dopant cation in the Bi-site of NBT perovskite improves its microstructural,optical,and electrical properties.

关键词： Rare earth doped NBT Microstructural analysis Optical band gap AC Conductivity Dielectric relaxation Rare earths

Mechanism of Cu entry into the brain:many unanswered questions

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Neural Regeneration Research 2024年第11期19卷 2421-2429页

作者： Shubhrajit roy Svetlana Lutsenko Department of Physiology Johns Hopkins University School of MedicineBaltimoreMDUSA

Brain tissue requires high amounts of copper(Cu)for its key physiological processes,such as energy production,neurotransmitter synthesis,maturation of neuropeptides,myelination,synaptic plasticity,and radical *** requirements for Cu in the brain vary depending on specific brain regions,cell types,organism age,and nutritional *** imbalances cause or contribute to several life-threatening neurologic disorders including Menkes disease,Wilson disease,Alzheimer’s disease,Parkinson’s disease,and *** the well-established role of Cu homeostasis in brain development and function,the mechanisms that govern Cu delivery to the brain are not well *** review summarizes available information on Cu transfer through the brain barriers and discusses issues that require further research.

关键词： ATOX1 ATP7A ATP7B blood-brain barrier brain choroid plexus copper SLC31A1

enhanced in-vitro degradation resistance and cytocompatibility of a thermomechanically processed novel Mg alloy:Insights into the role of microstructural attributes

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Journal of Magnesium and Alloys 2024年第2期12卷 700-725页

作者： Darothi Bairagi Santanu Mandal Mangal roy Manas Paliwal Sumantra Mandal Department of Metallurgical and Materials engineering Indian Institute of TechnologyKharagpur 721302India

The role of microstructural features on in-vitro degradation and surface film development of a thermomechanically processed Mg-4Zn-0.5Ca-0.8Mn alloy has been investigated employing electrochemical studies,scanning electron microscopy and X-ray photoelectron *** specimen forged at 523 K temperature developed a coarse unimodal microstructure consisting of basal oriented grains,whereas the specimens forged at 623 K and 723 K temperatures exhibited bimodal microstructures containing randomly oriented fine grains and basal oriented coarse *** bimodal microstructures exerted higher resistance to corrosion compared to the unimodal microstructure in presence of a protective surface *** optimum size distribution of fine and coarse grains as well as the prevalence of basal oriented grains led to the lowest anodic current density in the specimen forged at 623 *** morphology of Ca_(2)Mg_(6)Zn_(3)precipitates governed the cathodic kinetics by controlling the anode to cathode surface area *** the specimen forged at 723 K comprised comparatively lower fraction of precipitates than at 623 K,the mesh-like precipitate morphology increased the effective cathodic surface area,leading to enhanced localised corrosion in the former *** microstructural features developed at 623 K forging temperature formed a well-protective surface film with lower Mg(OH)_(2)to MgO ratio,exhibiting distinctly high polarization resistance and superior cytocompatibility in terms of cell-proliferation and cell-differentiation.

关键词： Magnesium alloy Microstructure Corrosion electrochemical impedance spectroscopy X-ray photoelectron spectroscopy Cytotoxicity

Low-loss and polarization insensitive 32×4 optical switch for ROADM applications

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Light(Science & Applications) 2024年第5期13卷 875-884页

作者： Xiaotian Zhu Xiang Wang Yanlu Huang Liyan Wu Chunfei Zhao Mingzhu Xiao Luyi Wang roy Davidson Yanni Ou Brent e.Little Sai T.Chu Department of Physics City University of Hong KongTat Chee AvenueHong KongChina. QXP Technologies Inc. NO.15th Shanglinyuan 1st RoadXi’anShaanxi 710119China. State Key Laboratory of Information of Photonics and Optical Communications School of Electronic EngineeringBeijing University of Posts and TelecommunicationsBeijing 100876China

Integrated switches play a crucial role in the development of reconfigurable optical add-drop multiplexers(ROADMs)that have greater flexibility and compactness,ultimately leading to robust single-chip *** decades of research on switches with various structures and platforms,achieving a balance between dense integration,low insertion loss(IL),and polarization-dependent loss(PDL)remains a significant *** this paper,we propose and demonstrate a 32×4 optical switch using high-index doped silica glass(HDSG)for ROADM *** switch is designed to route any of the 32 inputs to the express ports or drop any channels from 32 inputs to the target 4 drop ports or add any of the 4 ports to any of the 32 express *** switch comprises 188 MachZehnder Interferometer(MZI)type switch elements,88 optical vias for the 44 optical bridges,and 618 waveguidewaveguide crossings with three-dimensional(3D)*** 1550 nm,the fiber-to-fiber loss for each express channel is below 2 dB,and across the C and L bands,below 3 *** each input channel to all 4 drop/add channels at 1550 nm,the loss is less than 3.5 dB and less than 5 dB across the C and L *** PDLs for all express and input channels to the 4 drop/add channels are below 0.3 dB over the C band,and the crosstalk is under−50 dB for both the C and L bands.

关键词： polarization ROADM optical

earliest megafossils of scandent calamoid palms from the Deccan Intertrappean Beds of Central India and their paleobiogeographic implications

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Journal of Palaeogeography 2024年第3期13卷 509-527页

作者： Sanchita Kumar Kaustav roy Robert A.Spicer Mahasin Ali Khan Palaeobotany and Palynology Laboratory Department of BotanySidho-Kanho-Birsha UniversityRanchi RoadPurulia-723104India CAS Key Laboratory of Tropical Forest ecology Xishuangbanna Tropical Botanical GardenChinese Academy of SciencesMengla 666303Yunnan ProvinceChina School of environment Earth and Ecosystem SciencesThe Open UniversityMilton KeynesMK76AAUK State Key Laboratory of Tibetan Plateau earth System Resources and Environment(TPESRE)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China

Two well-preserved petrified palm stems from the latest Maastrichtian(Late Cretaceous) to earliest Danian(early Paleocene) sediments of the Deccan Intertrappean Beds of Madhya Pradesh, Central India are described. Their significant anatomical characteristics include a Calamus-type general stem pattern,the presence of well-preserved fibrovascular bundles(fvbs) with two wide metaxylem vessel elements(230 μm-250 μm) and one phloem strand, uniform density of fvbs, lack of continuity between protoxylem and metaxylem vessel elements, and an absence of centrifugal differentiation of sclerenchymatous fibrous *** features reveal a close resemblance to those of extant genera of scandent Calamoideae. The permineralized stems are described as a new species namely, Palmoxylon calamoides Kumar, roy et Khan sp. *** fossils represent the oldest reliable fossil records of this family, supporting their Gondwanan origin, their importance in tracing their migration pathways from India to europe and other continents after the docking of the Indian subcontinent with eurasia during the Paleocene, and an “Out-of-India” dispersal hypothesis. Today the subfamily Calamoideae is disjunctly occurred in Africa, Asia, Australia, europe, and South America, but the poor deep-time fossil record of this subfamily with a small number of Cenozoic fossils makes hypotheses concerning its origin and dispersal difficult to evaluate. The present study has significant implications for the origin and migration of this subfamily and the paleoclimate.

关键词： Scandent Calamoideae Stem anatomy K-Pg Paleobiogeography Paleoclimate Central India

Association between people’s attitudes towards human-elephant conflict and their locational,demographic,and socio-economic characteristics in Buxa Tiger Reserve and its adjoining area,India

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Regional Sustainability 2024年第1期5卷 11-25页

作者： Chiranjib NAD Tamal BASU-roy Department of Geography Raiganj UniversityRaiganj733134India

“Human-elephant conflict(HeC)”,the alarming issue,in present day context has attracted the attention of environmentalists and policy *** rising conflict between human beings and wild elephants is common in Buxa Tiger Reserve(BTR)and its adjoining area in West Bengal State,India,making the area ***’s attitudes towards elephant conservation activity are very crucial to get rid of HeC,because people’s proximity with wild elephants’habitat can trigger the occurrence of *** aim of this study is to conduct an in-depth investigation about the association of people’s attitudes towards HeC with their locational,demographic,and socio-economic characteristics in BTR and its adjoining area by using Pearson’s bivariate chi-square test and binary logistic regression *** is one of the constituent parts of eastern Doors elephant Reserve(eDeR).We interviewed 500 respondents to understand their perceptions to HeC and investigated their locational,demographic,and socio-economic characteristics including location of village,gender,age,ethnicity,religion,caste,poverty level,education level,primary occupation,secondary occupation,household type,and source of *** results indicate that respondents who are living in enclave forest villages(eFVs),peripheral forest villages(PFVs),corridor village(CVs),or forest and corridor villages(FCVs),mainly males,at the age of 18–48 years old,engaged with agriculture occupation,and living in kancha and mixed houses,have more likelihood to witness ***,respondents who are illiterate or at primary education level are more likely to regard elephant as a main problematic animal around their villages and refuse to participate in elephant conservation *** the sake of a sustainable environment for both human beings and wildlife,people’s attitudes towards elephants must be friendly in a more prudent way,so that the two communities can live in harmony.

关键词： Human-elephant conflict elephant conservation Chi-square test statistics Binary logistic regression Demographic and socioeconomic characteristics Buxa Tiger Reserve

Role of self-help groups on socioeconomic development and the achievement of Sustainable Development Goals(SDGs)among rural women in Cooch Behar District,India

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Regional Sustainability 2024年第2期5卷 63-74页

作者： Debanjan BASAK Indrajit roy CHOWDHURY Department of Geography and Applied Geography University of North BengalSiliguri734013India

This study examines the transformative role of self-help groups(SHGs)in the socioeconomic development of rural women in Cooch Behar District,India,and their contribution toward achieving Sustainable Development Goals(SDGs)of the United *** this study,we explored the effect of SHGs on rural women by specifically addressing SDGs,such as no poverty(SDG 1),zero hunger(SDG 2),good health and well-being(SDG 3),quality education(SDG 4),and gender equality(SDG 5).Given this issue,a cross-sectional survey and comparison analyses are needed to assess the socioeconomic development of rural women and their awareness level before and after the participation of rural women in *** survey conducted as part of this study was divided into three sections,namely,demographic characteristics,socioeconomic development,and awareness level,with each focusing on different aspects.A group of 400 individuals who were part of SHGs completed the questionnaire survey *** results showed that the participation of rural women in SHGs significantly improved their socioeconomic development and awareness level,as supported by both mean values and t test *** in SHGs and microcredit programs were the major elements that boosted the socioeconomic development of rural women,which also achieves SDGs 1,2,3,4,and *** study revealed that participation in SHGs and related financial services significantly aided rural women in economically disadvantaged communities in accumulating savings and initiating entrepreneurial ***,participation in SHGs was instrumental in enhancing the self-confidence,self-efficacy,and overall self-esteem of rural ***,doing so enabled them to move more freely for work and other activities and to make family and common decisions.

关键词： Self-help groups Rural women Socioeconomic development Sustainable Development Goals(SDGs) Microcredit India

Quantized Redshift and its Significance for Recent Observation

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Research in Astronomy and Astrophysics 2024年第9期24卷 156-166页

作者： Arindam Mal Sarbani Palit Christopher C.Fulton Sisir roy Indian Space Research Organization Space Applications CentreAhmedabadIndia Indian Statistical Institute CVPR UnitKolkataIndia Protostar Inc.15652 Carrousel DriveCanyon CountryCA 91387USA National Institute of Advanced Studies IISC CampusBangaloreIndia

With the recent observational evidence in extragalactic astronomy,the interpretation of the nature of quasar redshift continues to be a research *** high redshifts are being detected for extragalactic objects that are presumably very distant and young while also exhibiting properties that are characteristic of a more mature galaxy such as *** to Halton Arp and Geoffrey Burbidge,redshift disparities consist of an intrinsic component and are related to an evolutionary *** observed redshift periodicity at integer multiples of0.089 in log scale and Burbidge observed redshift periodicity at integer multiples of 0.061 in linear *** Singular Value Decomposition based periodicity estimation is known to be superior for noisy data sets,especially when the data contain multiple harmonics and overtones,mainly irregular in nature,we have chosen it to be our primary tool for analysis of the quasar-galaxy pair redshift *** have observed a fundamental periodicity of0.051 with a confidence interval of 95%in linear scale with the site-available Sloan Digital Sky Survey Data Release 7(SDSS DR7)quasar-galaxy pair data *** have independently generated quasar-galaxy pair data sets from both 2d F and SDSS and found fundamental periodicities of 0.077 and 0.089,respectively,in log scale with a confidence interval of 95%.

关键词： galaxies:distances and redshifts (galaxies:)quasars:absorption lines cosmology:observations