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基于机器学习预测的M-SV投资组合决策研究

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数学的实践与认识 2024年第5期54卷 70-82页

作者：张鹏李璟欣崔淑琳华南师范大学经济与管理学院广东广州510006

运用随机森林(Random forest,RF)、极端梯度提升(eXtremeGradient boosting,XGBoost)、支持向量回归(Support vectorreg ression,SVR)三种机器学习方法预测股票的收益率.运用预测的平均股票收益率,计算投资组合的期望收益、下半方差和... 详细信息

运用随机森林(Random forest,RF)、极端梯度提升(eXtremeGradient boosting,XGBoost)、支持向量回归(Support vectorreg ression,SVR)三种机器学习方法预测股票的收益率.运用预测的平均股票收益率,计算投资组合的期望收益、下半方差和下半协方差.考虑交易成本、借贷约束和交易量限制等,构建了基于机器学习预测的均值-下半方差(M-SV)投资组合模型,并运用不等式的旋转算法求解.最后,运用中证100指数成分股,进行样本内和样本外实证分析.研究结果表明,在样本内检验中SVR+M-SV模型的有效前沿水平相较于RF+M-SV、XGBoost+M-SV模型更高;在样本外检验中,三种机器学习混合方法+M-SV模型在收益、夏普比率、索提诺比率等的表现优于M-SV和等比例模型.

关键词：投资组合均值-下半方差随机森林极端梯度提升支持向量回归

Study on Multiplexing Ability of Identical Fiber Bragg Gratings in a Single Fiber

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Chinese Journal of Aeronautics 2011年第5期24卷 607-612页

作者： liU Jiansheng ZHANG jing li xin ZHENG Zheng School of Electronics and lnformation Engineering Beihang University Beijing 100191 China

The multiplexing ability of a novel multiplexing fiber Bragg grating （FBG） method based on Optical Time Domain Reflecto meter （OTDR） and Time Division Multiplexing TDM technologies has been theoretically analyzed and studied. This method permits the interrogation of hundreds of identical FBGs with low reflectivity in a single fiber, making the FBG sensors more applicable in the aerospace health monitoring engineering. The analysis shows that the multiplexing ability can be greatly improved if the FBG reflectivity is sufficiently low. And hence, an inexpensive large-scale distributed sensing system based on this method can be realized, When evaluating the multiplexing ability of this system, we propose for the first time that the interference effect of multi-reflections among FBGs should be taken into consideration.

关键词： Bragg gratings multiplexing low reflectivity multi-reflection interference effect

Transition metal clusters with precise numbers of atoms anchored on graphdiyne as multifunctional electrocatalysts for OER/ORR/HER:a computational study

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Rare Metals 2024年第7期43卷 3107-3117页

作者： xin-Yang liu jing-Wei liu Gang li jing-Xiang Zhao College of Chemistry and Chemical Engineering Harbin Normal UniversityHarbin 150025China

Subnanometer metal clusters play an increasingly important role in heterogeneous catalysis due to their high catalytic activity and *** this work,by means of the density functional theory(DFT) calculations,the catalytic activities of transition metal clusters with precise numbers of atoms supported on graphdiyne(TM_(1-4)@GDY,TM=V,Cr,Mn,Fe,Co,Ni,Cu,Ru,Rh,Pd,Ir,Pt) were investigated for oxygen evolution reactions(OER),oxygen reduction reactions(ORR) and hydrogen evolution reactions(HER).The computed results reveal that the Pd_(2),Pd_(4) and Pt_(1) anchored graphdiyne can serve as trifunctional catalysts for OER/ORR/HER with the overpotentials of 0.49/0.37/0.06,0.45/0.33/0.12 and 0.37/0.43/0.01 V,respectively,while Pd_(1) and Pt_(2)@graphdiyne can exhibit excellent catalytic performance for water splitting(OER/HER) with the overpotentials of 0.55/0.17 and 0.43/0.03 *** addition,Ni_(1) and Pd_(3) anchored GDY can perform as bifunctional catalysts for metal-air cells(OER/ORR) and fuels cells(ORR/HER) with the overpotentials of 0.34/0.32 and 0.42/0.04 V,***,by precisely controlling the numbers of atoms in clusters,the TM_(1-4) anchored graphdiyne can serve as promising multifunctional electrocatalysts for OER/ORR/HER,which may provide an instructive strategy to design catalysts for the energy conversation and storage devices.

关键词： Density functional theory Graphdiyne Single-cluster catalysts Multifunctional electrocatalysts Overpotential

后冬奥时期我国冰雪体育保险的价值意蕴、现实困境与纾解方略

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哈尔滨体育学院学报 2024年第1期42卷 22-28页

作者：吴建曹电康李晓栋时丽珍荆立新中北大学体育学院山西太原030051 西南大学体育学院重庆400715 哈尔滨体育学院体育人文社会学院黑龙江哈尔滨150008

采用文献资料、逻辑分析等研究方法,立足冰雪体育保险,分析其在后冬奥时期的价值意蕴和现实困境,并提出纾解方略。研究认为:后冬奥时期发展冰雪体育保险可以拓宽保障范围,完善体育保险市场体系;繁荣冰雪经济,推动冰雪体育产业高质量发展... 详细信息

采用文献资料、逻辑分析等研究方法,立足冰雪体育保险,分析其在后冬奥时期的价值意蕴和现实困境,并提出纾解方略。研究认为:后冬奥时期发展冰雪体育保险可以拓宽保障范围,完善体育保险市场体系;繁荣冰雪经济,推动冰雪体育产业高质量发展;巩固冬奥成果,保障“带动三亿人参与冰雪运动”可持续发展。冰雪体育保险发展面临的现实困境:体育保险法律体系不完善;冰雪体育参与者保险意识淡薄;冰雪体育保险中介市场发展缓慢;冰雪体育保险产品单一,保险数据匮乏;冰雪体育保险专业人才短缺等。纾解方略:制度推进,完善体育保险法律法规体系;宣传引领,提升国民冰雪体育保险意识;企业为先,夯实冰雪体育保险中介市场;创新导向,丰富冰雪体育保险产品供给;人才保障,培育冰雪体育保险专业人才。以期为冰雪运动提供良好的支持和保障,为冰雪体育产业高质量发展保驾护航。

关键词：后冬奥时期冰雪运动体育保险冰雪体育保险

基于改性粉煤灰材料的双滤筒VOCs吸附装置开发

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中国环保产业 2024年第3期 55-58页

作者：齐立强高唯恒李晶欣罗积琛华北电力大学河北保定071000

针对挥发性有机物(VOCs)污染,基于改性粉煤灰材料的理化性质设计了一种新型VOCs高效吸附装置。采用改性粉煤灰为吸附剂,其成本低廉且再生操作简单;内外双滤桶设计大大增加了被处理气体和吸附剂的接触面积;旋转上升的气流设计使气压分配... 详细信息

针对挥发性有机物(VOCs)污染,基于改性粉煤灰材料的理化性质设计了一种新型VOCs高效吸附装置。采用改性粉煤灰为吸附剂,其成本低廉且再生操作简单;内外双滤桶设计大大增加了被处理气体和吸附剂的接触面积;旋转上升的气流设计使气压分配均匀,避免沟流的出现,减小死层厚度,提高吸附剂的利用率;设有再生装置,吸附剂可与滤筒整体更换,避免散料运输时造成二次污染。本装置贴近工业生产气体处理实际,是一种可实现VOCs高效捕集及回收、吸附剂反复利用的VOCs处理新工艺。

关键词：吸附装置挥发性有机物双滤筒旋流再生

同方期刊数据库博看期刊评论

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新型冠状病毒疫苗异源加强免疫的研究进展

江苏预防医学 2024年第2期35卷 141-147,197页

作者：冯佳璐朱雅文周利朱凤才李靖欣南京医科大学公共卫生学院国家医学攻关产教融合疫苗研发创新平台江苏南京211166 江苏省疾病预防控制中心国家卫生健康委员会肠道病原微生物重点实验室江苏省医学创新中心

截至2023年3月,11款新冠疫苗被列入世界卫生组织(WHO)紧急使用清单。这些新冠疫苗在短期的临床试验观察中均展示出了显著的保护性,但疫苗的保护效果持久性不佳、针对变异株的保护效力均持续降低。为了探索更优化的免疫程序,多国开展了... 详细信息

截至2023年3月,11款新冠疫苗被列入世界卫生组织(WHO)紧急使用清单。这些新冠疫苗在短期的临床试验观察中均展示出了显著的保护性,但疫苗的保护效果持久性不佳、针对变异株的保护效力均持续降低。为了探索更优化的免疫程序,多国开展了多种新冠疫苗的异源序贯免疫研究探索。多项研究显示,不同新冠疫苗的组合免疫,不但可以提高疫苗的可及性和免疫程序的灵活性,还可避免重复使用同一种疫苗可能带来的安全问题,同时能够诱导出更强的免疫原性和对变异株更好的保护效果。现对国内外报告的新冠疫苗异源加强免疫的安全性、免疫原性和疫苗效力(或效果)等3个方面进行系统阐述,旨在为后续新冠疫苗或其他应急疫苗免疫策略选择提供参考。

关键词：新型冠状病毒疫苗异源加强免疫安全性免疫原性疫苗效力/效果

Coronavirus disease 2019 vaccines:landscape of global studies and potential risks

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Chinese Medical Journal 2021年第17期134卷 2037-2044页

作者： Hu-Da-Chuan Jiang Yan-Yang Tao Si-Yue Jia jing-xin li Feng-Cai Zhu School of Public Health Southeast UniversityNanjingJiangsu 210009China NHC Key Laboratory of Enteric Pathogenic Microbiology Jiangsu Provincial Center for Disease Control and PreventionNanjingJiangsu 210009China Center for Global Health School of Public HealthNanjing Medical UniversityNanjingJiangsu 210009China

With the outbreak of the coronavirus disease 2019(COVID-19)pandemic,the importance of vaccines in epidemic prevention and public health has become even more obvious than ***,the emergence of multiple severe acute respiratory syndrome coronavirus 2 variants worldwide has raised concerns about the effectiveness of current COVID-19 ***,we review the characteristics of COVID-19 vaccine candidates in five platforms and the latest clinical trial results of *** addition,we further discuss future directions for the research and development of the next generation of COVID-19 *** also summarize the serious adverse events reported recently after the large-scale vaccination with the current COVID-19 vaccines,including the thromboembolism caused by the AstraZeneca and Johnson&Johnson vaccines.

关键词： Severe acute respiratory syndrome coronavirus 2 COVID-19 Vaccine Immunogenicity Safety Clinical trial

High salt-induced weakness of anti-oxidative function of natriuretic peptide receptor-C and podocyte damage in the kidneys of Dahl rats

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Chinese Medical Journal 2020年第10期133卷 1182-1191页

作者： Xiao-Long Zhu Tao Zhang Zhen-Qiang Xu Xiao-Chun Ma Zheng-Jun Wang Cheng-Wei Zou jing-xin li Hai-Yan jing departm ent of Cardiovascular Surgery Shandong Provincial Hospital Affiliated to Shandong UniversityJinanShandong 250021China Department of Physiology Medical School of Shandong UniversityJinanShandong 250021China Department of Pathology Shandong Provincial Hospital Affiliated to Shandong UniversityJinanShandong 250021China.

Background:Atrial natriuretic peptide(ANP)and its natriuretic peptide receptors A(NPR-A)and C(NPR-C)are involved in the regulation of physiological and pathophysiological process of blood *** present study aimed to determine the role of NPR-C in the development of salt-sensitive ***::The Dahl salt-sensitive(DS)and salt-resistant(DR)rats were used in this *** were matched according to their age and weight,and then placed on either a high-salt(HS,8%)or a normal-salt(NS,0.4%)diet for 6 weeks randomly using random number *** systolic blood pressure(SBP),plasmatic sodium concentration(PL Na),urinary sodium excretion(UV Na),and serum creatinine concentration(Scr)were *** concentration of ANP in blood and tissues(heart and kidney)was detected by enzyme-linked immunosorbent *** expression of ANP,NPR-A,and NPR-C in kidney was evaluated with western blot *** renal redox state,the concentration changes in malondialdehyde(MDA),lipofuscin,nicotinamide adenine dinucleotide phosphate(NADPH)oxidase(Nox),and nitric oxide synthase(NOS)in kidney were detected by a spectrophotometric *** kidney damage was evaluated using pathological techniques and the succinodehydrogenase(SDHase)***,after an intra-peritoneal injection of C-atrial natriuretic peptide(ANP)4-23(C-ANP 4-23),an NPR-C receptor agonist,the SBP,biochemical values in blood and urine,and renal redox state were *** paired Student’s t test and analysis of variance followed by the Bonferroni test were performed for statistical analyses of the comparisons between two groups and multiple groups,***::The baseline SBP in all groups was within the normal *** the end of the 6-week experiment,HS diet significantly increased the SBP in DS rats from 116.63±2.90 mmHg to 162.25±2.15 mmHg(t=-10.213,P<0.001).The changes of SBP were not significant in DS rats on an NS diet and DR rats on an NS diet or on an HS diet(

关键词： Natriuretic peptide receptor-C Nicotinamide adenine dinucleotide phosphate oxidase 4 Oxidative stress Podocyte Salt-sensitive hypertension

LONG-TERM OBSERVATION FOR OSSEOINTEGRATION OF CALCIUM PHOSPHATE SOL-GEL COATING ON Ti-6Al-4V IMPLANTS

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Chinese Medical Sciences Journal 2007年第3期22卷 183-186页

作者： Cheng Yang Yuan-ying li li-e Meng jing-xin Chen Yi Huang Stomatology Center Union Hospital Tongji Medical College Huazhong University of Science ＆ Technology Wuhan 430022

Objective To observe the long-term impact of calcium phosphate （CaP） sol-gel coating on bone growth around porous-surfaced implant. Methods The porous-surfaced Ti-6Al-4V implants were prepared with the addition of a thin film of CaP sol-gel coating, and implanted into the tibiae of 8 rabbits, each with two implants. Implanted sites were allowed to heal for 2, 8, 12, and 24 weeks, after which specimens were obtained for scanning electron microscope analysis using the freezefracture technique. Results The sol-gel coated implants recovered by freeze-fracture technique showed extensive bone growth from the endosteum along the implant surface. The bone was in direct contact with the CaP layer. The cement line-like layer was clearly demonslxated to be an intervening electron dense afibrillar layer between the CaP coat and the overlying newly deposited bone. The stability and osseointegration of the porous-surfaced implants seemed not to be affected by the osteoclastic resorption of CaP layer occurred during 24 weeks of healing. Conclusion Based on the findings in the long-term observation, the addition of a thin layer of CaP promotes an extensive osseointegrated interface between the porous-surfaced Ti-6Al-4V implants and the newly deposited bone.

关键词： calcium phosphate sol-gel implant osteoconduction scanning electron microscopy