检索结果-南通市图书馆

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

基于MVC5B混合模型的中国股指预测研究

计算机工程与应用 2024年第15期60卷 284-296页

作者：崔晨豪李勇中国科学技术大学管理学院合肥230026

为了提高中国股指的预测表现,提出一个融合了变分模态分解(VMD)、卷积注意力模块(CBAM)和双向长短期记忆网络(BiLSTM)的混合模型MVC5B(multi-channel-VMD-CBAM5-BiLSTM)。不同于混合模型常用的分解-集成构造方法,MVC5B基于提出的多通道... 详细信息

为了提高中国股指的预测表现,提出一个融合了变分模态分解(VMD)、卷积注意力模块(CBAM)和双向长短期记忆网络(BiLSTM)的混合模型MVC5B(multi-channel-VMD-CBAM5-BiLSTM)。不同于混合模型常用的分解-集成构造方法,MVC5B基于提出的多通道输入方法构造而成。多通道输入方法基于自身一次性预测的特点可以有效规避分解-集成方法多次预测带来的累计误差和巨大计算成本,从而提升MVC5B的预测表现。CBAM的引入不但提升了股指的预测表现,而且还丰富了股指预测问题中关于CBAM的研究。基于多个具有代表性的中国股指数据集的实证结果显示MVC5B的预测表现和模拟收益显著优于流行的预测模型。实证结果还进一步证实了多通道输入方法相比于分解-集成方法的优越性以及CBAM在股指预测问题中的有效性。

关键词：股指预测卷积注意力模块双向长短期记忆网络变分模态分解多通道输入

Pseudorabies virus manipulates mitochondrial tryptophanyl-tRNA synthetase 2 for viral replication

在线全文

学校读者我要写书评

暂无评论

Virologica Sinica 2024年第3期39卷 403-413页

作者： Xiu-Qing li Meng-Pan Cai Ming-Yang Wang Bo-Wen Shi Guo-Yu Yang Jiang Wang Bei-Bei Chu Sheng-li Ming College of Veterinary Medicine Henan Agricultural UniversityZhengzhou 450046China Key Laboratory of Animal Biochemistry and Nutrition Ministry of Agriculture and Rural AffairsZhengzhou 450046China Key Laboratory of Veterinary Biotechnology of Henan Province Henan Agricultural UniversityZhengzhou 450046China Longhu Advanced Immunization Laboratory Zhengzhou 450046China International Joint Research Center of National Animal Immunology Henan Agricultural UniversityZhengzhou 450046China Ministry of Education Key Laboratory for Animal Pathogens and Biosafety Zhengzhou 450046China School of Basic Medicine Chongqing Medical UniversityChongqing 400016China

The pseudorabies virus(PRV)is identified as a double-helical DNA virus responsible for causing Aujeszky's disease,which results in considerable economic impacts *** enzyme tryptophanyl-tRNA synthetase 2(WARS2),a mitochondrial protein involved in protein synthesis,is recognized for its broad expression and vital role in the translation *** findings of our study showed an increase in both mRNA and protein levels of WARS2 following PRV infection in both cell cultures and animal *** WARS2 expression via RNA interference in PK-15 cells led to a reduction in PRV infection rates,whereas enhancing WARS2 expression resulted in increased infection ***,the activation of WARS2 in response to PRV was found to be reliant on the cGAS/STING/TBK1/IRF3 signaling pathway and the interferon-alpha receptor-1,highlighting its regulation via the type I interferon signaling *** analysis revealed that reducing WARS2 levels hindered PRV's ability to promote protein and lipid *** research provides novel evidence that WARS2 facilitates PRV infection through its management of protein and lipid levels,presenting new avenues for developing preventative and therapeutic measures against PRV infections.

关键词： Pseudorabies virus WARS2 Innate immunity Protein synthesis lipid synthesis

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

基于能量法的被动柔性棚洞防护结构设计理论

工程力学 2016年第11期33卷 95-104页

作者：刘成清倪向勇杨万理李福海赵世春西南交通大学土木工程学院四川成都610031 高速铁路线路工程教育部重点实验室四川成都610031

由于被动柔性棚洞防护结构缺少相关的设计理论,为此,首先将复杂的结构转化为简单的力学模型,通过增量变刚度法分析了钢拱架变成机构的力学行为,明确了钢拱架与钢绳索的屈服机制,研究了钢绳索耗能与钢拱架极限承载力,建立被动柔性棚洞防... 详细信息

由于被动柔性棚洞防护结构缺少相关的设计理论,为此,首先将复杂的结构转化为简单的力学模型,通过增量变刚度法分析了钢拱架变成机构的力学行为,明确了钢拱架与钢绳索的屈服机制,研究了钢绳索耗能与钢拱架极限承载力,建立被动柔性棚洞防护结构的耗能计算原理,为柔性棚洞结构提供了基于能量法的设计理论。然后,结合工程实例,进行有限元分析与理论计算的结果对比,验证基于能量法的设计理论的准确性。最后,根据提出的基于能量法的设计理论,给出了关于柔性棚洞防护结构方案设计与选型方面的建议。研究结果表明:工程实例的理论计算结果与有限元分析结果较吻合;在选型方面,为提高整体结构耗能,应使钢绳索先于钢拱架屈服,并加大钢绳索使用长度及屈服拉力;抛物线式钢拱架极限承载力高于同等条件下其他形式钢拱架,应优先选用。

关键词：结构工程被动柔性棚洞防护结构能量法钢拱架极限承载力设计理论

Drought shifts soil nematode trophic groups and mediates the heterotrophic respiration

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Journal of Plant Ecology 2024年第2期17卷 100-109页

作者： Cancan Zhao Yuanhu Shao Huijie Lu Aimée T.Classen Zuyan Wang Ying li Yanchun liu Zhongling Yang Guoyong li Shenglei Fu International Joint Research Laboratory for Global Change Ecology School of Life SciencesHenan UniversityKaifeng 475004China Henan Dabieshan National Field Observation and Research Station of Forest Ecosystem Zhengzhou 450046China Key Laboratory of Geospatial Technology for the Middle and Lower Yellow River Regions Ministry of EducationCollege of Environment and PlanningHenan UniversityKaifeng 475004China Henan Key Laboratory of Integrated Air Pollution Control and Ecological Security Kaifeng 475004China Department of Ecology and Evolutionary Biology University of MichiganAnn ArborMI 48109USA South China Botanical Garden Chinese Academy of SciencesGuangzhou 510650China Department of Natural Resource of Henan Province Institute of Natural Resources Survey and PlanningZhengzhou 450000China

As the most diverse metazoan taxa,soil nematodes serve a diversity of functions in soil food webs and thus can regulate microbial community composition and affect organic matter decomposition and nutrient turnover *** nematodes depend on water flms to access food resources,drought can negatively affect nematode-microbial food webs,yet the impacts of drought on nematode diversity and abundance and how these changes may infuence food web members and their functions are hardly ***,we coupled research along a drought gradient in arid and semiarid grasslands with a detailed intact plant-soil microcosm experiment to explore the patterns and mechanisms of how drought impacts nematode abundance and carbon footprint,microbial phospholipid fatty acid(PLFA)and heterotrophic soil ***,in the feld and the microcosm experiments,we found that nematode abundance,carbon footprint and diversity,microbial PLFA and heterotrophic respiration were reduced under drier *** addition,drought altered nematode and microbial community composition,through reducing the nematode channel ratio and increasing the relative fungivorous nematode abundance and the fungal to bacterial *** soil decomposition channel shifted from a bacterial to a fungal pathway in response to drought,indicating decelerated heterotrophic respiration under *** results highlight the important contribution of soil nematodes and their associated microbial food web to soil carbon *** fndings underscore the need to incorporate key soil fauna into terrestrial ecosystem model evaluation.

关键词： soil biota fungal energy channel bacterial energy channel carbon footprint arid grassland

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

静止无功补偿器的最优电容投切阈值分析

电力系统及其自动化学报 2007年第3期19卷 77-81页

作者：李永丽范群芳李岐虎天津大学电气与自动化工程学院天津300072 黄陵矿业集团有限责任公司岐山727307

针对晶闸管投切电容TSC的静止无功补偿装置的阈值整定问题,从运筹学的角度,对投切电容的二进制编码方式及其投切阈值系数对补偿效果的影响作了详细分析,得出了最佳投切阈值系数的取值以及基于二进制编码方式的最优电容投入阈值与切除阈... 详细信息

针对晶闸管投切电容TSC的静止无功补偿装置的阈值整定问题,从运筹学的角度,对投切电容的二进制编码方式及其投切阈值系数对补偿效果的影响作了详细分析,得出了最佳投切阈值系数的取值以及基于二进制编码方式的最优电容投入阈值与切除阈值系数的等值分配原则。分析表明,按照等值分配原则整定的最优投切阈值,能提高无功补偿的动态响应速度,减小投切误差。以投切阈值系数是1.2为例,等值分配投、切阈值时,其精度可提高30%。因此,根据系统运行的状况,合理调整电容器投和切阈值,才能对系统快速、准确地进行无功补偿。

关键词：电力系统静止无功补偿晶闸管投切电容二进制编码投切阈值等值分配

Research and development of a 0.5-m-long helical superconducting undulator prototype

在线全文

学校读者我要写书评

暂无评论

NUCLEAR SCIENCE AND TECHNIQUES 2024年第10期35卷 1-10页

作者： Yang, Xiang-Chen Yu, Xiao-Wu Wei, Jun-Hao Zhang, Xiang-Zhen Chen, Zi-lin Bian, Xiao-Juan li, He-Ting Feng, Guang-Yao li, Yu-Hui Univ Sci & Technol China Natl Synchrotron Radiat Lab Hefei 230029 Peoples R China Chinese Acad Sci Inst High Energy Phys Beijing 100049 Peoples R China Chinese Acad Sci Inst High Energy Phys China Spallat Neutron Source Dongguan 523000 Peoples R China Chinese Acad Sci Inst Plasma Phys ASIPP Hefei 230031 Peoples R China

The helical undulator is in high demand in synchrotron radiation facilities for circular polarization generation. Owing to the higher field strength provided by the superconducting undulator compared to the conventional permanent-magnet undulator, greater research efforts should be directed toward this area. The helical superconducting undulator holds great potential in synchrotron radiation facilities, especially in low-energy storage rings that seek circularly polarized radiation with the highest possible radiation flux. Following the successful development of planar superconducting undulators, the Institute of High Energy Physics conducted research and development for the helical superconducting undulator. A 0.5-m-long Delta-type superconducting undulator prototype was developed and tested. Detailed information on the design, fabrication, and cryogenic testing of the prototype is presented and discussed.

关键词： Helical Superconducting undulator Delta DESIGN

柿庄北煤层气区块煤层压裂裂缝扩展规律及影响因素

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

煤炭科学技术 2024年第S01期52卷 127-136页

作者：韩文龙李勇王力王延斌深圳大学土木与交通工程学院广东深圳518060 中国矿业大学(北京)地球科学与测绘工程学院北京100083 中联煤层气有限责任公司北京100011

揭示煤层气储层压裂裂缝扩展规律及影响因素,对于制定压裂工艺及高效开发煤层气资源具有重要的意义。利用沁水盆地柿庄北煤层气区块的钻井取心、测井、井下节理观测、压裂施工及微震监测等数据,系统分析了水力压裂裂缝扩展规律及影响因... 详细信息

揭示煤层气储层压裂裂缝扩展规律及影响因素,对于制定压裂工艺及高效开发煤层气资源具有重要的意义。利用沁水盆地柿庄北煤层气区块的钻井取心、测井、井下节理观测、压裂施工及微震监测等数据,系统分析了水力压裂裂缝扩展规律及影响因素。结果表明:研究区主要采用清水压裂液,压裂施工曲线可分划为上升型、下降型、平稳型和波动型4类;微震监测表明压裂裂缝走向主要在37°~55°和42°~70°,压裂裂缝网络长度范围在69.5~157.5 m,宽度在35.0~68.5 m。Ⅰ型地应力(σ_(v)>σ_(H)>σ_(h))状态下,压裂裂缝容易沿着垂向扩展,多数压裂曲线为下降型或稳定型;Ⅱ型地应力(σ_(H)>σ_(v)>σ_(h))状态下,压裂裂缝扩展方向相对单一,多数为单一形状的垂直裂缝,裂缝网络宽度较小;Ⅲ型地应力(σ_(H>σ_(h)>σ_(v))状态下,压裂裂缝沿水平方向扩展,裂缝形态复杂。侧压系数λ与压裂裂缝网络长度呈正相关关系,与压裂裂缝网络宽度呈负相关;若λ大于0.3,压裂裂缝网络长度常大于90 m。压裂裂缝扩展到节理(裂隙)时能够出现穿越、沟通和俘获3种类型;其中沟通型压裂效果较好,多数煤层气井具有高产稳产的特点;穿越型的压裂裂缝延展长度有限,俘获型的压裂裂缝多数与节理(裂隙)重合,这2类压裂井的产气效果相对较差。随着原生+碎裂结构煤占比的增大,压裂裂缝网络长度逐渐增大,宽度逐渐减小;当原生+碎裂结构煤厚度占比小于40%,压裂裂缝网络长度难以超过110 m。上述成果可为煤层压裂改造提供理论基础及地质保障。

关键词：沁水盆地煤层气水力压裂裂缝扩展微震监测

Genetic source,migration and accumulation of helium under deep thermal fluid activities:A case study of Ledong diapir area in Yinggehai Basin,South China Sea

在线全文

学校读者我要写书评

暂无评论

Petroleum Exploration and Development 2024年第3期51卷 753-766页

作者： FENG Ziqi HAO Fang HU lin HU Gaowei ZHANG Yazhen li Yangming WANG Wei li Hao XIAO Junjie TIAN Jinqiang State Key Laboratory of Deep Oil and Gas China University of Petroleum(East China)Qingdao 266580China School of Geosciences China University of Petroleum(East China)Qingdao 266580China Laboratory for Marine Mineral Resources Qingdao Marine Science and Technology CenterQingdao 266237China Hainan Branch of CNOOC(China)Co. Ltd.Haikou 570312China

Based on the geochemical parameters and analytical data,the heat conservation equation,mass balance law,Rayleigh fractionation model and other methods were used to quantify the in-situ yield and external flux of crust-derived helium,and the initial He concentration and thermal driving mechanism of mantle-derived helium,in the Ledong Diapir area,the Yinggehai Basin,in order to understand the genetic source,migration and accumulation mechanisms of helium under deep thermal fluid *** average content of mantle-derived He is only 0.0014%,the ^(3)He/^(4)He value is(0.002–2.190)×10^(−6),and the R/Ra value ranges from 0.01 to 1.52,indicating the contribution of mantle-derived He is 0.09%–19.84%,while the proportion of crust-derived helium can reach over 80%.Quantitative analysis indicates that the crust-derived helium is dominated by external input,followed by in-situ production,in the Ledong diapir *** crust-derived helium exhibits an in-situ 4 He yield rate of(7.66–7.95)×10^(−13)cm^(3)/(a·g),an in-situ 4 He yield of(4.10–4.25)×10^(−4)cm^(3)/g,and an external 4 He influx of(5.84–9.06)×10^(−2)cm^(3)/*** results may be related to atmospheric recharge into formation fluid and deep rock-water *** ratio of initial mole volume of 3 He to enthalpy(W)is(0.004–0.018)×10^(−11) cm^(3)/J,and the heat contribution from the deep mantle(X_(M))accounts for 7.63%–36.18%,indicating that deep hot fluid activities drive the migration of mantle-derived 3 *** primary helium migration depends on advection,while the secondary migration is controlled by hydrothermal degassing and gas-liquid *** deep to shallow layers,the CO_(2/3) He value rises from 1.34×10^(9)to 486×10^(9),indicating large amount of CO_(2)has *** the influence of deep thermal fluid,helium migration and accumulation mechanisms include:deep heat driven diffusion,advection release,vertical hydrothermal degassing,shallow lateral migration,accumulation in traps far from faults,

关键词： deep thermal fluid helium genetic source migration and accumulation mechanism Yinggehai Basin

Robust Estimation of Average Treatment Effects with Observational Studies

在线全文

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 2024年第2期29卷 117-124页

作者： XIAO li YU Peichao Department of Physical Education Guilin University of Aerospace TechnologyGuilin 541004GuangxiChina School of Statistics and Mathematics Zhongnan University of Economics and LawWuhan 430073HubeiChina

Estimating treatment effects has always been one of the hot issues in empirical *** brings great challenges to estimating treatment effects because heterogeneity exists in the distribution of covariates between treated and controlled *** score methods have been widely used to adjust for heterogeneity in observational ***,the propensity score is usually unknown and needs to be *** this article,we propose a generalized single-index model to estimate the propensity score and use the propensity score residuals to reduce the estimation *** finite-sample performance of the proposed method is evaluated through simulation *** use the proposed method to evaluate the policy of"Sunshine Running"and find that the physical test scores of college students par-ticipating in the"Sunshine Running"can be improved by 3.72 points.

关键词： treatment effect propensity score generalized single-index model partial linear model