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基于长序列的航空发动机剩余使用寿命预测方法

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北京航空航天大学学报 2024年第3期50卷 774-784页

作者：郭俊锋刘国华刘国伟兰州理工大学机电工程学院兰州730050 新乡学院机电工程学院新乡453003

针对多传感器长序列数据下航空发动机剩余使用寿命预测方法存在预测准确度不足的问题,提出一种基于堆叠膨胀卷积神经网络(SDCNN)的航空发动机剩余使用寿命预测方法。将多传感器长序列数据归一化处理,降低因量纲和取值范围不同引起的误差... 详细信息

针对多传感器长序列数据下航空发动机剩余使用寿命预测方法存在预测准确度不足的问题,提出一种基于堆叠膨胀卷积神经网络(SDCNN)的航空发动机剩余使用寿命预测方法。将多传感器长序列数据归一化处理,降低因量纲和取值范围不同引起的误差;构建预测目标函数表征航空发动机的真实退化情况;搭建基于SDCNN的预测模型,扩大模型感受野,提取数据中的长期、深层和全局时序特征用于回归分析,得到航空发动机的剩余使用寿命预测结果;采用Hyperband优化算法和StratifiedKFold交叉验证方法优化模型,提升模型预测准确度和不同条件下的适应性,并采用商用模块化航空推进系统仿真(C-MAPSS)数据集验证所提方法的有效性。在C-MAPSS中FD003数据集上的实验结果表明:所提方法可有效提高基于长序列的航空发动机剩余使用寿命预测准确度,模型预测准确度得分指标明显降低32.62%。

关键词：堆叠膨胀卷积剩余使用寿命预测 Hyperband超参数优化算法航空发动机长序列信号

Photochemical production of carbonyl sulfide,carbon disulfide and dimethyl sulfide in a lake water

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Journal of Environmental Sciences 2017年第1期29卷 146-156页

作者： Qianqian Du Yujing Mu Chenglong Zhang junfeng liu Yuanyuan Zhang Chengtang liu Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China Center for Excellence in Urban Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China University of Chinese Academy of Sciences Beijing 100049China

Photochemical production of carbonyl sulfide（COS）,carbon disulfide（CS_2） and dimethyl sulfide（DMS） was intensively studied in the water from the Aohai Lake of Beijing city.The lake water was found to be highly supersaturated with COS,CS_2 and DMS,with their initial concentrations of 0.91 ± 0.073 nmol/L,0.55 ± 0.071 nmol/L and 0.37 ± 0.062 nmol/L,respectively.The evident photochemical production of COS and CS_2 in the lake water under irradiation of 365 nm and 302 nm indicated that photochemical production of them might be the reason for their supersaturation.The similar dependence of wavelength and oxygen for photochemical production of COS,CS_2 and DMS implied that they might be from the same precursors.The water cage effect was found to favor COS production but inhibit CS_2and DMS formation,indicating that COS photochemical production was mainly from direct degradation of the precursors and the formation of CS_2 and DMS needed intermediates via combination of carbon-centered radicals and sulfur-centered radicals.The above assumptions were further confirmed by simulation experiments with addition of carbonyls and amino acids（cysteine and methionine）,and the photochemical formation mechanisms for COS,CS_2 and DMS in water were derived from the investigations.

关键词： Photochemical production Carbonyl sulfide Carbon disulfide Dimethyl sulfide Water

Ambient levels of atmospheric carbonyls in Beijing during the 2008 Olympic Games

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Journal of Environmental Sciences 2010年第9期22卷 1348-1356页

作者： Zhu Xu junfeng liu Yujie Zhang Peng Liang Yujing Mu Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China Graduate School of Chinese Academy of Sciences Beijing 100039 China

The measurements of atmospheric carbonyls concentrations in Beijing were conducted from 12 July to 8 October, 2008, covering the periods of the 2008 Olympic Games and Paralympic Games. Six carbonyls, including formaldehyde, acetaldehyde, acetone, butyraldehyde, valeraldehyde, and hexaldehyde, were identified in all air samples. The total average concentrations of these carbonyls before, during, and after traffic restriction were （48.1 ± 15.2）, （36.6 ± 14.5） and （23.4± 12.3） μg/m^3, respectively. Compared with the period after traffic restriction, the distinct high concentrations of the carbonyls before and during traffic restriction were primarily ascribed to the remarkable contribution of photochemical reactions. With respect to our previous investigation in the summer of 2005, the reductions of formaldehyde, acetaldehyde and acetone during traffic restriction period were about 64%, 47% and 27%, respectively, indicating that the air cleaning actions adopted by the Chinese government for the two games were efficient. The lowest levels of atmospheric carbonyls and the extremely high composition proportion of acetone after the traffic restriction were mainly attributed to the long-term effect of the control measures for the two games.

关键词： Olympic Games Paralympic Games carbonyl compounds traffic restriction photochemical reactions vehicular exhaust

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2023年采油采气工程技术热点回眸

科技导报 2024年第1期42卷 136-149页

作者：刘合金旭师俊峰中国石油勘探开发研究院北京100083 多资源协同陆相页岩油绿色开采全国重点实验室大庆163712

2023年,采油采气工程围绕新区效益建产、老油气田挖潜增效、数字化智能化发展和绿色低碳转型等方面开展技术攻关并取得突出创新成果。分层注入领域,智能化水平不断提高、技术适应范围进一步拓展,大幅提升了分层注入的精细化水平;人工举... 详细信息

2023年,采油采气工程围绕新区效益建产、老油气田挖潜增效、数字化智能化发展和绿色低碳转型等方面开展技术攻关并取得突出创新成果。分层注入领域,智能化水平不断提高、技术适应范围进一步拓展,大幅提升了分层注入的精细化水平;人工举升领域,新型高效举升技术指标再创新高、机采提效效果明显、数字化水平明显提升,节能降耗成效显著;采气工艺向绿色智能化采气、全生命周期精细采气、复合排水采气等方向发展,有效推动了天然气产量跨越式增长;储层改造技术取得重大进步,非常规水平井体积压裂2.0向精细化、个性化方向发展,压裂理论、装备工具材料、裂缝监测技术等取得创新突破,为油气高效勘探开发提供有力保障;井下作业领域在带压作业、连续油管作业、数字化智能化修井作业和复杂工况井下作业等方面技术进展明显,有效保障了油气水井健康生产。

关键词：采油采气分层注入人工举升储层改造采气工艺井下作业

Study on Traditional Chinese Medicine theory of lung being connected with large intestine

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Journal of Traditional Chinese Medicine 2012年第3期32卷 482-487页

作者： Ping liu Ping Wang Daizhi Tian junfeng liu Gang Chen Songlin Li Key Laboratory of Traditional ChineseMedicine Resource and Compound Prescription Hubei Col-lege of Traditional Chinese MedicineMinistry of EducationHubeiWuhan 430065China

OBJECTIVE:The theory of lung being connected with large intestine,which is a major topic in Traditional Chinese Medicine(TCM),has guided clinical practice for thousands of years in China.METHODS:In this study,we analyzed the history,main contents,clinical application,and material basis of the theory,to attempt to improve the potential clinical significance of "lung being connected with large intestine" in China.RESULTS:The lung being connected with large intestine was first described in "Huang Di Nei Jing",and formed one of the basic theories of TCM.For thousands of years,the majority of TCM practitioners explored this theory continuously,leading to its development and use as an important theory in the guidance of TCM clinics In the last decade,researchers in the field of integrated TCM and Western medicine have studied clinical applications and biomedical mechanisms with experimental methods to explore the implications of the theory.CONCLUSION:With the further development of science and technology,research concerning the theory of lung being connected with large intestine will be greatly stimulated and contribute to the modernization of TCM.

关键词：传统医药大肠中国医学理论肺临床应用中医药临床实践

The Clumpy Structure of Five Star-bursting Dwarf Galaxies in the MaNGA Survey

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Research in Astronomy and Astrophysics 2024年第2期24卷 83-103页

作者： Mengting Ju Jun Yin Lei Hao Chenxu liu Chao-Wei Tsai junfeng Wang Zhengyi Shao Shuai Feng Yu Rong Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical ObservatoryChinese Academy of SciencesShanghai 200030China University of Chinese Academy of Sciences Beijing 100049China Key Lab for Astrophysics Shanghai 200034China South-Western Institute for Astronomy Research Yunnan UniversityKunming 650500China National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China Institute for Frontiers in Astronomy and Astrophysics Beijing Normal UniversityBeijing 102206China Department of Astronomy Physics BuildingXiamen UniversityXiamenFujian 361005China College of Physics Hebei Normal UniversityShijiazhuang 050024China Hebei Key Laboratory of Photophysics Research and Application Shijiazhuang 050024China Department of Astronomy University of Science and Technology of ChinaHefei 230026China

The star-forming clumps in star-bursting dwarf galaxies provide valuable insights into understanding the evolution of dwarf galaxies.In this paper,we focus on five star-bursting dwarf galaxies featuring off-centered clumps in the Mapping Nearby Galaxies at Apache Point Observatory survey.Using the stellar population synthesis software Fitting Analysis using Differential evolution Optimization,we obtain the spatially resolved distribution of the star formation history,which allows us to construct the g-band images of the five galaxies at different ages.These images can help us to probe the evolution of the morphological structures of these galaxies.While images of a stellar population older than 1 Gyr are typically smooth,images of a stellar population younger than 1 Gyr reveal significant clumps,including multiple clumps which appear at different locations and even different ages.To study the evolutionary connections of these five galaxies to other dwarf galaxies before their star-forming clumps appear,we construct the images of the stellar populations older than three age nodes,and define them to be the images of the"host"galaxies.We find that the properties such as the central surface brightness and the effective radii of the hosts of the five galaxies are in between those of dwarf ellipticals(dEs)and dwarf irregulars(dIrrs),with two clearly more similar to dEs and one more similar to dIrrs.Among the five galaxies,8257-3704 is particularly interesting,as it shows a previous starburst event that is not quite visible from its gri image,but only visible from images of the stellar population at a few hundred million years.The star-forming clump associated with this event may have appeared at around 600 Myr ago and disappeared at around 40 Myr ago.

关键词： galaxies dwarf-galaxies evolution-galaxies formation-Galaxy structure

Recent advances in chemical protein synthesis:method developments and biological applications

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Science China Chemistry 2024年第4期67卷 1060-1096页

作者： Suwei Dong Ji-Shen Zheng Yiming Li Huan Wang Gong Chen Yongxiang Chen Gemin Fang Jun Guo Chunmao He Honggang Hu Xuechen Li Yanmei Li Zigang Li Man Pan Shan Tang Changlin Tian Ping Wang Bian Wu Chuanliu Wu junfeng Zhao Lei liu State Key Laboratory of Natural and Biomimetic Drugs and School of Pharmaceutical SciencesPeking UniversityBeijing 100191China Division of Life Sciences and Medicine University of Science and Technology of ChinaHefei 230027China School of Food and Biological Engineering Engineering Research Center of Bio-processMinistry of EducationHefei University of TechnologyHefei 230009China School of Chemistry and Chemical Engineering Nanjing UniversityNanjing 210023China State Key Laboratory of Elemento-Organic Chemistry Nankai UniversityTianjin 300071China Department of Chemistry Tsinghua UniversityBeijing 100084China Institute of Health Sciences Anhui UniversityHefei 230601China College of Chemistry Central China Normal UniversityWuhan 430079China School of Chemistry and Chemical Engineering South China University of TechnologyGuangzhou 510640China School of Medicine or Institute of Translational Medicine Shanghai UniversityShanghai 200444China Department of Chemistry The University of Hong KongHong Kong 999077China Shenzhen Graduate School Peking UniversityShenzhen 518055China School of Chemistry and Chemical Engineering Shanghai Jiao Tong UniversityShanghai 200240China School of Life Sciences University of Science and Technology of ChinaHefei 230026China Department of Chemical Biology Shanghai Jiao Tong UniversityShanghai 200240China Institute of Microbiology Chinese Academy of SciencesBeijing 100101China Department of Chemistry Xiamen UniversityXiamen 361005China School of Pharmaceutical Science Guangzhou Medical UniversityGuangzhou 511436China

The central dogma of modern biology underscores the pivotal roles proteins play in diverse biological processes,the study of which necessitates advanced methods to produce proteins with precision and versatility.Chemical protein synthesis,a powerful approach utilizing chemical reactions for the de novo construction of structurally accurate proteins,has emerged as a transformative tool for studying proteins and generating protein derivatives/mimics inaccessible by natural biological machinery,including post-translationally modified proteins,proteins comprised of unnatural amino acids,as well as mirror-image proteins.This review summarizes recent strides in synthetic method developments for chemical protein synthesis,including innovative techniques in solid-phase peptide synthesis,the challenges presented by difficult sequences in either synthesis or folding and the exploration of novel ligation reactions using both chemical and enzymatic methods.Furthermore,the review also delves into newly developed protocols for site-selective protein modifications and the generation of stapled or macrocyclized peptides/miniproteins,highlighting the power of chemical methods to make structurally diverse proteins.Recent applications of synthetic proteins in investigating post-translational modifications(phosphorylation,lipidation,glycosylation,ubiquitination,etc.),mirror-image biological processes and drug development are further discussed.Together,these topics provide a comprehensive overview of the current landscape of chemical protein synthesis.

关键词： chemical protein synthesis solid-phase peptide synthesis ligation reactions post-translational modifications mirror-image proteins peptide drugs

Focused Widely Linear Beamforming

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Journal of Beijing Institute of Technology 2019年第4期28卷 744-749页

作者： Yougen Xu junfeng liu Zhiwen liu School of Information and Electronics Beijing Institute of TechnologyBeijing 100081China

The problem addressed in this paper concerns the extension of widely linear beamforming to the wideband case,developing a wide-focused linear beamformer for the extraction of a wideband second-order(SO)noncircular signal-of-interest(SOI)contaminated by uncorrelated interferences and noise.In the proposed beamformer,the beamforming array observation is first focused to adopt a standard linear minimum variance distortionless response(MVDR)framework.The augmented SOI steering vector then is obtained by estimating the SOI noncircularity parameter with the newly proposed oblique projection with an augmented sparse representation scheme.The covariance matrix of the virtual interference,true interference and noise is further reconstructed using the newly presented complementary spatial spectrum technique.The wideband widely linear spatial filtering is finally realized via MVDR like beamforming.The performance of the proposed beamformer is verified by simulation.

关键词： array signal processing adaptive beamforming direction-of-arrival estimation noncircularity wideband

Reviews of emission of biogenic volatile organic compounds(BVOCs) in Asia

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Journal of Environmental Sciences 2020年第9期32卷 266-277页

作者： Xiaoxiu Lun Ying Lin Fahe Chai Chong Fan Hong Li junfeng liu College of Environmental Science and Engineering Beijing Forestry UniversityBeijing 100083China State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 100012China Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China

Biogenic volatile organic compounds(BVOCs) in the atmosphere play important roles in the formation of ground-level ozone and secondary organic aerosol(SOA) in global scale and also in regional scale under some condition due to their large amount and relatively higher reactivity.In places with high plant cover in the tropics and in China where air pollution is serious,the effect of BVOCs on ozone and secondary organic aerosols is strong.The present research aims to provide a comprehensive review about the emission rate,emission inventory, research methods,the influencing factors of BVOCs emissions,as well as their impacts on atmospheric environment quality and human health in recent years in Asia based on the summary and analysis of literatures.It is suggested to use field direct measurement method to obtain the emission rate and model method to calculate the emission amount.Several recommendations are given for future investigation and policy development on BVOCs emission.

关键词： BVOCs pollution volatile