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Numerical study of vortex breaker optimization in a first stage oxygen tank

Propulsion and Power Research 2023年第3期12卷 322-335页

作者： Yixiu Shen yimeng li Zhenggang Du College of Design and Engineering National University of Singapore9 Engineering Drive 1Block EA#07-08117575Singapore Department of Mechanical Engineering University of CaliforniaBerkeley2521 Hearst AveBerkeleyCA 94709United States Propulsion Department Landspace Company13 Ronghua South RoadYizhuang Economic and Technological Development ZoneBeijing 100176China

One of the crucial factors affecting the carrying capacity of the cryogenic liquid launch vehicle is the effective volume of the tank.Theoretical and experimental investigations on vortex breaker mechanisms have proposed promising schemes applied in the oxygen tank of the liquid-propellant launch vehicle to ensure the normal operation of the engine.In this paper,the liquid surface profile functions of the laminar core when the vortex generates were derived based on the Rankine vortex model.The dimensionless residual volume V/d3 and the Froude number were applied to compare the theoretical prediction of critical height with the actual simulation data of liquid oxygen.This comparison method can improve the model’s accuracy.The efficiency of different basic shapes of vortex breakers was tested by conducting CFD modelling on a non-vertical outflow tank under a specific operating condition.Simulation results suggest negligible effects of heat transfer and surface tension.A circular plate is considered the optimal vortex breaker shape in traditional vertical outflow tanks,while a higher optimize efficiency was discovered in the half baffle basic shape in a non-vertical outflow tank by comparing the dimensionless residual volume and flow coefficient.A 34.26%reduction in flow resistance of half baffle breaker can be reached when applying a twenty-degree outlet pipe chamfering setting compared to a zero-degree chamfer.Considering practical operating limitations,it is concluded that a vortex breaker mechanism in a half baffle basic shape with a radius of 2.5d and a height of 4/d is the optimal scheme,which is suitable for all types of tanks.Its optimization efficiency of the residual volume reduction is about 56.68%compared to a nobreaker installation case.Lastly,a general equation based on CFD simulation for predicting the residual volume under a certain outflow velocity was proposed:V=d3yaFr0:3,which trend is consistent with that of mathematical prediction V=d3yaFr1=3.This consistency proves the accuracy and applicabilit

关键词： liquid launch vehicle Cryogenic propellant Vortex breaker CFD simulation Surface collapse

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Conductive fibers for biomedical applications

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Bioactive Materials 2023年第4期22卷 343-364页

作者： Leqian Wei Shasha Wang Mengqi Shan yimeng li Yongliang Wang Fujun Wang Lu Wang Jifu Mao Key Laboratory of Textile Science&Technology Ministry of EducationCollege of TextilesDonghua UniversityShanghai201620China Key Laboratory of Textile Industry for Biomedical Textile Materials and Technology Donghua UniversityShanghai201620China School of Health and life Sciences University of Health and Rehabilitation SciencesQingdao CityShandong Province266071China

Bioelectricity has been stated as a key factor in regulating cell activity and tissue function in electroactive tissues.Thus,various biomedical electronic constructs have been developed to interfere with cell behaviors to promote tissue regeneration,or to interface with cells or tissue/organ surfaces to acquire physiological status via electrical signals.Benefiting from the outstanding advantages of flexibility,structural diversity,customizable mechanical properties,and tunable distribution of conductive components,conductive fibers are able to avoid the damage-inducing mechanical mismatch between the construct and the biological environment,in return to ensure stable functioning of such constructs during physiological deformation.Herein,this review starts by presenting current fabrication technologies of conductive fibers including wet spinning,microfluidic spinning,electrospinning and 3D printing as well as surface modification on fibers and fiber assemblies.To provide an update on the biomedical applications of conductive fibers and fiber assemblies,we further elaborate conductive fibrous constructs utilized in tissue engineering and regeneration,implantable healthcare bioelectronics,and wearable healthcare bioelectronics.To conclude,current challenges and future perspectives of biomedical electronic constructs built by conductive fibers are discussed.

关键词： Conductive fibers Conductive biomaterials Tissue repair Implantable bioelectronics Wearable bioelectronics

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风光储参与电网预防-紧急控制策略研究

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太阳能学报 2024年第4期45卷 404-415页

作者：万庆祝袁润娇李伊梦李治萱北方工业大学电气与控制工程学院北京100144

基于风光储有功功率连续平滑调节能力,提出一种风光储协同切负荷优化的电网预防-紧急控制策略。首先,分析风光储参与电网预防-紧急控制原理,给出风光储参与电网预防-紧急控制策略。在故障发生前通过削减风光出力预留有功备用容量,通过... 详细信息

基于风光储有功功率连续平滑调节能力,提出一种风光储协同切负荷优化的电网预防-紧急控制策略。首先,分析风光储参与电网预防-紧急控制原理,给出风光储参与电网预防-紧急控制策略。在故障发生前通过削减风光出力预留有功备用容量,通过调整发电机机组出力、储能充放电状态平抑风光出力改变引起的系统功率波动;在故障发生后,优先考虑风光预留有功备用量填补系统功率不平衡量,若风光预留有功备用量不足,则采取切负荷措施进行紧急控制。然后,综合考虑风光有功备用成本、预防、紧急控制措施成本,分别建立风光储参与电网预防、紧急控制模型,采用Matlab/CPLEX求解模型。最后在改进IEEE 39节点系统进行仿真验证本文所提控制策略的有效性。

关键词：可再生能源优化成本风光有功备用预防-紧急控制策略

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Improving Baculovirus Transduction of Mammalian Cells by Incorporation of Thogotovirus Glycoproteins

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Virologica Sinica 2019年第4期34卷 454-466页

作者： liangbo Hu yimeng li Fei Deng Zhihong Hu Hualin Wang Manli Wang State Key Laboratory of Virology Wuhan Institute of VirologyChinese Academy of SciencesWuhan 430071China University of the Chinese Academy of Sciences Beijing 100049China

Baculovirus can transduce a wide range of mammalian cells and is considered a promising gene therapy vector. However,the low transduction efficiency of baculovirus into many mammalian cells limits its practical application. Co-expressing heterologous viral glycoproteins(GPs), such as vesicular stomatitis virus G protein(VSV G), with baculovirus native envelope protein GP64 is one of the feasible strategies for improving virus transduction. Tick-borne thogotoviruses infect mammals and their GPs share sequence/structure homology and common evolutionary origins with baculovirus GP64.Herein, we tested whether thogotovirus GPs could facilitate the entry of the prototype baculovirus Autographa californica multiple multiple nucleopolyhedrovirus(AcMNPV) into mammalian cells. The gp genes of two thogotoviruses, Thogoto virus and Dhori virus, were inserted into the AcMNPV genome. Both GPs were properly expressed and incorporated into the envelope of the recombinant AcMNPVs. The transduction rates of recombinant AcMNPVs expressing the two thogotovirus GPs increased for approximately 4–12 fold compared to the wild type AcMNPV in six of the 12 tested mammalian cell lines. It seemed that thogotovirus GPs provide the recombinant AcMNPVs with different cell tropisms and showed better performance in several mammalian cells compared to VSV G incorporated AcMNPV. Further studies showed that the improved transduction was a result of augmented virus-endosome fusion and endosome escaping, rather than increased cell binding or internalization. We found the AcMNPV envelope protein GP64-mediated fusion was enhanced by the thogotovirus GPs at relatively higher p H conditions. Therefore, the thogotovirus GPs represent novel candidates to improve baculovirus-based gene delivery vectors.

关键词： Autographa californica multiple nucleopolyhedrovirus(AcMNPV) Baculovirus Thogotovirus Glycoprotein Transduction Mammalian cells

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Continuous morphing trailing-edge wing concept based on multi-stable nanomaterial

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Chinese Journal of Aeronautics 2021年第7期34卷 219-231页

作者： Fengqian HAO Tao TANG Yuan GAO yimeng li Shenghui YI Jian LU Department of Mechanical Engineering City University of Hong KongHong Kong 999077China Centre for Advanced Structural Materials City University of Hong Kong Shenzhen Research InstituteGreater Bay Joint DivisionShenyang National Laboratory for Materials ScienceShenzhen 518057China Beijing Thm Technology Co. Ltd.Beijing 100084China

Morphing technology is one of the most effective methods to improve the flight efficiency of aircraft.Traditional control surfaces based morphing method is mature and widely used on current civil and military aircraft,but insufficiently effective for the entire flight envelope.Recent research on morphing wing still faces the challenge that the skin material for morphing should be both deformable and stiff.In this study,a continuous morphing trailing-edge wing with a new multi-stable nano skin material fabricated using surface mechanical attrition treatment technology was proposed and designed.Computational fluid dynamics simulation was used to study the aerodynamic performance of the continuous morphing trailing-edge wing.Results show that the lift coefficient increases with the increase of deflection angle and so does the lift-drag ratio at a small angle of attack.More importantly,compared with the wing using flaps,the continuous morphing trailing-edge wing can reduce drag during the morphing process and its overall aerodynamic performance is improved at a large angle of attack range.Flow field analysis reveals that the continuous morphing method can delay flow separation in some situations.

关键词： Aerodynamic performance Computational fluid dynamics Continuous morphing trailing-edge wing Multi-stable nanomaterial Surface mechanical attrition treatment

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《隋炀帝艳史》之“艳”

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内江师范学院学报 2024年第3期39卷 35-40页

作者：李艺萌华中科技大学人文学院湖北武汉430074

齐东野人在前人文本的基础上,从取材、编排、用辞三个方面将“艳”之意涵融入隋炀帝故事,使得《隋炀帝艳史》在帝妃之情的主题下呈现出有别以往的审美趣味。他以“艳”为取材标准选取史书及小说素材,在增删与重写中改变原文主题使之为... 详细信息

齐东野人在前人文本的基础上,从取材、编排、用辞三个方面将“艳”之意涵融入隋炀帝故事,使得《隋炀帝艳史》在帝妃之情的主题下呈现出有别以往的审美趣味。他以“艳”为取材标准选取史书及小说素材,在增删与重写中改变原文主题使之为“艳”“奇”所用;利用巧妙的结构安排与叙事技法,让情节富有波澜;辅之以诗词赋文的华美辞藻,让宫廷之奢、后宫之美、情欲之深更具艳丽之感。读者在“艳羡”与“可惊可喜”的氛围中,体味到《隋炀帝艳史》中的帝王之“艳”。

关键词：《隋炀帝艳史》主题艳情小说

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高端装备制造企业数字化转型驱动路径研究

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科研管理 2024年第1期45卷 21-30页

作者：杨红李依梦陈银忠杨柏重庆工商大学工商管理学院重庆400067 四川外国语大学国际金融与贸易学院重庆400031

高端装备制造企业数字化转型是制造业价值链升级,实现高质量发展的重要引擎。文章基于TOE分析框架,以2016—2020年68家高端装备制造企业为研究对象,利用NCA和fsQCA方法,从组态视角探究“技术-组织-环境”维度的前因条件驱动高端装备制... 详细信息

高端装备制造企业数字化转型是制造业价值链升级,实现高质量发展的重要引擎。文章基于TOE分析框架,以2016—2020年68家高端装备制造企业为研究对象,利用NCA和fsQCA方法,从组态视角探究“技术-组织-环境”维度的前因条件驱动高端装备制造企业数字化转型的路径。研究表明:任何单一的前因条件均无法独立成为驱动高端装备制造企业数字化转型的必要条件。高企业数字化转型水平受到互联网宽带接入用户数、规模以上工业企业R&D经费支出、企业数字人才投入、企业数字专利数、企业数字化业务模式和数字技术市场成交额六个条件的“多重并发”影响,并形成了数字环境孕育和内外联动渐进两类组态路径。环境维度因素是导致高端装备制造企业数字化转型失败的重要原因。结合该研究结论,从加强前因条件联动匹配、因地制宜探索驱动路径、统筹优化数字环境等方面提出促进高端装备制造企业加快数字化转型的相关政策建议。

关键词：高端装备制造企业数字化转型必要条件分析模糊集定性比较分析

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刘伶的三重形象刍议

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豫章师范学院学报 2024年第2期39卷 38-42页

作者：李艺萌华中科技大学人文学院湖北武汉430074

刘伶在不同的人生阶段呈现出“酒客”“草民”“失意士人”三种不同形象。早期的刘伶反叛名教,借酒追寻精神自由,凭借“酒德精神”显名,形成“酒客”形象并被后世广为传颂;魏晋之交,刘伶声名骤减,逐渐暴露出其草民的本质身份;入晋后,刘... 详细信息

刘伶在不同的人生阶段呈现出“酒客”“草民”“失意士人”三种不同形象。早期的刘伶反叛名教,借酒追寻精神自由,凭借“酒德精神”显名,形成“酒客”形象并被后世广为传颂;魏晋之交,刘伶声名骤减,逐渐暴露出其草民的本质身份;入晋后,刘伶有两段入仕经历,但碍于外部因素都未取得太大建树,宏伟的志愿终未能实现。通过对刘伶的相关史料梳理,可以勾勒出刘伶三种形象的构建过程,以及形象背后刘伶的现实处境与心理诉求。

关键词：刘伶人物形象竹林七贤魏晋南北朝

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Analysis on Antibacterial, Detumescent and Antioxidant Activity of Huoshan Large-leaf Yellow Tea

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Medicinal Plant 2023年第4期14卷 1-5页

作者： Jinwu CHEN Wen HU yimeng li Jiaojiao WANG Yafei liU Yi li Lulu QI School of Biology and Food Engineering Hefei Normal UniversityHefei 230601China School of life Sciences Anhui UniversityHefei 230039China

[Objectives] To provide experimental basis for the effective development and utilization of Huoshan large-leaf yellow tea resources and the screening of safe and effective active ingredients of large-leaf yellow tea. [Methods] The active substances of Huoshan large-leaf yellow tea were extracted by hot-water extraction, and the freeze-dried powder of Huoshan large-leaf yellow tea was obtained by freeze drying. The antibacterial activity of the extract was preliminarily confirmed using the Oxford cup method, and its antimicrobial spectrum was analyzed using 14 strains. A xylene-induced mouse auricle swelling test was carried out to detect the swelling inhibition rate of the extract and analyze its in-vitro detumescent activity. Then, the antioxidant activity of the extract was identified through a DPPH free radical scavenging capacity test and a ferric reducing antioxidant power assay. [Results] The extract had significant inhibitory effects on various bacteria. The extract could effectively inhibit the growth of Escherichia coli, Staphylococcus aureus, Enterococcus hirae, Acinetobacter baumannii, Klebsiella pneumonia, Pseudomonas aeruginosa, Bacillus subtilis , and other strains. The diameter of the inhibition zone increased with the increase of sample concentration. The extract had a significant inhibitory effect on auricle swelling induced by xylene in mice. When the concentration of the drug reached 1.0 mg/mL, its inhibition rate on mouse auricle swelling reached 55.2% ( P lightly lower than the swelling inhibition rate of the aspirin group (66.52%, P <0.01). The results of the antioxidant test showed that large-leaf yellow tea extract also had strong activity. Within the concentration range of 0.1-1.0 mg/mL, its DPPH radical scavenging rate increased with the increase of sample concentration. Within the concentration range of 0.1-1.0 mg/mL, its DPPH radical scavenging rate increased with the increase of sample concentration. When the concentration reached 1.0 mg/mL, the scavenging rate reached 69.75%

关键词： Huoshan large-leaf yellow tea Antibacterial activity Detumescence Antioxidant activity

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Characterization of intestinal microbiota and fecal cortisol,T3,and IgA in forest musk deer(Moschus berezovskii)from birth to weaning

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Integrative Zoology 2021年第3期16卷 300-312页

作者： yimeng li Tianxiang ZHANG Minghui SHI Baofeng ZHANG Xin HU Shanghua XU Jianhong DING Shuqiang liU Defu HU Daniel RUBENSTEIN School of Ecology and Nature Conservation Beijing Forestry UniversityBeijingChina Department of Ecology and Evolutionary Biology Princeton UniversityPrincetonNew JerseyUSA Beijing Key Laboratory of Captive Wildlife Technology Beijing ZooBeijingChina

Analysis of the intestinal microbiota and physiological parameters in mammalian infancy can reveal health status.In this study,we used a combination of molecular and immunochemical approaches to assess fecal microbiota as well as Cortisol(Cor),Triiodothyronine(T3),and immunoglobulin A(IgA)levels of young forest musk deer(FMD),from birth to one month after weaning(7 days of age–110 days of age).During development as the diet of FMD changes from consuming milk to eating plants,the richness and diversity of intestinal microbiota of young FMD increased significantly.Cor levels remained unchanged throughout early development while significantly increased after weaning,T3 and IgA initially were derived from milk during lactation,significantly decreased after weaning.Correlation network analysis showed that the community of food-oriented microbes were highly structured and that many genera were correlated.Overall,this study provides scientific insights into effective management strategies for the protection of FMD population.

关键词： forest musk deer intestinal microbiota weaning

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