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A novel high-order scheme for numerical simulation of wake flow over helicopter rotors in hover

Chinese Journal of Aeronautics 2022年第5期35卷 260-274页

作者： Shaoqiang han Wenping SONg Zhonghua han Institute of Aerodynamic and Multidisciplinary Design Optimization National Key Laboratory of Science and Technology on Aerodynamic Design and ResearchSchool of AeronauticsNorthwestern Polytechnical UniversityXi’an 710072China

Accurate prediction of tip vortices is crucial for predicting the hovering performance of a helicopter rotor.A new high-order scheme(we call it WENO-K)proposed by our research group is employed to minimize numerical dissipation and extended to numerical simulation of unsteady compressible viscous flows dominated by tip vortices over hovering ***-K is referred to as an adaptively optimized WENO scheme with gauss-Kriging reconstruction,and its advantage is to reduce dissipation in smooth regions of flow while preserving high-resolution around *** WENO-K scheme is adopted to reconstruct left and right state values within the Roe Riemann solver updating the inviscid fluxes on a structured dynamic overset *** minimize the accuracy loss for high-order reconstruction on artificial boundaries of overset grid,a method of multilayer fringes is proposed to carry out interpolation between background grid and blade *** parallel computing considering automatic load balance on averagely partitioned overset grid is developed to reduce the wall-clock time of an unsteady *** results for Caradonna-Tung(C-T)rotor in hover at the conditions of subsonic and transonic tip Mach numbers show that the thrust coefficient error for the result of WENO-K scheme is no more than 3%.Compared with WENO-JS scheme,WENO-K scheme achieves about 40%improvement on accuracy of predicting rotor thrust with only 4.1%extra computational *** importantly,WENO-K scheme can capture more sophisticated unsteady flow structures and resolve tip vortices to a larger wake age with an increment of about 270°compared to WENO-JS scheme.

关键词： Dynamic overset grid Helicopter rotors High-order scheme Unsteady flow Vortex flow WENO scheme

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Differences in clinical and genetic characteristics between early-and late-onset narcolepsy in a han Chinese cohort

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Neural Regeneration Research 2020年第10期15卷 1887-1893页

作者： Hui Ouyang Fang han Ze-Chen Zhou Jun Zhang Department of Clinical Neurology Peking University People’s HospitalBeijingChina Department of Clinical Pulmonology Peking University People’s HospitalBeijingChina Department of Epidemiology and Biostatistics School of Public HealthPeking University Health Science CenterBeijingChina

Early-and late-onset narcolepsy constitutes two distinct diagnostic ***,it is not clear whether symptomology and genetic risk factors differ between early-and late-onset *** study compared clinical data and single-nucleotide polymorphisms(SNPs)between early-and late-onset patients in a large cohort of 899 han Chinese narcolepsy ***,cerebrospinal fluid,and clinical data were prospectively collected from patients,and patients were genotyped for 40 previously reported narcolepsy risk-conferring *** risk scores(gRSs),associations of five different sets of SNPs(gRS1–gRS5)with early-and late-onset narcolepsy,were evaluated using logistic regression and receiver operating characteristic *** sleep latency was significantly shorter in early-onset cases than in late-onset *** severity was greater among late-onset patients,with higher rates of sleep paralysis,hypnagogic hallucinations,health-related quality of life impairment,and concurrent presentation with four or more *** levels did not differ significantly between early-and late-onset *** rs3181077(CCR1/CCR3)and rs9274477(HLA-DQB1)were more prevalent among early-onset *** gRS1(26 SNPs;OR=1.513,95%CI:0.893–2.585;PgRS5(6 SNPs;OR=1.893,95%CI:1.204–2.993;Pg characteristic curves of 0.731 and 0.732,*** gRS1 nor gRS5 included SNPs in HLA *** results indicate that symptomology and genetic risk factors differ between early-and late-onset *** protocol was approved by the Institutional Review Board(IRB)Panels on Medical Human Subjects at Peking University People’s Hospital,China(approval *** 86)in October 2011.

关键词： case-control studies clinical features genetic association studies genetic load genetic loci genetic phenomena hypothalamic diseases precision medicine risk assessment single nucleotide polymorphism

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Data-Driven Based Fault Prognosis for Industrial Systems:A Concise Overview

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IEEE/CAA Journal of Automatica Sinica 2020年第2期7卷 330-345页

作者： Kai Zhong Min han Bing han Faculty of Electronic Information and Electrical Engineering Dalian University of TechnologyDalian 116024China Key Laboratory of Intelligent Control and Optimization for Industrial Equipment of Ministry of Education Dalian University of TechnologyDalian 116024China State Key Laboratory of Navigation and Safety Technology Shanghai Ship and Shipping Research InstituteShanghai 200135China

Fault prognosis is mainly referred to the estimation of the operating time before a failure occurs,which is vital for ensuring the stability,safety and long lifetime of degrading industrial *** to the results of fault prognosis,the maintenance strategy for underlying industrial systems can realize the conversion from passive maintenance to active *** the increased complexity and the improved automation level of industrial systems,fault prognosis techniques have become more and more ***,the datadriven based prognosis approaches,which tend to find the hidden fault factors and determine the specific fault occurrence time of the system by analysing historical or real-time measurement data,gain great attention from different industrial *** this context,the major task of this paper is to present a systematic overview of data-driven fault prognosis for industrial ***,the characteristics of different prognosis methods are revealed with the data-based ones being ***,based on the different data characteristics that exist in industrial systems,the corresponding fault prognosis methodologies are illustrated,with emphasis on analyses and comparisons of different prognosis ***,we reveal the current research trends and look forward to the future challenges in this *** review is expected to serve as a tutorial and source of references for fault prognosis researchers.

关键词： Data-driven fault prognosis feature extraction industrial systems

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Elastic, Piezoelectric and Acoustic Properties of Wurtzite MnO from Density Functional Calculation

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Communications in Theoretical Physics 2013年第6期59卷 751-755页

作者： han han Surface Physics Laboratory (National Key Laboratory) Key Laboratory of Computational Physical Sciencesand Department of Physics ~dan University Shanghai 200433 China

The wurtzite MnO has been obtained lately and is expected to have large potentiai in varies applications. Since elastic properties are the bases of various applications, we calculate these properties of wurtzite MnO based on the density-functionai theory and compare it with other two phases of MnO （rocksalt and zinc-blende MnO）. The Young＇s modulus of wurtzite and zinc-blende MnO are 65.6 gPa and 73.4 gPa, respectively, which are much lower than those of rocksaJt MnO （177.6 gPa）. More importantly, both the Poisson ratio and the bulk modulus to shear modulus ratio indicate that wurtzite MnO should have much better ductile properties than rocksalt MnO. The calculated piezoelectric constants of wurtzite MnO are comparable to those of ZnO, This suggests wurtzite MnO is a good piezoelectric material. Furthermore, the slowness surfaces of acoustic waves of them are given from Christoffel equation.

关键词： wurtzite MnO density functional calculation elastic properties piezoelectric properties acousticproperties

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Cell-protecting regeneration from anode carbon deposition using in situ produced oxygen and steam:A combined experimental and theoretical study

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Journal of Materials Science & Technology 2018年第12期34卷 2375-2383页

作者： Zongying han Zhibin Yang Minfang han Union Research Center of Fuel Cell School of Chemical and Environmental EngineeringChina University of Mining and Technology Department of Energy and Power Engineering Tsinghua University College of Chemical and Environmental Engineering Shandong University of Science and Technology

Carbon deposition is a primary concern during the operation of solid oxide fuel cells（SOFCs） fueled with hydrocarbon fuels, leading to cell degradation and even cell damage. Carbon elimination is expected to be a promising approach to prolong cell life. This work reports on a combined experimental and theoretical investigation of cell regeneration from anode carbon deposition of tubular SOFCs fabricated by phase-inversion and co-sintering techniques. The as-prepared cell exhibits a maximum power density of 0.20 W cm;at 800 ℃ fueling with wet CH;, but fails to stable operation due to severe carbon *** on thermodynamic predictions, a successive cell-protecting regeneration process is proposed to eliminate deposited carbon without oxidizing Ni catalysts, during which CH;and H;fuels are provided in circulation. Through a total of 35 cycling tests, cell performance can always successfully restore to the initial *** possible carbon elimination mechanism is investigated in detail based on thermodynamic and first-principle calculations. The feasibility of carbon elimination using in situ produced oxygen or steam through electrochemical reaction has been revealed, providing a novel continuous operation mode for hydrocarbon-based SOFCs.

关键词： Solid oxide fuel cells Carbon deposition Cell regeneration Carbon elimination First-principle

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食物饱腹感研究及其测试技术进展

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食品科学 2025年第2期46卷 299-307页

作者：姚孟丽韩晓峰王若永韩小伟韩忠曾新安黄京美刘义凤苑鹏柳嘉段盛林中国食品发酵工业研究院北京100020 空军特色医学中心北京100142 中国人民解放军总医院第五医学中心北京100139 华南理工大学食品科学与工程学院广东广州510640

饱腹感,即为进食后满足感和不再渴望进食的状态,在维护正常食欲、控制体质量、预防肥胖及改善代谢性疾病方面具有重要意义。文章系统分析影响饱腹感的多种因素,包括食物成分、感官特征、能量密度、心理因素及饮食行为等,并阐述这些因素... 详细信息

饱腹感,即为进食后满足感和不再渴望进食的状态,在维护正常食欲、控制体质量、预防肥胖及改善代谢性疾病方面具有重要意义。文章系统分析影响饱腹感的多种因素,包括食物成分、感官特征、能量密度、心理因素及饮食行为等,并阐述这些因素对饱腹感的作用机制。同时,重点介绍模拟视觉量表、胃肠道激素检测及闪烁扫描等新兴技术在饱腹感测试中的应用,展示这些技术在评估饱腹感方面的科学性和有效性。此外,文章还讨论饱腹感及其测试技术的研究意义与未来展望,旨在为饱腹感相关机制的深入研究、饱腹感测试技术的创新以及高饱腹感食品的开发提供理论支持和实践参考。

关键词：饱腹感食物成分感官特征能量密度心理因素饮食行为模拟视觉量表生化指标

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Pitch link loads reduction of variable speed rotors by variable tuning frequency fluidlastic isolators

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Chinese Journal of Aeronautics 2015年第5期28卷 1408-1415页

作者： han Dong National Key Laboratory of Science and Technology on Rotorcraft Aeronautics College of Aerospace EngineeringNanjing University of Aeronautics and Astronautics

To reduce the pitch link loads of variable speed rotors, variable tuning frequency fluid- lastic isolators are proposed. This isolator utilizes the variation of centrifugal force due to the change of rotor speed to change the tuning port area ratio, which can change the tuning frequency of the isolator. A rotor model including the model of fluidlastic isolator is coupled with a fuselage model to predict the steady responses of the rotor system in forward flight. The aeroelastic analyses indicate that distinct performance improvement in pitch link load control can be achieved by the utilization of variable frequency isolators compared with the constant tuning frequency isolators. The 4/rev （per revolution） pitch link load is observed to be reduced by 87.6% compared with the increase of 56.3% by the constant frequency isolator, when the rotor speed is reduced by 16.7%. The isolation ability at different rotor speeds in different flight states is investigated. To achieve overall load reduction within the whole range of rotor speed, the strategy of the variation of tuning frequency is adjusted. The results indicate that the 4/rev pitch link load within the whole rotor speed range is decreased.

关键词： Fluidlastic isolator Loads Pitch link Reduction Rotor Variable frequency Variable speed

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Diffusion-reaction compromise the polymorphs of precipitated calcium carbonate

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Particuology 2013年第3期11卷 301-308页

作者： han Wang Wenlai Huang Yongsheng han EMMS group State Key Laboratory of Multiphase Complex SystemsInstitute of Process EngineeringChinese Academy of Sciences graduate School of Chinese Academy of Sciences

Diffusion is seldom considered by chemists and materialists in the preparation of materials while it plays an important role in the field of chemical engineering. If we look at crystallization at the atomic level, crystal growth in a solution starts from the diffusion of ions to the growing surface followed by the incorporation of ions into its lattice. Diffusion can be a rate determining step for the growth of crystals. In this paper, we take the crystallization of calcium carbonate as an example to illustrate the microscopic processes of diffusion and reaction and their compromising influence on the morphology of the crystals produced. The diffusion effect is studied in a specially designed three-cell reactor. Experiments show that a decrease of diffusion leads to retardation of supersaturation and the formation of a continuous concen- tration gradient in the reaction cell, thus promoting the formation of cubic calcite particles. The reaction rate is regulated by temperature. Increase of reaction rate favors the formation of needle-like aragonite particles. When diffusion and reaction play joint roles in the reaction system, their compromise dominates the formation of products, leading to a mixture of cubic and needle-like particles with a controllable ratio. Since diffusion and reaction are universal factors in the preparation of materials, the finding of this paper could be helpful in the controlled synthesis of other materials.

关键词： Calcium carbonate Shape control Crystallization Diffusion Compromise

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基于地理分区的陕北黄土高原生态系统服务权衡/协同的尺度效应研究

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水土保持研究 2025年第1期32卷 305-315页

作者：温昕王继军韩晓佳中国科学院水土保持与生态环境研究中心中国科学院水利部水土保持研究所中国科学院大学西北农林科技大学水土保持研究所中国科学院生态环境研究中心

[目的]明晰生态系统服务的权衡/协同关系，保证生态系统服务长期有效供应，实现流域生态保护与高质量发展。[方法]以典型退耕区陕北黄土高原为例，利用1990—2020年土地利用变化数据，基于InVEST模型量化4种关键生态系统服务即碳储量、... 详细信息

[目的]明晰生态系统服务的权衡/协同关系，保证生态系统服务长期有效供应，实现流域生态保护与高质量发展。[方法]以典型退耕区陕北黄土高原为例，利用1990—2020年土地利用变化数据，基于InVEST模型量化4种关键生态系统服务即碳储量、产水量、土壤保持量和生境质量的时空分布特征，通过相关性分析探讨了各类生态系统服务间的权衡/协同关系和呈现的尺度特征。[结果](1) 1990—2020年碳储量和生境质量处于不断增加的趋势，产水量和土壤保持量呈现先降低后增加总体增加的趋势，空间上呈东南略低西北略高的分布。(2)陕北黄土高原生态系统服务以协同作用为主，且在1990—2020年协同效应不断增强，权衡作用主要发生在产水量与其他生态系统服务之间，权衡作用的区域主要分布在研究区西部和东北部地区。(3)生态系统服务间的权衡/协同作用存在着空间尺度效应，随着空间尺度的增加，相关性逐渐增强而显著性有所下降，且作用关系的方向性会发生改变。[结论]陕北黄土高原生态系统服务以协同为主，生态系统服务间的权衡/协同作用存在着空间尺度效应。

关键词：生态系统服务权衡/协同作用尺度效应地理分区陕北黄土高原

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超临界循环流化床锅炉深度调峰时水冷壁流动不稳定特性计算分析

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西安交通大学学报 2025年第1期59卷 68-77,92页

作者：李维腾郭泽瑞韩磊杨冬西安交通大学动力工程多相流国家重点实验室西安710049

针对深度调峰时超临界循环流化床锅炉水冷壁管道内的汽液两相流动不稳定问题,提出了一种适用于不同工况的频域法数学模型。通过对质量、能量、动量方程进行小扰动线性化后经拉普拉斯变换得到了用于描述管道内汽液流体流动稳定性的传递函... 详细信息

针对深度调峰时超临界循环流化床锅炉水冷壁管道内的汽液两相流动不稳定问题,提出了一种适用于不同工况的频域法数学模型。通过对质量、能量、动量方程进行小扰动线性化后经拉普拉斯变换得到了用于描述管道内汽液流体流动稳定性的传递函数,通过图解奈奎斯特图的方法判断管内工质流动的稳定性。然后,通过该模型计算了某350 MW超临界循环流化床锅炉水冷壁管段的不稳定边界并研究了不同参数对流动不稳定特性的影响。计算结果表明:所选回路在20%和50%锅炉最大连续蒸发量负荷发生流动不稳定时,热负荷分别为76.09 kW·m^(-2)和113.52 kW·m^(-2),水冷壁管道流动稳定且安全;入口过冷度对临界热流密度的影响呈非单值性;增大质量流速使流体的进口和出口密度差减小,有利于流动的稳定;增大入口节流系数,可以抑制入口处流量的脉动,有利于流动的稳定;在不同的工况条件下,改变管段倾斜角度会对流动稳定性产生不同的影响。

关键词：深度调峰流动不稳定性频域法超临界循环流化床锅炉

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