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Numerical study on the wave pattern characteristic of air layer in cavity and the effects of multiple influence factors

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Journal of Hydrodynamics 2023年第5期35卷 923-941页

作者： Xiao-song Zhang xue-qin Ji Lei-qiang Chen Li-jin Gao Hong-bo Huang Fang-wen Hong CSSC Shanghai Marine Energy Saving Technology Co.Ltd. Shanghai200011China China Ship Scientific Research Center Shanghai Branch Shanghai200011China China Ship Scientific Research Center Wuxi214082China School of Naval Architecture Ocean and Civil EngineeringState Key Laboratory of Ocean EngineeringShanghai Jiao Tong UniversityShanghai200240China

Air-layer drag reduction (ALDR) technology for ship energy saving is getting more and more attention in recent years because of the outstanding drag reduction effect. In order to promote practical application, it is necessary to fully understand the two phase flow characteristics of the air layer. Recent experimental studies have shown that the surface of the air layer presents wave pattern, which has an important influence on its damage risk. However, it is difficult to measure the wave pattern quantificationally due to the interference of equipment. The main goal of the present paper is to investigate the wave pattern characteristic of air layer in cavity using numerical simulation method. On this basis, the effect of flow and geometric influence factors are discussed to understand the key control conditions. A computational fluid dynamics (CFD) numerical method based on Reynolds averaged Navier-Stokes (RANS) equations and volume of fluid (VOF) interface capturing method is established, and has been successfully applied in the simulation of air layer wave pattern. Both 2-D and 3-D simulations are carried out, aiming at analyzing air-water interface flow and vortex flow directly. Based on the simulation results, several important conclusions about the mechanism of air layer wave pattern can be obtained. Firstly, it is found to be an inherent characteristic that the wave height of the upstream air layer is higher than that of the downstream. The extremely high wave peak is easy to contact with the flat plate, leading to the breakup of air layer and a “central blank area” phenomenon. With the help of flow analysis, it is found that this characteristic is mainly caused by the strong counterclockwise vortex behind the bow wedge block. Secondly, the air layer stability is reduced with the increase of water flow velocity by affecting the wave height. There is a saturation point of air flow rate to reach maximum thickness of air layer. Thirdly, cavity configuration has ob

关键词： Air layer drag reduction wave pattern of air-water interface numerical simulation multiple influence factors vortex flow fields

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Anchoring Mo on C_(9)N_(4) monolayers as an efficient single atom catalyst for nitrogen fixation

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Journal of Energy Chemistry 2021年第6期30卷 443-450,I0011页

作者： Zhe xue Xinyu Zhang Jiaqian qin Riping Liu State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004HebeiChina Metallurgy and Materials Science Research Institute Chulalongkorn UniversityBangkok 10330Thailand

Electrochemical nitrogen fixation via a convenient and sustainable manner,exhibits an intriguing prospect for ammonia generation under ambient ***,the design and development of high-efficiency and low-cost electrocatalysts remains the major challenge confronting nitrogen reduction reaction(NRR).Herein,anchoring the single Mo atom on the C_(9)N_(4) substrate(Mo@C_(9)N_(4)) to form an efficient single-atom catalyst(SAC) is proposed for the conversion of N2 to *** employing density functional theory(DFT) calculations,we demonstrated that gas phase N2 can be sufficiently activated and efficiently reduced to NH3 on the surface of Mo@C_(9)N_(4).Meanwhile,we found that the NRR dominantly occurred on the Mo center via a preferred distal pathway with favorable limiting potential of 0.40 ***,the as-established Mo@C_(9)N_(4) catalyst exhibits an outstanding structural stability and good selectivity toward *** findings provide a promising platform for designing Mo-based SACs for electrochemical N2 fixation.

关键词： Carbon nitride covalent compounds Electrochemical nitrogen reduction Single-atom catalyst Ammonia synthesis First-principles calculations

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TMN4 complex embedded graphene as bifunctional electrocatalysts for high efficiency OER/ORR

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Journal of Energy Chemistry 2021年第4期30卷 437-443页

Developing highly active bifunctional electrocatalysts for oxygen evolution reaction(OER)and oxygen reduction reaction(ORR)is of great significance in energy conversion and storage *** this study,we systematically investigated the OER/ORR electrocatalytic activity of TMN_(4)@G system by using density functional theory(DFT)***,IrN_(4)@G is a very promising bifunctional catalyst for both OER and ORR with the extremely low overpotentials of 0.30 and 0.26 V,*** outstanding electrocatalytic performance is mainly attributed to the synergistic effect of Ir and *** importantly,by constructing 2D activity volcano plots,we obtained the limiting overpotentials of TMN_(4)@G system with the values of 0.26 V for OER and 0.24 V for *** findings open up new opportunities for further exploring graphene-based materials for highly efficient OER/ORR electrocatalysts.

关键词： N-doped graphene Transition Metal-N4 cluster First-principles calculations Oxygen evolution reaction Oxygen reduction reaction

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Wave Attenuation Performance and the Influencing Factors of A Lower Arc-Plate Breakwater

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China Ocean Engineering 2020年第1期34卷 89-98页

作者： LI xue-yan WANG qing YOU Zai-jin GUO Wei-jun ZHANG Jun-bin ZHAN Chao ZHANG Zhi-chen WANG Li-xue LI qin Coast Institute Ludong UniversityYantai 264025China Dalian Maritime University Dalian 116026China Institute of Sea-Crossing Engineering Ludong UniversityYantai 264024China College of Environmental Sciences and Engineering Dalian Maritime UniversityDalian 116026China

Comprehensive experimental and numerical studies have been undertaken to investigate wave energy dissipation performance and main influencing factors of a lower arc-plate breakwater. The numerical model, which considers nonlinear interactions between waves and the arc-plate breakwater, has been constructed by using the velocity wave- generating method, the volume of fluid (VOF) method and the finite volume method. The results show that the relative width, relative height and relative submergence of the breakwater are three main influencing factors and have significant influence on wave energy dissipation of the lower arc-plate open breakwater. The transmission coefficient is found to decrease with the increasing relative width, and the minimum transmission coefficient is 0.15 when the relative width is 0.45. The reflection coefficient is found to vary slightly with the relative width, and the maximum reflection coefficient is 0.53 when the relative width is 0.45. The transmission and reflection coefficients are shown to increase with the relative wave height for approximately 85% of the experimental tests when the relative width is 0.19 0.45. The transmission coefficients at relative submergences of 0.04, 0.02 and 0 are clearly shown to be greater than those at relative submergences of 0.02 and 0.04, while the reflection coefficient exhibits the opposite relationship. After the wave interacts with the lower arc-plate breakwater, the wave energy is mainly converted into transmission, reflection and dissipation energies. The wave attenuation performance is clearly weakened for waves with greater heights and longer periods.

关键词： arc-plate breakwater wave attenuation performance influencing factors VOF method

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系统性红斑狼疮380例外周血淋巴细胞亚群变化及临床意义

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解放军医药杂志 2015年第5期27卷 69-72,93页

作者：杨宇峰朱剑茹晋丽车国柱靳志勇孙慧萍靳雪琴陈伟华李小峰解放军总医院风湿免疫科北京100039 解放军264医院风湿免疫科太原030001 山西医科大学第二医院风湿科太原030001

目的探讨T淋巴细胞亚群、B淋巴细胞及NK细胞的变化在系统性红斑狼疮(SLE)发生和发展中的作用。方法选取解放军264医院和山西医科大学第二医院诊治的SLE 380例及健康体检者58例,SLE患者分为稳定期组157例、轻度活动期组79例、中度活动期... 详细信息

目的探讨T淋巴细胞亚群、B淋巴细胞及NK细胞的变化在系统性红斑狼疮(SLE)发生和发展中的作用。方法选取解放军264医院和山西医科大学第二医院诊治的SLE 380例及健康体检者58例,SLE患者分为稳定期组157例、轻度活动期组79例、中度活动期组82例、重度活动期组62例。检测各组外周血中T、B淋巴细胞、NK细胞、Th、Ts细胞计数及百分比,并分析SLE患者外周血淋巴细胞亚群与SLE疾病活动指数(SLEDAI)的相关性。结果活动期SLE T、Th及NK细胞计数及百分比、Ts细胞计数低于健康对照组和稳定期组,B细胞百分比高于健康对照组和稳定期组(P<0.05)。T、Th、Ts、NK细胞计数、T细胞百分比与SLEDAI评分呈负相关,B细胞百分比与SLEDAI评分呈正相关(r=-0.347、-0.311、-0.326、-0.351、-0.318、0.455,P<0.05)。结论外周血淋巴细胞亚群的变化可以为SLE患者病情评估及诊治效果提供依据。

关键词：免疫系统疾病红斑狼疮,系统性淋巴细胞亚群

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An Improved F-Expansion Method and Its Application to Coupled Drinfel'd-SokolovWilson Equation

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Communications in Theoretical Physics 2008年第8期50卷 309-314页

作者： ZHAO xue-qin ZHI Hong-Yan Department of Mathematics Qufu Normal University Shandong Rizhao 276826 China Department of Applied Mathematics Dalian University of Technology Dalian 116024 China

With the aid of computerized symbolic computation, an improved F-expansion method is presented to uniformly construct more new exact doubly periodic solutions in terms of rational formal Jscobi elliptic function of nonlinear partial differential equations （NPDFs）. The coupled Drinfel＇d-Sokolov-Wilson equation is chosen to illustrate the method. As a result, we can successfully obtain abundant new doubly periodic solutions without calculating various Jacobi elliptic functions. In the limit cases, the rational solitary wave solutions and trigonometric function solutions are obtained as well.

关键词： Jacobi elliptic function doubly periodic solution rational solitary wave solution

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Random Forest-Based Fatigue Reliability-Based Design Optimization for Aeroengine Structures

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Computer Modeling in Engineering & Sciences 2024年第7期140卷 665-684页

作者： xue-qin Li Lu-Kai Song School of Energy and Power Engineering Beihang UniversityBeijing100191China Department of Mechanical Engineering The Hong Kong Polytechnic UniversityKowloonHong Kong999077China Research Institute of Aero-Engine Beihang UniversityBeijing100191China

Fatigue reliability-based design optimization of aeroengine structures involves multiple repeated calculations of reliability degree and large-scale calls of implicit high-nonlinearity limit state function,leading to the traditional direct Monte Claro and surrogate methods prone to unacceptable computing efficiency and *** this case,by fusing the random subspace strategy and weight allocation technology into bagging ensemble theory,a random forest(RF)model is presented to enhance the computing efficiency of reliability degree;moreover,by embedding the RF model into multilevel optimization model,an efficient RF-assisted fatigue reliability-based design optimization framework is *** the low-cycle fatigue reliability-based design optimization of aeroengine turbine disc as a case,the effectiveness of the presented framework is *** reliabilitybased design optimization results exhibit that the proposed framework holds high computing accuracy and computing *** current efforts shed a light on the theory/method development of reliability-based design optimization of complex engineering structures.

关键词： Random forest reliability-based design optimization ensemble learning machine learning

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A New General Algebraic Method and Its Application to Shallow Long Wave Approximate Equations

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Communications in Theoretical Physics 2007年第5X期48卷 781-786页

作者： ZHAO xue-qin ZHI Hong-Yan Department of Mathematics Qufu Normal University Rizhao 276826 China Department of Applied Mathematics Dalian University of Technology Dalian 116024 China

A new general algebraic method is presented to uniformly construct a series of exact solutions for nonlinear evolution equations （NLEEs）. For illustration, we apply the new method to shallow long wave approximate equations and successfully obtain abundant new exact solutions, which include rational solitary wave solutions and rational triangular periodic wave solutions. The method is straightforward and concise, and it can also be applied to other nonlinear evolution equations in mathematical physics.

关键词： new general algebraic method nonlinear evolution equations solitary wave solutions

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New Family of 3-DOF UP-Equivalent Parallel Mechanisms with High Rotational Capability

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Chinese Journal of Mechanical Engineering 2018年第1期31卷 66-77页

作者： Wei Ye qin-Chuan Li Xin-xue Chai Faculty of Mechanical Engineering and Automation Zhejiang Sci-Tech University

Parallel mechanisms(PMs) having the same motion characteristic with a UP kinematic chain(U denotes a universal joint, and P denotes a prismatic joint) are called UP-equivalent PMs. They can be used in many applications, such as machining and milling. However, the existing UP-equivalent PMs suffer from the disadvantages of strict assembly requirements and limited rotational capability. Type synthesis of UP-equivalent PMs with high rotational capability is *** special 2 R1 T motion is briefly discussed and the fact that the parallel module of the Exechon robot is not a UP-equivalent PM is disclosed. Using the Lie group theory, the kinematic bonds of limb chains and their mechanical generators are presented. Structural conditions for constructing such UP-equivalent PMs are proposed,which results in numerous new architectures of UP-equivalent PMs. The high rotational capability of the synthesized mechanisms is illustrated by an example. The advantages of no strict assembly requirements and high rotational capability of the newly developed PMs will facilitate their applications in the manufacturing industry.

关键词： Parallel mechanism Group theory Type synthesis High rotational capability

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Synthesis of Polybutadienes with Controllable Microstructure by a Novel Binary Nd(3-NBSO_3)_3/Alkylaluminum Catalyst System

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Chinese Journal of Polymer Science 2015年第3期33卷 475-480页

作者： Ji-qin Wen xue-quan Zhang 代全权 Key Laboratory of Synthetic Rubber Changchun Institute of Applied ChemistryChinese Academy of Sciences Jiangsu Province Institute for Medical Equipment Testing

The polymerization of 1,3-butadiene was examined by using a novel halogen-free neodymium m-nitrobenzenesulfonate （Nd（3-NBSOa）3·donors）/alkylaluminum binary catalyst system. The catalyst showed fairly high activity and controllable selectivity. The microstructure of the resultant polymer was adjustable by variation of electron donor and/or the alkylaluminum. ^13C-NMR and thermal analysis demonstrate that the produced polybutadienes have stereo-block chain structures of cis-1,4 and trans-1,4 segments with adjustable Tm and To. The neodymium sulfonate-based catalyst is believed to be significant in regulating the chain structure of polydienes and in exploring 1,3-diene polymerization mechanism.

关键词： Polybutadiene Microstructure Ziegler-Natta polymerization.

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