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Scale Effects on Propeller Cavitating Hydrodynamic and Hydroacoustic Performances with Non-uniform Inflow

Chinese Journal of Mechanical Engineering 2013年第2期26卷 414-426页

作者： yang Qiongfang WANG Yongsheng ZHANG Zhihong College of Marine Power Engineering Naval University of Engineering College of Science Naval University of Engineering

Considering the lack of theoretical models and ingredients necessary to explain the scaling of the results of propeller cavitation inception and cavitating hydroacoustics from model tests to full scale currently, and the insufficient reflection of the nuclei effects on cavitation in the numerical methods, the cavitating hydrodynamics and cavitation low frequency noise spectrum of three geometrically similar 7-bladed highly skewed propellers with non-uniform inflow are addressed. In this process, a numerical bridge from the multiphase viscous simulation of propeller cavitation hydrodynamics to its hydro-acoustics is built, and the scale effects on performances and the applicability of exist scaling law are analyzed. The effects of non-condensable gas（NCG） on cavitation inception are involved explicitly in the improved Sauer＇s cavitation model, and the cavity volume acceleration related to its characteristic length is used to produce the noise spectrum. Results show that, with the same cavitation number, the cavity extension on propeller blades increases with diameter associated with an earlier shift of the beginning point of thrust decline induced by cavitation, while the three decline slopes of thrust breakdown curves are found to be nearly the same. The power of the scaling law based on local Reynolds number around 0.9R section is determined as 0.11. As for the smallest propeller, the predominant tonal noise is located at blade passing frequency（BPF）, whereas 2BPF for the middle and both 2BPF and 3BPF for the largest, which shows the cavitating line spectrum is fully related to the interaction between non-uniform inflow and fluctuated cavity volume. The predicted spectrum level exceedance from the middle to the large propeller is 6.65 dB at BPF and 5.94 dB at 2BPF. Since it just differs less than 2 dB to the increment obtained by empirical scaling law, it is inferred that the scale effects on them are acceptable with a sufficient model scale, and so do the scaling

关键词： propeller cavitation inception cavitation noise scale effect cavitation model turbulence model

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2D materials for solar fuels via artificial photosynthesis

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National Science Review 2022年第5期9卷 19-21页

作者： Jian Du Hao yang Licheng Sun Institute of Natural Sciences Westlake Institute for Advanced Study Center of Artificial Photosynthesis for Solar Fuels School of ScienceWestlake University Department of Chemistry School of Engineering Sciences in Chemistry Biotechnology and Health KTH Royal Institute of Technology State Key Laboratory of Fine Chemicals DUT-KTH Joint Education and Research Centre on Molecular Devices Dalian University of Technology

To create a globally carbon neutral society,sustainable energy systems to replace fossil fuels are needed *** in nature converts CO2and H2O into carbohydrates and O2and is driven by solar energy via photosystemⅡ(PSⅡ...

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A Multi-scale Corrosion Fatigue Damage Model of Aluminum Alloy Considering Multiple Pits and Cracks

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Acta Mechanica Solida Sinica 2018年第6期31卷 731-743页

作者： Bin Sun yang Zheng Zhaoxia Li Department of Engineering Mechanics Jiangsu Key Laboratory of Engineering MechanicsSoutheast UniversityNanjing 210000China Department of Information Center The Second Affiliated Hospital of Southeast UniversityNanjing 210000China

A multi-scale model is developed to link the continuum damage variable in macroscale to the number density of multiple pits and cracks in microscale for studying the corrosion fatigue of aluminum alloy from multi-scale *** developed model is used to predict the coherent multi-scale corrosion fatigue process of aluminum alloy component in the 3.5 wt% NaC1water solution under constant stress amplitude at a nominal frequency of 5Hz, and the numerical prediction results are compared with the experimental *** shows that the model is effective and can be used to study the corrosion fatigue mechanisms of alurninum alloy from both macro and microscale viewpoints.

关键词： Multi-scale Continuum damage Pit Crack Corrosion fatigue Aluminum alloy

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Hybrid particle swarm optimization for multiobjective resource allocation

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Journal of Systems Engineering and Electronics 2008年第5期19卷 959-964页

作者： Yi yang Li Xiaoxing Gu Chunqin Computer Science Dept. Sun Yat-sen Univ. Guangzhou 510275 P. R. China

Resource allocation （RA） is the problem of allocating resources among various artifacts or business units to meet one or more expected goals, such a.s maximizing the profits, minimizing the costs, or achieving the best qualities. A complex multiobjective RA is addressed, and a multiobjective mathematical model is used to find solutions efficiently. Then, all improved particie swarm algorithm （mO_PSO） is proposed combined with a new particle diversity controller policies and dissipation operation. Meanwhile, a modified Pareto methods used in PSO to deal with multiobjectives optimization is presented. The effectiveness of the provided algorithm is validated by its application to some illustrative example dealing with multiobjective RA problems and with the comparative experiment with other algorithm.

关键词： resource allocation multiobjective optimization improved particle swarm optimization.

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Advance of tolerance engineering on microbes for industrial production

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Synthetic and Systems Biotechnology 2023年第4期8卷 697-707页

作者： Siyuan Gao yang Liao Hao He Huiling yang Xuewei yang Sheng Xu Xin Wang Kequan Chen Pingkai Ouyang State Key Laboratory of Materials-Oriented Chemical Engineering College of Biotechnology and Pharmaceutical EngineeringNanjing Tech UniversityNanjing211816JiangsuChina Petrochemical Research Institute of PetroChina Co.Ltd. Beijing102206China

Industrial microbes have become the core of biological manufacturing,which utilized as the cell factory for production of plenty of chemicals,fuels and ***,the challenge that the extreme stress conditions exist in production is unavoidable for cell ***,to enhance robustness of the chassis cell lays the foundation for development of ***,the researches on cell tolerance covered various aspects,involving reshaping regulatory network,cell membrane modification and other stress *** fact,the strategies employed to improve cell robustness could be summarized into two directions,irrational engineering and rational *** this review,the metabolic engineering technologies on enhancement of microbe tolerance to industrial conditions are ***,the novel thoughts emerged with the development of biological instruments and synthetic biology are discussed.

关键词： Tolerance engineering Stress condition Industrial microbe Metabolism engineering Synthetic biology

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Paleoenvironment controls on organic matter accumulation in transitional shales from the eastern Ordos Basin,China

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Frontiers of Earth Science 2021年第4期15卷 737-753页

作者： Jianwei LV Songhang ZHANG Ning yang Chunbo FU Xinlu YAN yang LI School of Energy Resources China University of GeosciencesBeijing 100083China Chinese Academy of Natural Resources Economics Beijing 101149China Huadian Coal Industry Group Co. Ltd.Beijing 100035China Second Oil Production Plant PetroChina Changqing Oilfield CompanyQingyang 745100China

To investigate the paleoenvironmental controls on organic matter accumulation of Upper Paleozoic shales in the eastern Ordos Basin,China,26 shale samples were collected from two wells drilled into the Shanxi and Taiyuan *** total organic carbon(TOC)content,mineral compositions and elemental geochemistry of the samples were ***(35.42%)and clay minerals(48.34%)are the dominant minerals and trace elements(Li,Cs,Cu,V,Co,and Cr)are commonly enriched in the shale samples compared to the Upper Continental Crust.C-values(ranging from 0.2 to 4.5),chemical indices of weathering(CIW)values(48.82 to 99.11),and Sr/Cu ratios(1.00 to 11.05)suggest that the paleoclimate was humid in the study area during the Late *** redox indices(e.g.,Al_(2)O_(3)/(Al_(2)O_(3)+Fe_(2)O_(3)),V/Cr,Ni/Co,V/(V+Ni)and U/Th)indicate a dysoxic to oxic paleoenvironment characterized by transi-tional sedimentary deposits in a continental margin *** addition,chemical index of alteration(CIA,ranging from 77.92%to 98.36%)and CIW(89.19%to 99.11%)values suggest that there was intense chemical weathering in the study area,while the Al_(2)O_(3)-CaO^(*)+Na_(2)O-K_(2)O(A-CN-K)ternary diagram demonstrates that the shales were not subjected to potassium metasomatism during ***_(2)O_(3)/TiO_(2)and TiO_(2)/Zr ratios,as well as REE characteristics suggest a felsic source rocks and discount seawater as an REE *** anomalies indicate an oxic environment with terrigenous input during black shale deposition,and LREE enrichment with negative Eu anomalies suggests that both shale formations were affected by detrital input rather than hydrothermal *** correlation of TOC(ranging from 1.10%to 6.39%,with an average of 2.77%)with trace elemental redox indices(Sr/Cu,Sr/Ba,V/Cr,and U/Th)indicates that a warm-humid,dysoxic to oxic environment preserved much of the organic matter.

关键词： Late Paleozoic shale geochemistry paleoenvironment eastern Ordos Basin

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A bioinspired path planning approach for mobile robots based on improved sparrow search algorithm

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Advances in Manufacturing 2022年第1期10卷 114-130页

作者： Zhen Zhang Rui He Kuo yang School of Mechatronic Engineering and Automation Shanghai UniversityShanghai 200444People’s Republic of China

In this paper,a bioinspired path planning approach for mobile robots is *** approach is based on the sparrow search algorithm,which is an intelligent optimization algorithm inspired by the group wisdom,foraging,and anti-predation behaviors of *** obtain high-quality paths and fast convergence,an improved sparrow search algorithm is proposed with three new ***,a linear path strategy is proposed,which can transform the polyline in the corner of the path into a smooth line,to enable the robot to reach the goal ***,a new neighborhood search strategy is used to improve the fitness value of the global optimal individual,and a new position update function is used to speed up the ***,a new multi-index comprehensive evaluation method is designed to evaluate these *** results show that the proposed algorithm has a shorter path and faster convergence than other state-ofthe-art studies.

关键词： Path planning Linear path strategy Sparrow search algorithm Multi-index comprehensive evaluation algorithm

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Dynamic stiffness testing-based flutter analysis of a fin with an actuator

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Chinese Journal of Aeronautics 2015年第5期28卷 1400-1407页

作者： Zhang Renjia Wu Zhigang yang Chao School of Aeronautic Science and Engineering Beihang University

Engineering-oriented modeling and synthesized modeling of the fin-actuator system of a missile fin are introduced, including mathematical modeling of the fin, motor and multi-stage gear reducer. The fin-actuator model is verified using dynamic stiffness testing. Good agreement is achieved between the test and theoretical results. The parameter-variable analysis indicates that the inertia of the motor rotor, reduction ratio of the reducer, connection stiffness and damping between the actuator and fin shaft have significant impacts on the dynamic stiffness characteristics. In flutter analysis, test data are directly used in the frequency domain method and indirectly used in the time domain method through the updated fin-actuator model. The two methods play different roles in engineering applications but are of equal importance. The results indicate that dynamic stiffness and constant stiffness treatments may lead to completely different flutter characteristics. Attention should be paid to the design of the fin-actuator system of a missile.

关键词： Actuator Aeroelasticity Dynamic stiffness Flutter Ground vibration test Structural dynamics

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Application of Bat Algorithm Based Time Optimal Control in Multi-robots Formation Reconfiguration

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Journal of Bionic Engineering 2018年第1期15卷 126-138页

作者： Guannan Li Hongli Xu yang Lin State Key Laboratory of Robotics Shenyang Institute of Automation Chinese Academy of Sciences (CAS) Shenyang 110016 China University of Chinese Academy of Sciences Beijing 100049 China

This paper proposes a Bat Algorithm （BA） based Control Parameterization and Time Discretization （BA-CPTD） method to acquire time optimal control law for formation reconfiguration of multi-robots system. In this method, the problem of seeking for time optimal control law is converted into a parameter optimization problem by control parameterization and time discretization, so that the control law can be derived with BA. The actual state of a multi-robots system is then introduced as feedback information to eliminate formation error. This method can cope with the situations where the accurate mathematical model of a system is unavailable or the disturbance from the environment exists. Field experiments have verified the effectiveness of the proposed method and shown that formation converges faster than some existing methods. Further experiment results illustrate that the time optimal control law is able to provide smooth control input for robots to follow, so that the desired formation can be attained rapidly with minor formation error. The formation error will finally be eliminated by using actual state as feedback.

关键词： Bat Algorithm CPTD method multi-robots formation control time optimal control

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Reliability of Relative Paleointensity Recorded in Chinese Loess-Paleosol Sediments

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Acta Geologica Sinica(English Edition) 2012年第5期86卷 1276-1288页

作者： yang Tianshui LI Haiyan WU Huaichun yang Zhenyu ZHANG Shihong HYODO Masayuki State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesBeijing 100083China School of the Earth Sciences and Resources China University of GeosciencesBeijing 100083China School of Ocean Sciences and Resources China University of GeosciencesBeijing 100083China Institute of Geomechanics Chinese Academy of Geological SciencesBeijing 100081China Research Center for Inland Seas Kobe UniversityKobe 657-8501Japan

A detailed paleomagnetic and rock-magnetic investigation spanning loess L7 to paleosol S8 has been carried out at the Baoji and Xifeng sections. Results of anisotropy of magnetic susceptibility confirm that the studied loess-paleosol sediments retain primary sedimentary fabrics. Stepwise thermal demagnetization shows that two well-defined magnetization components can be isolated from both loess and paleosol specimens. A low-temperature component, isolated between 100°C and 200°C, is consistent with the present geomagnetic field direction, and a high-temperature component, isolated between 200-300°C and 620-680°C, includes clearly normal and reversed polarities. Isothermal remanent magnetization and thermomagnetic analyses indicate that characteristic remanent magnetization is mainly carried by magnetite and hematite. The Day plot, together with the stratigraphic variations of rock-magnetic parameters, shows that the uniformity of magnetic mineralogy and grain size fulfills the criteria for relative paleointensity （RPI） studies. RPI records have been constructed using natural remanent magnetization （NRM） intensity after thermal demagnetization at 300°C normalized by low-frequency magnetic susceptibility （NRM 300 /χ）. The results show that the RPI record from the Baoji section, where pedogenesis is quite weak, is compatible with the stacked PISO-1500 paleointensity record, suggesting that it might reflect the paleointensity variation of the geomagnetic field. The RPI record from the Xifeng section, where pedogenesis is rather strong, indicates a clear dissimilarity with the stacked PISO-1500 paleointensity record, implying that it does not reflect the paleointensity variation of the geomagnetic field. Our new results show that the NRM 300 /χ from the strongly pedogenetic paleosols does not completely eliminate the pedogenetic （climatic） influence, so it might be unsuitable for a reliable paleointensity study.

关键词： Chinese loess pedogenesis relative paleointensity rock magnetism geomagnetic field

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