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arXiv 2023年

作者： He, Ming Zhang, Shuai Wang, Shi-Ping Jin, Ze-Yu Sagar, Hemant State Key Laboratory for Turbulence and Complex Systems Department of Mechanics and Engineering Science BIC-ESAT College of Engineering Peking University Beijing100871 China College of Shipbuilding Engineering Harbin Engineering University 145 Nantong Street Harbin150001 China Nanhai Institute of Harbin Engineering University Sanya572024 China Green & Smart River-Sea-Going Ship Cruise and Yacht Research Center Wuhan University of Technology Hubei Wuhan430063 China Institute of Ship Technology Ocean Engineering and Transport Systems University of Duisburg-Essen Bismarckstr. 69 Duisburg47057 Germany

The large equivalent shallow-depth explosion problem is very significant in the field of naval architecture and ocean engineering, as such explosions can be used to attack and demolish ships and anti-ship missiles. In the current work, a refined numerical study of the flow-field characteristics of a large equivalent shallow-depth explosion is carried out using a self-developed Eulerian finite element solver. Firstly, the numerical model is validated against theoretical results and a small equivalent explosion test in a tank. The numerical results are found to agree well with the theoretical and experimental results. In the next step, the cavitation cut-off effect is added to the underwater explosion model, and the cavitation phenomenon is quantitatively analyzed through the flow-field pressure. In addition, the dynamic characteristics of the bubble and water hump under various initial conditions for different stand-off parameters are analyzed. The effect of gravity on these physical processes is also discussed. The bubble pulsation period, taking into account the free surface effect, is then quantitatively studied and compared with Cole's experimental formula for an underwater explosion. Overall, when the stand-off parameter γ > 2, the influence of the free surface on the empirical period of the bubble is not significant. Our investigation provides broad insights into shallow-depth underwater explosions from theoretical, experimental, and numerical perspectives. © 2023, CC BY.

关键词： Underwater explosions

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Influence of Asymmetric Pre-Whirl Stator Spacing on Unsteady Characteristics of Pump-Jet Propulsor

SSRN

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SSRN 2022年

作者： Li, Fuzheng Liu, Guanshan Huang, Qiao-Gao Sun, Guocang Pan, Guang Qin, Denghui Key Laboratory of Unmanned Underwater Vehicle School of Marine Science and Technology Northwestern Polytechnical University Xi’an710072 China CSSC Systems Engineerings Research Institute Beijing100000 China Wuhan Second Ship Design and Research Institute Wuhan430205 China State Key Laboratory of Turbulence and Complex Systems Department of Aeronautics and Astronautics College of Engineering Peking University Beijing100871 China

This work studies the effect of the asymmetric pre-whirl stator spacing on the hydrodynamic performance of a pump-jet propulsor (PJP). The PJP contains a 13-stator and 7-rotor. The stator count is altered in the upper and lower half, and the total count is held constant. Results show that the steady performance is independent of the stator non-uniformity at design conditions. While the unsteady fluctuation of the rotor force and flow field is deeply affected by this adjustment. The cause is that the different incident angles of each rotor resulted from various stator spacing. The larger the stator count on one side, the great the incident angle in the corresponding location. Eventually, the stator root vortices in the lower half, where stator count is relatively larger, are weakened, whereas the tip vortex shape and intensity are not affected by the stator non-uniformity. Most notably, the PJP with a slight change of stator arrangement, in which the difference between two half parts is one, does not cause a significant change in flow, and the thrust amplitude at specific frequency decreases by 40% compared to the uniform stator case. © 2022, The Authors. All rights reserved.

关键词： Stators

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Biodegradation behavior of micro-arc oxidation coating on magnesium alloy-from a protein perspective

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Bioactive Materials 2020年第2期5卷 398-409页

作者： Zhao-Qi Zhang Li Wang Mei-Qi Zeng Rong-Chang Zeng M.Bobby Kannan Cun-Guo Lin Yu-Feng Zheng Corrosion Laboratory for Light Metals College of Material Science and EngineeringShandong University of Science and TechnologyQingdao266590China State Key Laboratory for Marine Corrosion and Protection Luoyang Ship Material Research InstituteQingdao266101China School of Materials Science and Engineering Zhengzhou UniversityZhengzhou450002China Biomaterials and Engineering Materials(BEM)Laboratory College of ScienceTechnology and EngineeringJames Cook UniversityTownsville4811Australia State Key Laboratory for Turbulence and Complex Systems and Department of Materials Science and Engineering College of EngineeringPeking UniversityBeijing100871China

Protein exerts a critical influence on the degradation behavior of absorbable magnesium(Mg)-based ***,the interaction mechanism between protein and a micro-arc oxidation(MAO)coating on Mg alloys remains ***,a MAO coating was fabricated on AZ31 Mg *** its degradation behavior in phosphate buffer saline(PBS)containing bovine serum albumin(BSA)was investigated and compared with that of the uncoated *** morphologies and chemical compositions were studied using Field-emission scanning electron microscope(FE-SEM),Fourier transform infrared spectrophotometer(FT-IR)and X-ray diffraction(XRD).The degradation behavior of the bare Mg alloy and its MAO coating was studied through electrochemical and hydrogen evolution *** assay was applied to evaluate the biocompatibility of Mg alloy substrate and MAO *** indicated that the presence of BSA decreased the degradation rate of Mg alloy substrate because BSA(RCH(NH2)COO‾)molecules combined with Mg2+ions to form(RCH(NH2)COO)2Mg and thus inhibited the dissolution of Mg(OH)2 by impeding the attack of Cl‾*** the case of MAO coated Mg alloy,the adsorption of BSA on MAO coating and the formation of(RCH(NH2)COO)2Mg exhibited a synergistic effect and enhanced the corrosion resistance of the coated alloy ***,cell bioactive assay suggested that the MAO coating had good viability for MG63 cells due to its high surface area.

关键词： Magnesium alloy Protein Degradation Micro-arc oxidation Biocompatibility

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Two-Phase Flow Simulations of Surface Waves in Wind-Forced Conditions

arXiv

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arXiv 2022年

作者： Loft, Malte Kühl, Niklas Buckley, Marc P. Carpenter, Jeffrey R. Hinze, Michael Veron, Fabrice Rung, Thomas Institute for Fluid Dynamics and Ship Theory Hamburg University of Technology Am Schwarzenberg-Campus 4 HamburgD-21075 Germany Institute of Coastal Ocean Dynamics Helmholtz-Zentrum Hereon Max-Planck-Straße 1 GeesthachtD-21502 Germany Modeling Simulation & Optimization of Complex Systems Universität Koblenz-Landau Universitätsstraße 1 KoblenzD-56070 Germany School of Marine Science and Policy University of Delaware NewarkDE19716 United States

The paper is devoted to two-phase flow simulations and investigates the ability of a diffusive interface Cahn-Hilliard Volume-of-Fluid model to capture the dynamics of the air-sea interface at geophysically relevant Reynolds numbers. It employs a hybrid filtered/averaging Improved Detached Eddy Simulation method to model turbulence, and utilizes a continuum model to account for surface tension if the diffuse interface is under-resolved by the grid. A numerical wind-wave tank is introduced to limit computational costs and results obtained for two wind-wave conditions are analyzed in comparison to experimental data at matched Reynolds numbers. The focus of the comparison is on both time-averaged and wave-coherent quantities, and includes pressure, velocity as well as modeled and resolved Reynolds stresses. In general, numerical predictions agree well with the experimental measurements and reproduce many wave-dependent flow features. Reynolds stresses near the water surface are found to be especially important in modulating the critical layer height. It is concluded that the diffusive interface approach proves to be a promising method for future studies of air-sea interface dynamics in geophysically relevant flows. Copyright © 2022, The Authors. All rights reserved.

关键词： Reynolds number

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Double Deep Q-learning for Anti-saturation Attack Problem of Warship Group

Double Deep Q-learning for Anti-saturation Attack Problem of...

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Digital Twins and Parallel Intelligence (DTPI), IEEE International Conference on

作者： Wei Li Gang Xiong Hao Tao Yunjun Han Fang Wang Xisong Dong Zhen Shen State Key Laboratory for Management and Control of Complex Systems Institute of Automation Chinese Academy of Sciences School of Artificial Intelligence University of Chinese Academy of Sciences Beijing Engineering Research Center of Intelligent Systems and Technology Institute of Automation Guangdong Engineering Research Center of 3D Printing and Intelligent Manufacturing Cloud Computing Center Chinese Academy of Sciences China China Ship Development and Design Center Wuhan China School of Control Science and Engineering (CSE) Shandong University Jinan China Guangdong Engineering Research Center of 3D Printing and Intelligent Manufacturing Cloud Computing Center Chinese Academy of Sciences Dongguan China

Anti-saturation attack (ASA) strategy is vital for the survival of a warship group, and attracts the focus of many researchers. In this paper, the dynamics of ASA is formulated as a Markov Decision Process (MDP) with an enhanced states space since those characters are involved, such as the formation and detection and interception areas of warship group. A reinforcement learning method (Double Deep Q-leaning, DDQN) is developed to solve the problem and deal with the curse of dimensionality whereby the cost-to-go value is calculated by a marine engagement simulation system. A heuristic defense algorithm guided by field expert knowledge is designed for comparison. The experimental results show that the DDQN method performs better in anti-saturation attack scenarios.

关键词： Industries Heuristic algorithms Digital twin Conferences Knowledge based systems Reinforcement learning Markov processes

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Stroke genetics informs drug discovery and risk prediction across ancestries (vol 611, pg 115, 2022)

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NATURE 2022年第7938期612卷 E7-E7页

作者： Mishra, Aniket Malik, Rainer Hachiya, Tsuyoshi Jurgenson, Tuuli Namba, Shinichi Posner, Daniel C. Kamanu, Frederick K. Koido, Masaru Le Grand, Quentin Shi, Mingyang He, Yunye Georgakis, Marios K. Caro, Ilana Krebs, Kristi Liaw, Yi-Ching Vaura, Felix C. Lin, Kuang Winsvold, Bendik Slagsvold Srinivasasainagendra, Vinodh Parodi, Livia Bae, Hee-Joon Chauhan, Ganesh Chong, Michael R. Tomppo, Liisa Akinyemi, Rufus Roshchupkin, Gennady V. Habib, Naomi Jee, Yon Ho Thomassen, Jesper Qvist Abedi, Vida Carcel-Marquez, Jara Nygaard, Marianne Leonard, Hampton L. Yang, Chaojie Yonova-Doing, Ekaterina Knol, Maria J. Lewis, Adam J. Judy, Renae L. Ago, Tetsuro Amouyel, Philippe Armstrong, Nicole D. Bakker, Mark K. Bartz, Traci M. Bennett, David A. Bis, Joshua C. Bordes, Constance Borte, Sigrid Cain, Anael Ridker, Paul M. Cho, Kelly Chen, Zhengming Cruchaga, Carlos Cole, John W. de Jager, Phil L. de Cid, Rafael Endres, Matthias Ferreira, Leslie E. Geerlings, Mirjam I. Gasca, Natalie C. Gudnason, Vilmundur Hata, Jun He, Jing Heath, Alicia K. Ho, Yuk-Lam Havulinna, Aki S. Hopewell, Jemma C. Hyacinth, I. Hyacinth Inouye, Michael Jacob, Mina A. Jeon, Christina E. Jern, Christina Kamouchi, Masahiro Keene, Keith L. Kitazono, Takanari Kittner, Steven J. Konuma, Takahiro Kumar, Amit Lacaze, Paul Launer, Lenore J. Lee, Keon-Joo Lepik, Kaido Li, Jiang Li, Liming Manichaikul, Ani Markus, Hugh S. Marston, Nicholas A. Meitinger, Thomas Mitchell, Braxton D. Montellano, Felipe A. Morisaki, Takayuki Mosley, Thomas H. Nalls, Mike A. Nordestgaard, Borge G. O'Donnell, Martin J. Okada, Yukinori Onland-Moret, N. Charlotte Ovbiagele, Bruce Peters, Annette Psaty, Bruce M. Rich, Stephen S. Rosand, Jonathan Sabatine, Marc S. Sacco, Ralph L. Saleheen, Danish Sandset, Else Charlotte Salomaa, Veikko Sargurupremraj, Muralidharan Sasaki, Makoto Satizabal, Claudia L. Schmidt, Carsten O. Shimizu, Atsushi Smith, Nicholas L. Sloane, Kelly L. Sutoh, Yoichi Sun, Yan V. Tanno, Kozo Tiedt, Steffen Tatlisumak, Turgut Torres-Aguila, Nuria P. Tiwari, Hemant K. Tregouet, Bordeaux Population Health Research Center University of Bordeaux Inserm UMR 1219 Bordeaux France Department of Public Health Bordeaux University Hospital Bordeaux France Department of Neurology Memory Clinic Bordeaux University Hospital Bordeaux France Department of Neurology Institute for Neurodegenerative Diseases CHU de Bordeaux Bordeaux France Institute for Stroke and Dementia Research (ISD) University Hospital LMU Munich Munich Germany Center for Genomic Medicine Massachusetts General Hospital Boston MA USA Program in Medical and Population Genetics Broad Institute of Harvard and the Massachusetts Institute of Technology Cambridge MA USA Munich Cluster for Systems Neurology Munich Germany German Center for Neurodegenerative Diseases (DZNE) Munich Germany Iwate Tohoku Medical Megabank Organization Iwate Medical University Iwate Japan Estonian Genome Centre Institute of Genomics University of Tartu Tartu Estonia Institute of Mathematics and Statistics University of Tartu Tartu Estonia Department of Computational Biology University of Lausanne Lausanne Switzerland Swiss Institute of Bioinformatics Lausanne Switzerland University Center for Primary Care and Public Health Lausanne Switzerland Department of Statistical Genetics Osaka University Graduate School of Medicine Suita Japan Department of Genome Informatics Graduate School of Medicine The University of Tokyo Tokyo Japan Laboratory for Systems Genetics RIKEN Center for Integrative Medical Sciences Yokohama Japan Laboratory of Statistical Immunology Immunology Frontier Research Center (WPI-IFReC) Osaka University Suita Japan Integrated Frontier Research for Medical Science Division Institute for Open and Transdisciplinary Research Initiatives Osaka University Suita Japan Center for Infectious Disease Education and Research (CiDER) Osaka University Suita Japan Massachusetts Veterans Epidemiology Research and Information Center (MAVERIC) VA Boston Healthcare System Boston MA USA TIMI S

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Energy constrained multi-platform network underwater detection performance 9

Energy constrained multi-platform network underwater detecti...

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9th ACM International Conference on Underwater Networks and systems, WUWNet 2014

作者： Dong, Weijia Sheng, Xueli Jia, Lu Ling, Qing Jiang, Xu Harbin Engineering University Science and Technology on Underwater Acoustic Laboratory Harbin China Science and Technology on Complex Ship Systems Simulation Laboratory Beijing China

ISBN: (纸本)9781450332774

Collaborative multi-platform network for underwater detection in the future have advantages like comprehensive data acquisition, highly parallel operation, better concealment, stronger antiinterference ability, more flexible configuration. The performance of multi-platform underwater network is determined by the characteristic of acoustic propagation environment, collaboration ability between sensors and the cost of the system. In order to exploit the advantages of the system and maximize the use of existing platforms, this paper studied the underwater detection performance considering the interference between each other in the energy constrained underwater acoustic channels. We summarized the relationship between the underwater detection performance and the platform number, position of platform, operating parameters, interference suppression capabilities, target heading parameters. Provide a theoretical basis for the formation of multi-platform network under the performance requirements.

关键词： Data acquisition

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The research on the coverage area of multistatic sonar under various work modes

The research on the coverage area of multistatic sonar under...

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OCEANS

作者： Jia Lu Xueli Sheng Qing Ling Jiang Xu Yanyi Yuan College of Underwater Acoustic Engineering Harbin Engineering University Harbin China Science and Technology on Complex Ship Systems Simulation Laboratory Beijing China

Absorption loss which is an important characteristic in the field of underwater acoustic, caused by sea water is often neglected in the research on the coverage area of bistatic sonar, in this article, the coverage area of bistatic sonar considering absorption loss is studied. When multistatic sonar works in different modes, detection criterion varies, so the coverage area can't be considered as the direct sum of coverage area of each bistatic sonar unit. This article discussed the coverage area respect to the most relaxed criterion and the most strict criterion.

关键词： Propagation losses Absorption Sonar detection Receivers Underwater acoustics

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Research of interacting multiple model particle filter based on passive multi-sonar

Research of interacting multiple model particle filter based...

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OCEANS

作者： Xueli Sheng Chunyan Sun Qing Ling Jia Lu Jingwei Yin Longxiang Guo Science and Technology on Underwater Acoustic Laboratory Harbin Engineering University College of Underwater Acoustic Engineering Harbin Engineering University Science and Technology on Complex Ship Systems Simulation Laboratory Beijing China

ISBN: (纸本)9781479913084

The passive target tracking problem of multi-sonar belongs to nonlinear problem, and the background noise is not guass noise entirely, so a kind of filtering method which suit for nonlinear and non-guassian system of is needed. In this paper, the interacting multiple model particle filter which combined by particle filter and interacting multiple model is applied in tracking maneuvering target. Combing the particle filter's ability of disposing nonlinear and non-guass problem and the IMM's ability of tracking target's arbitrary maneuvering, the difficulty that traditional filter encounters in tracking maneuvering target under the circumstance of nonlinear and non-guassian can be solved. The interacting multiple model particle filter is simulated in two different model set, the results indicate that, under the case of model matching, this method has good ability in tracking the maneuvering target of nonlinear and non-guassian system.

关键词： Mathematical model Particle filters Target tracking Equations Noise Radar tracking Filtering algorithms

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Research on active detection and direction finding method of autonomous underwater vehicle based on vector sensor

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The Journal of the Acoustical Society of America 2012年第4_SUPPLEMENT期131卷 3485-3485页

作者： Qing Ling Xue-li Sheng Yan-yi Yuan Jia Lu Chun-Yan Sun Ye Bai Science and Technology on Complex Ship Systems Simulation Laboratory Beijing 100000 shengxueli@*** Science and Technology on Underwater Acoustic Laboratory Harbin Engineering University Harbin 150001 Science and Technology on Complex Ship Systems Simulation Laboratory Beijing 100000

To resolve the detection and orientation problem of autonomous underwater vehicle which platform is limited, single vector sensor with orientation ability is selected. The method of detection and bearing estimation based on vector sensor and its performance are researched in this paper. Vector sonar synthetical copy correlator and vector sonar synthetical adaptive correlator are put forward here, which use both pressure and velocity information. The composing principle and realizing method of the two processors above are studied and the processing gain, detecting probability and bearing estimation ability of the two are analyzed in acoustic multi-path condition. The theoretical results simulation and experiments show that all methods studied above have better performance than common copy correlation, and in multipath condition, the vector sonar synthetical adaptive correlation does better than vector sonar synthetical copy correlation in the aspect of processing gain and bearing estimation. Keywords: active detection; direction finding; autonomous underwater vehicle; vector sensor; synthetical copy correlator; synthetical adaptive correlator

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