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Influences of Floater Motion on Gap Resonance Triggered by Focused Wave Groups

中国海洋工程:英文版 2023年第4期37卷 685-697页

作者： gao jun-liang LYU Jing ZHANG Jian ZANG jun School of Naval Architecture and Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212100China Key Laboratory of Port Waterway and Sedimentation Engineering of MOTNanjing Hydraulic Research InstituteNanjing 210029China Key Laboratory of Water Security Guarantee in Guangdong-Hong Kong-Marco Greater Bay Area of Ministry of Water Resources Guangzhou 510611China Centre for Infrastructure Geotechnical and Water Engineering(IGWE)Department of Architecture and Civil EngineeringUniversity of BathBA27AYUK

The current study investigates the hydrodynamic characteristics of gap resonance within a narrow gap formed by two adjacent boxes subjected to incident focused transient wave groups.A two-dimensional(2D)numerical wave tank based on the OpenFOAM package is utilized for this purpose.The weather-side box is fixed while the lee-side box is allowed to heave freely under wave actions.The effects of the focused wave amplitude and spectral peak period on the wave amplification within the gap,motion of the lee-side box,and wave forces(including horizontal and vertical wave forces)acting on each box are systematically examined.For comparison,another structural layout consisting of two fixed boxes is also considered.The results reveal that the release of the heave degree of freedom(DoF)of the lee-side box results in remarkably distinct resonance features.In the heave-box system,both its fluid resonant period and the period corresponding to the maximum heave displacement of the lee-side box are significantly larger(i.e.,1.6-1.7 times)than the fluid resonant period of the fixed-box system.However,the wave amplification factor inside the gap in the heave-box system is significantly lower than that in the fixed-box one.Both the variations of the maximum horizontal and vertical wave forces with the spectral peak period and their magnitudes are also significantly different between the two structural systems.

关键词： gap resonance focused waves wave amplification wave forces OpenFOAM

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Hydrodynamic Behavior of Fluid Resonance Between Twin Boxes in Moonpool with Various Edge Profiles Under Wave Actions

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中国海洋工程:英文版 2023年第4期37卷 547-557页

作者： LAN jun-jie JIANG Sheng-chao gao jun-liang Faculty of Vehicle Engineering and Mechanics Dalian University of TechnologyDalian 116024China School of Naval Architecture and Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212100China

Fluid resonance in moonpool formed by twin boxes under wave actions is investigated by using a viscous numerical wave flume with ReNormalization Group(RNG)turbulent model.The accuracy of the numerical model is validated by available experimental data.Three types of edge profiles,the sharp edge,concave edge and convex edge are con-sidered.Numerical simulations show that the normalized resonant amplitude in moonpool decreases with the decrease of moonpool opening or increase of incident wave amplitude.The increased reflection coefficients are the major reason for the phenomena,implying less wave energy is able to support the wave resonance in moonpool.With the increase of incident wave height,the energy coefficients increase for convex edges around resonant fre-quency,which are oppositely with those of sharp and concave edges.Various flow patterns of the wave resonance in the vicinity of the moonpool entrance are also identified,which are mainly dependent on the edge profiles.

关键词： moonpool wave resonance corner shape RNG turbulent model OpenFOAM® flow pattern

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Numerical Investigations on Harbor Oscillations Induced by Falling Objects

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China Ocean Engineering 2023年第3期37卷 458-470页

作者： gao jun-liang BI Wen-jing ZHANG Jian ZANG jun School of Naval Architecture and Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212100China Key Laboratory of Port Waterway and Sedimentation Engineering of MOTNanjing Hydraulic Research InstituteNanjing 210029China Key Laboratory of Water Security Guarantee in Guangdong-Hong Kong-Marco Greater Bay Area of Ministry of Water Resources Guangzhou 510611China Centre for Infrastructure Geotechnical and Water Engineering(IGWE)Department of Architecture and Civil EngineeringUniversity of BathBA27AYUK

In this paper,the open-sourced computational fluid dynamics software,OpenFOAM~?,is used to study the fluctuation phenomenon of the water body inside a horizontally one-dimensional enclosed harbor basin with constant water depth triggered by falling wedges with various horizontal falling positions,initial falling velocities and masses.Based on both Fourier transfo rm analysis and wavelet spectrum analysis for the time series of the free surface elevations inside the harbor basin,it is found for the first time that the wedge falling inside the harbor can directly trigger harbor resonance.The influences of the three factors(including the horizontal falling position,the initial falling velocity,and the mass)on the response amplitudes of the lowest three resonant modes are also investigated.The results show that when the wedge falls on one of the nodal points of a resonant mode,the mode would be remarkably suppressed.Conversely,when the wedge falls on one of the anti-nodal points of a resonant mode,the mode would be evidently triggered.The initial falling velocity of the wedge mainly has a remarkable effect on the response amplitude of the most significant mode,and the latter shows a gradual increase trend with the increase of the former.While for the other two less significant modes,their response amplitudes fluctuate around certain constant values as the initial falling velocity rises.In general,the response amplitudes of all the lowest three modes are shown to gradually increase with the mass of the wedge.

关键词： harbor oscillations seiches falling objects resonant mode response amplitude

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Stock Efficiency Evaluation Based on Multiple Risk Measures:A DEA-Like Envelopment Approach

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Journal of Systems Science & Complexity 2022年第4期35卷 1480-1499页

作者： LI jun gao Hengxuan LI Yongjun JIN Xi liang liang School of Management University of Science and Technology of ChinaHefei230026China School of Management Hefei University of TechnologyHefei230009China

This paper proposes a new approach for stock efficiency evaluation based on multiple risk measures. A derived programming model with quadratic constraints is developed based on the envelopment form of data envelopment analysis(DEA). The derived model serves as an input-oriented DEA model by minimizing inputs such as multiple risk measures. In addition, the Russell input measure is introduced and the corresponding efficiency results are evaluated. The findings show that stock efficiency evaluation under the new framework is also effective. The efficiency values indicate that the portfolio frontier under the new framework is more externally enveloped than the DEA efficient surface under the standard DEA framework.

关键词： Data envelopment analysis(DEA) multiple risk measures portfolio selection stock efficiency evaluation

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Investigations on Fluid Resonance Within A Narrow Gap Formed by Two Fixed Bodies with Varying Breadth Ratios

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China Ocean Engineering 2023年第6期37卷 962-974页

作者： GONG Shu-kai gao jun-liang MAO Hong-fei School of Naval Architecture and Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212100China State Key Laboratory of Hydraulic Engineering Intelligent Construction and Operation Tianjin UniversityTianjin 300350China College of Ocean Engineering and Energy Guangdong Ocean UniversityZhanjiang 524000China Guangdong Provincial Key Laboratory of Intelligent Equipment for South China Sea Marine Ranching Guangdong Ocean UniversityZhanjiang 524088China

The resonant motion of the fluid inside a narrow gap between two fixed boxes induced by incident regular waves with various wave heights is investigated by adopting a two-dimensional numerical wave flume based on an opensourced CFD package,OpenFOAM.The two boxes have identical draft and height,but the upstream box has a variable breadth.This article focuses on the influences of the breadth ratio,defined as the ratio of the breadth of the upstream box to that of the downstream box,on the following three aspects of hydrodynamic characteristics of gap resonance:(1)the wave height amplifications inside the gap,and in front and at the rear of the structure system,(2)the reflection,transmission,and energy loss coefficients of the structure system,and(3)the response and damping time of the fluid resonance.It is found that the fluid resonant frequency,the amplification factor of the resonant wave height inside the gap and the maximum energy loss coefficient of the structure system are shown to gradually decrease with the increase of the breadth ratio.The response time of gap resonance is shown to first increase and then decrease with the breadth ratio overall,regardless of the incident wave height,and the configuration that the two boxes have the same breadth would bring the largest response time of gap resonance.

关键词： gap resonance wave amplification varying breadth ratios OpenFOAM

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Multichannel adaptive signal detection: basic theory and literature review

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Science China(Information Sciences) 2022年第2期65卷 5-44页

作者： Weijian LIU jun LIU Chengpeng HAO Yongchan gao Yong-liang WANG Wuhan Electronic Information Institute Department of Electronic Engineering and Information Science University of Science and Technology of China State Key Laboratory of Acoustics Institute of Acoustics Chinese Academy of Sciences School of Electronic Engineering Xidian University

Multichannel adaptive signal detection uses test and training data jointly to form an adaptive detector to determine whether a target exists. The resulting adaptive detectors typically possess constant false alarm rate(CFAR) properties; thus, no additional CFAR processing is required. In addition, a filtering process is also not required because the filtering function is embedded in the adaptive detector. Adaptive detection typically exhibits better detection performance than the filtering-then-CFAR detection technique.It has been approximately 35 years since the first multichannel adaptive detector was proposed by Kelly in 1986. However, there are few overview articles on this topic. Thus, in this study, we present a tutorial overview of multichannel adaptive signal detection with an emphasis on the Gaussian background. We discuss the main design criteria for adaptive detectors, investigate the relationship between adaptive detection and filtering-then-CFAR detection techniques, investigate the relationship between adaptive detectors and adaptive filters, summarize typical adaptive detectors, present numerical examples, provide a comprehensive literature review, and discuss potential future research tracks.

关键词： constant false alarm rate multichannel signal signal mismatch statistical distribution subspace signal

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Numerical study of edge waves using extended Boussinesq equations

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Water Science and Engineering 2017年第4期10卷 295-302页

作者： Gang Wang Zhong-bin Sun Jun-liang Gao Xiao-zhou Ma Jiangsu Key Laboratory of Coast Ocean Resources Development and Environment Security(Hohai University) Nanjing 210098China Nanjing Hydraulic Research Institute Nanjing 210029China School of Naval Architecture and Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116023China

An edge wave numerical model was developed based on extended Boussinesq equations with the internal wave-generation method. The form of edge waves near a seawall was chosen as the input signal in order to avoid treatment of the moving shoreline on a sloping beach. As there was an energy transfer between different edge wave modes, not only the target mode but also other modes appeared in the simulations. Due to the nonlinear effect, the simulation results for mode-0 edge waves were slightly modulated by mode-1 and mode-2 waves. As the magnitudes of these higher-mode waves are not significantly related to those of the target mode, the internal wave-generation method in Boussinesq equations can produce high-quality edge waves. The numerical model was used to investigate the nonlinear properties of standing edge waves, and the numerical results were in strong agreement with theory.

关键词： Edge waves Boussinesq equations Internal wave-generation method Nonlinear wave interaction

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The effect of hydrodynamics alone on the subhalo population in aΛCDM rich cluster sized dark matter halo

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Research in Astronomy and Astrophysics 2020年第11期20卷 213-221页

作者： jun-Yi Jia liang gao Yan Qu Key Laboratory for Computational Astrophysics National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China Institute of Computational Cosmology Department of PhysicsUniversity of DurhamSouth RoadDurham DH13LEUK

We perform a set of non-radiative hydro-dynamical(NHD)simulations of a rich cluster sized dark matter halo from the Phoenix Project with three different numerical resolutions,to investigate the effect of hydrodynamics alone on the subhalo population in the halo.Compared to dark matter only(DMO)simulations of the same halo,subhaloes are less abundant for relatively massive subhaloes(Msub>2.5×109h 1M⊙,or Vmax>70 km s 1)but more abundant for less massive subhaloes in the NHD simulations.This results in different shapes in the subhalo mass/Vmax function in two different sets of simulations.At given subhalo mass,the subhaloes less massive than 1010h 1M⊙have larger Vmax in the NHD than DMO simulations,while Vmax is similar for the subhaloes more massive than the mass value.This is mainly because the progenitors of present day low mass subhaloes have larger concentration parameters in the NHD than DMO simulations.The survival number fraction of the accreted low mass progenitors of the main halo at redshift 2 is about 50 percent higher in the NHD than DMO simulations.

关键词： cosmology baryon-methods numerical

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Investigation on Effects of Vertical Degree of Freedom on Gap Resonance Between Two Side-by-Side Boxes Under Wave Actions

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China Ocean Engineering 2022年第3期36卷 403-412页

作者： HE Zhi-wei gao jun-liang SHI Hua-bin ZANG jun CHEN Hong-zhou LIU Qian School of Naval Architecture and Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212100China State Key Laboratory of Internet of Things for Smart City and Department of Civil and Environmental Engineering University of MacaoMacao 999078China Centre for Infrastructure Geotechnical and Water Engineering(IGWE)Department of Architecture and Civil Engi-neeringUniversity of BathBA27AYUK School of Civil Engineering and Architecture Northeast Electric Power UniversityJilin 132012China

The possible wave resonance in the narrow gap formed by the parallel arrangement of ships will lead to the sharp increase of wave loads and the rapid growth of motion response.The fluid resonance inside a narrow gap between two side-by-side boxes is investigated numerically based on an open-source CFD package,OpenFOAM.The upstream box remains fixed,while the downstream box is allowed to heave freely under wave actions.This work aims to examine the influence of the motion of the downstream box on the fluid resonant behaviors inside the gap.The hydrodynamic behaviors considered include the wave height inside the gap,the heave displacement,and the reflection,transmission,and energy loss coefficients.gao et al.(2021)reported the influence of the motion of the upstream box on gap resonant behaviors.For comparative study,some results of gao et al.(2021)are also presented in this work.It is found that the heave motion of any box in the two-box system leads to a smaller resonant wave height amplification and a larger fluid resonance frequency.The frequency at which the maximum heave displacement of the downstream box occurs is less than the fluid resonant frequency.The heave motion of any box in the two-box system results in a larger reflection coefficient and a smaller energy loss coefficient.

关键词： gap resonance wave height amplification heave motion OpenFOAM

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Study on Transient Gap Resonance with Consideration of the Motion of Floating Body

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China Ocean Engineering 2022年第6期36卷 994-1006页

作者： gao jun-liang LYU Jing WANG Jing-hua ZHANG Jian LIU Qian ZANG jun ZOU Tao School of Naval Architecture and Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212100China Key Laboratory of Port Waterway and Sedimentation Engineering of MOTNanjing Hydraulic Research InstituteNanjing 210029China Department of Civil and Environmental Engineering the Hong Kong Polytechnic UniversityHong KongChina Centre for Infrastructure Geotechnical and Water Engineering(IGWE)Department of Architecture and Civil EngineeringUniversity of BathBA27AYU.K Shandong Provincial Key Laboratory of Ocean Engineering Qingdao 266100China

In this paper, the transient fluid resonance phenomenon inside a narrow gap between two adjacent boxes excited by the incident focused waves with various spectral peak periods and focused wave amplitudes is simulated by utilizing the open-sourced computational fluid dynamics software, Open FOAM. The weather-side box is allowed to heave freely under the action of waves, and the lee-side box keeps fixed. This paper mainly focuses on how both the spectral peak period and the focused wave amplitude affect the free-surface amplification inside the gap, the motion of the weather-side box, and the wave loads(including the vertical and the horizontal wave forces) acting on both boxes.For comparison, another two-box system with both boxes fixed is also considered as a control group. It is found that the motion of the weather-side box significantly changes the characteristics of the transient gap resonance, and it would cause that the fluid resonant period becomes 1.4-1.6 times that of the two-box system with both boxes fixed.All the concerned physical quantities(i.e., the free-surface amplification in the gap, the motion of the weather-side box, the wave loads) are found to closely depend on both the spectral peak period and the focused wave amplitude.

关键词： transient gap resonance focused waves free-surface amplification wave loads heave motion OpenFOAM

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