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Analytical and Experimental Research on Wave Scattering by an Open-Type Rectangular Breakwater with Horizontal Perforated Plates

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Journal of ocean University of China 2024年第5期23卷 1185-1201页

作者： HE Shuyue LIU Yong LI Huajun Fisheries College Ocean University of China Shandong Province Key Laboratory of ocean Engineering Ocean University of China

This study proposes a novel open-type rectangular breakwater combined with horizontal perforated plates on both sides to enhance the sheltering effect of the rectangular box-type breakwaters against longer waves. The hydrodynamic characteristics of this breakwater are analyzed through analytical potential solutions and experimental tests. The quadratic pressure drop conditions are exerted on the horizontal perforated plates to facilitate assessing the effect of wave height on the dissipated wave energy of breakwater through the analytical solution. The hydrodynamic quantities of the breakwater, including the reflection, transmission, and energyloss coefficients, together with vertical and horizontal wave forces, are calculated using the velocity potential decomposition method as well as an iterative algorithm. Furthermore, the reflection and transmission coefficients of the breakwater are measured by conducting experimental tests at various wave periods, wave heights, and both porosities and widths of the horizontal perforated plates. The analytical predicted results demonstrate good agreement with the iterative boundary element method solution and measured data. The influences of variable incident waves and structure parameters on the hydrodynamic characteristics of the breakwater are investigated through further calculations based on analytical solutions. Results indicate that horizontal perforated plates placed on the water surface for both sides of the rectangular breakwater can enhance the wave dissipation ability of the breakwater while effectively decreasing the transmission and reflection coefficients.

关键词： analytical solution experimental test horizontal perforated plates hydrodynamic characteristics rectangular breakwater

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Optimized parameters of downhole all-metal PDM based on genetic algorithm

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Petroleum Science 2024年第4期21卷 2663-2676页

作者： Jia-Xing Lu Ling-Rong Kong Yu Wang Chao Feng Yu-Lin Gao China University of geosciences (Beijing) Key Laboratory on Deep geo-Drilling Technology of Ministry of Natural Resources

Currently, deep drilling operates under extreme conditions of high temperature and high pressure,demanding more from subterranean power motors. The all-metal positive displacement motor, known for its robust performance, is a critical choice for such drilling. The dimensions of the PDM are crucial for its performance output. To enhance this, optimization of the motor's profile using a genetic algorithm has been undertaken. The design process begins with the computation of the initial stator and rotor curves based on the equations for a screw cycloid. These curves are then refined using the least squares method for a precise fit. Following this, the PDM's mathematical model is optimized, and motor friction is assessed. The genetic algorithm process involves encoding variations and managing crossovers to optimize objective functions, including the isometric radius coefficient, eccentricity distance parameter,overflow area, and maximum slip speed. This optimization yields the ideal profile parameters that enhance the motor's output. Comparative analyses of the initial and optimized output characteristics were conducted, focusing on the effects of the isometric radius coefficient and overflow area on the motor's performance. Results indicate that the optimized motor's overflow area increased by 6.9%, while its rotational speed reduced by 6.58%. The torque, as tested by Infocus, saw substantial improvements of38.8%. This optimization provides a theoretical foundation for improving the output characteristics of allmetal PDMs and supports the ongoing development and research of PDM technology.

关键词： Positive displacement motor Genetic algorithm Profile optimization Matlab programming Overflow area

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A detailed rock density model of the Hong Kong territories

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geodesy and geodynamics 2024年第1期15卷 75-81页

作者： Albertini Nsiah Ababio Robert Tenzer Department of Land Surveying and geo-Informatics Hong Kong Polytechnic UniversityHong KongChina

We used the geological map and published rock density measurements to compile the digital rock density model for the Hong Kong *** then estimated the average density for the whole *** to our result,the rock density values in Hong Kong vary from 2101 to 2681 kg·m^(-3).These density values are typically smaller than the average density of 2670 kg·m^(-3),often adopted to represent the average density of the upper continental crust in physical geodesy and gravimetric geophysics *** finding reflects that the geological configuration in Hong Kong is mainly formed by light volcanic formations and lava flows with overlying sedimentary deposits at many locations,while the percentage of heavier metamorphic rocks is very low(less than 1%).This product will improve the accuracy of a detailed geoid model and orthometric heights.

关键词： Density model Rock types Gravimetric modeling Hong Kong

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The effect of topographic density variations on the geoid and orthometric heights in Hong Kong

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geodesy and geodynamics 2024年第5期15卷 495-503页

作者： Albertini Nsiah Ababio Department of Land Surveying and geo-Informatics Hong Kong Polytechnic UniversityHong KongChina

Utilizing the adopted average topographic density of 2670 kg/m^(3)in the reduction of gravity anomalies introduces errors attributed to topographic density variations,which consequently affect geoid modeling ***,the mean gravity along the plumbline within the topography in the definition of Helmert orthometric heights is computed approximately by applying the Poincar e-Prey gravity reduction where the topographic density variations are *** Helmert orthometric heights of benchmarks are then affected by *** errors could be random or systematic depending on the specific geological setting of the region where the leveling network is physically established and/or the geoid model is *** example of systematic errors in orthometric heights can be given for large regions characterized by sediment or volcanic deposits,the density of which is substantially lower than the adopted topographic density used in Helmert's definition of *** same applies to geoid modeling *** this study,we investigate these errors in the Hong Kong territory,where topographic density is about 20%lower than the density of 2670 kg/m^(3).We use the digital rock density model to estimate the effect of topographic density variations on the geoid and orthometric *** results show that this effect on the geoid and Helmert orthometric heights reach maxima of about 2.1 and 0.5 cm,*** results provide clear evidence that rock density models are essential in physical geodesy applications involving gravimetric geoid modeling and orthometric height determination despite some criticism that could be raised regarding the reliability of these density ***,in regions dominated by sedimentary and igneous rocks,the geological information is essential in these applications because topographic densities are substantially lower than the average density of 2670 kg/m^(3),thus introducing large systematic errors in geoid and orthometric

关键词： Rock density geoid Topography Heights Leveling network

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Isotope constraints on seasonal dynamics of nitrogen in Zhanjiang Bay, a typical mariculture bay in South China

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Acta oceanologica Sinica 2024年第6期43卷 60-70页

作者： Chunqing Chen Qibin Lao Fajin Chen Guangzhe Jin Jiacheng Li Qingmei Zhu College of ocean and Meteorology Guangdong Ocean UniversityZhanjiang 524088China School of Chemistry and Environment Guangdong Ocean UniversityZhanjiang 524088China Key Laboratory for Coastal ocean Variation and Disaster Prediction Guangdong Ocean UniversityZhanjiang 524088China Key Laboratory of Climate Resources and Environment in Continental Shelf Sea and Deep Sea of Department of Education of Guangdong ProvinceGuangdong Ocean UniversityZhanjiang 524088China

Eutrophication in coastal waters has been increasing remarkably,severely impacting the water quality in mariculture *** this study,we conducted multiple isotopic measurements on suspended particulate nitrogen(δ^(15)N-PN) and dissolved nitrate(δ^(15)N-NO_(3)^(-)and δ^(18)O-NO_(3)^(-)) in Zhanjiang Bay,a typical mariculture bay with a high level of eutrophication in South China,to investigate the changes in nitrogen sources and their cycling between the rainy and dry *** the rainy season,the study found no significant relation between δ^(15)NPN and δ^(15)N-NO_(3)^(-)due to the impact of heavy rainfall and terrestrial *** the upper bay,a slight nitrate loss and slightly higher δ_(15)N-NO_(3)^(-)and δ^(18)O-NO_(3)^(-)values were observed,attributed to intense physical sedimentwater *** some fluctuations,nitrate concentrations in the lower bay mainly aligned with the theoretical mixing line during the rainy season,suggesting that nitrate was primarily influenced by terrestrial erosion and that nitrate isotopes resembled the ***,the isotopic values of nitrate can be used for source apportionment in the rainy *** results indicated that soil nitrogen(36%) and manure and sewage(33%) were the predominant nitrogen sources contributing to nitrogen loads during this *** contrast,the dry season saw a deficient ammonium concentration(geochemical processes during the dry season may be related to decreased runoff and increased water retention ***,our study illustrated the major seasonal nitrogen sources and their dynamics in Zhanjiang B ay,providing valuable insights for formulati

关键词： nitrogen stable nitrogen isotopes biogeochemical processes eutrophication Zhanjiang Bay

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Distribution and sources of sedimentary organic matter in different aquaculture areas of northeastern Zhanjiang Bay using stable carbon and nitrogen isotopes

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Acta oceanologica Sinica 2024年第6期43卷 38-48页

作者： Fengxia Zhou Shuangling Wang Han Fang Jiani He Liang Ye Zhaohai Ding Cuiting Li Fajin Chen Xuan Lu Chunqing Chen Yafei Meng College of ocean and Meteorology Guangdong Ocean UniversityZhanjiang 524088China Key Laboratory for Coastal ocean Variation and Disaster Prediction Guangdong Ocean UniversityZhanjiang 524088China Key Laboratory of Climate Resources and Environment in Continental Shelf Sea and Deep Sea of Department of Education of Guangdong ProvinceGuangdong Ocean UniversityZhanjiang 524088China

Zhanjiang Bay is a major aquaculture area in China with many types of mariculture products(such as oysters,fish,and shrimp).The culture area and shrimp output in Zhanjiang Bay are ranked first in *** investigated the total organic carbon(TOC),total nitrogen(TN),TOC/TN ratio,and stable isotopes(δ^(13)C and δ^(15)N) of the fish and shrimp feed,fish and shrimp feces,and sedimentary organic matter(SOM) in and around different aquaculture areas of northeastern Zhanjiang B ay to study the impact of aquaculture activities on *** average TOC contents of fish and shrimp feed were 39.20%±0.91% and 39.29%±0.21%,*** average TOC content in the surface sediments of the oyster culture area,the mixed(fish and shrimp) culture area,and the cage fish farm area were 0.66%,0.88%±0.10%,and 0.58%±0.19%,respectively,which may indicate that mixed culture had a greater impact on *** relatively high TOC and TN contents and relatively low TOC/TN ratios,and δ^(15)N values in the upper layer of the core sediment in the mixed culture area could also support the significant influence of mixed *** average δ^(13)C and δ^(15)N values of fish and shrimp feed were -20.6‰±2.2‰ and 1.8‰±1.2‰,respectively,which were different from the isotopic values of SOM in the study area.δ^(13)C and δ^(15)N values for SOM in different aquaculture areas were different from those of nearby reference stations,probably reflecting the influence of *** δ^(13)C and δ^(15)N values in the oyster culture area(-25.9‰ and6.0‰,respectively) seemed to have reduced δ^(13)C and enriched δ^(15)N relative to those of the reference station(-24.6‰ and 5.8‰,respectively).This may reflect the influence of organic matter on oyster *** δ^(15)N value of the station in the mixed culture area(7.1‰±0.4‰) seemed to be relatively enriched in δ^(15)N relative to that of the reference station(6.6‰).Sedimentation and the subsequent degradation of organic matter from mixed cultures may have contrib

关键词： sedimentary organic matter aquaculture stable isotopes sources Zhanjiang Bay

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Mating behaviors in ovoviviparous black rockfish(Sebastes schlegelii):molecular function of prostaglandin E2 as both a hormone and pheromone

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Marine Life Science & Technology 2024年第1期6卷 15-30页

作者： Likang Lyu Yijia Yao Songyang Xie Xiaojie Wang Haishen Wen Yun Li Jianshuang Li Chenpeng Zuo Shaojing Yan Jingyi Dong Xin Qi Key Laboratory of Mariculture(ocean University of China) Ministry of EducationOcean University of ChinaQingdao 266003China Institute of Evolution and Marine Biodiversity Ocean University of ChinaQingdao 266003China

Prostaglandins(PGs)are profound hormones in teleost sexual behavior,especially in *** act as pheromones that affect the olfactory sensory neurons of males,inducing the initiation of a series of mating ***,the molecular mechanism by which PGs trigger mating behavior in ovoviviparous teleosts is still *** the present study,we employed the ovoviviparous black rockfish(Sebastes schlegelii),an economically important marine species whose reproductive production is limited by incomplete fertilization,as a model *** results showed that when the dose of PGE2 was higher than 10 nmol/L,a significant(P<0.05)increase in mating behaviors was ***-fluorescence in situ hybridization indicated that PGE2 could fire specific neurons in different brain regions and receptor cells in the olfactory *** combining with specific neurons in the central nervous system(CNS),a series of genes related to reproduction are *** intracerebroventricular administration of PGE_(2) significantly increased lhb levels(P<0.05)in both ***,steroidogenesis in gonads was also affected,inducing an increase(P<0.05)in E_(2) levels in males and T levels in ***_(2) levels were also increased significantly(P<0.05)in both *** present study revealed that PGE2 can activate mating behavior in black rockfish in both hormone and pheromone pathways,leading to variations in sex steroid levels and activation of reproductive *** results provide not only novel insight into the onset of mating behaviors in ovoviviparous teleosts but also solutions for the incomplete fertilization caused by natural mating in cage aquaculture.

关键词： Black rockfish Mating behavior Ovoviviparity Prostaglandin E2

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A Comparative Study on the Post-Buckling Behavior of Reinforced Thermoplastic Pipes(RTPs)Under External Pressure Considering Progressive Failure

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China ocean Engineering 2024年第2期38卷 233-246页

作者： DING Xin-dong WANG Shu-qing LIU Wen-cheng YE Xiao-han College of Engineering Ocean University of ChinaQingdao 266100China Shandong Provincial Key Laboratory of ocean Engineering Ocean University of ChinaQingdao 266100China Department of Marine Technology Norwegian University of Science and Technology(NTNU)Trondheim NO-7491Norway

The collapse pressure is a key parameter when RTPs are applied in harsh deep-water *** investigate the collapse of RTPs,numerical simulations and hydrostatic pressure tests are *** the numerical simulations,the eigenvalue analysis and Riks analysis are combined,in which the Hashin failure criterion and fracture energy stiffness degradation model are used to simulate the progressive failure of composites,and the“infinite”boundary conditions are applied to eliminate the boundary *** for the hydrostatic pressure tests,RTP specimens were placed in a hydrostatic chamber after filled with *** has been observed that the cross-section of the middle part collapses when it reaches the maximum *** collapse pressure obtained from the numerical simulations agrees well with that in the ***,the applicability of NASA SP-8007 formula on the collapse pressure prediction was also *** has a relatively greater difference because of the ignorance of the progressive failure of *** the parametric study,it is found that RTPs have much higher first-ply-failure pressure when the winding angles are between 50°and 70°.Besides,the effect of debonding and initial ovality,and the contribution of the liner and coating are also discussed.

关键词： reinforced thermoplastic pipes post-buckling behavior progressive failure of composites debonding initial ovality

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Highly Accurate Golden Section Search Algorithms and Fictitious Time Integration Method for Solving Nonlinear Eigenvalue Problems

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Computer Modeling in Engineering & Sciences 2024年第5期139卷 1317-1335页

作者： Chein-Shan Liu Jian-Hung Shen Chung-Lun Kuo Yung-Wei Chen Center of Excellence for ocean Engineering Taiwan Ocean UniversityKeelung202301TaiwanChina Department of Marine Engineering Taiwan Ocean UniversityKeelung202301TaiwanChina

This study sets up two new merit functions,which are minimized for the detection of real eigenvalue and complex eigenvalue to address nonlinear eigenvalue *** each eigen-parameter the vector variable is solved from a nonhomogeneous linear system obtained by reducing the number of eigen-equation one less,where one of the nonzero components of the eigenvector is normalized to the unit and moves the column containing that component to the right-hand side as a nonzero input vector.1D and 2D golden section search algorithms are employed to minimize the merit functions to locate real and complex ***,the real and complex eigenvectors can be computed very accurately.A simpler approach to the nonlinear eigenvalue problems is proposed,which implements a normalization condition for the uniqueness of the eigenvector into the eigenequation *** real eigenvalues can be computed by the fictitious time integration method(FTIM),which saves computational costs compared to the one-dimensional golden section search algorithm(1D GSSA).The simpler method is also combined with the Newton iterationmethod,which is convergent very *** the proposed methods are easily programmed to compute the eigenvalue and eigenvector with high accuracy and efficiency.

关键词： Nonlinear eigenvalue problem quadratic eigenvalue problem two new merit functions golden section search algorithm fictitious time integration method

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Numerical simulation of inlet placement on sewage characteristics in the rounded square aquaculture tank with single inlet

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Journal of oceanology and Limnology 2024年第4期42卷 1359-1382页

作者： Xiaozhong REN Yixuan HU Yinxin ZHOU Shupeng DU Wei SUN Hangfei LIU Chenxu ZHAO Ying LIU Key Laboratory of Environment Controlled Aquaculture(Dalian ocean University)Ministry of Education Dalian 116023China College of Marine Science and Environment Dalian Ocean UniversityDalian 116023China College of ocean and Civil Engineering Dalian Ocean UniversityDalian 116023China Zhejiang University Hangzhou 310058China

To improve the self-cleaning ability of aquaculture tank and the efficiency of circulating water,physical and numerical experiments were conducted on the influence of inlet structure on sewage discharge in a rounded square aquaculture tank with a single *** on the physical model of the tank,analysis of how inlet structure adjustment affects sewage discharge efficiency and flow field characteristics was conducted to provide suitable flow field conditions for sinkable solid particle *** addition,an internal flow field simulation was conducted using the RNG k-εturbulence model in hydraulic drive *** a solid-fluid multiphase model was created to investigate how the inlet structure affects sewage collection in the rounded square aquaculture tank with single inlet and *** finding revealed that the impact of inlet structure is considerably affecting sewage *** conditions of C/B=0.07-0.11(the ratio of horizontal distance between the center of the inlet pipe and the tank wall(C)to length of the tank(B))andα=25°(αis the angle between the direction of the jet and the tangential direction of the arc angle)resulted in optimal sewage collection,which is similar to the flow field experiment in the rounded square aquaculture tank with single inlet and *** excellent correlation was revealed between sewage collection and fluid circulation stability in the aquaculture *** present study provided a reference for design and optimization of circulating aquaculture tanks in aquaculture industry.

关键词： rounded square aquaculture tank sewage collection characteristic inlet structure computational fluid dynamic

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