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Identifying the turbulent flow developing inside and around the bottom trawl by Electromagnetic Current Velocity Meter approach in the flume tank

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Journal of Hydrodynamics 2021年第3期33卷 636-656页

作者： nyatchouba nsangue bruno thierry Hao Tang Liu-xiong Xu Fuxiang Hu Xinxing You Micah Adekunle David Njomoue Pandong Achille College of Marine Sciences Shanghai Ocean UniversityShanghai201306China National Engineering Research Center for Oceanic Fisheries Shanghai201306China Key Laboratory of Oceanic Fisheries Exploration Ministry of Agriculture and Rural AffairsShanghai201306China The Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources Shanghai Ocean UniversityMinistry of EducationShanghai201306China Scientific Observing and Experimental Station of Oceanic Fishery Resources Ministry of Agriculture and Rural AffairsShanghai201306China Department of Marine Biosciences Tokyo University of Marine Science and TechnologyMinatoTokyoJapan College of Fisheries and Life Sciences Shanghai Ocean UniversityShanghai201306China Faculty of Industrial Engineering University of DoualaDoualaCameroon

The Knowledge of turbulent flow developing inside and around the bottom trawl net is of great importance not only for improving the hydrodynamic performance of the gear but also for the selectivity via the fish response,such as the herding response or escape *** 3-D Electromagnetic Current Velocity Meter(ECVM)measurements were performed to investigate the effect of turbulent flow on the bottom trawl net performance and to analyze the turbulence intensity and velocity ratio inside and around different parts of the trawl *** orthogonal decomposition(POD)method was applied in order to extract the phase averaged mean velocity field of turbulent flow from each available ECVM instantaneous *** results demonstrated the existence of turbulence flow,consisting of turbulent boundary layer flow and the turbulence due to the trawl wake developing all inside and around the bottom trawl *** input streamwise velocity results in faster trawl movement and a significant turbulent *** maximum turbulence intensity inside and around trawl wing,square part,first belly,second belly,third belly,cod-end is 0.95%,1.34%,3.40%,4.10%,4.25%and 3.80%,*** was found that the mean velocity field in a turbulent flow inside and around trawl net cod-end recovered on the average was~77.58%of the input streamwise *** is~12.92%,~13.07%,~11.40%,~13.00%and~0.45%less than that inside and around trawl wing,square part,first belly,second belly,and third belly of the bottom trawl net,*** turbulent flow behavior depends strongly on the structure oscillation,input streamwise velocity and,porosity of the net *** is necessary to take into account the velocity reduction inside and around a different part of the trawl net to improve the entire drag force determination,cod-end design,and further selectivity control of the fishing gear.

关键词： Hydrodynamic bottom trawl net turbulent flow Electromagnetic Current Velocity Meter(ECVM) turbulence intensity proper orthogonal decomposition(POD)

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Revealing the Fluttering Motions of Mid-Water Trawl Codend Through Sea Trials:Case Study of Antarctic Krill Trawl Codend

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Journal of Ocean University of China 2023年第2期22卷 555-564页

作者： LIU Wei TANG Hao nyatchouba nsangue bruno thierry ZHANG Feng YIN Liqiang XU Liuxiong HU Fuxiang LIU Pengfei College of Marine Sciences Shanghai Ocean UniversityShanghai 201306China National Engineering Research Center for Oceanic Fisheries Shanghai 201306China Key Laboratory of Oceanic Fisheries Exploration Ministry of Agriculture and Rural AffairsShanghai 201306China The Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources Shanghai Ocean UniversityMinistry of EducationShanghai 201306China Scientific Observing and Experimental Station of Oceanic Fishery Resources Ministry of Agriculture and Rural AffairsShanghai 201306China Faculty of Marine Science Tokyo University of Marine Science and TechnologyMinatoTokyo 108-8477Japan Tendering Office Shanghai Ocean UniversityShanghai 201306China

The dynamic coupling between the fluttering motions and hydrodynamic characteristics of codend is essential in understanding the trawl selectivity through fish response and the drag force acting on the whole *** study investigated the effect of towing speed,warp length,warp tension,and catch size on the fluttering motions of Antarctic krill trawl codend during net shooting,towing,and hauling by using sea trial *** time-periodicity of codend oscillation was analyzed by the Morlet wavelet transform *** indicated that the period of codend oscillation was between 50 s and 90 s and showed an increasing trend with the warp tension but a decreased value at the towing *** coefficient amplitude of codend oscillation was between 0 and 4 at the net shooting and hauling stages,and between 0.2 and 0.6 at the towing *** amplitude of codend oscillation increased with the warp tension,towing speed,and catch size,but decreased with the increase of the warp *** addition,the period of codend oscillation increased with the towing speed at the net shooting and hauling stages,but decreased at the towing *** results from codend fluttering motions can improve the understanding of fish behavior and gear shape that modify the hydrodynamic force on the codend instantaneously.

关键词： codend fluttering motions sea trials Morlet wavelet periodicity

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The deformation characteristics and flow field around knotless polyethylene netting based on fluid structure interaction(FSI)one-way coupling

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Aquaculture and Fisheries 2022年第1期7卷 89-102页

作者： Baiqiang Zou nyatchouba nsangue bruno thierry Hao Tang Liuxiong Xu Shuchuang Dong Fuxiang Hu College of Marine Sciences Shanghai Ocean UniversityShanghai201306PR China National Engineering Research Center for Oceanic Fisheries Shanghai201306PR China Key Laboratory of Oceanic Fisheries Exploration Ministry of Agriculture and Rural AffairsShanghai201306China The Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources Shanghai Ocean UniversityMinistry of EducationShanghai201306China Scientific Observing and Experimental Station of Oceanic Fishery Resources Ministry of Agriculture and Rural AffairsShanghai201306China Institute of Industrial Science The University of Tokyo5-1-5 KashiwanohaKashiwaChiba277-8574Japan Faculty of Marine Science Tokyo University of Marine Science and TechnologyMinatoTokyo108-8477Japan

Knotless polyethylene(PE)netting is widely used in fisheries because of its excellent hydrodynamic performance and low *** deformation and the surrounding flow field distribution play an important role in determining the hydrodynamic characteristics of netting in moving *** order to investigate the effect of solidity ratio and attack angle on drag,netting deformation,and flow field distribution through the netting,a fluid-structure interaction(FSI)model based on a one-way coupling combining the shear stress turbulent(SST)k-omega model and the large deformation nonlinear structural finite element model was *** results showed the difference between the parallel and normal drag forces found in the present numerical model and experimental flume tank data were 9.17%and 11.58%,*** mean relative error in the inclined hydrodynamic drag for different flow velocities and attack angles was 8.35%,6.69%,and 5.37%for the nettings 1,2,and 3,*** results show that the present numerical simulation based on FSI one-way coupling can be used to examine hydrodynamic forces on *** flow simulation results show that there is a noticeable flow velocity decrease through the netting and a rather large velocity reduction region downstream from the netting for different attack *** results reveal the existence of turbulent flow due to the netting *** was found that the equivalent stress and total deformation increase as the flow velocity increases and solidity ratio decreases.

关键词： Knotless netting Fluid structure interaction Deformation characteristics Flow field SST k-omega model

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Hydrodynamic Performance of a Newly-Designed Pelagic and Demersal Trawls Using Physical Modeling and Analytical Methods for Cameroonian Industrial Fisheries

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Open Journal of Marine Science 2023年第3期13卷 41-65页

作者： Tcham Leopold Vanlie Maurice Kontchou nyatchouba nsangue bruno thierry Abdou Njifenjou Njomoue Pandong Achille Laboratory of Energy Materials Modeling and Method (E3M) National Higher Polytechnic School of Douala University of Douala Douala Cameroon College of Marine Science Shanghai Ocean University Shanghai China

This study proposed the newly-designed Pelagic and demersal trawls for the fishing vessels operating in Cameroonian waters in pelagic and demersal fishing grounds. The engineering performances of both trawls were investigated using physical modelling method and analytical method based on the predicted equations. In a flume tank, a series of physical model tests based on Tauti’s law were performed to investigate the hydrodynamic and geometrical performances of both trawls and to assess the applicability of the analytical methods based on predicted equations. The results showed that in model scale, the working towing speed and door spread for the pelagic trawl were 3.5 knots and 1.85 m, respectively, and for the bottom trawl net they were 4.0 knots and 1.8 m. At that speed and door spread, the drag force, net opening height, and wing-end spread of the pelagic model trawl were 36.73 N, 0.89 m, and 0.86 m, respectively, and the swept area was 0.76 m2. Bottom trawl speed and door spread were 30.43 N, 0.38 m, and 0.45 m, respectively, and the swept area was 0.25 m2. The maximum difference between the experimental and analytical results of hydrodynamic performances was less than 56.22% and 41.45%, respectively, for pelagic and bottom trawls, the results of the geometrical performances obtained using predicted equations were close to the experimental results in the flume tank with a maximum relative error less than 12.85%. The newly developed pelagic and bottom trawls had advanced engineering performance for high catch efficiency and selectivity and could be used in commercial fishing operations in Cameroonian waters.

关键词： Cameroonian Waters Pelagic Trawl Bottom Trawl Engineering Performances Physical Model Test Analytical Methods Formatting

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拖网性能:底拖网不同优化方法的比较

拖网性能:底拖网不同优化方法的比较

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2018年中国水产学会学术年会

作者： nyatchouba nsangue bruno thierry ZHOU Cheng Liuxiong Xu College of Marine Sciences shanghai Ocean University

目前,渔业正面临着诸如燃料价格增加、渔业资源下降等因素限制。为了提高盈利能力并确保资源的可持续性,许多国家不断探索效率高同时选择性能好的底拖网设计。这篇综述中,我们探讨了研究人员和渔具设计公司多年采用的使拖网效率高同时... 详细信息

目前,渔业正面临着诸如燃料价格增加、渔业资源下降等因素限制。为了提高盈利能力并确保资源的可持续性,许多国家不断探索效率高同时选择性能好的底拖网设计。这篇综述中,我们探讨了研究人员和渔具设计公司多年采用的使拖网效率高同时选择性能好的不同方法。底拖网的动态特性很大程度上受其形状、设计、结构、索具以及沿海床拖曳时所经受的水动力和摩擦力的影响。为了使底拖网在燃料消耗和选择性方面更加经济,许多研究人员在数值模拟方面考虑了以下几个因素,即:拖网拖力,扫海面积,材料和周围流场特征。他们开发了数值模拟方法,结合水槽试验和海上实测,以了解和预测不同条件下几何形状,强度和对海底向下的力。这项工作使得开发有效的数值模拟软件成为可能,例如渔具制造商和研究人员最常用的DynamiT（法国）,SimuTrawl（韩国）和Trawl Vision PRO（乌拉圭）。详细探讨了拖网性能的演变、采用的方法、以及每种数值模拟结果的评估、不同渔具设计软件的实验和数值模拟方法、以及这些结果的可靠性。该研究为渔业公司、拖网设计师、网具制造商、研究人员和教育工作者等使用数值模拟方法和水槽研究来改善底拖网性能研究提供了有效的参考。

关键词：底拖网数值模拟拖网性能水槽

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Experimental and Numerical Investigations of the Hydrodynamic Characteristics, Twine Deformation, and Flow Field Around the Netting Structure Composed of Two Types of Twine Materials for Midwater Trawls

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Journal of Ocean University of China 2021年第5期20卷 1215-1235页

作者： thierry bruno nyatchouba nsangue TANG Hao ACHILE Njomoue Pandong XU Liuxiong ZHOU Cheng HU Fuxiang College of Marine Sciences Shanghai Ocean UniversityShanghai 201306China National Engineering Research Center for Oceanic Fisheries Shanghai 201306China Key Laboratory of Oceanic Fisheries Exploration Ministry of Agriculture and Rural AffairsShanghai 201306China The Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources Ministry of EducationShanghai Ocean UniversityShanghai 201306China Scientific Observing and Experimental Station of Oceanic Fishery Resources Ministry of Agriculture and Rural AffairsShanghai 201306China Laboratory E3M National High Polytechnic School of DoualaUniversity of DoualaDouala 2701Cameroon Faculty of Marine Science Tokyo University of Marine Science and TechnologyMinatoTokyo 108-8477Japan

Nettings are complex flexible structures used in various *** the hydrodynamic characteristics,de-formation,and the flow field around nettings is important to design successful fishing *** study investigated the hydrodynamic characteristics and deformation of five nettings made of polyethylene and nylon materials in different attack angles through numeri-cal simulation and physical model *** numerical model was based on the one-way coupling between computational fluid dynamics(CFD)and large deflection nonlinear structural ***-Stokes equations were solved using the finite volume ap-proach,the flow was described using the k-ωshear stress turbulent model,and the large deflection structural dynamic equation was derived using a finite element approach to understand the netting deformation and nodal *** porous media model was chosen to model the nettings in the CFD *** data were compared with the experimental results of the physical model to validate the numerical *** showed that the numerical data were compatible with the experimental data with an average relative error of 2.34%,3.40%,6.50%,and 5.80%in the normal drag coefficients,parallel drag coefficients,inclined drag coefficients,and inclined lift coefficients,*** hydrodynamic forces of the polyethylene and nylon nettings decreased by approxi-mately 52.56%and 66.66%,respectively,with decreasing net *** drag and lift coefficients of the nylon netting were appro-ximately 17.15%and 6.72%lower than those of the polyethylene netting.A spatial development of turbulent flow occurred around the netting because of the netting ***,the flow velocity reduction downstream from the netting in the wake region in-creased with increasing attack angle and net *** addition,the deformation,stress,and strain on each netting increased with in-creasing solidity ratio.

关键词： netting k-ωshear stress turbulent(SST)model porous media model large deflection nonlinear structural model hydrodynamic characteristics

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Ichthyofaunic Inventory and Fish Landings of Lom Pangar Hydropower Dam Reservoir in the Eastern Region of Cameroon

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Open Journal of Marine Science 2020年第4期10卷 245-259页

作者： Achille Njomoue Pandong bruno thierry nyatchouba nsangue Ekmon Mbangue N’Souvi Kodjo Maurice Vanlie Kontchou Asser Yoke Léopold Tcham Dieudonné Essola Micah Adekunle David Laboratory E3M National High Polytechnic School of Douala University of Douala Douala Cameroon College of Marine Science Shanghai Ocean University Shanghai China College of Economics and Management Shanghai Ocean University Shanghai China Netherlands Development Organisation SNV Yaounde Cameroon College of Fisheries and Life Science Shanghai Ocean University Shanghai China

The Lom Pangar hydroelectric dam project located in the eastern region of Cameroon was implemented by Electricity Development Corporation (EDC). The impoundment of the Lom Pangar dam created a large reservoir with an area ~590 km2 and a useful storage capacity ~6 billion m3. Thereby, this impoundment has created favourable conditions for the proliferation of fishery resources. However, a fisheries assessment study based on fishing activities is essential to attain reliable information for implementing a management plan to achieve rational and sustainable exploitation. This study was carried out on the ichtyofaunic inventory and the assessment of fish landings in Lom Pangar hydroelectric dam reservoir from April 2016 to September 30, 2016. Three main groups of fishing gear have been identified, among which gillnets, traps and longlines occupy major fishing activities. Indeed, the spatial and landing sites surveies were conducted on species composition, size composition, and quantities of fish landed during the study period. Moreover, 37 species of fish divided into 16 families were found in seven different selected fish landing sites. Carp (Cyprinus carpio) was the major fish species abundantly caught by these fishing gears which accounted for 81.60% of the total catch, and the least species was sardine (Sardinella aurita). A total of 623,229 Kg of fish were landed which were dominated by those of the Wami landing site with 480,773 Kg representing 76.96% of the total landed catches. The smallest species caught was the white carp (7 cm) while the longest one was the catfish (71 cm). In addition, the species of fish in the breeding season are carp, catfish, viper fish and red tail.

关键词： Artisanal Fishing Gears Ictyofaunal Inventory Lom Pangar Hydropower Dam

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Characterization of random stress fields obtained from polycrystalline aggregate calculations using multi-scale stochastic finite elements

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Frontiers of Structural and Civil Engineering 2015年第2期9卷 121-140页

作者： bruno SUDRET Hung Xuan DANG Marc BERVEILLER Asmahana ZEGHADI thierry YALAMAS Risk Safety and Uncertainty Quantification ETH Zurich Stefano-Franscini-Platz 5 Zurich CH-8093 Switzerland Phimeca Engineering S.A. Centre d'affaires du Zenith 34 rue de Sarlieve Cournon F-63800 France EDF R&D Dept. of Materials and Mechanics of Components Site des Renardieres Moret-sur-Loing Cedex 77250 France

The spatial variability of stress fields resulting from polycrystalline aggregate calculations involving random grain geometry and crystal orientations is investigated. A periodogram-based method is proposed to identify the properties of homogeneous Gaussian random fields (power spectral density and related covariance structure). Based on a set of finite element polycrystalline aggregate calculations the properties of the maximal principal stress field are identified. Two cases are considered, using either a fixed or random grain geometry. The stability of the method w.r.t the number of samples and the load level (up to 3.5% macroscopic deformation) is investigated.

关键词： polycrystalline aggregates crystal plasticity random fields spatial variability correlation structure

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A SEM-based method to determine the mineralogical composition and the particle size distribution of suspended sediment

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International Journal of Sediment Research 2019年第2期34卷 85-94页

作者： Sylvain Pinet bruno Lartiges Jean-Michel Martinez Sylvain Ouillonc University of Toulouse (Paul Sabatier) Geosciences Environment ToulouseCNRS(Centre National de la Recherche Scientifique)IRD(Institut de Recherche pour le Développement) Instituto de Geosciencias Universidade de BrasiliaCampus Universitario Darcy RibeiroICC Centro University of Toulouse LEGOS(Laboratoire d'Etudes en Géophysique et Océanographie Spatiales)

A robust method for characterizing the mineralogy of suspended sediment in continental rivers is *** encompasses 3 steps:the filtration of a few milliliters of water,measurements of X-ray energy dispersive spectra using Scanning Electron Microscopy(SEM),and robust machine learning tools of *** method is applied to suspended particles collected from various Amazonian rivers.A total of more than 204,000 particles were analyzed by SEM-EDXS(Energy Dispersive X-ray Spectroscopy),*** 15,700 particles per sampling station,which lead to the identification of 15 distinct groups of mineralogical *** size distribution of particles collected on the filters was derived from the SEM micrographs taken in the backscattered electron imaging mode and analyzed with ImageJ *** determination of the main mineralogical groups composing the bulk sediment associated with physical parameters such as particle size distribution or aspect ratio allows a precise characterization of the load of the terrigenous particles in rivers or *** the case of the Amazonian rivers investigated,the results show that the identified mineralogies are consistent with previous studies as well as between the different samples *** method enabled the evolution of grain size distribution from fine to coarse material to be described in the water *** about hydrodynamic sorting of mineral particles in the water column are also briefly *** proposed method appears well suited for intensive routine monitoring of suspended sediment in river systems.

关键词： Mineralogy Scanning Electron Microscopy Suspended sediment Machine learning Particle size distribution

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Sasa-Satsuma’s Dynamical Equation and Optical Solitary Wave Solutions

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Optics and Photonics Journal 2022年第5期12卷 128-145页

作者： Clovis Taki Djeumen Tchaho Jean Pierre Ngantcha Hugues Martial Omanda bruno Rodin Mbock Um thierry Blanchard Ekogo Jean Roger Bogning African Centre for Advanced Studies Yaoundé Cameroon Lycée Technique Fulbert Bongotha Moanda Gabon Laboratoire de Mécanique des Matériaux Ecole Polytechnique Université des Sciences et Techniques de Masuku Franceville Gabon Laboratoire Pluridisciplinaire des Sciences Ecole Normale Supérieure Libreville Gabon Département de Physique Université des Sciences et Techniques de Masuku Franceville Gabon Institut International de Recherches Biomédicales et de Biotechnologies Carl Kambangoye (IRBK) Université Internationale de Libreville (UIL) Libreville Gabon Department of Physics Higher Teacher Training College University of Bamenda Bamenda Cameroon

This work proposes the construction of a prototype of pulse-kink hybrid solitary waves with a strong Kink dosage of the Sasa-Satsuma equation which describes the dynamics of the wave propagating in an optical fiber where the stimulated Raman scattering effect is bethinking during modeling. The ultimate goal of this work is to propose a plateful of solutions likely to serve as signals during studies on computer or laboratory propagation studies. The resolution of such an equation is not always the easiest thing, and we used the Bogning-Djeumen Tchaho-Kofané method extended to the implicit functions of Bogning to obtain the results. The flexibility of the iB-functions made it possible to deduce the trigonometric solutions, from the obtained solitary wave solutions with a hyperbolic analytical sequence of the studied Sasa-Satsuma equation. A better appreciation of the nature of the solutions obtained is made through the profiles of some solutions obtained during the different analyses.

关键词： Sasa-Satsuma’s Dynamical Equation Bogning-Djeumen Tchaho-Kofané Method Optical Soliton iB-Functions Stimulated Raman Scattering

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