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  • 2020 Volume 47 Issue 6
    Published: 20 December 2020
      
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  • Research progress of high performance netting materials for fishing
    SUN Bin1,2, YU Wenwen1, SHI Jiangao1, LIU Yongli1, WANG Lei1, WANG Yue1,2, SHU Aiyan1,2
    2020, 47(6): 1.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Netting is an important fishing material, which directly affects the efficiency and safety of fishery production. In this study, the performance, modification research and application status of three high performance netting materials for fishing: ultra-high molecular weight polyethylene netting, copper alloy netting and polyester netting, were summarized. The advantages and disadvantages of their comprehensive properties such as impact resistance, wear resistance and antifouling performance, as well as the modification research on creep properties of ultra-high molecular weight polyethylene netting and crystallization properties of polyester netting, were analyzed. The development of the three kinds of netting in fishery field was introduced to provide theoretical reference for further research and development and application of new materials for fishing. In addition, this paper also discussed the future research direction and key difficulties in application technology of high-performance netting materials for fishing, and suggested strengthening the basic research and industrial application technology research of netting materials.
  • Research progress and future development direction of fishing port engineering
    WANG Gang, SUN Yiyan, CHEN Ding
    2020, 47(6): 8.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    With the increasing attention to the construction of coastal fishery disaster prevention and mitigation system and modern fishing port system, it is urgent to carry out relevant technical research in fishing port engineering, improve the ability of integrated innovation and introduce and digest the ability of re-innovation, and promote the modernization of fishing port and the high-quality development of fisheries. In this paper, the research status of disaster prevention and mitigation, engineering simulation, soft foundation treatment and new structure of breakwater wharf in China is systematically summarized, the research progress of fishing port development strategy and related planning, disaster prevention and mitigation, environmental protection and natural coordinated fishing port construction in developed countries is analyzed, the development trend of disaster prevention and mitigation project on fishing port in China in the future is discussed by comparing the gap between domestic and international, and the research direction of the 14th five year plan in the aspects of planning technology, disaster prevention and mitigation technology, facility construction technology and eco-environmental technology is put forward.
  • Improvement and motion simulation analysis of rotary live fish grading device based on ADAMS#br#
    XU Hongzhi1, CHEN Jun2, JIANG Tao2, HONG Yang2, ZHU Ye2, ZHANG Xianguang2
    2020, 47(6): 13.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to solve the problem of high damage and low efficiency in the grading process of live fish, an improved scheme of rotary live fish grading device was put forward. Replacement of the way of CAM mechanism and spring return mechanism to rotate graded baffle with the way of pinion and rack mechanism to raise graded gate could reduce the manufacturing cost and fault incidence. The 3d model was established and the method of motion simulation of key components was given. First, based on the contour parameters and grading capacity of the target fish, the structure of the live fish grader and the key parameters of the graded gate were determined, the opening and closing conditions of the graded gate were analyzed based on the thickness parameters of the graded grass carp, and the design parameters of the grader were determined. Second, the kinematics model of the grader key mechanism in the rotary process was established, the contour line of the graded regulation track was designed, and the movement analysis of the liftgate was carried out. Finally, Solidworks was used to establish the virtual prototype of grader, the virtual prototype was imported into ADAMS virtual software, and relevant parameters were set for simulation analysis. The simulation results show that when the grading device operates at a motor speed of 12 r/min, the graded gate can complete three rise actions (each rise is 10 mm) and one return action, and the time of each rise or return can be controlled within 1.25s, indicating that replacing the original mechanism with a pinion and rack mechanism can also meet the movement requirements. The results show that the rotary live fish grader has stable maneuverability and can achieve smooth movement, which meets the requirements of live fish grading. The design of the device is reasonable, which provides the basis for the design of the test prototype.
  • Study on the effect of dual channel drainage system on flow field characteristics in rectangular arc angle aquaculture tank #br#
    ZHANG Qian1,2, GUI Jinsong2, XUE Boru1,2, REN Xiaozhong1, XIONG Yuyu1, WANG Guofeng3
    2020, 47(6): 19.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to improve the hydrodynamic conditions in the aquaculture tanks and the self-cleaning capacity of the aquaculture tanks, a dual channel drainage system was used to achieve the first effective separation of solid waste in the aquaculture tanks, and the flow field characteristics in the dual channel aquaculture tanks were studied. Based on computational fluid dynamics (CFD) technology, the three-dimensional turbulent numerical model of rectangular arc angle aquaculture tanks was established in this paper, and the flow field characteristics of single channel and dual channel aquaculture tanks were compared and analyzed. The results show that in the case of single-tube inflow, the average velocity in dual channel aquaculture tanks was about 7% higher than that of single channel aquaculture tank, the resistance coefficient was about 13% lower and the uniformity coefficient UC50 was about 23% higher greatly. While in the case of double-tube inflow, the average velocity in dual channel aquaculture tanks was about 8% higher than that of single channel aquaculture tank, the resistance coefficient was about 14% lower and the uniformity coefficient UC50 was about 7% higher. The results indicate that the underflow split ratio in the dual channel aquaculture tanks has little effect on the flow field characteristics, and the dual channel drainage system can effectively improve the hydrodynamic conditions in the aquaculture tank and enhance the hydraulic mixing characteristics.
  • Study on removal of pollutants from marine aquaculture wastewater by electrocoagulation-filtration technology#br#
    XU Jianping1,2, ZHOU Li1,3, QIU Tianlong1,3, LI Ye1,2, CHEN Fudi1,2, DU Yishuai1,3,
    2020, 47(6): 26.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to improve the pretreatment of marine aquaculture wastewater, and reduce the scale and energy consumption of subsequent water treatment equipment, a continuous flow electrocoagulation (EC)-filtration pretreatment system was designed to investigate the influences of anode materials, hydraulic retention time (HRT) of EC reactor and filtration pore size on its water treatment capacity. It was found that the removal rate of EC on chemical oxygen demand (CODMn) increased with the addition of the Fe electrode proportion in the anode, and the effect was significant (P < 0.05). The anode materials had no significant effect on the removal of total nitrogen (TN) (P > 0.05). The pH of water decreased during EC. Compared with Al or Fe anode, when Al-Fe compound electrode was used as anode, the system could better remove COMMn and TN. In addition, with the increase of HRT and the decrease of filtration pore size, the removal rate of the system on CODMn and TN increased. When HRT was 4.5 min, anode was 2Al+2Fe and filtration pore size was 45 μm, the removal rate of the system on CODMn and TN was the highest, respectively (53.02±0.74)% and (58.90±1.96)%, the energy consumption was (31.35±0.6)×10-3 kWh/m3, and the dissolution rate of Al anode and Fe anode was (0.11±0.01) mg/s and (0.05±0.00) mg/s respectively. The study showed that EC-filtration system had fairly good removal effects on CODMn and TN, and ECcould significantly enhance the treatment efficiency of subsequent filtration equipment.
  • Research on automatic counting of shrimp fry based on improved convolutional neural network #br#
    FAN Songwei1, LIN Xiangyu2, ZHOU Ping1
    2020, 47(6): 35.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Shrimp fry counting is an important part of the shrimp fry breeding and transaction process. Shrimp fries are small, dense and easily inactivated, which makes it difficult to count shrimp fry upon emergence. An automatic counting technology for shrimp fry with a convolutional neural network model is proposed. First, each target object in the data sample is labeled with a pixel point to obtain the true density map, then the training samples are input to the improved convolutional neural network learning to generate an estimated density map from the image features, and finally the total number of shrimp fry in the entire field of view is obtained from the density map. In order to verify the effectiveness of the method, the shrimp fry images taken in the fry farm are used as data sets and comparative experiments are conducted on different models. The results show that: compared with the classical networks such as MCNN, CSRnet and CAN, the average absolute error can be reduced by 7.6, 4.8and 3.2 respectively, and the root mean square error can be reduced by 3.35, 5.19 and 6.39 respectively. Researches have shown that this method can accurately estimate the number of shrimp fry of a certain density under a uniform backlight environment, which meets the counting requirements of shrimp aquaculture.
  • Effect of ecological suspended bed measures on water environment restoration in Baiyangdian Lake#br#
    ZHU Hao1, 2, CAO Kun3, CHEN Xiaolong1, YE Shaowen4
    2020, 47(6): 42.
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    In order to solve the problem of submerged vegetation restoration in deep water area of Baiyangdian Lake, an ecological suspended bed constructed by aquatic plants, ropes and supporting rods was developed. The position of the ecological suspended bed can be adjusted according to the change of water level. Through monitoring of water quality around the suspended bed from July 2019 to November 2019, the purification effect of submerged plants on the suspended bed on nitrogen and phosphorus nutrients in deep water area of lake was studied. The results showed that Myriophyllum grows well on the suspended bed, and could effectively reduce the nitrogen and phosphorus nutrients in the water body. One month after the start of the experiment, the removal rates of total nitrogen, total phosphorus and nitrite nitrogen in the water around the suspended bed were 40.54%, 53.45% and 99%, respectively. At the end of the experiment, the total nitrogen, nitrite nitrogen and COD decreased by 12.43%, 33.93% and 17.09% respectively compared with those at the start of the experiment. The study shows that submerged plants on the suspended bed can effectively solve the problem of insufficient light for submerged plant growth, making it one of the effective measures to restore submerged vegetation in northern algal lakes.
  • Effect of heating temperature on muscle quality of Lateolabrax japonicus
    WU Yanyan1, LI Jinxing1,2, WANG Yueqi1, CHEN Shengjun1, DENG Jianchao1
    2020, 47(6): 49.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to ascertain the effect of heating temperature on the muscle quality of Lateolabrax japonicus, the dorsal meat of Lateolabrax japonicus is used as raw material to study the moisture content, total sulfhydryl content, myofibrillar protein concentration, color difference, flavor, weight loss rate, texture, Ca2+-ATP enzyme activity, surface hydrophobicity and other indicators when the core temperature reaches 40℃, 50℃, 60℃, 70℃, 80℃, 90℃ and 100℃ after heat treatment. The results showed that the L* value, a* value and b* value of fish color increased with the increase of temperature, and the rising speed was first fast and then slow. The hardness, cohesion, chewiness and hydrophobicity of the protein surface of fish meat first increased and then decreased with the increase of temperature, while elasticity, moisture content, myofibrillar protein concentration, total sulfhydryl content and Ca2+- ATPase enzyme activity have been decreasing. SDS-PAGE electrophoresis bands showed that with the increase of core temperature, most of myofibrillar protein was denatured, but a very small amount of actin did not undergo denaturation. According to the variation of color difference, texture and sensory score, the end heating temperature of Lateolabrax japonicus should be controlled at 70℃.
  • Seakeeping performance analysis of deep-sea aquaculture platform based on the three-dimensional potential flow theory#br#
    HAN Bing1, CHEN Zhixin1,2, CUI Mingchao2, WANG Qingwei2, WANG Yifan1, GAO Rui2
    2020, 47(6): 58.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The deep-sea aquaculture platform is a typical engineering ship with self-propelled capability and long-term mooring in fixed sea areas. Due to the diversity of working conditions, the analysis of seakeeping performance of the aquaculture platform is more complicated than that of the common ships. Based on the actual design project of aquaculture platform, this paper studies the seakeeping performance of aquaculture platform under self-propelled and mooring working conditions according to the three-dimensional potential flow theory, and then combines with the simulation analysis of frequency and time domain to evaluate the aquaculture platform’s seakeeping performance with personnel safety, equipment safety and aquaculture safety as indicators. The results show that the ship’s seakeeping performance is good under the  sea states 1 to 5, which can effectively ensure the safety indicators. Under the sea state 6, the ship’s sway angle exceeds the limit, at which time it can be handled by operation management or installation of anti-rolling device. This paper preliminarily builds a systematic seakeeping performance analysis method and evaluation system of aquaculture platform, which can provide a reference for the seakeeping performance design and optimization of other aquaculture platform project.
  • Analysis of beamforming performance of cylindrical array multi-beam fishery sonar#br#
    ZONG Yanmei1, LI Guodong1,2, CHEN Zhixin1,2, TANG Xueda1, YIN Xiangbo2, TANG Taolin 1,2
    2020, 47(6): 66.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Cylindrical array multi-beam fishery sonar, as important acoustic equipment for accurate fishing in marine fisheries, can realize omni-directional scanning of the detection waters. Its beamforming ability is one of the main technical indicators reflecting the detection performance of fishery sonar. In this research starting from the analysis of beamforming ability of cylindrical array multi-beam fishery sonar, the vertical and horizontal beamforming was simulated and the effects of amplitude shift, phase shift and frequency shift on the vertical and horizontal beamforming performance of the cylindrical array were analyzed by using the simulation method of underwater acoustic algorithm. The results show that the amplitude and phase shift has little influence on the main lobe in the vertical and horizontal directions of the cylindrical array, and the main lobe becomes wider; the influence on the side lobe is great, and the side lobe is significantly enlarged; when the offset is -5~15 dB, the gain of the first lobe is within 3dB, and when the offset is too large, the gain of the first lobe can be more than 6dB; the frequency shift has a little influence on beam directivity, the working frequency has a great influence on the width of the beam main lobe, and the width deviation of the main lobe is about 3°. This research can provide a reference for the independent development of high-precision and long-distance cylindrical array multi-beam fishery sonar in the future.
  • Research on graphical MMI of fishing vessel attitude navigation
    FENG Shuqing, XU Zhiqiang, WANG Zhiyong, CHEN Zhixin
    2020, 47(6): 74.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to meet the requirements of fast interaction between autonomous navigation and attitude navigation information of vessels, research and design of a multi function vessel attitude navigation graphical display interface based on attitude ball and navigation compass is proposed by drawing on the concept of aviation multi function display. Based on the OpenGL technology, the interface graphics generation algorithm, the viewport control algorithm, the Chinese character display algorithm and the color optimization are developed; the algorithms are drawn by using Lab Windows CVI development platform, the interface is displayed, and the software efficiency and detail experience are optimized and adjusted. The results show that, with the movement of fishing vessel carrier, the interface can indicate the platform swing data in the form of attitude ball, indicate heading data in the form of compass rotation, indicate current velocity value information, changing trend and changing rate information in the form of scale translation, thus achieving the design goals. With demonstration, the software interface has the advantages of large information expression capacity, high interactive efficiency and good human-machine efficiency. It can be used as the basic supporting component of fishing vessel digital cockpit and unmanned fishing vessel remote control base station, with strong practical value.
  • Fish target recognition and counting based on Dual-frequency Identification Sonar
    SHEN Wei1,2, ZHU Zhenhong1, ZHANG Jin1, CAO Zhengliang1, PENG Zhanfei1
    2020, 47(6): 81.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Fish resource survey is a basic work of fishery management, and the investigation of fish resources using underwater acoustic detection technology has become a mainstream method. Aiming at the acoustic data collected by Dual-frequency Identification Sonar (DIDSON) in the reservoir, the acoustic data post-processing software Echoview and related algorithms were used to conduct fish identification and counting research. First, the Kovesi image denoising method and the background difference method were utilized to remove speckle noise and water background in acoustic images, then targets were identified according to the echo threshold, the α-β trajectory tracking algorithm was used to track moving targets to prevent double counting, and finally fish counting and length extraction were performed. The results show that, compared with munual counting, fish counting error of this method is within 10%, and the average error is 7.2%, with a very high statistical accuracy. Studies have proven that DIDSON can be used for fish identification and counting, and has a very broad application space for fish resource detection and management in shallow waters.
  • Optimization Design of 320 GT Ocean-going Double Deck Trawler
    LI Na，LIANG Jiansheng
    2020, 47(6): 88.
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    In order to achieve the goal of ocean-going fishing vessel renewal, transformation and upgrading and gradually realize the specialization, standardization and modernization of ocean-going fishing vessels, by relying on the digital research and development platform of fishing vessels, the optimization design of 320 GT ocean-going double deck trawlers is systematically carried out by means of the main dimensions and main parameters of vessel form, optimization method and comprehensive performance analysis of fishing vessel form, application of energy-saving measures of bulbous bow and stern ball of small and medium sized fishing vessels, optimization and matching study of parameters of fishing vessel engine and propeller, and research on high efficiency fishing machinery hydraulic drive system of trawlers. Through the demonstration and popularization of the vessel form, it is proved that the design of the vessel is reasonable, the supporting equipment is technologically advanced, the layout of the cabin is reasonable, and the comprehensive performance such as seaworthiness, rapidity, maneuverability and safety is obviously better than similar vessels. The energy saving is over 20%, the economic benefits are considerable, solving some key technical problems of vessel form optimization, resistance reduction, energy saving and double deck safety for ocean-going small and medium-sized trawlers subject to the gross tonnage limit, and the application of relevant technical achievements will play an important role in promoting the renewal and transformation of China’s ocean-going trawlers.