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A numerical study on the effect of tidal flat's slope on tidal dynamics in the Xiangshan Bay, China

Acta Oceanologica Sinica 2018年第9期37卷 29-40页

作者： LI Li YE Taoyan he zhiguo XIA Yuezhang Ocean College Zhejiang University State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyState Oceanic Administration

The Xiangshan Bay is a semi-enclosed and narrow bay, which is characterized by large scale tidal flats and has been historically utilized through coastal construction and aquaculture engineering. The hydrodynamic model using the Finite Volume Coastal Ocean Model（FVCOM） was constructed to examine the changes of tidal dynamics due to the variation of tidal flat slopes. According to the model results, a decreased slope of a tidal flat would amplify the M2 tidal amplitude and delay the M2 tidal phase in the inner harbor, due to an increased tidal prism, and vice versa. The amplitude of the main shallow-water tide M4 would be amplified/dampened in the entire bay due to the changed bottom friction, if the tidal flat＇s slope were reduced/increased at the Tie inlet. The phase was advanced. The change of a tidal flat＇s slope at the Tie inlet had greater impacts on tidal amplitude,phase and duration asymmetry, than that at the Xihu inlet. The impact of changes of the tidal flat slope at the Xihu inlet was small and was constrained locally. Changes in the tidal flats＇ slopes at the Tie and Xihu inlets changed the tidal duration asymmetry, residual current and tidal energy via modulating tides. The ebb dominance decreased when the tidal flat＇s slope at the Tie inlet was changed. Decreased/increased ebb dominance occurred when the tidal flat＇s slope was reduced/increased at the Xihu inlet. The residual current and tidal energy density was amplified/dampened and more/less tidal energy was dissipated, with reduced/increased slope at both of the inlets. The findings in this study are instructive to coastal engineering and estuarine management.

关键词： tidal flat＇s slope tidal dynamics tidal asymmetry tidal energy Xiangshan Bay

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Variations of temperature, salinity and current in the southern tidal passage of the Hangzhou Bay, China

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Acta Oceanologica Sinica 2016年第3期35卷 30-37页

作者： he zhiguo HUANGFU Kailong YUAN Yeping SONG Dan LI Li Ocean College Zhejiang University State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyState Oceanic Administration

Field surveys covering a spring-neap tidal period were conducted to investigate the characteristics of tidal dynamics within a curved channel in the southern Hangzhou Bay, China. The channel has a maximum depth of more than 100 m with an average tidal range of 2.5 m, serving as the main tidal passage in the southern part of the Hangzhou Bay. Water salinity, temperature and velocity data were collected from the ship-based transects and mooring measurements. During flood tide, the tidal current intrudes into the Hangzhou Bay through the northern side of the channel with a maximum velocity of about 2 m/s, while retreats through the southern side during ebb tide with a maximum velocity of 1.8 m/s. Due to the pressure, density gradients, the Coriolis force and centrifugal effect, a lateral exchange flow is generated as the tidal current relaxes from flood to ebb. Salinity and temperature data show that the water in the channel is weakly stratified during both spring and neap tides in summer time.However, mixing in the middle region will be enhanced by the lateral circulation. Mooring data indicate that the temperature and salinity are varying at a frequency similar to tidal current but higher than sea level oscillation.Our results support the hypothesis that the high frequency salinity and temperature variations could be generated by combination of the tidal current and the lateral exchanging flow.

关键词： macro-tidal estuary mooring observations temperature and salinity variations tidal current curved channel

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白改黑沥青路面反射裂缝防治技术分析

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科学技术创新 2024年第15期 167-170页

作者：何治国湖南远程建设集团有限公司湖南益阳

反射裂缝是一种极为常见的道路质量缺陷,尤其是在白改黑沥青路面中最为普遍。本文对某市政道路“白改黑”工程中防裂技术效果进行了全方位探究;通过防治裂缝施工方案的综合运用,成功达到了白改黑路面工程反射裂缝防治目的。

关键词：旧水泥混凝土路面白改黑沥青路面反射裂缝

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Surface pollen assemblages of human-disturbed vegetation and their relationship with vegetation and climate in Northeast China

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Chinese Science Bulletin 2012年第5期57卷 535-547页

作者： LI ManYue LI YueCong XU QingHai PANG RuiMing DING Wei ZHANG ShengRui he zhiguo College of Resources and Environment and hebei Key Laboratory of Environmental Change and Ecological Construction Hebei Normal UniversityShijiazhuang 050024China

Pollen assemblages of 53 surface pollen samples from farmlands and wastelands in Northeast China were analyzed. Tree pollen percentages were usually higher than 30%, with Pinus (26.9%), Quercus (0.9%), Betula (0.9%) and Populus (0.7%) as the major types, and herb pollen percentages were usually higher than 50%, with weedy Poaceae (8.7%), Chenopodiaceae (7.1%), Artemisia (1.9%) and Compositae (3.5%) as the major taxa. Thus, the pollen assemblages were consistent with the regional vegetation compositions. However, there were differences in pollen assemblages among regions, especially among different geomorphological units. For example, in the mountains, there were more types of tree pollen and higher total percentages (average 42%) than in other areas, while cereal pollen percentages were lowest (11.2%). In the hills and high plains, herbs made up more than 60% of the pollens, with cereals (average 53.6%) the dominant type. In the low plains, pollen types were similar to those in the hills and high plains, but total pollen concentrations and the proportion of Concentricystes were much higher, while cereal pollen percentages were slightly lower (average 41.6%). Pollen assemblages in different land use types also differed. For example, in farmland, cereal pollen percentages were more than 40% and Chenopodiaceae was usually less than 2.5%, while in wasteland, weedy Poaceae was usually less than 10% and Chenopodiaceae was usually higher than 25%. Total pollen concentrations in farmland (average 3909 grains/g) were much lower than in wasteland (average 15074 grains/g). Redundancy analysis revealed that pollen assemblages were significantly negatively correlated with mean annual temperature (-0.73) and July mean temperature (-0.81) and significantly positively correlated with mean annual precipitation (0.48), indicating that pollen assemblages in the artificial or human-disturbed vegetation reflect regional climate well. Comparison of pollen assemblages in different areas of northern China showed that pollen concentratio

关键词：中国东北地区花粉组合植被组成区域气候人为干扰年平均气温禾本科杂草花粉浓度

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Palaeogeothermal response and record of the effusing of Emeishan basalts in the Sichuan basin

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Chinese Science Bulletin 2010年第10期55卷 949-956页

作者： ZHU ChuanQing XU Ming YUAN YuSon ZHAO YongQing SHAN JingNan he zhiguo TIAN YunTao HU ShengBiao Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China The Graduate University of Chinese Academy of Sciences Beijing 100049 China Exploration and Production Research Institute SINOPEC Beijing 100083 China Exploration Department of South Company of Prospecting SINOPEC Chengdu 610041 China Exploration and Development Research Institute of SINOPEC Southwest Branch Chengdu 610081 China

Thermal history of the Sichuan basin is reconstructed based on vitrinite reflectance from boreholes in the basin using a paleo-heat flow method.The results show that the Sichuan basin experienced a relatively low heat flow period in the Early Paleozoic,and an elevated paleo-heat flow,ranging 60-80 mW/m2 with a maximum as high as 100 mW/m2 around 259 Ma,from the beginning of the Late Paleozoic to the end of the early Permian,and a decreased paleo-heat flow from the late Permian to the late Triassic,and then maintained nearly stable to the present.The Late Paleozoic paleo-heat flow was quite high where there were extensive Emeishan flood basalts or concealed basalts which erupted between the early and the late Permian,such as the southwestern and northeastern areas of the Sichuan basin.According to the distribution of paleo-heat flow,it can be inferred that,the northeastern Sichuan basin was also influenced by the Emeishan magmatic activity during the Dongwu movement though there was lack of Emeishan flood basalts.In addition,the results of thermal history reconstruction of the Sichuan basin provide paleogeothermal evidence for the existence and onset of the Emaishan mantle plume.

关键词：四川盆地东北部峨眉山玄武岩盆地热史古地温涌出反应镜质组反射率晚古生代

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Hydrodynamics of high-speed robots driven by the combustion-enabled transient driving method

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2022年第10期23卷 820-831页

作者： Yang YANG Yingzhong LOU Guanzheng LIN zhiguo he Pengcheng JIAO Hainan Institute Zhejiang UniversitySanya 572000China Institute of Port Coastal and Offshore EngineeringOcean CollegeZhejiang UniversityZhoushan 316021China Department of Civil and Environmental Engineering University of WashingtonSeatleWA98195USA Engineering Research Center of Oceanic Sensing Technology and Equipment of Ministry of Education Zhejiang UniversityZhoushan316021China Department of Electronic Engineering Faculty of EngineeringThe Chinese University of Hong KongHong Kong 999077China

Underwater vehicles play important roles in underwater observation, ocean resource exploration, and sample collection.Soft robots are a unique type of underwater vehicles due to their good environmental adaptability and motion flexibility, although they are weak in terms of actuation and response ability. The transient driving method(TDM) was developed to resolve these shortcomings. However, the interaction between the robots’ swift motions and flow fields has not yet been fully studied. In this study, a computational fluid dynamic model is developed to simulate the fluid fields disturbed by transient high-speed motions generated by the robots. Focusing on the dependence of robot dynamics on thrust force and eccentricity, typical structures of both flow and turbulence fields around the robots are obtained to quantitatively analyze robot kinematic performance, velocity distribution, vortex systems, surface pressure, and turbulence. The results demonstrate the high-speed regions at the robots’ heads and tails and the vortex systems due to sudden expansion, indicating a negative relationship between the maximum fluid velocity and eccentricity. The reported results provide useful information for studying the environmental interaction abilities of robots during operating acceleration and steering tasks.

关键词： Underwater vehicle Computational fluid dynamics(CFD) Robotics Transient driving method(TDM) Combustion actuation Hydrodynamics

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Underwater minirobots actuated by hybrid driving method

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2023年第7期24卷 596-611页

作者： Xinghong YE Yang YANG Pengcheng JIAO zhiguo he Lingwei LI Institute of Port Coastal and Offshore EngineeringOcean CollegeZhejiang UniversityZhoushan 316021China Engineering Research Center of Oceanic Sensing Technology and Equipment of Ministry of Education Zhejiang UniversityZhoushan 316021China Department of Biomedical Engineering(BME) National University of SingaporeSingapore 119077Singapore Key Laboratory of Marine Geotechnical Engineering and Materials Zhoushan 316021China

Underwater minirobots have attracted significant interest due to their value in complex application scenarios.Typical underwater minirobots are driven mainly by a soft or rigid actuator.However,soft actuation is currently facing challenges,including inadequate motional control accuracy and the lack of a continuous and steady driving force,while conventional rigid actuation has limited actuation efficiency,environmental adaptability,and motional flexibility,which severely limits the accomplishment of complicated underwater tasks.In this study,we developed underwater minirobots actuated by a hybrid driving method(HDM)that combines combustion-based actuators and propeller thrusters to achieve accurate,fast,and flexible underwater locomotion performance.Underwater experiments were conducted to investigate the kinematic performance of the minirobots with respect to the motion modes of rising,drifting,and hovering.Numerical models were used to investigate the kinematic characteristics of the minirobots,and theoretical models developed to unveil the mechanical principle that governs the driving process.Satisfactory agreement was obtained from comarisons of the experimental,numerical,and theoretical results.Finally,the HDM was compared with selected hybrid driving technologies in terms of acceleration and response time.The comparison showed that the minirobots based on HDM were generally superior in transient actuation ability and reliability.

关键词： Hybrid driving method(HDM) Underwater minirobots Operation reliability Transient actuation

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Study on a Gas Plunger Lift Model for Shale Gas Wells and Its Effective Application

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Fluid Dynamics & Materials Processing 2022年第4期18卷 933-955页

作者： Peng Liu Man Chen zhiguo he Wei Luo Shiyu Miao Sichuan Changning Gas Development Company PetroChina Southwest Oil&Gas Field CompanyChengdu610051China Petroleum Engineering Institute of Yangtze University Wuhan430100China Key Laboratory of Drilling and Production Engineering for Oil and Gas Yangtze UniversityWuhan430100China

The problem of efficient gas lift for gas well annulus packers that rely on their own energy plungers is considered.The complex related gas-liquid problem is addressed in the frame of model where the gas inflow dynamics and liquid inflow dynamics of the considered shale gas wells are weakly coupled.On this basis,and with the aiding support of indoor simulation experimental data,a new gas plunger lift design taking into account liquid leakage is obtained.Finally,a dedicated software relying on this approach is developed and used to verify the reliability of the model by means of field examples.

关键词： Packers their own energy plungers shale gas wells weakly coupled liquid leakage

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崖州湾海域三维海洋水动力特性的数值模拟研究

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科技通报 2024年第4期40卷 6-14页

作者：李典燃李莉沈方舟刘必劲施华斌贺治国浙江大学海洋学院浙江舟山316021 浙江大学海南研究院海南三亚572025 澳门大学中国澳门999078

掌握崖州湾海域的水动力变化规律,对该区域海岸带工程建设和社会经济的可持续发展具有重要的实际意义。本文基于非结构网格有限体积海洋模型(finite-volume coastal ocean model,FVCOM),建立崖州湾海域高分辨率三维水动力数值模型,研究... 详细信息

掌握崖州湾海域的水动力变化规律,对该区域海岸带工程建设和社会经济的可持续发展具有重要的实际意义。本文基于非结构网格有限体积海洋模型(finite-volume coastal ocean model,FVCOM),建立崖州湾海域高分辨率三维水动力数值模型,研究该海域潮位、潮流和余流的分布特性和变化规律。结果表明:在崖州湾海域,潮汐潮流类型整体为不规则全日潮,近岸潮流呈现明显的往复运动;崖州湾两侧流速明显大于湾内,在大潮期内涨潮时间约为落潮时间的1倍,最大流速约2.2 m/s,最大潮差约1.5 m;崖州湾海域整体余流偏向西北方向,在西侧海域受到岸线地形突出的影响,余流较大,湾内弧形东侧区域存在滞流点,容易造成淤积。

关键词：崖州湾潮汐潮流余流 FVCOM

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Automatic detection and assessment of crack development in ultra-high performance concrete in the spatial and Fourier domains

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Frontiers of Structural and Civil Engineering 2024年第3期18卷 350-364页

作者： Jixing CAO Yao ZHANG Haijie he Weibing PENG Weigang ZHAO zhiguo YAN hehua ZHU School of Safety Engineering and Emergency Management Shijiazhuang Tiedao UniversityShijiazhuang 050043China College of Civil Engineering and Architecture Zhejiang UniversityHangzhou 310058China College of Civil and Architectural Engineering Taizhou UniversityTaizhou 318000China College of Civil Engineering and Architecture Zhejiang University of TechnologyHangzhou 310014China Department of Geotechnical Engineering Tongji UniversityShanghai 200092China

Automatic detection and assessment of surface cracks are beneficial for understanding the mechanical performance of ultra-high performance concrete(UHPC).This study detects crack evolution using a novel dynamic mode decomposition(DMD)method.In this method,the sparse matrix‘determined’from images is used to reconstruct the foreground that contains cracks,and the global threshold method is adopted to extract the crack patterns.The application of the DMD method to the three-point bending test demonstrates the efficiency in inspecting cracks with high accuracy.Accordingly,the geometric features,including the area and its projection in two major directions,are evaluated over time.The relationship between the geometric properties of cracks and load-displacement curves of UHPC is discussed.Due to the irregular shape of cracks in the spatial domain,the cracks are then transformed into the Fourier domain to assess their development.Results indicate that crack patterns in the Fourier domain exhibit a distinct concentration around a central position.Moreover,the power spectral density of cracks exhibits an increasing trend over time.The investigation into crack evolution in both the spatial and Fourier domains contributes significantly to elucidating the mechanical behavior of UHPC.

关键词： dynamic mode decomposition ultra-high performance concrete crack detection geometric features Fourier domain

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