检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

渤海沙脊和沙席分布及与M_2潮流的关系

海洋地质与第四纪地质 2015年第2期35卷 23-32页

作者：王鹏贾凯吴建政胡日军国家海洋环境监测中心大连116023 中国海洋大学海洋地球科学学院青岛266100

基于渤海海底地形调查资料,识别了辽东浅滩、辽东湾东岸、六股河河口、曹妃甸等4个沙脊区的21条沙脊,利用收集到的渤海8个站位的实测潮流数据,通过数值模拟的方法,研究了潮流与渤海沙脊、沙席发育的动力学关系。在物源充足的前提下,M2... 详细信息

基于渤海海底地形调查资料,识别了辽东浅滩、辽东湾东岸、六股河河口、曹妃甸等4个沙脊区的21条沙脊,利用收集到的渤海8个站位的实测潮流数据,通过数值模拟的方法,研究了潮流与渤海沙脊、沙席发育的动力学关系。在物源充足的前提下,M2分潮潮流椭圆长半轴在50～75cm/s,椭率绝对值小于0.4时,能够发育潮流沙脊,沙脊的方向与潮流椭圆长轴方向基本一致;椭圆长半轴为40～50cm/s,椭率绝对值在0.4～0.6之间时,能够发育潮流沙席。M2分潮潮流椭圆长半轴过大或过小,均不能发育潮流沙脊和沙席。

关键词：沙脊沙席 M2潮流渤海

Characteristics of sediment transport in the Zhoushan Archipelago sea area

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2009年第5期28卷 116-127页

作者： HU Rijun 1,2 , wu jianzheng 1,2 ? , LI Guangxue 1,2 , ZHU Longhai 1,2 , MA Fang 3 1 College of Marine Geoscience, Ocean University of China, Qingdao 266100, China 2 Key Lab of Submarine Geosciences and Prospecting Techniques, Ministry of Education, Ocean University of China, Qingdao 266100, China 3 North China Sea Branch of the State Oceanic Administration, Qingdao 266033, China College of Marine Geoscience Ocean University of China Shandong Qingdao 266100 North China Sea Branch of the State Oceanic Administration Shandong Qingdao 266033

Based on the field data including tidal current, suspended sediment concentration, grain size of surface sediments, the transport mechanism and movement trend of sediments are analyzed using the method of flux decomposition and Grain Size Trend Analysis. The results show that the concentration and flux of suspended sediments decrease sharply from the Hangzhou Bay to the offshore area. The suspended sediment transport is mainly controlled by advection transport including average current transport and Stokes drift-induced transport and the gravitational circulation transport. The surface sediments are transported from the entrance of the Hangzhou Bay to the offshore area in general; meanwhile, the sediment transport has two obvious transport trends in the offshore area. The interaction of tidal currents, residual currents,the East China Sea coastal current, Taiwan Warm Current and wind waves appear to play important roles in the sediment transport. Furthermore, the sediment distribution and transport are significantly affected by the Zhoushan Archipelago.

关键词： the Zhoushan Archipelago suspended sediments surface sediments sediment transport dynamic mechanism

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

近20年辽河三角洲地貌演化

地理学报 2009年第3期64卷 357-367页

作者：朱龙海吴建政胡日军徐永臣王楠中国海洋大学海底科学与探测技术教育部重点实验室青岛266100 中国海洋大学海洋地球科学学院青岛266100 中国海洋大学工程勘察设计开发院．青岛266100

运用钻探和浅地层探测等最新调查成果．对近20年的辽河三角洲潮流沉积进行了研究。根据不同时期水深地形和卫星影像资料对比分析了现代辽河三角洲潮流地貌变化．现代辽河三角洲的沉积主体位于双台子河口。研究区10m深度内的地层主要包... 详细信息

运用钻探和浅地层探测等最新调查成果．对近20年的辽河三角洲潮流沉积进行了研究。根据不同时期水深地形和卫星影像资料对比分析了现代辽河三角洲潮流地貌变化．现代辽河三角洲的沉积主体位于双台子河口。研究区10m深度内的地层主要包括：潮滩相、潮道相和浅海相沉积，其下为古三角洲相。潮滩相沉积物以砂和粉砂为主，分选中等．跳跃和悬浮组分各占50％左右；浅海相和潮道相沉积物主要为软弱的粘土质粉砂和粉砂质粘土．以悬浮组分为主。全新世以来至1896年．研究区为古辽河、古大凌河和绕阳河之间的小海湾。1896年，双台子河被人工开挖为分洪河道以来，口门外形成盖州滩等潮滩、并快速发育。1958年，双台子河建闸后，人海径流量和输沙量减小。目前，双台子河口整体处于淤积状态，潮滩面积不断增加，整体向南、西、北3个方向扩展。潮滩最大淤进速率为87～683m／a．平均淤积速率为0．189m／a。潮滩东侧局部发生侵蚀，平均侵蚀速率为0．122m／a。潮道面积缩小，具有向西、向北迁移的趋势，最大迁移速率为48～200m／a。双台子河口地貌发育受径流、海洋动力和人类活动的影响．沉积物的主要来源由双台子河河流输沙演变为潮流和沿岸流输沙。

关键词：辽河三角洲地貌

在线全文

学校读者我要写书评

暂无评论

倒置喷管发动机性能测定方法的比较与分析

推进技术 1995年第3期16卷 26-29页

作者：毛根旺陈福连牛嵩高吴建政西北工业大学航天工程学院

采用三种试验方案对喷管倒置１５０°引起的比冲损失进行了测定、分析和比较。结果表明，双室串并发动机顺倒置四喷管引起的比冲相对损失为１．８％左右；如果将顺置采用单喷管，那么该项损失大约为４．１％。采用双室串并发动机时，测... 详细信息

采用三种试验方案对喷管倒置１５０°引起的比冲损失进行了测定、分析和比较。结果表明，双室串并发动机顺倒置四喷管引起的比冲相对损失为１．８％左右；如果将顺置采用单喷管，那么该项损失大约为４．１％。采用双室串并发动机时，测试系统和判读系统误差不能进入测试数据中，所以它比单独采用顺置和倒置时测定的数据可靠。

关键词：固体推进剂火箭发动机喷管

Ballistic performances of the hourglass lattice sandwich structures under high-velocity fragments

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第1期31卷 312-325页

作者： He-xiang wu Jia Qu Lin-zhi wu Key Laboratory of Advanced Ship Materials and Mechanics College of Aerospace and Civil EngineeringHarbin Engineering UniversityHarbin150001China School of Civil Engineering Northeast Forestry UniversityHarbin150040China

In this paper,the numerical simulation method is used to study the ballistic performances of hourglass lattice sandwich structures with the same mass under the vertical incidence of *** is paid to elucidating the influences of rod cross-section dimensions,structure height,structure layer,and rod inclination angle on the deformation mode,ballistic performances,and ability to change the ballistic direction of *** results show that the ballistic performances of hourglass lattice sandwich structures are mainly affected by their structural *** this respect,structural parameters optimization of the hourglass lattice sandwich structures enable one to effectively improve their ballistic limit velocity and,consequently,ballistic performances.

关键词： Hourglass lattice sandwich structures Ballistic performances high-velocity Finite element analysis

Resilience-incorporated seismic risk assessment of precast concrete frames with“dry”connections

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2024年第2期23卷 403-425页

作者： wu Chenhao Tang Yuchuan Cao Xuyang wu Gang Key Laboratory of Concrete and Prestressed Concrete Structures of the Ministry of Education Nanjing 211102China Department of Civil and Environmental Engineering University of CaliforniaLos AngelesCA 90095USA School of Civil Engineering Southeast UniversityNanjing 211102China College of Civil and Transportation Engineering Hohai UniversityNanjing 210024China

A resilience-incorporated risk assessment framework is proposed and demonstrated in this study to manifest the advantageous seismic resilience of precast concrete frame(PCF)structures with“dry”connections in terms of their low damage and rapid *** framework integrates various uncertainties in the seismic hazard,fragility,capacity,demand,loss functions,and post-earthquake *** this study,the PCF structures are distinguished from ordinary reinforced concrete frame(RCF)structures by characterizing multiple limit states for the PCF based on its unique damage ***,probabilistic story-wise pushover analyses are performed to yield story-wise capacities for the predefined limit *** the seismic resilience analysis,a step-wise recovery model is proposed to idealize the functionality recovery process,with separate considerations of the repair and non-repair *** recovery model leverages the economic loss and downtime to delineate the stochastic post-earthquake recovery curves for the resilience loss *** such,contingencies in the probabilistic post-earthquake repairs are incorporated and the empirical judgments on the recovery parameters are largely *** proposed framework is demonstrated through a comparative study between two“dry”connected PCFs and one RCF designed as alternative structural systems for a prototype *** results from the risk quantification indicate that the PCFs show reduced loss hazards and lower expected losses relative to the ***,the PCF equipped with energy dissipation devices at the“dry”connections largely reduces the expected economic loss,downtime,and resilience loss by 29%,56%,and 60%,respectively,compared to the RCF.

关键词： precast concrete frame non-emulative precast system seismic resilience seismic risk functional recovery

迥异、变迁与赓续:农业合作化运动中的农民心态及行为(1949—1957)

在线全文

学校读者我要写书评

暂无评论

兰州学刊 2023年第7期 14-23页

作者：庞琳武力吴建征河北大学历史学院北华航天工业学院马克思主义学院中国近现代史纲要教研室河北省中国特色社会主义理论体系研究基地不详中国社会科学院当代中国研究所

在整个农业合作化运动的演进发展历程中,国家通过自上而下的政策推动予以实施,大体经历了“互助组—初级社—高级社”的三部曲,农民对此呈现出多阶段、多阶层、多维度的心态与行为逻辑变化,并成为这场运动的主体。这一过程中,农民的传... 详细信息

在整个农业合作化运动的演进发展历程中,国家通过自上而下的政策推动予以实施,大体经历了“互助组—初级社—高级社”的三部曲,农民对此呈现出多阶段、多阶层、多维度的心态与行为逻辑变化,并成为这场运动的主体。这一过程中,农民的传统思维惯行受到一定冲击,合作化进程中的不同阶段与合作化后的农民心态与行为也呈现了迥异、变迁与赓续的发展轨迹,并与合作化进程紧密呼应。在国家政策与农民心态的博弈互动与碰撞中,乡村社会的生产、生活模式得以重塑,农民的心态与行为变化亦反映了农业合作化进程中的国家与农民互动,从某种程度上映射出集体化时期乡村体制改革的发展脉络。

关键词：农业合作化运动农民心态行为

New findings on the influence of El Nino events on tropical cyclone formation

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2024年第3期67卷 892-893页

作者： Liguang wu Department of Atmospheric and Oceanic Sciences Institute of Atmospheric SciencesFudan UniversityShanghai 200438China

Tropical cyclones typically form over warm tropical and subtropical ocean surfaces, as their formation and intensification rely primarily on the energy provided by the ocean. Pioneering research by Gray (1968) revealed that the formation of tropical cyclones requires the sea surface temperature (SST) to be no less than 26.5℃. Consequently, SST is commonly recognized as a crucial parameter among the environmental factors influencing tropical cyclone formation(Gray, 1979;Emanuel and Nolan, 2004).

关键词： tropical cyclone ocean

发挥供销合作社在农业供给侧改革中的引领作用

在线全文

学校读者我要写书评

暂无评论

北华航天工业学院学报 2019年第4期29卷 30-32页

作者：庞琳吴建征北华航天工业学院文法系河北廊坊065000 北华航天工业学院组织部河北廊坊065000

农业供给侧改革是推动农业现代化的重要路径,在推动实施过程中面临着诸多难题和需要突破的瓶颈.而供销合作社作为新时期党和国家做好“三农”工作的重要载体,应该发挥对农业供给侧改革的引领作用.

关键词：供销合作社农业供给侧改革引领