共查询到20条相似文献，搜索用时 240 毫秒
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日本新任首相安倍晋三于2006年10月8日访华。他就任后第一次出访就到中国,说明很重视与中国和亚洲的外交关系,旨在改变小泉时代留下的政治后遗症——中日关系冷淡,日本亚洲外交危机。安倍访华期间中日发表联合公报,其内容包括坚持东海磋商,加快共同开发步伐,寻求双方都能接受的方案等。安倍访华标志着中日紧张关系开始缓和,但并不等于中日东海问题就此迎刃而解。中日东海问题是长期形成的,错综复杂的,不可能通过一两次首脑访问就能解决根本问题,充其量只能起到遏制势头恶化的作用。以笔者之见,在东海问题上日方仍然掌握着主动权,海上保安厅出动武装舰船和飞机始终控制着我国固有领土——钓鱼岛及其周边海域。至今没有任何迹象表明日本政府要收回授权民间企业在东海试开采的成命,强行试钻的可能性依然存在。中日双方虽然就东海共同开发达成继续进行磋商的一致意见,但从发展趋势分析最终仍有利日方。 相似文献
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以印度洋深层海水,用柴油和石油作为混合碳源经富集培养、分离获得一株具有很强的柴油降解能力的茵株P40.茵株P40革兰氏染色阴性,接触酶和氧化酶为阳性,能还原硝酸盐,不能还原亚硝酸盐.16S rDNA Blastn 结果表明其与 Alcanivorax dieselolei B-5T(柴油食烷茵)及 A.dieselolei NO1A具有最高相似性,均为99.8%.茵株P40的gyrB序列与 A.dieselolei NO1A同源性也高达99.2%.而与A.dieselolei B-5T只有86.9%.此外,从茵株P40中克隆到两个烷烃羟化酶alkB基因片断,分别命名为P40-alkB1和P40-alkB2.其中P40-alkBl与报道的 A.dieselolei B-5T 中的 alkB 同源性较高,达96.3%,而与同为深海来源的茵株NO1A的alkB的同源性更是达100%,P40-alkB2则与A.borkumensis SK2T(泊库岛食烷茵)的alkB1同源性最高,但仅为65%. 相似文献
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保障渔民合法权益是深化海洋管理工作面临的重要课题 总被引：2，自引：0，他引：2
舟山是我国唯一以群岛设立的地级市,区域总面积2.22万km2,其中海域面积2万hm2余,“港、景、渔”等海洋资源十分丰富,是名副其实的海洋大市。 相似文献
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YU Yue-min 《中国海洋工程》2021,35(2):301-307
The performance of dual perforated floating plates in a rectangular tank is investigated based on the model tests under different external excitations for different filling rates.It is found that dual perforated floating plates in the tank can remarkably mitigate violent resonant sloshing responses compared with the clean tank,especially when the external excitation frequency is in the vicinity of the first-order resonant frequency.Next,the parametric studies based on different filling rates and external excitation amplitudes are performed for the first-order resonant frequencies.The presence of dual perforated floating plates seldom shifts the sloshing natural frequencies.Further,dual perforated floating plates change the sloshing modes from the standing-wave mode in the clean tank to the Utube mode,which can arise from the sloshing reduction to some extent. 相似文献
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GPU-Based DEM Simulations of Global Ice Resistance on Ship Hull During Navigation in Level Ice 总被引：1，自引：0，他引：1
The ice resistance on a ship hull affects the safety of the hull structure and the ship maneuvering performance in icecovered regions.In this paper,the discrete element method(DEM)is adopted to simulate the interaction between level ice and ship hull.The level ice is modeled with 3D bonded spherical elements considering the buoyancy and drag force of the water.The parallel bonding approach and the de-bonding criterion are adopted to model the freezing and breakage of level ice.The ship hull is constructed with rigid triangle elements.To improve computational efficiency,the GPU-based parallel computational algorithm was developed for the DEM simulations.During the interaction between the ship hull and level ice,the ice cover is broken into small blocks when the interparticle stress approaches the bonding strength.The global ice resistance on the hull is calculated through the contacts between ice elements and hull elements during the navigation process.The influences of the ice thickness and navigation speed on the dynamic ice force are analyzed considering the breakage mechanism of ice cover.The Lindqvist and Riska formulas for the determination of ice resistance on ship hull are employed to validate the DEM simulation.The comparison of results of DEM,Lindqvist,and Riska formula show that the DEM result is between those the Lindqvist formula and Riska formula.Therefore the proposed DEM is an effective approach to determine the ice resistance on the ship hull.This work can be aided in the hull structure design and the navigation operation in ice-covered fields. 相似文献
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以长海县1993年和2005年Landsat-TM数据为基础,运用遥感软件ENVI,经噪音剔除、主成分变换、彩色合成、分类处理、差值运算提取出长山列岛新增建设用地,生成新增建设用地矢量数据,结合GIS软件MapInfo,经过投影转换、叠加分析、缓冲区分析、空间信息统计,分析新增建设用地的空间分布及影响机制,结果表明:长海县的建设用地在1993-2005年不同程度地增加,人口及经济发展是建设用地增加的主要促进因子;交通干线对新增加的建设用地具有空间吸引效应;新增建设用地有向港口等基础设施集中的特征;新增建设用地空间分布受到已有产业功能分区的影响.研究表明,RS&GIS支持下,利用TM数据分析海岛建设用地变化具有一定的应用前景. 相似文献
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LI Dong ZHAO Jun LIU Chenggang SUN Chengjun CHEN Jianfang PAN Jianming HAN Zhengbing HU Ji 《海洋湖沼学报（英文）》2020,(3):619-633
Knowledge about organic carbon loadings(ratio of sedimentary organic carbon(SOC)content to specific surface area(SSA))and the fate of organic carbon(OC)is critical to understand the marine carbon cycle.We investigated the variations in the patterns of OC loadings and the preservation capacities of sedimentary OC in the Yap Trench and other marine environments.The average OC loading in sediment cores from various marine environments decreases with increasing water depth at a rate of^0.06 mg OC/(m^2·km)(R^2=0.23,P<0.01).Distinct low OC loadings(0.09±0.04 mg OC/m^2)were observed in the Yap Trench,with the lowest values as^0.02 mg OC/m^2.A further comparative analysis indicated that OC/SSA=0.2 mg OC/m^2 is a good indicator to distinguish between oxic deep-sea regions and suboxic energetic deltaic areas.Regression analysis between OC loading and bulk carbon isotope compositions indicates that marine OC(δ13C^-20.4‰to-18.6‰)dominates the lost OC within the Yap Trench and does not differ from that of the abyssal zone.In contrast,terrestrial OC withδ13C values of approximately-27.4‰to-20.5‰was the major source of remineralized OC in the sublittoral zone.The ratios of OC loadings in the bottom layer relative to those in the top layers of sediment cores indicate that the preservation capacities of hadal trenches are much lower than those of other environments,and only approximately 30%of the SOC deposited in hadal trenches is finally buried.The value is equivalent to 0.066%of the primary production-derived OC and much lower than the global ocean average(~0.3%).Overall,the hadal zone exhibits the lowest OC loading and preservation capacity of SOC of the different marine environments investigated,despite the occurrence of a notable funneling effect. 相似文献
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An analytical solution is proposed to predict the wave set-up over permeable reef flat based on porous flow model and momentum conservation. A laboratory experiment is carried out to verify the analytical solution. Good agreement is obtained by comparing the analytical results and the experimental data. Both the analytical results and the experimental data show the wave setup increases with the increase of the incident wave height and the decrease of the submergence water depth. The influences of the porous properties of the coral reef on wave set-up are discussed based on the analytical solution and experiment results. The wave set-up on the reef flat is found to decrease with the increasing particle size of porous media layer. The increase of the porosity and the height of porous media layer can lead to significant reduction in the wave set-up on the reef flat. 相似文献
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通过在波浪水槽中进行一系列物理模型实验, 研究珊瑚礁礁坪宽度变化对珊瑚礁海岸附近波浪传播变形及礁坪上波浪增水的影响。物理实验采用理想化的珊瑚礁模型, 测试了3种礁坪宽度下的一系列不规则波工况。实验结果分析表明: 波浪沿礁传播过程中, 短波持续衰减; 低频长波波高沿礁逐渐增大, 直到海岸线附近达到最大; 随着礁坪宽度的增加, 海岸线附近的短波波高呈下降趋势, 低频长波波高的变化规律不显著; 礁坪上的波浪增水受礁坪宽度变化的影响不明显; 通过对海岸线附近的波浪进行频谱分析发现, 礁坪上低频长波的运动存在着一阶共振模式, 且共振放大效应强度受礁坪水深、入射波峰周期和礁坪宽度共同影响。 相似文献
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本文采用圆柱体阵列来模拟珊瑚礁面的大糙率,通过波浪水槽实验研究礁面糙率对孤立波传播变形及岸滩爬高的影响。结果表明,粗糙礁面的存在显著削弱了礁坪上孤立波的首峰和礁后岸滩反射造成的次峰,同时降低了波浪在珊瑚礁面的传播速度;垂直于岸线方向沿礁相对波高随着入射波增大而减小,随着礁坪水深的增大而增大,粗糙礁面上波高沿礁的衰减更为显著;礁前斜坡的无量纲反射波高随无量纲入射波高的变化与礁坪水深有关,当入射波高足够大时其趋于常值,粗糙礁面略微增大了礁前斜坡的反射;无量纲透射波高和岸滩爬高随着无量纲入射波高的增大而减小,特别是礁坪水深较大时更为显著,粗糙礁面时的无量纲岸滩爬高相对于光滑礁面平均减小46%;通过回归分析得出了同时适合于光滑和粗糙礁面的预测孤立波岸滩爬高的经验关系式。 相似文献
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为研究珊瑚礁坪上采掘坑位置变化对珊瑚礁海岸波浪传播变形的影响, 本文通过物理模型试验测试了采掘坑在不同位置和无坑情况下一系列不规则波工况的波浪特征。结果表明, 随着采掘坑位置朝岸线附近移动直至无坑时, 岸线附近的短波波高逐渐减小; 采掘坑的存在减弱了岸线附近的低频长波波高, 当采掘坑位于岸线附近时, 长波波高还受到局部水深增加的影响而进一步减弱。采掘坑从礁缘移动至岸线附近直到无坑时, 岸线附近的增水逐渐增大, 这种趋势在礁坪水深较大时更为明显。通过相干函数分析, 证明了礁坪上低频长波是由于短波群破碎点的移动而产生, 采掘坑位置的变化对低频长波的产生无明显影响; 通过传递函数分析, 验证了礁坪上的低频长波存在一阶共振放大效应, 采掘坑的存在减弱了这种放大效应, 当坑位于礁坪中间和岸线附近时, 这种减弱效应更为显著。 相似文献
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This paper presents the results of a parametric study of irregular wave run-up over fringing reefs using the shock-capturing Boussinesq wave model Funwave-TVD to better understand the role of fringing reefs in the mitigation of wave-driven flooding. Laboratory experiments were newly performed with a typical fringing reef profile and typical hydrodynamic conditions to validate the model. Experimental data shows irregular wave run-ups are dominated by the low-frequency motions and confirms the run-up resonant phenomenon over the back-reef slope, which has been revealed in previous numerical studies. It is demonstrated that irregular wave evolution and run-up over fringing reefs are reasonably reproduced by the present model with a proper grid size. However, the infragravity run-up height and highest 2% run-up height over the back-reef slope are under-predicted due to the underestimation of the infragravity wave height over the reef flat. The validated model was then utilized to model irregular wave transformations and run-ups under different conditions. Through a series of numerical experiments, the effects of key hydrodynamic and reef geometry parameters, including the reef flat width, water depth over the reef flat, fore-reef slope angle and back-reef slope angle, on the irregular wave run-up were investigated. Variations of spectral components of irregular wave run-ups were examined to better understand the physical process underlying the effect of each parameter. 相似文献
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The wave-induced setup and circulation in a two dimensional horizontal (2DH) reef-lagoon-channel system is investigated by a non-hydrostatic model. The simulated results agree well with observations from the laboratory experiments, revealing that the model is valid in simulating wave transformation and currents over reefs. The effects of incident wave height, period, and reef flat water depth on the mean sea level and wave-driven currents are examined. Results show that the distributions of mean sea level and current velocities on the reef flat adjacent to the channel vary significantly from those in the area close to the side walls. From the wave averaged current field, an obvious alongshore flux flowing from the reef flat to the channel is captured. The flux from the reef flat composes the second source of the offshore rip current, while the first source is from the lagoon. A detailed momentum balance analysis shows that the alongshore current is mainly induced by the pressure gradient between the reef flat and the channel. In the lagoon, the momentum balances are between the pressure and radiation stress gradient, which drives flow towards the channel. Along the channel, the offshore current is mainly driven by the pressure gradient. 相似文献
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基于礁坪上高分辨率的波浪测量,通过波浪水槽试验分析了短波、低频长波、平均水位、波形参数和非线性参数的沿礁变化规律,重点探讨礁坪中部存在人工采掘坑对上述波浪传播变形特征的影响,并与无坑的情况进行对比。研究表明:当人工采掘坑存在时,短波波高在坑前和坑内分别增大和减小,在礁后岸滩附近却无显著变化;低频长波波高在坑附近变化不大,在岸滩附近却略微减小;波浪增水在坑和岸滩附近均无显著变化。采掘坑存在的情况下,波浪的偏度和不对称度在坑附近分别减小和增大,而厄塞尔数在坑附近却几乎不变。相关性分析发现低频长波的产生机理几乎不受采掘坑的影响,采掘坑的存在增加了低频长波的反射,破坏了礁坪的共振模式,从而使低频长波在岸滩附近有所削弱。 相似文献
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通过测试一系列不规则波工况研究了防浪建筑物存在下珊瑚礁海岸附近短波、低频长波和增水的变化规律，并对比了防浪建筑物的不同位置情况。分析结果表明：波浪在沿礁传播过程中，短波波高沿礁坪持续衰减，低频长波波高沿礁坪逐渐增大，波浪增水则沿礁坪基本保持不变；海岸附近短波随着防浪建筑物与礁缘距离的变大而减小，低频长波则在防浪建筑物处于礁坪后部时达到最大，防浪建筑物位置的变化对于礁坪波浪增水的影响可以忽略。通过理论分析证明了珊瑚礁地形上低频长波是由于群波破碎造成的破碎点移动而产生的；当特定波况作用于特定位置的防浪建筑物时，低频长波在礁坪上会发生一阶共振效应导致其能量在海岸附近达到最大值。 相似文献
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根据现场地形在港池中建立三维珊瑚礁?潟湖?裂口海岸定床整体物理模型,采用波高传感器、流速仪和表面流速测量系统分别测量了规则波作用下珊瑚礁海岸不同位置的波浪和流场特征。结果表明:礁坪上,波高在向岸方向逐渐减小,总减小幅度为86.7%,增水先增大后减小,沿礁坪下降幅度为65.9%,水流以向岸流为主,存在着先增大后减小的趋势;潟湖中,波高靠近裂口处较大,中部最大值约为两侧最小值的2.8倍,增水则靠近裂口处最小,相比两侧最大值下降了25.5%,水流主要为对称地指向裂口的沿岸流,流速从两侧到裂口先增大后减小;裂口中波高变化不大,增水在靠近潟湖处最大,为礁坪上增水的47.6%,水流主要为离岸流,流速同样是先增大后减小。量化分析了环流驱动力、辐射应力与波面压力梯度的空间变化规律,发现礁坪上向岸流变化是平均水位梯度和辐射应力相互作用的结果,在裂口中的离岸流驱动力主要为辐射应力,而潟湖中的沿岸流变化由平均水位梯度决定的。 相似文献
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基于非静压单相流模型NHWAVE建立了高精度二维数值波浪水槽,采用日本2011年实测真实海啸波型系统研究了海啸波在岛礁上传播变形的规律,并且分析了波高、礁坪淹没水深和礁前斜坡坡度等因素对孤立波和真实海啸传播变形的影响。结果表明,相比孤立波,类海啸波的波长明显大于孤立波波长,在测点处引起的水面变化持续时间更长,同等波高情况下真实海啸波型比孤立波能够携带更多的能量,与岛礁的相互作用也更为复杂,在礁坪上形成的淹没水深约为孤立波的两倍。礁前斜坡坡度和礁坪淹没水深均对类海啸波的反射和透射系数有显著影响。随着礁前斜坡坡度的增加,反射系数和透射系数均逐渐增加。随着礁坪淹没水深的增加,反射系数逐渐减小,而透射系数逐渐增大。但是,反射系数和透射系数均随着入射波高的增加而逐渐减小。 相似文献