《极地水域船舶作业国际规则》的法律属性析论     

袁雪  童凯 《极地研究》2019,31(3):334-345

《极地水域船舶作业国际规则》(简称《极地规则》)是国际海事组织为极地水域船舶航行安全与防止环境污染制定的技术性国际规则。该规则的体系构成是以MARPOL、SOLAS和STCW三大公约修正案为基础,因此使其对缔约国具有强制约束力,并沿袭了技术性、前瞻性等属性。从普适性角度衡量,该规则因为制定主体、立法结构与实际履约等问题尚不足以构成“一般接受的国际规则和标准”。我国应当吸取其中的先进立法理念,并积极加强国内履约,为即将到来的北极航运高峰做准备。此外,鉴于《极地规则》与《联合国海洋法公约》(简称《公约》)的冰封区域条款之间相对独立,我国在遵守沿海国单边立法的同时应积极倡导在极地地区适用以《极地规则》为核心的统一标准。我国对北极航道的使用呈逐年增加的趋势,这势必要求厘清《极地规则》的法律属性以维护我国的北极航运利益。  相似文献   

Water entry of a finite width wedge near a floating body     

《Applied Ocean Research》2019

The problem of a two-dimensional finite-width wedge entering water near a freely floating body is considered through the velocity potential theory for the incompressible liquid with the fully nonlinear boundary conditions on the free surface. The problem is solved by using the boundary element method in the time domain. The numerical process is divided into two phases based on whether the interaction between the wedge and floating body is significant. In the first phase, when the single wedge enters water at initial stage, only a small part near its tip is in the fluid, the problem is studied in a stretched coordinate system and the presence of the floating body has no major effect. In the second phase, the disturbance by water entry of the wedge has reached the floating body, and both are considered together in the physical system. The auxiliary function method is adopted to decouple the nonlinear mutual dependence between the motions of the wedge and floating body, both in three degrees of freedom, and the fluid flow, as well as the interaction effects between them. Case studies are undertaken for a wedge entering water in forced or free fall motion, vertically or obliquely. Results are provided for the accelerations, velocities, pressure distribution and free surface deformation, and the interaction effects are discussed.  相似文献   

Modelling a spade rudder as a hollow two-way tapered Kirchhoff’s plate : free dry and wet vibration study with numerical verification     

《Applied Ocean Research》2019

A semi-analytical approach to free dry and wet vibration of a trapezoidal, 2-way tapered, pivoted hollow spade rudder is presented. The rudder is modeled as a hollow Kirchhoff’s plate, with a NACA0018 profile chord section. The rudder pivot is modeled as a combination of a translational spring and a rotational spring. The span-wise and chord-wise non-uniform beam vibration is first analyzed by the Rayleigh-Ritz method, to establish the non-uniform beam modeshapes, which act as admissible functions to the Galerkin’s method for plate vibration. Eigenvalue analysis generates the plate natural frequencies and the plate modeshapes. Alternately, uniform beam modeshapes themselves are used as admissible functions into the Galerkin’s method. Frequencies are analyzed for various pivot positions, taper ratios, and NACA sections. For the wet vibration, constant strength source distribution technique is used to generate the added mass of a 2D aerofoil. Also, 3D panel method is used to generate the modal added masses, and hence the wet natural frequencies. The added mass coefficient is generated for various aerofoil fineness ratios, pivot fixities, taper ratios, aspect ratios.  相似文献   

Interaction of uniform current with a circular cylinder submerged below an ice sheet     

《Applied Ocean Research》2019

The problem of a uniform current passing through a circular cylinder submerged below an ice sheet is considered. The fluid flow is described by the linearized velocity potential theory, while the ice sheet is modelled through a thin elastic plate floating on the water surface. The Green function due to a source is first derived, which satisfies all the boundary conditions apart from that on the body surface. Through differentiating the Green function with respect to the source position, the multipoles are obtained. This allows the disturbed velocity potential to be constructed in the form of an infinite series with unknown coefficients which are obtained from the boundary condition. The result shows that there is a critical Froude number which depends on the physical properties of the ice sheet. Below this number there will be no flexural waves propagating to infinity and above this number there will be two waves, one on each side of the body. When the depth based Froude number is larger than 1, there will always be a wave at far upstream of the body. This is similar to those noticed in the related problem and is different from that in the free surface problem without ice sheet. Various results are provided, including the properties of the dispersion equation, resistance and lift, ice sheet deflection, and their physical features are discussed.  相似文献   

Path following control of fully-actuated autonomous underwater vehicle in presence of fast-varying disturbances     

《Applied Ocean Research》2019

This paper presents an improved active disturbances rejecter control (ADRC) for path following control of autonomous underwater vehicles under significant fast-varying disturbances caused by waves and sea currents. Two significant and efficient improvements are introduced to the traditional ADRC in order to accomplish this task. First, a generalized ESO (GESO) and Harmonic ESO (HESO) were designed to achieve a high disturbances estimation quality. Secondly, two AUV path following controllers based on ADRC-GESO and ADRC-HESO were designed to ensure a high performance tracking in presence of periodic-type disturbances. Finally, numerical simulations were performed and the obtained results showed very significant enhancements of robustness and tracking accuracy by the proposed methods compared to conventional ADRC.  相似文献   

Free fall water entry of a wedge tank into calm water in three degrees of freedom     

《Applied Ocean Research》2019

The hydrodynamic problem of a two dimensional wedge tank filled with liquid entering a calm water surface is analysed based on the incompressible velocity potential theory. The motion effect of inner liquid on the entry process is investigated through comparison with the result containing equivalent solid mass or the liquid being frozen. The problem is solved through the boundary element method in the time domain. Two separated computational regions are constructed. One is the inner domain for the internal liquid, and the other is the outer open domain for the open water. The former is solved in the physical coordinate system, and the latter is solved in a stretched coordinate system. The solutions of two separated domains are connected through the motion of the body. The auxiliary function method is extended to decouple the nonlinear mutual dependence between fluid loads from two separated domains and the body motion. Detailed results for wedge motion, external impact pressure and free surface, and for internal pressure, free surface deformation and liquid motion are provided. Through comparison with the results of a wedge tank with frozen ice, in-depth discussion on the effect of the inner liquid is provided.  相似文献   

Piezoelectric Energy Analysis on Diverse Buoy Coupling with Hydrodynamic Parameters     

Liu  Heng-xu  Liu  Ming  Chai  Yuan-chao  Shu  Guo-yang  Jing  Feng-mei  Wang  Li-quan 《中国海洋工程》2019,33(3):279-287

This paper mainly describes the influence factors of the captured energy power by huge wave energy harvesters, in which the vertical motion of buoy can transform ocean’s potential energy into piezoelectric energy power by undulating waves. Firstly, related environmental coefficients are analyzed by means of the incident wave theory. Besides, the geometric structural parameters are also analyzed and compared under optimal environmental coefficients with semi-analytical solutions. Thirdly, the numerical results also show the impact trend of hydrodynamic parameters and geometric volume on motion, voltage and power with qualitative agreement. The numerical simulation confirms that the improved structure parameters could markedly deliver sufficient power under the same conditions with long-time stability.  相似文献   

楔形物体在静水与波浪中自由入水砰击试验研究     

邹丽  李振浩  孙铁志  马伟佳  裴玉国 《海洋工程》2019,37(1):1-11

通过自由落体的入水方式,分别在静水和规则波中开展了两种不同横剖面的曲面楔形体入水砰击问题试验研究。使用高速摄像系统记录楔形体入水过程流场演变和运动特性,采用加速度传感器和压力传感器进行数据的动态采集。试验结果表明,在静水中入水时,外凸剖面楔形体入水砰击后模型两侧的射流飞溅比反曲剖面更剧烈,而在楔形体前端的水面以下部分形成的气腔更小;在规则波中入水时,对于相同模型,在波峰和上跨零点相位下模型入水砰击后两侧的射流飞溅比在波谷相位更剧烈。相同工况时,反曲剖面模型所受砰击的加速度峰值和压力峰值更小;在相同的入水速度下,对于相同模型,波浪载荷和砰击载荷的共同作用会使模型所受砰击压力显著增大。  相似文献   

农作物冠层光谱分析及反演技术综述   总被引：1，自引：0，他引：1  

李月  何宏昌  王晓飞  张国民 《测绘通报》2019,(9):13-17

农作物的冠层光谱反射率与作物的氮含量、叶绿素含量及叶面积指数等参数之间具有很强的相关性,通过对作物冠层光谱进行分析可反演出作物的生物物理参数,并应用在长势分析、产量预测、病虫害预警等领域。本文首先阐述了作物冠层反射率采集方法,对地面、机载及遥感卫星3个采集层面的优缺点进行了对比;其次给出了植被指数构建原理及常用植被指数,分析了物理模型反演法和统计反演法的复杂度和性能;最后提出了农作物冠层光谱分析及反演技术的下一步发展方向及面临的挑战。  相似文献   

高光谱图像子空间的波段选择     

赵亮  王立国  刘丹凤 《遥感学报》2019,23(5):904-910

为降低高光谱遥感数据光谱空间的冗余度,提出一种快速的波段选择方法。该方法在波段子空间下进行,依次选择各子空间中方差最大的波段作为初始波段,设定目标函数,然后逐子空间替换波段使得目标性能更加优化,直至没有替换可以使得目标更优为止。在两个公开高光谱影像数据集上对比3种常用波段选择方法(ABC、AP、ABS)来验证提出方法的有效性,实验结果表明:(1)在印第安纳数据上,本文方法与ABC、AP、ABS所选波段子集相比平均相关性分别降低22.04%、52.61%、55.71%,最佳指数分别提高0.58%、51.73%、0.95%,总体分类精度分别提高0.16%、1.39%、23.07%,在搜索效率上与同类型的ABC方法相比提高6.61%—69.02%;(2)在帕维亚大学数据上,本文方法与ABC、AP、ABS所选波段子集相比平均相关性分别降低2.38%、0.51%、32.83%,最佳指数分别提高1.34%、17.97%、12.92%,总体分类精度分别提高0.31%、0.69%、8.53%,在搜索效率上与同类型的ABC方法相比提高19.13%—86.34%。本文提出的波段选择方法能够选择合适的波段子集满足不同的应用需要,是一种有效的波段选择方法。  相似文献