甲板上浪船舶随机横摇响应的数值模拟

数值模拟随机横浪中甲板上浪船舶的横摇响应．考虑随机横浪激励和甲板上浪引起的横倾力矩,建立船舶随机横摇运动方程．基于伯努利方程,推导船舶甲板上浪水质量的计算公式．以一条拖网渔船为例,计算不同波高作用下船舶的横摇响应,分析甲板上浪对船舶倾覆的影响．研究表明：考虑加工甲板上浪后,船舶有2个横摇中心,在响应过程中发生由一个横摇中心到另一个横摇中心的随机跳跃;单独考虑捕鱼甲板上浪或加工甲板上浪时,船舶可以承受大的波浪载荷而不发生倾覆;同时考虑捕鱼甲板上浪和加工甲板上浪时,横摇过程中捕鱼甲板上浪水量突然增大,导致船舶倾覆．     

破舱进水对船舶横摇运动的影响

为研究船舱破损进水对船舶横摇运动的影响,建立了破舱进水船舶在规则横浪中的横摇运动微分方程,将进舱水晃荡产生的动力矩作为作用于船舶的外力矩.利用FLOW-3D对进舱水产生的动力矩进行仿真模拟计算,利用Matlab编程对破舱进水的横摇运动方程求解,计算分析破舱进水晃荡对船舶横摇运动的影响.以一艘拖轮为例,用时域法对不同波浪频率下的横摇运动响应进行计算,对比分析了规则横浪中的完整和破舱状态船舶的横摇运动响应特性.结果表明,在船舶大幅运动时,进舱水液面会成波浪状,产生翻卷和破碎,引起较大的合外力矩,使横摇运动幅值增大,危及船舶安全.     

基于OpenFOAM的破损船舶横摇阻尼

运用OpenFOAM对完整和破损船舶在静水中进行自由横摇衰减运动的数值模拟,分析得到船舶的线性和非线性横摇阻尼系数.从初始横摇角、舭龙骨附体、破损形式以及破损过程等多个角度对横摇阻尼进行细致的比较和讨论,揭示了破损船舶的横摇阻尼特性.同时开展破损模型试验以验证数值方法的可靠性.在破损船舶的横摇运动数值模拟中,建立了第二类及第三类破损模型,成功处理了内外水耦合及内外水相通的复杂流体流动问题,为破损船舶的横摇运动和倾覆研究奠定了基础,并为破损船舶的稳性衡准制定提供了技术参考.     

船舶横摇与纵摇运动的非线性耦合方程

以欧拉角描述船舶的摇摆运动,考虑规则波浪力及船舶受定常力矩的情形,将水动力展为Ｔａｙｌｏｒ级数,利用欧拉动力学方程推导出船舶横摇与纵摇二自由度耦合的非线性运动方程,为船舶内共振运动响应动力行为分析奠定基础。     

基于非线性横摇运动的风翼助航船舶航行安全性研究

应用非线性动力学理论与随机理论，建立随机风浪作用下风翼助航船舶非线性横摇运动数学模型，分析风翼助航船舶在随机风浪作用下的非线性横摇运动。以一艘76000 DWT巴拿马型散货船为目标船，仿真分析其加装风翼前后在轻载和满载时的横摇特性。仿真结果表明，风翼助航船舶轻载状态较满载状态产生的固定横倾角大得多。风翼助航船舶应尽量避免轻载航行或轻载航行时应减少风翼数量，以提高船舶航行安全性。     

船舶振荡运动仿真

为节约昂贵的海上试验费用,以6个自由度最关键的横摇运动为例说明了仿真计算过程。在由船模试验得到船舶响应幅值算子（RAO）的基础上,采用ITTC单参数标准波谱计算船舶的运动幅值谱,然后采用线性迭加法得到船舶振荡运动的时域序列。仿真信号序列的频谱与实船采集的横摇运动数据的频谱具有相似性,对频率区间细分可以提高仿真结果的精度。     

应用路径积分法求解船舶横摇倾覆概率

通过对船舶非线性横摇运动进行分析,建立了船舶横摇运动的非线性微分方程.以路径积分法(PIS)为基础,在时间域内求解相应的二维Fokker-Planck方程,得到随时间演变的船舶横摇运动的转移概率密度.运用首次通过理论,求得船舶倾覆前时间的概率分布.研究了外部激励、横摇阻尼和非线性复原力矩对船舶横摇运动转移概率密度与首次通过时间的影响.研究结果表明,PIS能用于预测船舶首次通过时间概率分布,从而为船舶设计和稳性衡准提供相关的参考.
     

基于小波理论的舰船非线性横摇运动特性分析

探索采用小波分析方法研究船舶在波浪中非线性摇摆运动的动力学特性．对在几种不同的典型波浪参数情况下，得到的船舶在波浪中非线性摇摆的响应，进行小波变换．利用小波变换所特有的时频窗，可以同时在时域和频域中研究船舶横摇响应的模图和相图．通过分析所得模图和相图的典型特征，得到舰船非线性横摇幅值和频率等动力学特性．且小波变换适应不同频率的窗口特性具有更好的分辨率，可以获得更多的横摇运动响应特性信息．研究表明，小波分析在非线性横摇运动动力学特性分析的研究中是可行的，可以加强对船舶横摇非线性复杂动力学特性的分析能力．     

船舶航向/横摇鲁棒容错控制研究

为提高船舶航向/横摇控制系统的可靠性,改善系统故障情况下的容错控制效果,采用基于线性矩阵不等式(LMI)的鲁棒容错控制方法,对船舶航向/横摇系统进行容错控制研究.建立船舶航向/横摇耦合运动模型,分析故障导致的模型等效不确定性,通过定义广义干扰,将模型变换为适合于H2/H∞鲁棒容错控制设计的标准模型.设计系统的性能评价指标,求解鲁棒容错控制器,并进行仿真验证.结果表明,船舶航向/横摇鲁棒容错控制系统具有良好的容错性能.     

基于重叠网格的C11集装箱船自由衰减横摇模拟

为研究C11型集装箱船的大幅横摇阻尼,基于STAR-CCM+软件平台,使用重叠网格技术和流体体积函数(VOF)方法,通过求解纳维-斯托克斯方程,对该船零航速和有航速下自由衰减横摇运动进行数值模拟.数值模拟结果表明:湍流模型、运动方程约束自由度设置情况、初始横摇角释放时间等对横摇结果影响较大;使用k-epsilon湍流模型、放开6自由度、待流场稳定后释放船模所得的计算结果与试验值符合较好.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.