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1.
The floating production storage and offloading unit (FPSO) is an offshore vessel that produces and stores crude oil prior to tanker transport. Robust prediction of extreme hawser tensions during the FPSO offloading operation is an important safety concern. Excessive hawser tension may occur during certain sea conditions, posing an operational risk. In this paper, the finite element method (FEM) software ANSYS AQWA has been employed to analyze vessel response due to hydrodynamic wave loads, acting on a specific FPSO vessel under actual sea conditions.In some practical situations, it would be useful to improve the accuracy of some statistical predictions based on a certain stochastic random process, given another synchronous highly correlated stochastic process that has been measured for a longer time, than the process of interest. In this paper, the issue of improving extreme value prediction has been addressed. In other words, an efficient transfer of information is necessary between two synchronous, highly correlated stochastic processes. Two such highly correlated FPSO hawser tension processes were simulated in order to test the efficiency of the proposed technique.  相似文献   
2.
以太平洋鳕鱼为原料,从鳕鱼脑中分离硫苷脂,确立了提取及纯化的条件,并对硫苷脂的纯度和分子种进行分析。首先,采用氯仿/甲醇(2∶1,v/v)提取总脂。然后,依次采用氯仿/甲醇/水(7∶3∶0.3,v/v/v)洗脱硅胶柱层析,含0.2mol/L乙酸铵的氯仿/甲醇/水(30∶60∶8,v/v/v)洗脱DEAE Sephadex-A25离子交换柱层析,40%甲醇脱盐和100%甲醇洗脱反相C8柱层析,获得硫苷脂纯品。最后,利用500YMC Diol液相色谱柱(3.0mm×250mm,5μm)分离,以正己烷/异丙醇(70∶30,v/v),异丙醇/水/甲酸/氨水(100∶13∶1∶0.14,v/v/v/v)为流动相梯度洗脱,采用负电喷雾电离(ESI)和母离子扫描模式,用液相色谱-串联质谱(LC-MS/MS)法分析了鳕鱼脑硫苷脂的纯度和分子种组成,并比较了其与哺乳动物脑中硫苷脂分子种组成的异同。结果表明,本实验制得的鳕鱼脑硫苷脂纯度为90.74%,与哺乳动物类似,鳕鱼脑硫苷脂的长链碱基以鞘氨醇为主,主要分子种为d18∶1-C24∶1,但脂肪酸的羟基化程度略低,且含少量独特的分子种,如d18∶1-22∶1和d18∶2-25∶2。  相似文献   
3.
A numerical study of flow around two tandem cylinders with unequal diameters was carried out. The upstream larger cylinder was fixed and the downstream smaller cylinder was allowed to oscillate in the transverse direction only. Comparisons of the experimental and numerical results were made to investigate the effects of the gap ratio on the maximum vibration amplitude and vortex shedding frequency. The results showed that the vibration response of the smaller cylinder was significantly affected by the presence of the upstream larger cylinder, and resulted in greatly reduced vibration amplitudes. With an increasing gap ratio, the vibration amplitude increased. However, the magnitude was lower than that corresponding to a single cylinder (with the same diameter as that of the downstream smaller cylinder) under the same flow conditions.  相似文献   
4.
在优化的条件下,用电喷雾电离质谱(ESI-MS)检测了多种纺织品中由偶氮染料还原获得的芳香胺。当毛细管温度为100℃、鞘气流速为25单位、进样流速为10μL/min、电压为5kV时,信号的总离子流强度高且较稳定。实验分析了19种致癌芳香胺标准溶液的二级质谱,获得了相应物质的特征碎片离子;在此基础上,建立了基于ESI-MS对毛巾、棉布等样品中芳香胺进行快速定性分析的方法,具有灵敏度高、特异性好、检测速度快等优点。  相似文献   
5.
深海柔性立管涡激振动问题广受关注,其中多立管涡激振动较传统单立管涡激振动更为复杂。使用基于Open FOAM自主开发的深海柔性立管流固耦合求解器viv-FOAM-SJTU,对阶梯流中串列双立管涡激振动展开研究。首先针对阶梯流中串列双立管模型试验工况开展验证计算,下游立管的位移响应以及频率响应与试验结果基本吻合;而后改变立管浸没长度,分别选取浸没长度为0.4L(工况1)、0.55L(工况2)以及0.7L(工况3)的三种工况进行数值计算,其中L为立管长度。数值结果表明:3种浸没长度下,上下游立管的横流向振动均为一阶模态,且工况2和工况3中上下游立管的横流向位移均方根均大于工况1;上下游立管的顺流向主振模态在工况2和工况3中均为二阶,而在工况1中为一阶,且下游立管在工况2和工况3中的顺流向振动均表现出明显的多模态振动特性。  相似文献   
6.
7.
The dynamic response of two flexible model risers in tandem arrangement immersed in a stepped current was analyzed. The risers, with an external diameter of 20 mm and a total length of 6200 mm, had an aspect ratio of 310. They were hinged to the support structure at the center-to-center distances away 3?12 times the external diameter. The top 1200 mm was exposed to a uniform current at a speed which was up to 0.9 m/s (the Reynolds number was 18000) and the rest in still water. The dynamic responses, which were obtained through the Fiber Bragg Grating strain gauges mounted on the surface, were analyzed by studying the cross-flow amplitudes and modal weights. The cross-flow vibration were observed up to the third mode, and the modal transformation from the second mode to the third mode was clearly observed. The experiment confirmed that the typical vortex-induced vibration (VIV) had occurred on the up-stream riser. But for the down-stream riser, the main excitation mechanism was wake-induced vibration (WIV). The modal transformation of WIV was more complex than that of VIV, which might be helpful for other researchers to study the interference effect.  相似文献   
8.
Moss samples (Pleurozium schreberi) exposed to traffic‐related emission of Pd, Pt and Rh were analysed in this study. Successful elimination of interferences was achieved in the determination of Pd, Pt and Rh mass fractions in these samples using inductively coupled plasma‐tandem mass spectrometry (ICP‐MS/MS). Based on the results, a reliable determination of Pd, Pt and Rh mass fractions in microwave‐digested moss samples was obtained using ammonia (10% NH3 in He) in the collision/reaction cell when 103Rh was measured either on‐mass (103→103) or with mass‐shift (103→171) and mass‐shifts for 108Pd (108→159) and 195Pt (195→229) were used. The ICP‐MS/MS procedure was validated using BCR‐723 (road dust) as a reference material. In addition, a good agreement between the ICP‐MS/MS results and the results obtained with cloud point extraction and quadrupole ICP‐MS was observed for the moss samples.  相似文献   
9.
长牡蛎(Crassostrea gigas)串联重复序列分析研究较少,为了研究其在基因组转录本的基本结构特征并为长牡蛎中遗传多样性研究中提供有益的信息,利用NCBI公共数据库中的57 139条长牡蛎ESTs序列对串联重复序列结构类型、分布、丰度等进行系统比较分析.分析结果表明:1)长牡蛎EST中共有小卫星串联重复序列8...  相似文献   
10.
It is ideal to design the best hull shape for a floating production storage and offloading unit (FPSO) that meets all performance criteria from an engineering point of view. However, in reality, it is difficult to satisfy all the criteria at the same time. If one of the performances cannot meet the criteria, then additional equipment or systems are installed to improve that performance. In this paper, when an FPSO cannot meet the towing stability inherently, we attempt to establish a procedure for determining an auxiliary towing system. Firstly, various systems that can be applied to the FPSO are compared and reviewed to improve the towing stability of the FPSO. Among them, using three active thrusters was chosen as the auxiliary towing system. Improvement of towing stability was verified from a towing model test conducted at the Maritime Research Institute Netherlands (MARIN). However, thruster cavitation was raised as a key problem when using thrusters for a purpose for which they were not intended. A thruster cavitation model test was additionally performed to check the safety of the thrusters. Based on these results, a safe operating range under extreme condition was confirmed by observing the occurrence of thruster cavitation. The predicted maximum unit total thrust of each thruster was compared with the observed safe operating range. Finally, the effectiveness and safety of the auxiliary towing system was verified.  相似文献   
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