2012 Vol. 7, No. 4
Two major constraints in the sustained operation of submarines are the abominable air quality and thermal discomfort in cabins. In order to solve these problems，some researches were reviewed in this paper，and showed that the thermal senses were quite different due to the diversity of races and regions. Therefore，the standards derived from developed country are not suitable for instructing air-conditioning system design in China，not to mention that in the deep ocean submarine where the environment is much more complex. By combining the method of subjective questionnaires and objective physiological parameters，the submarine environment with good air quality and thermal comfort specific was developed. Regarding these issues，several measures for improving air quality were also suggested. The results show that with the proper standard and multiple measures，thermal comfort state and air quality can be significantly improved.
The stern appendages of a surface ship have great effects not only on the resistance，but also on the nominal wake field. Taking a ship which installed four propellers and two rudders as example，numerical simulation of the 3D viscous flow field on the hull with appendages was carried out based on RANS without considering the free surface effect. The analysis focused on the effects of the twin shaft bracket section profile and installation angle on the viscous resistance and nominal wake field. The results show that the installation angle of shaft bracket can be determined by the direction of flow velocity vector.
Collision force and its distribution which acted on the rubber fender of a ship moored to a platform were researched by considering the influence of wind，wave，flow and nonlinear stiffness of the platform fender. According to different angles of wind，wave and flow as well as different wind speed，wave height and flow velocity，the loads of wave and ocean current for mooring system were calculated. And also the analysis model for moored ship was established. Moreover the collision force between the moored ship and a platform were simulated through the method of time domain and frequency domain，and obtained the time history of collision force. Besides，the probability of occurrence of different collision force was analyzed in order to determine the direction of wind，wave and flow which maximum collision force occurred. The results show that the rubber fender stiffness has significant effect on the calculation of collision force， it is essential to choice non-linear fender stiffness when calculating the collision force on the platform. And there are relatively larger deviations by using empirical formula to calculate collision force.
Based on the theory of modal strain energy method and structural dynamic optimization，several methods for improving the application effects of damping materials on ships were presented. Within the same weight of damping materials，the loss factor of damping structure with a certain percentage of holes was improved by compared with damping structure without holes. Then，two models of composite cantilever plates were established with regard to meet the limited loss factor. One was for the optimization design of the thickness，whereas the other was for topology optimization design of the distribution of damping materials. The target function is total weight of damping materials. Finally，the optimal thickness and distribution of damping materials in the first three modes of models were obtained. The results indicate that damping materials with holes can improve the effect of vibroacoustics reduction.
为控制机械振动向船体结构传递，基于不均质结构振动隔离原理，对铺板连接结构进行减振设计。采用有限元方法建立各设计方案的计算模型，进行激励源在铺板不同位置工况下的动响应分析，对比各方案的减振效果并开展缩比模型试验。分析结果表明，U形连接结构对抑制振动从铺板向圆柱壳体传递效果较好；适当减小连接板厚度，减振效果呈增加的趋势。缩比模型测试结果显示，U形连接结构在2 Hz～4 kHz频段有大于4dB的减振效果，仿真计算结果与试验结果吻合较好。
According to impedance mismatch and wave mode conversion in heterogeneous structure which based on wave analysis method，the characteristics of vibration wave propagation in typical submarine structure were studied. Based on this，vibration and noise reduction performance of artificial transmission loss base was analyzed through FEM/BEM coupled method. By reviewing vibration wave transmission characteristics for composite plate，the conclusions are drawn that the structure impedance changes，when the structure cross section mutates. Thus，leading to impedance mismatch between the structures，so the vibration wave will reflect and transmit in the mutant cross-section，and reduce the transmission rate of vibration. An artificially constructed transmission loss base was designed using the theory，and the vibration and noise reduction performance of the base was verified by FEM / BEM coupled method.
Plate frame is the main structure of ships. With the AUTODYN common software，numerical model of the plate frame by underwater contact explosion was established by the couple of the Largange and Euler code，and the simulation results agreed well with the experiment failure mode. Then，the whole failure process of the plate frame by underwater contact explosion was analyzed，and the formation and extension of the crevasse with failure mode of reinforcement was discussed. Besides，the failure mode coupling effect of the plate frame and reinforcing plate was proposed. The results demonstrate the damage characteristics of the plate frame.
In order to improve the adsorption capacity per unit mass of adsorbent， reduce bed volume， and choose chemical adsorption as refrigerant，the multi-generator absorption ice-making system was introduced. Then the heat transfer performance of unit pipe in the adsorbent bed was researched，and the system influence of unit pipe heat transfer resistance was also analyzed. Besides，some methods of reducing the thermal resistance of each part were discussed. The results show that the percentage of thermal resistance of convective heat transfer is 89%，while heat performance parameter of the adsorption ice-making system driven by ship exhaust is up to 25%.
Using regression-based combination forecasting method to forecast ship equipment maintenance cost has fundamental drawback that the number of methods available is bigger than the cost samples'，making it insufficient to estimate the regression coefficient. This paper proposed to apply the Principal Component Analysis（PCA）on the results which obtained by the individual forecast method prior to building regression-based combination model of a ship equipment maintenance cost forecast，and then the regression model of a realistic ship equipment maintenance cost on selected principal components was established，further，the forecast combination model based on PAC was presented. Meanwhile，in the process of PCA，there was some subjectivity in deciding the number of principal components according as cumulate contribution rate of principal components，so we took the Akaike's Information Criterion（AIC）as a substitution. Finally an exampal was used to analyze and validate the performance of the above mentioned method. The results show that the presented method not only can solve the problem that the number of forecasting models is in excess of the sample's in the regression-based combination forecasting of ship equipment maintenance cost，but also can solve the collinear between individual forecast method. And the performance of the presented method obviously superior to the usual combined forecasting models.