Table of Content

28 April 2014, Volume 48 Issue 04 Previous Issue    Next Issue

Communication and Transportation

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Numerical Study of Hydrodynamic Interaction Between Berthed Ship and Passing Ship WANG Hongzhia,ZOU Zaojiana,b 2014, 48 (04):  445-449.  Abstract ( 991 )   Save In this paper, by using the dynamic mesh technique and solving the unsteady RANS equation in conjunction with a RNG k-ε turbulence model, numerical simulation of the threedimensional unsteady viscous flow around a passing ship and a berthed ship in shallow water was conducted, and the hydrodynamic forces acting on the berthed ship were calculated. The proposed method was verified by comparing the numerical results with those of empirical formulae. The hydrodynamic forces acting on the passing ship were also calculated and compared with those on the berthed ship. Finally, by analyzing the numerical results obtained at different water depths, lateral distances between the ships, berthed ship to bank distances and passing ship to bank distances, the influences of these factors on the hydrodynamic forces of the berthed ship were illustrated.   References | Related Articles | Metrics

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Effect of Moment Characteristics of Truncated Mooring System on Roll and Pitch Motions of a Semi-Submersible Platform QIAO Xuefeng,XIAO Longfei,YANG Lijun 2014, 48 (04):  450-456.  Abstract ( 879 )   Save Based on a semi-submersible platform operated at a water depth of  1.5 km, five truncated mooring systems were designed for the model test, which have similar horizontal restoring force characteristics, vertical force-horizontal displacement characteristics and top tension-horizontal displacement of single line as the full depth system, but different restoring moment characteristics. The timedomain coupling analysis method was applied to obtain and compare the roll and pitch motions using these different truncated mooring systems. The simulation results were compared with model test data. It is concluded that moment characteristics similarity has a significant impact on the roll and pitch motions of a semi-submersible platform. And the impact increases as the horizontal offset of the platform becomes larger. Therefore, keeping similar moment characteristics with the full depth system is essential while designing the truncated mooring system.   References | Related Articles | Metrics

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Propulsive Performance Analysis of Tandem Asynchronous Flapping Foil LIU Peng，SU Yumin，LIU Huanxing，LIAO Yulei 2014, 48 (04):  457-463.  Abstract ( 952 )   Save The hydrodynamic performance of 6 tandem asynchronous flapping foils (TAFFs), referring to the Wave Glide propulsor, was calculated based on the RANS equations by adopting the  dynamic mesh method. The relationship between the freestream velocity, flapping angle, distance between TAFFs, active period and flapping amplitude were investigated and a  prototype was built. The results show that TAFF represents different performances at different locations. TAFF can produce higher propulsion than a single asynchronous flapping foil. The characteristics of the wake were analyzed and the reason for TAFF’s different performance was found to be the interaction between TAFF’s wake which was advantageous for propulsive. It can produce higher propulsion when the distance between TAFFs  is shorter.   References | Related Articles | Metrics

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Parameter Selection for Support Vector Machine and Its Application in Structural Optimization HE Xiaoer,WANG Deyu 2014, 48 (04):  464-468.  Abstract ( 764 )   Save To select proper parameters for the support vector machine (SVM) regression model used for the prediction of nonlinear structural response, the particle swarm optimizer was introduced into parameter optimization. To make comparisons, the SVM regression model with regular parameters, the RSM and RBFNN regression models were also developed based on the  training data set. The results show that the SVM regression model based on optimized parameters has a better prediction ability than the regular SVM and can solve the overfitting problem in the regression model developed by the response surface method and radial based function neural network, thus possessing better generalization ability. The application of the SVM with optimimized parameters in structural optimizations proves that it has good engineering practicability.   References | Related Articles | Metrics

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Vibroacoustical Entropy Weighted Graph Method for Sound Transmission Path Analysis of Ship Cabin Noise   GAO Chu，YANG Deqing 2014, 48 (04):  469-474.  Abstract ( 156 )   Save The conventional vector superposition method is difficult to meet the requirements on the analysis of ship cabin noise transmission paths located in the mid and high frequency domain. By comparing the statistical energy analysis system to a thermodynamic system and by introducing the concepts of vibroacoustical temperature and entropy, the problem of ranking dominant paths can be posed as a variation of the socalled K shortest path problem in graph theory. The paths with maximum sum of mixing entropy rate become the dominant energy paths. Both comparative examples and practical application to a VLCC ship were included to demonstrate the effectiveness and the commonality of this method. The results preliminary revealed the mechanism of sound transmission through ship cabins and could provide guidance for the vibroacoustics design of very large ships. References | Related Articles | Metrics

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Prototype Measurement Methods for Horizontal Mooring Force of Soft Yoke Mooring System FAN Zheliang1,YUE Qianjin1,2,WU Wenhua1,SUN Qiang3,SUN Ye1 2014, 48 (04):  475-481.  Abstract ( 179 )   Save The horizontal monitoring force methods were discussed from the strain, displacement response and motion attitude  based on an on-site soft yoke mooring system of FPSO in service in Bohai Bay. The precision and accuracy of the three methods were also analyzed. The results show that the three methods have approximately the same precision, and the motionbased inclinometers are more stable and inexpensive than the others. In general, the present work can not only ensure the safty of  the mooring system of FPSO, but also provide important reference for performance evaluation of soft yoke mooring system.   References | Related Articles | Metrics

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Model Test Analysis of Hydrodynamics of Appendages of Hybrid Monohull 2014, 48 (04):  482-487.  Abstract ( 122 )   Save A certain hybrid monohull was selected to study the influence of appendages on hydrodynamics of hybrid monohull, and a model test in towing tank was conducted for different appendage plans in this paper. By the resistance and seakeeping performance test, the influence on hydrodynamic performance of different appendages was studied, and the influencing rules were summarized. The model test results indicate that the influence on the hydrodynamics of hybrid monohull is different between the seme-submerged body, fin and stern flap, which can provide some reference for the optimization design of builtup appendages and stern flaps. Key words： References | Related Articles | Metrics

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Performance Simulation and Optimization of a Large Marine Diesel Engine CHEN Hui1,TU Huan1,REN Wei2 2014, 48 (04):  488-492.  Abstract ( 104 )   Save A zero-dimensional model of a large-scale, low speed, two-stroke marine diesel engine was developed in a Matlab simulation environment. The model was validated by using the experimental data of propulsion characteristics. The effects of compression ratio and ignition point on engine performance parameters at rated operating point were analyzed based on the model. An optimization model was developed to optimize the engine performance under the rated operating condition. In the optimization model, the objective function was the specific fuel consumption, while the constraints were the peak pressure, and the difference between peak pressure and compression pressure, the maximum combustion temperature and exhaust temperature which were within the specified limits, and the design variables were the compression ratio and ignition point. Simulation results of obtained optimized scheme show that the engine performance in terms of fuel consumption and power at rated operating point are both improved.   References | Related Articles | Metrics

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6σ Design for Pressurized Cylindrical Shells Based on RBF   CHENG Yanxue1,PANG Yongjie1,YANG Zhuoyi1,FENG Liang2 2014, 48 (04):  493-497.  Abstract ( 137 )   Save To obtain a reliable pressure hull structure, the 6σ design was introduced into the optimization of pressure hull. The influences of the uncertainty of material and dimension error when processing were fully taken into consideration. Based on the MDO platform iSIGHT, a reliable optimal plan involving 6σ was obtained. In order to reduce the calculation expense, a sufficiently accurate RBF model was used to replace the simulation program ANSYS when iterating, which not only ensured the accuracy but also saves the calculating cost. Key words： References | Related Articles | Metrics

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A Modulus Algorithm Analysis of Ultimate Strength of  Pressured Hull for DeepSea Submarine   XIONG Zhixin,LUO Peilin 2014, 48 (04):  498-501.  Abstract ( 129 )   Save By introducing the symmetrical hypothesis of spherical shell deformation under pressure, the theoretical expression of pressured spherical shell was simplified to plate model. By using a parameter, a uniform expression was obtained with the modulus factor curve and other multimodulus theories. Based on the stressstrain curve, the modulus factor curve and its analytical expression were obtained. Take the tangent modulus theory and double modulus theory as examples,  the two theories were applied to calculate the pressure capacity of Tialloy spherical hull. The calculated values were then compared with the experimental datum. Finally,  the validity and applying scope of the ultimate strength for pressure hull calculation were obtained, providing a scientific reference for the early design of deep sea submarine.   References | Related Articles | Metrics

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An Optimization Approach Based on Particle Swarm Optimization and Ant Colony Optimization for Arrangement of Marine Engine Room JIANG Wenying,LIN Yan,CHEN Ming,YU Yanyun 2014, 48 (04):  502-507.  Abstract ( 138 )   Save Based on ant colony optimization and particle swarm optimization, an optimization approach was presented to solve the arrangement problem of marine engine room. Facility layout and pipe routing are two important parts in the arrangement of marine engine room. Due to the small layout space, the large number of facilities, pipelines and complex constraints, it is hard to obtain the optimal design solution. Furthermore, facility layout and pipe routing are achieved respectively in actual design, in which the relationship between the two is neglected. In order to solve this problem, a mathematical model was built according to the constraints of both facility layout and pipe routing. The global optimum solution was obtained by the proposed algorithm. Simulation results demonstrate the feasibility and effectiveness of the proposed algorithm. References | Related Articles | Metrics

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Hybrid Green Function Method for Time-Domain Analysis of Motions of Floating Body in Waves TANG Kai,ZHU Renchuan,MIAO Guoping,FAN Ju 2014, 48 (04):  508-514.  Abstract ( 87 )   Save A hybrid Green function method in time domain was applied for simulating the motions of floating body in waves. The fluid filed was decomposed into inner and outer domain by an imaginary control surface; the Rankine source method was applied in the inner domain while the transient Green function method was used in the outer domain. Two initial boundary value problems were solved by the continuity condition on control surface. The corresponding numerical codes were developed and the retard functions, wave exciting forces and motions in waves for a cylindrical platform and S175 containership were presented and verified. The comparison between numerical results, experimental data and frequency results were in good agreement, which shows that the present method is efficient and suitable for the hydrodynamic problem with or without forward speed. The good numerical stability is proved by solving divergence problem of ship with flare.   References | Related Articles | Metrics

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Group Decision-Making Method of  Warship Overall Scheme Based on Improved Delphi GUO Haipeng，HUANG Sheng，WANG Chao 2014, 48 (04):  515-519.  Abstract ( 46 )   Save According to the characteristics of the overall scheme decision-making of warships, the improved Delphi was introduced for decisionmaking. The scheme’s sequence of group and individual decision was transformed into a Boolean matrix. The difference of group and individual Boolean matrix elements reflected the group consistency of decision-making. Then, the optimization model based on sort consistency was constructed. The initial scoring matrix was adjusted within the correction range by FIPSO to search the feasible solution that can satisfy group consistency. The credibility function was built to analyze the overall credibility of the revised evaluation, and the credibility was also taken into account besides group consistency. The comparative analysis of an application example show that the method has well optimal decision stability and decisionmaking credibility. References | Related Articles | Metrics

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A Method for Panel Generation of Ship Hull and Free Surface Based on Spline ZHANG Weia,ZOU Zaojiana,b 2014, 48 (04):  520-524.  Abstract ( 110 )   Save Aimed at 3D Rankine panel method, a method for panel generation of ship hull and free surface based on Bspline was proposed in this paper. The bicubic B-splines was used to represent the geometric form of the ship hull and the generalized cross sections was used to describe more accurately the shape of bow and stern. The compatibility problem of the splines was solved by reconstructing the section curves twice. Parameterized discretization was conducted for the hull and different free surfaces. By modifying the parameter partition, the panel mesh density can be easily changed to meet the requirement of numerical computation.   References | Related Articles | Metrics

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Hierarchy Control Strategy for Active Hydro-Pneumatic Suspension Vehicles Based on Genetic Algorithm FENG Jinzhi1，YU Fan2，ZHENG Songlin1，SUN Tao1，GAO Dawei1 2014, 48 (04):  525-531.  Abstract ( 147 )   Save The purpose of this paper is to improve the performance of vehicles with active hydro-pneumatic suspension system. A new hierarchy control strategy for the active hydro-pneumatic suspension system was proposed with consideration of the actuator dynamic characteristics. The parameters of the upper controller of the fuzzy logic PID controller were optimized based on a genetic algorithm (GA). In addition, considering the practical implementation of the proposed control scheme, a GA-based self learning process was initiated only when the defined performance index of the vehicle dynamics went beyond a threshold for a debounce time. The proposed control strategy was implemented on the virtual prototype and cosimulations were launched with different road disturbance inputs. The co-simulation results show that the active hydro-pneumatic suspension system proposed in this paper can significantly improve the vehicle riding comfort characteristic. The robustness and adaptability of proposed controller were also examined even when the control system was subjected to severe road conditions or continuously extreme rough road conditions. Key words：    References | Related Articles | Metrics

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Simulation Method for Bonding Seam Failure of  Superplastic Forming and DiffusionBonded Structures CHAI Xianghai1,2,ZHANG Xiaoyun3,SHI Tongcheng1,2 2014, 48 (04):  532-537.  Abstract ( 162 )   Save In view of the fact that weld strength is usually lower than the material strength, and geometric characteristics of parts is affected by the significant features when using the superplastic forming and diffusion-bonded process to build the hollow warren thin wall structures, and based on the study of the deformation of diffusion bonding components and failure mechanism of bonding seam, this paper proposed a novel method in which thick shell elements were used to model diffusion bonded components. Moreover, the tied contact with failure mode was used to model bonding seam physical properties, and its strength parameters were related to geometric characteristics. The impact tests of hollow warren thin wall structures based on superplastic forming were performed, and numerical simulation results were compared with the test data. The results show that the method proposed in this paper can be used for dynamic analysis of model bonded hollow warren structures. References | Related Articles | Metrics

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A Calculating Method of Polar Navigation Parameters for Inertial Navigation System LIU Wenchao1,BIAN Hongwei1,WANG Rongying1,YUE Yazhou2 2014, 48 (04):  538-543.  Abstract ( 213 )   Save To solve the problems that heading error and velocity error of inertial navigation system (INS) increase and the heading angle of the great circle route changes rapidly in polar regions, a calculating method of polar navigation parameters for INS was proposed. First, the polar heading error restraint mechanism was studied and a ellipsoid grid heading reference model was built. Then, the calculating of grid heading and grid velocity was implemented using the calculating navigation parameter information of INS. Finally, the polar navigation performance evaluation of the method was completed. Theoretical analysis and simulation results show that the calculating  method is simple, the calculating navigation parameters  are conducive to polar sailing monitoring and plotting, and the precision of grid heading and velocity is superior to that of the geographic heading and velocity, which illustrates that the method could meet the requirement of polar navigation and improve the polar navigation performance of the inertial navigation system.   References | Related Articles | Metrics

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Coordinated Scheduling Problem for Block Choice and Slot Arrangement Under Outbound Container Random Arrival CHEN Chao，TAI Weili，YANG Yilan，ZENG Qingcheng 2014, 48 (04):  544-550.  Abstract ( 160 )   Save Aimed at the influence of scattered stacking and random slot choice for outbound containers under random arrival at port  on  truck travelling routes and yard crane picking-up operation, a coordinated scheduling problem of block choices and slot arrangements for outbound containers was proposed and formulated as a two-stage integreted non-linear programming model to minimize unit TEU average operating time and yard crane operating cost by using block location choice, quantity assignment, and slot arrangment in yard bays as decision variables. Meanwhile, a two-level GA-based heuristic algorithm was developed whose upper-level was used to search for the available blocks with quantities, while the lower-level was designed to optimize the slot arrangement in each yard bay based on the upper-level. The numerical experimentsal  results indicate that the coordinated scheduling to the block choice and slot arrangement under outbound container random arrival could reduce the unit TEU average operating time by 5.46% and  decrease the yard crane cost evidently, compared with the scenario where containers are gathered into the terminal and stacked together, which verifies the validity of the model and the algorithm. References | Related Articles | Metrics

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Analysis of Vessel Traffic Flow Based on Field Method GAN Langxiong1,2,3,ZHANG Lei2,3,ZOU Zaojian1,WEN Yuanqiao2,3,ZHANG Heng2,3 2014, 48 (04):  551-557.  Abstract ( 95 )   Save In order to investigate the characteristics of vessel traffic flow extensively and accurately, a field method was introduced to analyze the vessel traffic flow. Based on the ideal grid arrangement, this process used the AIS data of vessel traffic flow as samples and applied Delaunay subdivision for trigonometric interpolation to obtain the distribution diagram of vessel traffic flow field. The comparison with the actual traffic flow shows that the form of field can well characterize the distribution of vessel traffic flow and the safe state of navigation area. Utilizing the analysis results of vessel traffic flow field, the effectiveness of safety prewarning of ship navigation and maritime safety supervision can be improved.   References | Related Articles | Metrics

Astronomy,Geoscience

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Concept Design of a New Sandglass-Type  Floating Production Storage and Offloading System   YAO Yuxin,WANG Wenhua,HUANG Yi 2014, 48 (04):  558-564.  Abstract ( 212 )   Save In order to overcome the performance limitations of the traditional shiptype, cylindrical and prismatic FPSO, this paper presents a new concept of sandglass-type FPSO with new sandglasstype floating body and various function modules. For the sandglass-type model, the heave and pitch motion performance in wave were studied by potential flow boundary element and spectrum analysis methods in frequency domain, and the theories of probability and statistics were applied in the analysis of green water phenomenon. Furthermore, the variable displacement method was used to calculate the statical stability curve. Finally, by comparing with the cylindrical floating body model of Sevan Marine Company in Norway and octagon floating body model of CNOOC in China, it was found that the design of sandglass shape could obviously improve the stability and hydrodynamic characteristic of FPSO. Thus this paper provides an innovative engineering platform for the development of deepwater oil and gas. Key words： References | Related Articles | Metrics

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A Numerical Method to Predict the Behavior of Unbonded Flexible Risers Under Axial Compression REN Shaofei,TANG Wenyong,XUE Hongxiang 2014, 48 (04):  565-569.  Abstract ( 106 )   Save In order to avoid inaccurate stresses of simplified carcass and zeta layers resulted from the traditional numerical method, a numerical method to predict the behavior of unbonded flexible risers was presented by taking complicated crosssections of carcass, zeta layers and interaction between all layers into consideration, which not only made the finite element model highly consistent with the real geometrical shapes of layers, but also had high efficiency and precision. The numerical method could effectively conduct stress evaluation of carcass, zeta layers, failure modes and interaction between all layers. The behavior of an eightlayer unbonded flexible riser under axial compression was predicted. It is shown that numerical results are in good agreement with theoretical results; tensile armor layers are the main bearing layers; compressive stiffness is much smaller than tensile stiffness; and boundary conditions have little influence on the compressive property.   References | Related Articles | Metrics

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Coupling Hydrodynamic and Aerodynamic Computations of Offshore Floating Wind Turbines YAN Fasuo1,ZHANG Chengxiang1,YANG Hui1，PENG Cheng2 2014, 48 (04):  570-575.  Abstract ( 216 )   Save The method to perform coupling analysis of offshore floating wind turbines (OFWT) was developted by integrating hydrodynamic and aerodynamic modules in time domain. The Morison method was used for hydrodynamic computation of floating body and its mooring system, in which the relative velocity between structure elements and waves was implemented by the hybrid wave model with second order accuracy. Slender rods theories were applied to the mooring systems, and the wind turbine was modeled by the aero-elastic code-FAST. Loads and displacements were transferred between the submodules based mainly on floating body control equations in every time step by the Newmark- β method. Motion responses of a 5 MW 3 blades spar type OFWT was predicted with and without FAST to validate the combined program. A comparison of results from the available 3D linear potential flow method in a random sea condition shows that the code is capable of hydro-aero dynamic analysis of OFWT.   References | Related Articles | Metrics

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Fatigue Characteristics Analysis of Steel Catenary Riser near Touchdown Zone Based on Full Coupled Model and SCR-Soil Interaction Model   WANG Kunpeng,XUE Hongxiang,TANG Wenyong 2014, 48 (04):  576-582.  Abstract ( 110 )   Save The upper end responses of a steel catenary riser (SCR) were predicted using the hull/riser/mooring full coupled model, which was then applied to the global finite element analysis of the SCR, where the SCR-soil interaction was simulated by the developed touchdown zone (TDZ) element. The TDZ element could capture the mobilization and release of the clay suction, and account for the seabed trench shape. By changing the seabed characteristic parameters, the parametric studies were conducted, and the fatigue sensitivity of the SCR near touchdown point (TDP) to the seabed parameters was obtained by using the rain flow counting methodology.   References | Related Articles | Metrics

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Hill Stability Prediction of Deep-Sea Steel Catenary Riser XIAO Fei,YANG Hezhen 2014, 48 (04):  583-588.  Abstract ( 101 )   Save Hill stability of deep-sea steel catenary riser (SCR) was predicted based on bi-frequency excitation. The SCR was transferred into top tensioned riser (TTR) based on Vandiver theory, the multi-frequency signal is proposed to simulate the stochastic tension fluctuation, and Hill equation was obtained according to the dynamic motion equation of TTR under multi-frequency excitation. The parametric stability characteristic of the SCR system under bi-frequency excitation, a typical case of multi-frequency, was primarily discussed, and bi-frequency excitation was used for practical engineering analysis. The results show that multi-frequency excitation can better predict real sea condition than single frequency, the prediction of real external excitation is vital to the parametric stability prediction of SCR, and the riser safety design requirements are determined by the corresponding form of excitation function chosen.   References | Related Articles | Metrics