A new source number estimation method based on the beam eigenvalue

Most source number estimation methods based on the eigenvalues are decomposed by covariance matrix in MUSIC algorithm. To develop the source number estimation method which has lower signal to noise ratio and is suitable to both correlated and uncorrelated impinging signals, a new source number estimation method called beam eigenvalue method (BEM) is proposed in this paper. Through analyzing the space power spectrum and the correlation of the line array, the covariance matrix is constructed in a new way, which is decided by the line array shape when the signal frequency is given. Both of the theory analysis and the simulation results show that the BEM method can estimate the source number for correlated signals and can be more effective at lower signal to noise ratios than the normal source number estimation methods.     

美国墨西哥湾深水管道建设项目成本与安装方法分析（英文）

The offshore pipeline network in the U.S. Gulf of Mexico is the largest and most transparent system in the world. A review of deepwater projects in the region provides insight into construction cost and installation methods and the evolution of contract strategies. Pipeline projects are identified as export systems, infield flowline systems, and combined export and infield systems, and three dozen deepwater pipeline installations from 1980–2014 are described based on Offshore Technology Conference(OTC) and Society of Petroleum Engineers(SPE) industry publications and press release data. Export lines and infield flowlines are equally represented and many projects used a combination of J-lay, S-lay and reel methods with rigid steel, flexible line, and pipe-in-pipe systems. The average 2014 inflation-adjusted cost for pipeline projects based on OTC/SPE publications was $2.76 million/mi and ranged from $520 000/mi to $12.94 million/mi. High cost pipelines tend to be short segments or specialized pipeline. Excluding the two cost endpoints, the majority of projects ranged from $1 to $6 million/mi. The average inflation-adjusted cost to install deepwater pipelines in the U.S. Gulf of Mexico based on available public data is estimated at $3.1 million/mi.     

摩洛哥大西洋沿岸的波能评估（英文）

The aim of the present work is to assess the offshore wave energy potential along the Atlantic coast of Morocco. Research works of this paper focus on the identification of the most energetic sites for wave energy converters(WECs) deployment. For this purpose, 11 sites have been explored; all of them are located at more than 40 m depth on the Moroccan Atlantic coast. The wave power at each site is computed on the basis of wave data records in terms of significant wave height and energy period provided by the Wave Watch three(WW3) model. Results indicate that the coast sites located between latitudes 30° 30′ N and 33° N are the most energetic with an annual average wave power estimated at about 30 kW· m~(-1), whereas, in the other sites, the wave power is significantly lower. Moreover, the study of the monthly and seasonal temporal variability is found to be uniform in the powerful sites with values four times greater in winter than in summer. The directional investigation on the significant wave height has shown that for almost all the powerful sites, the incoming waves have a dominant sector ranging between Northern(N) and Western-Northern-Western(WNW) directions.     

通气空化中反向射流与双涡流型转换的数值研究（英文）

Contrary to natural cavitation, ventilated cavitation is controllable and is not harmful. It is particularly used to reduce the drag of the hydraulic vehicles. The ventilated cavitation is characterized by various gas regimes. The mechanisms of ventilated cavitation are investigated in the present work with CFD based on a 2D solver. The attention is especially focused on the transition between the reentrant jet and twin vortex regimes. The results confirm that the product of ventilated cavitation number and Froude number is lower than 1(σcFr 1) in the twin vortex regime, while it is higher than 1(σ_cFr 1) in the reentrant jet regime, as reported in the literature. Further analysis shows that ventilated cavitation is significantly influenced by the natural cavitation number.     

试验研究作用于准椭圆沉箱群墩上的不规则波波浪力（英文）

An experimental investigation of irregular wave forces on quasi-ellipse caisson structures is presented. Irregular waves were generated based on the Jonswap spectrum with two significant wave heights, and the spectrum peak periods range from 1.19 s to 1.81 s. Incident wave directions relative to the centre line of the multiple caissons are from 0° to 22.5°. The spacing between caissons ranges from 2 to 3 times that of the width of the caisson. The effects of these parameters on the wave forces of both the perforated and non-perforated caissons were compared and analyzed. It was found that the perforated caisson can reduce wave forces, especially in the transverse direction. Furthermore, the relative interval and incident wave direction have significant effects on the wave forces in the case of multiple caissons.     

A method of multi-channel reference signals acquiring in broadband ANC

In a flank array on an unmanned underwater vehicle （UUV）, self-generated noise which has broadband and colored spectrum property in frequency and spatial domain is the main factor affecting the performance of weak signal detection, so the technique of adaptive noise cancellation （ANC） as well as physical denoising and active noise cancellation are often used in practice. Because ANC is based on correlations, improvements in performance come from better correlation between reference signals and primary signals. Taking full advantage of the characteristics of flank arrays and the characteristics of information obtained from hydrophones, a new method for reference signal acquisition for adaptive noise cancellation is proposed, in which the multi-channel reference signals are obtained by accurate delaying for a given direction of arrival （DOA） and differencing between adjacent outputs of array elements. The validity of the proposed method was verified through system modeling simulations and lake experiments which showed good performance with little additional computational burden.     

振荡浮子式双浮体波浪能装置的阵列特性（英文）

As the energy supply problem worsens, the development and utilization of marine renewable energy have become a research hotspot. The development of wave energy is moving from the near shore to the distant sea. The power-generation efficiency of a single two-floating-body wave-energy converter is relatively low. To fully utilize wave energy and improve the wave-energy capture rate of a fixed sea area, arranging a two-floating-body wave-energy converter array is necessary. This paper first introduces the basic theory of multi-floating flow field, time-domain calculation method, and influence factor of the waveenergy converter array. Then, the development of AQWA software in Fortran language considers the effect of power takeoff.A calculation method based on ANSYS–AQWA is proposed to simulate the motion of the oscillating-buoy two-floating-body wave-energy converter. The results are compared with the experimental results from the National Renewable Energy Laboratory.Finally, the ANSYS–AQWA method is used to study the power characteristics of simple and complex arrays of wave-energy converters. The average power generation of simple arrays is largest at 0°, and the average power generation of complex arrays does not change with the wave direction. Optimal layout spacing exists for the simple and complex arrays. These findings can serve as a valuable reference for the large-scale array layout of wave-energy converters in the future.     

An experimental study of irregular wave forces on multiple quasi-ellipse caissons

An experimental investigation of irregular wave forces on quasi-ellipse caisson structures is presented. Irregular waves were generated based on the Jonswap spectrum with two significant wave heights, and the spectrum peak periods range from 1.19 s to 1.81 s. Incident wave directions relative to the centre line of the multiple caissons are from 0＆#176; to 22.5＆#176;. The spacing between caissons ranges from 2 to 3 times that of the width of the caisson. The effects of these parameters on the wave forces of both the perforated and non-perforated caissons were compared and analyzed. It was found that the perforated caisson can reduce wave forces, especially in the transverse direction. Furthermore, the relative interval and incident wave direction have significant effects on the wave forces in the case of multiple caissons.     

Construction of GM(2,1)Model for Oscillating Pitch Angle Series

GM(1, 1) is generally used in Grey System Theory which constructs an Ordinary Differential Equation for given se-ries. It is effective for monotone series, and its simulating effect is good and error is small. However, If the series dosen' t havea property of monotone, the simulating effect of GM(1,1) is not fine, and its error gets bigger. In this paper, we use GM(2,1) to handle the oxcillation series, which uses the Method of Minimum Squares in determining the uncertain parameters.The     

The motion analysis of fire video images based on moment features and flicker frequency

In this paper, motion analysis methods based on the moment features and flicker frequency features for early fire flame from ordinary CCD video camera were proposed, and in order to describe the changing of flame and disturbance of non-flame phenomena further more, the average changing pixel number of the first-order moments of consecutive flames has been defined in the moment analysis as well. The first-order moments of all kinds of flames used in our experiments present irregularly flickering, and their average changing pixel numbers of first-order moments are greater than fire-like disturbances. For the analysis of flicker frequency of flame, which is extracted and calculated in spatial domain, and therefore it is computational simple and fast. The method of extracting flicker frequency from video images is not affected by the catalogues of combustion material and distance. In experiments, we adopted two kinds of flames, i.e. , fixed flame and movable flame. Many comparing and disturbing experiments were done and verified that the methods can be used as criteria for early fire detection.     

Experimental investigation of TARMAX model for modeling of hydrodynamic forces on cylinder-like structures

A new approach that models lift and drag hydrodynamic force signals operating over cylindrical structures was developed and validated. This approach is based on stochastic auto regressive moving average with exogenous (ARMAX) input and its time-varying form, TARMAX. Model structure selection and parameter estimation were discussed while considering the validation stage. In this paper, the cylindrical structure was considered as a dynamic system with an incoming water wave and resulting forces as the input and outputs, respectively. The experimental data, used in this study, were collected from a full-scale rough vertical cylinder at the Delft Hydraulics Laboratory. The practicality of the proposed method and also its efficiency in structural modeling were demonstrated through applying two hydrodynamic force components. For this purpose, an ARMAX model is first used to capture the dynamics of the process, relating in-line forces provided by water waves;secondly, the TARMAX model was applied to modeling and analysis of the lift forces on the cylinder. The evaluation of the lift force by the TARMAX model shows the model is successful in modeling the force from the surface elevation.     

Asymptotic field of mode Ⅱ dynamic growing crack in visco-elastic material

A mechanical model of visco-elastic material is established in order to investigate viscous effect in dynamic growing crack-tip field of mode Ⅱ. It is shown that in stable creep growing phase, elastic deformation and viscous deformation are equally dominant in the near-tip field, the stress and strain have the same singularity, namely, (σε) ∝r^-1/(n-1). The asymptotic solutions of separatied variables of stress, stain and displacement in crack-tip field are obtained by asymptotic analysis, and the results of numerical value of stress and strain in crack-tip field are obtained by shooting method. Through numerical calculation, it is shown that the near-tip fields are mainly governed by the creep exponent n and Mach number M. By the asymptotic analysis to the crack-tip field, the fracture criterion of mode Ⅱ dynamic growing crack of visco-elastic materials is put forward from the point of view of strain.     

焊接参数对十字型接头焊缝根部和焊趾有效缺口应力的影响（英文）

Cruciform joints in ships are prone to fatigue damage and the determination of type of weld plays a significant role in the fatigue design of the joint.In this paper,the effect of weld geometry on fatigue failure of load carrying cruciform joints in ships is investigated using Effective Notch Stress(ENS) approach.A fictitious notch of 1 mm radius is introduced at the weld root and toe and fatigue stress is evaluated.The effect of weld leg length(l) and weld penetration depth(p) on ENS at weld ro...     

我所船模试验设备简介

1. GENERAL OF SSSRI Under the management of the Ministry of Communications, the Shanghai Ship and shipping Research Institute (SSSRI) was established in 1962. The site of its headquarter is No. 200 Ming-sheng Road, which is on the eastern side of the Huang-pu River in Shanghai, and two branch laboratories are at Bansongyuan Road and Gaoqiao respectively.     

Experimental observation and computer simulation on non-equilibrium grain-boundary segregation kinetics of phosphorus

An experimental study and computer simulation on non-equilibrium grain-boundary segregation kinetics and the critical time for phosphorus in 12Cr1MoV steel( which is used in steam pipeline of ships)are put forward in this paper. The segregation level of phosphorus with solution temperature 1050 ℃ at the isothermal holding temperature of 540 ℃ ,have been measured at grain-boundaries. A non-equilibrium grain-boundary segregation kinetics curve of phosphorus is given, The critical time for phosphorus non-equilibrium grain-boundary segregation is about 500 h at 540 ℃ for the experimental steel, When the holding time is longer than 1 500 h, non-equilibrium segregation disappears and the level of segregation reaches full equilibrium, The simulation using the kinetic equations of non-equilibrium grain-boundary segregation is in good accordance with the experimental observation for phosphorus in steel 12Cr1 MoV. The non-equilibrium grain-boundary segregation kinetic model is therefore proved.     

导流板对弯管流激噪声和流致振动的影响(英文)

The effect of a guide vane installed at the elbow on flow-induced noise and vibration is investigated in the range of Reynolds numbers from 1.70×105 to 6.81×105, and the position of guide vane is determined by publications. The turbulent flow in the piping elbow is simulated with large eddy simulation(LES). Following this, a hybrid method of combining LES and Lighthill's acoustic analogy theory is used to simulate the hydrodynamic noise and sound sources are solved as volume sources in code Actran. In addition, the flow-induced vibration of the piping elbow is investigated based on a fluid-structure interaction(FSI) code. The LES results indicate that the range of vortex zone in the elbow without the guide vane is larger than the case with the guide vane, and the guide vane is effective in reducing flow-induced noise and vibration in the 90° piping elbow at different Reynolds numbers.     

CHINA''''S SOE REFORM SCALES NEW HEIGHTS

State-owned enterprises (SOEs) in China have stepped out of the mire of the past and the reform of the nation's SOEs is set to deepen. The performance of China's SOEs in 2002 is far better than in 2001. Especially, the achievement was made against the backdrop of a global economic slowdown in 2001 and 2002, when the global trade volume and investment declined. Against such a backdrop, it is not easy     

自由衰减模型试验的横摇阻尼评估方法研究(英文)

The methodology to obtain the non-linear roll damping from decay tests is very old. It has been proposed by Froude in the 19th century and used from then on. Behind it there is a quadratic model [θ│θ│] for the damping and a subsequent equivalent linearization. Probably all model basin in the world follows this approach to assess the damping from a decay test. This is well documented and so is the methods to get the p1-p2 coefficients. This is very general in the sense that in principle,it could be applied t...     

Time-fuel synthetic optimal control of ship-borne special crane based on predictive average dynamic

Ship-bome special crane, a multi-joints and foldaway one, is important to study the most effective energy-saving ( i. e. synthetic time-fuel optimal) operation control mode. In this paper, by introducing weighted parameters, a time-fuel synthetic optimal criterion is obtained, and configuration of the optimal controller is verified. Furthermore, a predictive average dynamic method is put forward, and applied to treat nonlinearity and coupling of the crane. Finally, an optimal controller with feedback is designed. The validity of this approach is verified by simulation results.     

超大型浮体连接器载荷时域计算（英文）

Loads generated after an air crash, ship collision, and other accidents may destroy very large floating structures(VLFSs) and create additional connector loads. In this study, the combined effects of ship collision and wave loads are considered to establish motion differential equations for a multi-body VLFS. A time domain calculation method is proposed to calculate the connector load of the VLFS in waves. The Longuet–Higgins model is employed to simulate the stochastic wave load. Fluid force and hydrodynamic coefficient are obtained with DNV Sesam software. The motion differential equation is calculated by applying the time domain method when the frequency domain hydrodynamic coefficient is converted into the memory function of the motion differential equation of the time domain. As a result of the combined action of wave and impact loads, high-frequency oscillation is observed in the time history curve of the connector load. At wave directions of 0° and 75°, the regularities of the time history curves of the connector loads in different directions are similar and the connector loads of C1 and C2 in the X direction are the largest. The oscillation load is observed in the connector in the Y direction at a wave direction of 75° and not at 0°. This paper presents a time domain calculation method of connector load to provide a certain reference function for the future development of Chinese VLFS