响应面法模拟轴肩和搅拌针形状对铝合金搅拌摩擦的影响(英文)

The present paper discusses the modeling of tool geometry effects on the friction stir aluminum welds using response surface methodology. The friction stir welding tools were designed with different shoulder and tool probe geometries based on a design matrix. The matrix for the tool designing was made for three types of tools, based on three types of probes, with three levels each for defining the shoulder surface type and probe profile geometries. Then, the effects of tool shoulder and probe geometries on friction stirred aluminum welds were experimentally investigated with respect to weld strength, weld cross section area, grain size of weld and grain size of thermo-mechanically affected zone. These effects were modeled using multiple and response surface regression analysis. The response surface regression modeling were found to be appropriate for defining the friction stir weldment characteristics.     

搅拌工具轴肩和搅拌头轮廓对铝合金搅拌摩擦焊的影响一对比研究(英文)

In marine application,marine grade steel is generally used for haul and superstructures.However,aluminum has also become a good choice due to its lightweight qualities,while rusting of aluminum is minimal compared to steel.In this paper a study on friction stir welding of aluminum alloys was presented.The present investigation deals with the effects of different friction stir welding tool geometries on mechanical strength and the microstructure properties of aluminum alloy welds.Three distinct tool geometries with different types of shoulder and tool probe profiles were used in the investigation according to the design matrix.The effects of each tool shoulder and probe geometry on the weld was evaluated.It was also observed that the friction stir weld tool geometry has a significant effect on the weldment reinforcement,microhardness,and weld strength.     

Research and development of a digital design system for hull structures

Methods used for digital ship design were studied and formed the basis of a proposed frame model suitable for ship construction modeling. Based on 3-D modeling software, a digital design system for hull structures was developed. Basic software systems for modeling, modifying, and assembly simulation were developed. The system has good compatibility, and models created by it can be saved in different 3-D file formats, and 2D engineering drawings can be output directly. The model can be modified dynamically, overcoming the necessity of repeated modifications during hull structural design. Through operations such as model construction, intervention inspection, and collision detection, problems can be identified and modified during the hull structural design stage. Technologies for centralized control of the system, database management, and 3-D digital design are integrated into this digital model in the preliminary design stage of shipbuilding.     

A model of application system for man-machine-environment system engineering in vessels based on IDEF0

Applying man-machine-environment system engineering(MMESE)in vessels is a method to improve the effectiveness of the interaction between equipment, environment, and humans for the purpose of advancing operating efficiency, performance, safety, and habitability of a vessel and its subsystems. In the following research, the life cycle of vessels was divided into 9 phases, and 15 research subjects were also identified from among these phases. The 15 subjects were systemized, and then the man-machine-environment engineering system application model for vessels was developed using the ICAM definition method 0 (IDEF0), which is a systematical modeling method. This system model bridges the gap between the data and information flow of every two associated subjects with the major basic research methods and approaches included, which brings the formerly relatively independent subjects together as a whole. The application of this systematic model should facilitate the application of man-machine-environment system engineering in vessels, especially at the conceptual and embodiment design phases. The managers and designers can deal with detailed tasks quickly and efficiently while reducing repetitive work.     

An investigation of the performance of an electronic in-line pump system for diesel engines

WIT Electronic Fuel System Co., Ltd. has developed a new fuel injector, the Electronic In-line Pump （EIP） system, designed to meet China＇s diesel engine emission and fuel economy regulations. It can be used on marine diesel engines and commercial vehicle engines through different EIP systems. A numerical model of the EIP system was built in the AMESim environment for the purpose of creating a design tool for engine application and system optimization. The model was used to predict key injection characteristics under different operating conditions, such as injection pressure, injection rate, and injection duration. To validate these predictions, experimental tests were conducted under the conditions that were modeled. The results were quite encouraging and in agreement with model predictions. Additional experiments were conducted to study the injection characteristics of the EIP system. These results show that injection pressure and injection quantity are insensitive to injection timing variations, this is due to the design of the constant velocity cam profile. Finally, injection quantity and pressure vs. pulse width at different cam speeds are presented, an important injection characteristic for EIP system calibration.     

船舶航向模糊滑模控制器的设计与仿真

In considering the characteristic of a rudder,the maneuvers of a ship were described by an unmatched uncertain nonlinear mathematic model with unknown virtual control coefficient and parameter uncertainties.In order to solve the uncertainties in the ship heading control,specifically the controller singular and paramount re-estimation problem,a new multiple sliding-mode adaptive fuzzy control algorithm was proposed by combining Nussbaum gain technology,the approximation property of fuzzy logic systems,and a multiple sliding-mode control algorithm.Based on the Lyapunov function,it was proven in theory that the controller made all signals in the nonlinear system of unmatched uncertain ship motion uniformly bounded,with tracking errors converging to zero.Simulation results show that the demonstrated controller design can track a desired course fast and accurately.It also exhibits strong robustness peculiarity in relation to system uncertainties and disturbances.     

Application of large eddy simulation in the performance study of wave blocker

The configuration and aerodynamic performance of the inlet system are important aspects in the process of installing a gas turbine on a naval vessel. Under the requirements, large eddy simulation （LES） is used to simulate the three-dimensional fluid flow in the wave blocker of a marine inlet filter. The Smagorinsky-Lilly sub-grid model was used to model motions of small-scale structures. During numerical simulation, the SIMPLE algorithm was applied. The central-differencing spatial discretization scheme and the second order accuracy finite difference for the temporal discretization were used. Simulation gives satisfactory distribution of the vorticity fields and turbulent kinetic energy. Compared with the k-ε turbulent model, the results of LES are better for the distribution of parameters. The results of experimental study in a small-scale wind tunnel indicate that numerical calculation has higher accuracy. Therefore, the methods used are worthy of reference and introduction for the design of an inlet system.     

3D numerical modeling of wave forces on tandem fixed cylinders using the BEM

In this paper a 3D numerical model was developed to study the complicated interaction between waves and a set of tandem fixed cylinders.The fluid was considered to be inviscid and irrotational.Therefore,the Helmholtz equation was used as a governing equation.The boundary element method（BEM） was adopted to discretize the relevant equations.Open boundaries were used in far fields of the study domain.Linear waves were generated and propagated towards tandem fixed cylinders to estimate the forces applied on them.Special attention was paid to consideration of the effect on varying non-dimensional cylinder radius and distance between cylinders,ka and kd on forces and trapped modes.The middle cylinder wave forces and trapped modes in a set of nine tandem cylinders were validated utilizing analytical data.The comparisons confirm the accuracy of the model.The results of the inline wave force estimation on n tandem cylinders show that the critical cylinder in the row is the middle one for odd numbers of cylinders.Furthermore the results show that the critical trapped mode effect occurs for normalized cylinder radiuses close to 0.5 and 1.0.Finally the force estimation for n tandem cylinders confirms that force amplitude of the middle cylinder versus normalized separation distance fluctuates about that of a single cylinder.     

Added resistance acting on hull of a non ballast water ship

In this paper, added resistances acting on a hull of non ballast water ship(NBS) in high waves is discussed. The non ballast water ships were developed at the laboratory of the authors at Osaka Prefecture University, Japan. In the present paper, the performances of three kinds of bow shapes developed for the NBS were theoretically and experimentally investigated to find the best one in high waves. In previous papers, an optimum bow shape for the NBS was developed in calm water and in moderated waves. For a 2 m model for experiments and computations, the wave height is 0.02 m. This means that the wave height is 15% of the draft of the ship in full load conditions. In this paper, added resistances in high waves up to 0.07 m for a 2 m model or 53% of the full load draft are investigated. In such high waves linear wave theories which have been used in the design stage of a ship for a long time may not work well anymore, and experiments are the only effective tool to predict the added resistance in high waves. With the computations for waves, the ship is in a fully captured condition because shorter waves, λ/Lpp0.6, are assumed.     

中厚板高强钢冷热多丝复合埋弧焊热循环参数测量

为解决中厚板高强钢埋弧焊(Submerged Arc Welding, SAW)焊缝热影响区(Heat Affected Zone, HAZ)热循环参数准确测量难题，自主研制多通道热电偶测温软/硬件系统，测量并比较不同焊丝组合(单丝和冷热多丝复合)对应的焊缝HAZ热循环主要参数。试验结果表明：与单丝SAW工艺相比，冷热多丝复合SAW工艺可解决SAW较大热输入产生的焊缝HAZ脆化问题，提高焊缝组织性能和焊接质量；在中厚板高强钢焊接过程中，冷热多丝复合SAW工艺可为温度场数值模拟计算分析提供实测数据，为各种工艺参数的确定与优化、焊缝HAZ的组织性能改善提供必要的理论基础。     

基于三线激光结构光的船体大拼接焊缝交叉类型辨识

为实现船壁面的大拼接焊缝的全自主移动除锈,提出一种基于三线激光结构光的激光视觉焊缝辨识方法。针对船体大拼接焊缝的纵横交叉,根据三线激光的特征,对描述激光形态和激光条纹间距的5个变量进行定义,归纳3条激光条纹在焊缝交叉处的特征参量的变化规律,建立十字形、T字形焊缝交叉的统一辨识模型。试验验证:采用三线激光具有更好的抗干扰性、信息量丰富,在各种工况下都能准确辨识焊缝接头交叉类型。研究结果为后续的焊缝实时跟踪和轨迹规划奠定基础。     

Stress concentration factors at welds in pipelines and tanks subjected to internal pressure and axial force

In this paper, analytical expressions for stress concentration factors in pipes subjected to internal pressure and axial force are derived for a number of design cases based on classical shell theory. The effect of fabrication tolerances in simple butt welds is assessed. Analyses based on classical mechanics are compared with results from axisymmetric finite element analyses for verification of the presented methodology. Stress concentration factors are presented for circumferential butt welds in pipes welded together from pipes with different thicknesses, welds at buckling arrestors, welds at flanged connections in pipelines, and welds at ring stiffeners on the inside and the outside of the pipes. It also includes stress concentration factors at end closures in pipes for gas storage. Larger pipes are fabricated from plates with a longitudinal weld. This fabrication process introduces out-of-roundness in the pipes. The actual out-of-roundness is a function of internal pressure. An analytical expression for the bending stress in the pipe wall due to this out-of-roundness is presented. The derived stress concentration factors can be used together with a hot spot stress S–N curve for calculation of fatigue damage.     

水翼艇可调桨推进智能控制仿真研究

以MATLAB6．5为工作平台,设计了基于模糊逻辑工具箱的模糊控制器,编制了变尺度混沌算法的优化程序,建立了水翼艇可调桨推进的数学模型和仿真模型；通过对模糊控制器系数优化,并将优化后的系数代入仿真模型中,进行大量的实时仿真,仿真结果表明：无论是从超调量方面还是从稳定性方面,变尺度混沌优化模糊控制器都有很好的控制效果．     

基于AHP法的游艇造型设计模糊综合评价方法

针对在评价游艇造型设计时，评价指标复杂性和模糊性高的问题，提出将层次分析法和模糊综合法结合在一起进行综合评价。从识别性、艺术性、传达性、实用性和经济性5个方面构建多层次评价指标体系，计算分析权重向量。以Pershing72和Pershing90这2艘豪华游艇为例，结合模糊综合法进行综合评分，结果表明2艘游艇的造型设计均为良好等级。该实例验证了层次分析法和模糊综合评价法结合在一起进行评价的可行性，能为游艇造型设计评价提供一定的指导。     

Application of fuzzy neural network to the nuclear power plant in process fault diagnosis

The fuzzy logic and neural networks are combined in this paper, setting up the fuzzy neural network (FNN) ; meanwhile, the distinct differences and connections between the fuzzy logic and neural network are compared. Furthermore, the algorithm and structure of the FNN are introduced. In order to diagnose the faults of nuclear power plant, the FNN is applied to the nuclear power plant, and the intelligence fault diagnostic system of the nuclear power plant is built based on the FNN . The fault symptoms and the possibility of the inverted U-tube break accident of steam generator are discussed. In order to test the system‘ s validity, the inverted U-tube break accident of steam generator is used as an example and many simulation experiments are performed. The test result shows that the FNN can identify the fault.     

模糊控制器在船舶动力定位系统中的应用及改进

本文研究了船舶动力定位中模糊控制的应用问题,探讨了模糊控制中隶属函数和模糊规则的具体制定,并应用可变论域的思想对模糊控制器进行改进.对船舶的纵向运动进行了控制与仿真,并且做了比较与分析.仿真结果表明,改进的模糊控制器能对船舶的动力定位实施更有效的控制.     

一种自适应网格模糊交互多模型算法（英文）

This paper studies the algorithm of the adaptive grid and fuzzy interacting multiple model(AGFIMM) for maneuvering target tracking, while focusing on the problems of the fixed structure multiple model(FSMM) algorithm's cost-efficiency ratio being not high and the Markov transition probability of the interacting multiple model(IMM) algorithm being difficult to determine exactly. This algorithm realizes the adaptive model set by adaptive grid adjustment, and obtains each model matching degree in the model set by fuzzy logic inference. The simulation results show that the AGFIMM algorithm can effectively improve the accuracy and cost-efficiency ratio of the multiple model algorithm, and as a result is suitable for engineering applications.