A review of the Effect of α/W ratio on fracture toughness （Ⅱ） experimental investigation in LEFM

In part I of this series, experimental investigation in EPFM （elastic-plastic fracture mechanics） had been discussed. In this paper, experimental investigation in LEFM （ linear elastic fracture mechanics） is given. Fracture toughness tests had been carried out on three different strength steels, using both through-cracked specimens with different α/W ratio and semi-elliptical cracked specimens with variable crack size and shape. Results show that the fracture toughness KIC increases with decreasing α/W when α/W 〈 0.3 for three-point-bend specimens, and that for α/W 〉 0.3, it is independent of α/W. Shallow crack specimens, both through-cracked and surface-cracked, gave markedly higher values than deeply notched specimens. However, the effect of crack shape on fracture toughness is negligible. Results also show that the LEFM approach to fracture is not tenable for design stresses where αc is often very small, far less than 2.5 （ KIC/σy）^2.     

Market based framework for multiple AUVs cooperation

A“Market” based framework for multiple AUVs team is introduced in this paper. It is a distributed meta-level task allocation framwork. The formulation and the basic concepts of the “Market” such as “goods” and “price” are discussed first, then the basic algorithm of the “auction”. The loosely coupled v-MDTSP tasks are considered as an example of the task allocation mission. A multiple AUV team controller and a detailed algorithm are developed for such applications. The simulation results show that the controller has the advantages such as robustness and low complexity and it can achieve better optimization results than the classical central controller （ such as GA） in some tasks. And the comparison of two different local solvers also implies that we should get the reasonable task allocation even not using the high quality algorithm, which can considerably decrease the cooperation computation.     

Simulation analysis of static and dynamic characteristics of once-through steam generator in concentric annuli tube

1 Introduction1 Steam generator is an important equipment of an integrated pressurized water reactor. In recent design, the once-through steam generator (OTSG) is mostly applied because it delivers superheated steam and requires no separators. Moreover, i…     

潜器全方向推进器的研究

概述了全方向推进器工作的基本原理以及研究开发全方向推进器的意义;介绍了国内外针对全方向推进器的研究的现状以及哈尔滨工程大学在全方向推进器的研究方面所作的工作;给出了哈工大的定常和非定常状态下的理论计算结果,以及与日本三菱重工的试验值所作的比较;提出了两种新型全方向推进器调距机构的试验模型.     

Application of H∞ control in rudder/flap vector robust control of a ship＇s course

Given the uncertainty of parameters and the random nature of disturbances that effect a ships course, a robust course controller should be designed on the basis of rudder/flap vector control. This paper analyzes system uncertainty, and the choice of weighting functions is also discussed. When sea waves operate on a ship, the energy-concentrating frequency varies with the angle of encounter. For different angles of encounter, different weighting functions are designed. For the pole of a nominal model existing in an imaginary axis, the bilinear-transform method is used. The ＂2-Riccati＂ equation is adopted to solve the H∞ controller. A system simulation is given, and the results show that, compared with a PID controller, this system has higher course precision and more robust performance. This research has significant engineering value.     

永久式与可解脱式FPSO(英文)

浮式生产储卸油系统(FPSO)是一种经济有效的浮式平台方案,特别是在缺乏足够的输油管道系统的深海领域.大多数FPSO是永久系泊的,即整个系统能够抵抗工作海域内的各种极值环境条件.目前,能够将FPSO与其系泊及立管系统快速解脱的装置已经设计并发展了.可解脱式FPSO的主要特点是可解脱性,并能避免一定的环境条件,如冰山,美国摩西哥湾的飓风,中国南海的台风.本文将针对深水海域可解脱式FPSO,提出其主要技术和工程分析与设计思路,评估可解脱式FPSO与永久式FPSO的优缺点,等等.可见町解脱式FPSO与永久式FPSO都是十分有效的浮式系统,并根据平台设计的安全性、技术、成本和运行要求,来决定选择何种系泊方式.     

Comparison of robust H<Subscript>∞</Subscript> filter and Kalman filter for initial alignment of inertial navigation system

There are many filtering methods that can be used for the initial alignment of an integrated inertial navigation system. This paper discussed the use of GPS, but focused on two kinds of filters for the initial alignment of an integrated strapdown inertial navigation system （SINS）. One method is based on the Kalman filter （KF）, and the other is based on the robust filter. Simulation results showed that the filter provides a quick transient response and a little more accurate estimate than KF, given substantial process noise or unknown noise statistics. So the robust filter is an effective and useful method for initial alignment of SINS. This research should make the use of SINS more popular, and is also a step for further research.     

基于LES方法圆柱绕流三维数值模拟(英文)

采用计算流体软件CFX5中large.eddy simulation(LES)模型计算了均匀流场中三维圆柱绕流的水动力特性.使用有限体积法对三维N-S方程进行求解.数值模拟着重研究了高雷诺数时展向各截面的压力、阻力、升力及涡管特性.数值计算结果表明:展向各截面柱体受力关于中截面对称且小于二维情况,柱体周围流场呈现明显的三维特性.     

The asymptotic field of a dynamically growing crack in a viscoelastic materia

A mechanical model of a fracturing viscoelastic material was developed to investigate viscous effects in a dynamically growing crack-tip field. It was shown that in the stable creep-growing phase,elastic deformation and viscous deformation are equally dominant in the near-tip field,and stress and strain have the same singularity,namely,(σ,ε ) ∝ r?1 /( n?1) . The asymptotic solution of separating variables of stress,stain and displacement in the crack-tip field was obtained by asymptotic analysis,and the resulting numerical value of stress and strain in the crack-tip field was obtained by the shooting method and the boundary condition of a mode I crack. Through numerical calculation,it was shown that the near-tip fields are mainly governed by the creep exponent n and Mach number M . When n →∞,the asymptotic solution of a viscoelastic material can be degenerated into that of Freund's elastic-ideally plastic material by analyzing basic equations.     

Eradication of algae in ships＇ ballast water by electrolyzing

In order to verify the effectiveness of electrolytic treatment on ships＇ ballast water, experiments are carried out by a pilot system in laboratory. The raw seawater and seawater with different concentrations of different algae are simulated as ships＇ ballast water. The algae in the raw seawater can be killed if it is treated by electrolysis with an initial residual chlorine concentration of 5 mg/L. If the seawater with one kind of algae （Nitzschia closterum, Dicrateria spp., or Pyramidomonnas sp.105cells/mL） is treated by electrolysis with an initial residual chlorine concentration of 5 mg/L the alga can be sterilized, If the seawater with one kind of algae （Dunaliella sp., Platymonas or Chlorella spp.） is directly treated by electrolyzing with an initial residual chlorine concentration of 4 mg/L, the instant mortality changes with the concentration of different algae. However, after 72 hours, in all treated samples, there are no live algal cells found.     

柴-柴联合动力实验装置及其仿真设计

本文简要地介绍了国内第一套用于柴-柴联合动力系统运行控制技术研究的CO-DAD物理模拟实验装置，并用MATLAB/Simulink建立其数学模型及在此基础上进行了动态仿真。     

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.     

弹道导弹防御战略及技术发展的研究

弹道导弹的作战效能已经得到了充分的证明,对弹道导弹的防御逐渐受到了各国的高度重视.通过对比分析了美国和俄罗斯的弹道导弹防御系统的发展战略及基本思路,介绍了美围的弹道导弹防御系统的技术发展趋势,结合我国的实际情况,阐述了发展弹道导弹防御系统的思路.     

小攻角下驼背鲸减摇鳍的理论计算

通过应用仿驼背鲸前缘突起来提高船用翼的水动力特性已是目前非常热门的话题,为验证前缘突起的高度和突起个数与升力的关系,选用哈尔滨工程大学船舶控制工程教育部工程研究中心在船模水池实验室所做的减摇鳍动态水动力性能实验用的标准NACA00154号矩形鳍为研究对象,对其前缘进行正弦波变形,建立数学模型,并应用普朗特升力线性理论和切比雪夫数值逼近法,得出了前缘突起个数对升力的影响不大而突起幅值对升力有显著的决定性作用的结论.     

水下航行器多普勒导航系统误差辨识与修正

水下航行器(Autonomous Underwater Vehicles,AUV)在水下往往采用航位推算定位方式.由于存在传感器误差,航位推算的定位误差是随着时间发散的,而直接准确检测这类误差非常困难.对多普勒导航系统进行导航误差分析,简化航位推算算法,在此基础上推导出一种新的辨识AUV导航误差参数的方法.仿真结果表明,该算法能够准确辨识AUV导航误差参数向量,可以有效提高AUV自主导航精度,且方法合理、简单.     

Improvement in capacity factor and fatigue assessment of VLMOS for wind power generation based on navigation simulation

The very large mobile offshore structure (VLMOS) for wind power generation is one example of challenging future technologies to create a new backbone of energy resource of our country. The National Institute for Environmental Studies Japan has been studying this concept and found that increasing the capacity factor and reducing the weight of the structure are keys to make this concept successful. We investigated the navigation logic to improve the capacity factor and performed a fatigue assessment to ensure the structural safety of light weight design. Taking the knowledge on the seasonal weather condition in the Pacific Ocean into consideration, improved strategy of the VLMOS navigation for maximizing the generating power is proposed. Navigation simulations show that it is easy to achieve more than 40% capacity factor and to escape from high seas. Using wind and wave data obtained from the navigation simulations, an assessment of the fatigue damage has been performed. It is stated that the structure has enough fatigue strength for a 100 years of operation even if wind turbines get more than 40% of the capacity factor.     

CODAG动力装置控制系统研究

CODAG动力装置最适宜于工况变化范围大的大、中型水面舰艇,而CODAG推进装置可靠运行的关键在于双机并车运行时的负荷分配.文章以哈尔滨工程大学建立的柴燃联合动力装置物理模拟实验台为基础,对并车负荷分配进行了初步研究,设计并编制了并车控制软件和系统监控软件,经过多次调试,成功实现了柴燃并车运行.     

平台导航误差对导弹中末制导交班影响分析

针对多平台导航误差对导弹中末制导过程影响的问题,基于将多平台导航误差传递到目标和导弹位置误差的思想,提出了导航误差传递模型,并采用中末制导交班成功概率模型量化多平台导航误差对导弹中末制导交班过程的影响。仿真结果表明,一定范围的导航误差对导弹中末制导交班成功概率影响较小,但随着导航误差的增大,中末制导交班成功概率迅速减小。     

Segmentation of complex objects＇ sonar images using parameter-fixed MRF model

The effective method of the recognition of underwater complex objects in sonar image is to segment sonar image into target, shadow and sea-bottom reverberation regions and then extract the edge of the object. Because of the time-varying and space-varying characters of underwater acoustics environment, the sonar images have poor quality and serious speckle noise, so traditional image segmentation is unable to achieve precise segmentation. In the paper, the image segmentation process based on MRF （Markov random field） model is studied, and a practical method of estimating model parameters is proposed. Through analyzing the impact of chosen model parameters, a sonar imagery segmentation algorithm based on fixed parameters＇ MRF model is proposed. Both of the segmentation effect and the low computing load are gained. By applying the algorithm to the synthesized texture image and actual side-scan sonar image, the algorithm can be achieved with precise segmentation result.     

The implications of MARPOL Annex V on the management of ports and coastal communities

Abstract

The passage of the Marine Plastics Pollution Research and Control Act of 1987 (MPPRCA), which codified Annex V of the International Convention for the Prevention of Pollution from Ships (MARPOL), has encompassed every commercial and recreational shipping and boating facility in the United States. As a group, these ports, harbors, and marinas form a significant, although proportionately small, portion of the coastline of the country. More important, the economic benefits derived from the complex shoreside infrastructures required for international ocean trade, commercial and recreational fishing, and pleasure boating indicate just how critical it is for these facilities to be in conformance with effective and prudent coastal zone and environmental management practices.