舰载直升机起降区空气流场模拟方法研究

基于计算流体力学(CFD)技术建立了2种舰载直升机起降区空气流场的计算方法,以用于分析舰船/直升机之间的耦合干扰问题。在这2种方法中,控制方程选取N-S方程,求解方式采用隐式耦合方式,湍流模型为k-ε模型,分别使用"作用盘方法"和"运动嵌套网格方法"模拟旋翼。应用建立的方法,以SFS2简化船型、Robin旋翼和"Caradonna-Tung"旋翼分别作为算例,并与试验值进行对比,验证了方法的有效性。在此基础上,深入地进行起降区舰船/旋翼耦合流场的计算研究。研究结果表明:舰船上层建筑物的存在会引起起降区下洗速度增大,使得旋翼拉力减小;"作用盘方法"能有效地用于舰船/直升机耦合流场的分析,而"运动嵌套网格方法"可以捕捉到起降区空气流场的细节,但其需要耗费巨大的计算量。     

基于蚁群算法的舰载直升机维修资源优化调度研究*

针对舰载直升机远航时驻舰周期长、维修任务时间紧、资源有限的特殊性,合理构建舰载直升机驻舰维修模型,建立舰载直升机驻舰维修资源优化调度模型,采用改进蚁群算法进行仿真计算,通过计算验证表明：该算法较好的解决维修过程中出现的资源冲突问题,缩短舰载直升机维修工期。     

直升机舰上起降安全的影响因素研究

舰载直升机的起降安全涉及到舰机两方面,且影响因素较多。本文首先对舰载直升机起降安全因素进行了系统分析,梳理了其关键影响因素舰船空气流场中各特性参数对直升机操作性能的影响。然后介绍了用于舰船空气流场测量的三种典型方法,对舰船空气流场的深入研究有重要指导意义,并可为机舰动态配合研究提供参考。     

两栖攻击舰直升机出动回收流程分析

针对两栖攻击舰舰载直升机出动回收流程规划及能力评估问题,通过分析美国海军"黄蜂"级两栖攻击舰的舰载直升机典型任务样式和舰面作业流程,合理分解舰载直升机舰面保障作业流程,包括主要作业流程规划、作业区域及保障设施。构建出动回收全流程仿真模型,并从提高出动回收能力角度提出了相关建议,对指导两栖攻击舰舰载直升机作业规划具有参考意义。     

LHA多机起降过程中的耦合流场仿真

为研究多机起降过程中的舰面/旋翼流场干扰问题及耦合流场对直升机操纵量的影响,采用计算流体动力学(CFD)仿真方法及作用盘法对两栖攻击舰LHA上多机起降过程进行仿真研究.研究结果表明,前机侧舷进离场过程中,耦合流场对后方相邻起降点位置的直升机产生较大影响,后机开车时应避开前机进离场的时间区间;进离场过程中,前机对后机操纵量影响较大,当前机位于着舰点上方时,随着其高度的增加,后机总距先增大后减小、俯仰周期变距及滚转周期变距均增大;当前机偏离着舰点距离大于0.5R(直升机旋翼半径)时,随着前机高度的增加,后机总距、俯仰周期变距及滚转周期变距均减小.研究成果可为多机起降作业安全提供借鉴和参考.     

基于影响图的舰载电子战系统模型

文章把影响图理论应用到舰载电子战系统模型中,通过阐述影响图建模理论,并基于舰载电子战系统的工作过程,列出影响舰载电子战系统的表征参量,根据影响图建模理论,画出舰载电子战系统的影响图模型,根据各个参量之间的耦合关系,并列出微分方程。在研究中得出无源干扰系统干扰不确定半径,有源干扰系统干扰不确定半径,在舰载电子战系统作战中起着非常重要的作用。文章丰富了舰载电子战系统模型的建立方法,具有一定的理论意义。     

采用混合算法分析舰船雷达间电磁干扰耦合

为解决传统数值算法分析舰载雷达电磁兼容带来的计算机资源占用大、运算时间长和收敛性问题,对复杂环境下雷达电磁计算方法提出了改进思路,论述了舰上典型形状金属障碍物对舰载雷达波传播的影响,研究了矩量法和几何绕射理论混合算法在电磁干扰耦合分析中的应用方法,并在舰船电磁仿真模型上进行了计算,分析结果表明,相对于精确数值算法,该混合算法大幅提高了计算速度,计算误差优于3 dB,具有良好的工程适用性.     

舰载机阻尼着舰动力学建模

为了解决现有舰载机阻尼着舰动力学模型着舰时间较长与滑跑距离较远的问题,提出舰载机阻尼着舰动力学模型研究。采用转换方法对着舰坐标系进行选取转换,依据舰载机着舰运动学方程对舰载机进行模型化处理。根据模型特点对起落架结构进行简化,在此基础上依据刚体碰撞理论对阻尼着舰碰撞模型进行构建,并对阻尼着舰动力进行分析,实现舰载机阻尼着舰动力学模型的构建。通过实验得到,相较于现有的舰载飞机阻尼着舰动力学模型,构建的舰载机阻尼着舰动力学模型极大缩短了着舰时间与滑跑距离,充分说明构建的舰载机阻尼着舰动力学模型具备更好的性能。     

直升机舰上起降安全的影响因素研究

对舰载直升机起降安全因素进行系统分析,梳理其关键影响因素舰船空气流场中各特性参数对直升机操作性能的影响,介绍用于舰船空气流场测量的3种典型方法。研究表明:可通过CFD仿真、风洞试验以及实船测量三位一体的手段获取精确的直升机起降流场环境,结合直升机飞行特性获取准确的直升机载舰安全起降包线。研究结果对舰船空气流场的深入研究有重要指导意义,并可为机舰动态配合研究提供参考。     

舰用设备与船体一体化强度评估方法研究

舰载复杂设备与船体之间的弹性耦合效应不可忽略,在进行舰载大型设备抗冲击数值实验时必须确定合理的技术来妥善处理外部冲击环境、舰体结构、局部结构和舰用设备之间的关系。基于主从系统耦合振动理论,以舰用炮塔结构为研究对象,设计多种冲击输入对非一体化与一体化舰炮结构进行抗冲击数值计算,并将计算结果进行对比分析,对舰用设备抗冲击分析方法以及适用范围进行探讨,旨在寻找一套适合我国国情的舰用设备抗冲击的研究方法,为舰用设备抗冲击性能设计及性能评估提供参考。     

第十二届深水操作会议和展览会(英文)

正November 4-6,2014Moody Gardens HotelConvention Center/Galveston,TX The Deepwater Operations Conference and Exhibition is celebrating its 12th anniversary this year.This growing event will continue the tradition of excellence in addressing operational challenges involved in developing deepwater resources.We will return to the Moody Gardens Hotel and Convention Center on November 5-7,2014 in Galveston,Texas.     

The 11th International Conference on Hydrodynamics (ICHD 2014)

正19–24 October 2014 SingaporeCONFERENCE THEMES The overall aim of the ICHD Conference is to provide a forum for participants from around the world to review,discuss and present the latest developments in the broad discipline of hydrodynamics and fluid mechanics.The first International Conference on Hydrodynamics(ICHD)was initiated in 1994 in Wuxi,China.Since then,9 more ICHD conferences were held subsequently in Hong Kong,Seoul,Yokohama,Tainan,Perth,Ischia,Nantes,Shanghai and St Petersburg.Evidently the ICHD conference has become an important event among academics,researchers,engineers and operators,working in the fields closely related to the science and technology of hydrodynamics.The 11th ICHD will be held in Singapore in 2014.     

Catalyzing Coastal Management in Kenya and Zanzibar: Building Capacity and Commitment

Site-based projects were initiated in Chawka Bay-Paje, Zanzibar, and Nyali-Bamburi-Shanzu, Kenya, to demonstrate the benefits of an integrated coastal management (ICM) approach for addressing coastal issues such as tourism development and enhancement of resource-dependent village economies in eastern Africa. A two-year, multidonor project used three primary strategies to make rapid, but sustainable, progress toward ICM. These included using interagency government teams for ICM planning, adopting an internationally recognized framework for ICM as a project ''road map,'' and explicitly incorporating capacity-building strategies into all aspects of the project. Within two years, integrated ICM action strategies, prepared through participatory processes, were being implemented at both sites, and both teams were working to expand the scale and scope of ICM in their nation. More importantly, the project helped create committed, capable, interagency groups that continue to work together to address urgent ICM issues.     

A simplified method for reliability- and integrity-based design of engineering systems and its application to offshore mooring systems

This paper presents a simplified method for the reliability- and the integrity-based optimal design of engineering systems and its application to offshore mooring systems. The design of structural systems is transitioning from the conventional methods, which are based on factors of safety, to more advanced methods, which require calculation of the failure probability of the designed system for each project. Using factors of safety to account for the uncertainties in the capacity (strength) or demands can lead to systems with different reliabilities. This is because the number and arrangement of components in each system and the correlation of their responses could be different, which could affect the system reliability. The generic factors of safety that are specified at the component level do not account for such differences. Still, using factors of safety, as a measure of system safety, is preferred by many engineers because of the simplicity in their application. The aim of this paper is to provide a simplified method for design of engineering systems that directly involves the system annual failure probability as a measure of system safety, concerning system strength limit state. In this method, using results of conventional deterministic analysis, the optimality factors for an integrity-based optimal design are used instead of generic safety factors to assure the system safety. The optimality factors, which estimate the necessary change in average component capacities, are computed especially for each component and a target system annual probability of system failure using regression models that estimate the effect of short and long term extreme events on structural response. Because in practice, it is convenient to use the return period as a measure to quantify the likelihood of extreme events, the regression model in this paper is a relationship between the component demands and the annual probability density function corresponding to every return period. This method accounts for the uncertainties in the environmental loads and structural capacities, and identifies the target mean capacity of each component for maximizing its integrity and meeting the reliability requirement. In addition, because various failure modes in a structural system can lead to different consequences (including damage costs), a method is introduced to compute optimality factors for designated failure modes. By calculating the probability of system failure, this method can be used for risk-based decision-making that considers the failure costs and consequences. The proposed method can also be used on existing structures to identify the riskiest components as part of inspection and improvement planning. The proposed method is discussed and illustrated considering offshore mooring systems. However, the method is general and applicable also to other engineering systems. In the case study of this paper, the method is first used to quantify the reliability of a mooring system, then this design is revised to meet the DNV recommended annual probability of failure and for maximizing system integrity as well as for a designated failure mode in which the anchor chains are the first components to fail in the system.     

含裂纹钢板复合材料修补强度和刚度数值分析

用ANSYS有限元分析软件对复合材料补片修复含边裂纹和中心裂纹钢板的强度和刚度进行了数值分析.引入相对刚度的概念,研究了钻有止裂孔裂纹的长度对损伤钢板相对刚度的影响,分析了损伤钢板刚度复合材料贴片修补效果;引入屈服载荷提高率的概念,分析了损伤钢板强度的修复效果.     

混凝土道路、堆场面层裂缝的产生与防治

从混凝土道路、堆场的各个结构层分析裂缝产生的原因,并针对性地说明预防措施,阐述裂缝维修方法。     

利比亚米苏拉塔市萨瓦瓦区5000套住宅项目中心区设计

从确定符合项目实际情况的设计原则入手,通过利比亚米苏拉塔市萨瓦瓦住宅区中心区总体布局和建筑设计两个方面的设计实践,探讨了"传统、现代与文脉"这一当今时代无法回避的文化议题。并且针对具有鲜明文化、宗教和气候特征的建筑设计的特点、方法与风格进行了总结,为今后的实践提供借鉴。     

恶劣电磁环境下PLC控制系统抗干扰技术研究

该文结合工程实践,研究了某型船模PLC控制系统抗干扰技术。依据干扰产生的原因,分析了系统干扰的来源,并提出了抑制干扰的具体措施。通过硬件和软件的优化设计,提高了控制系统抗干扰能力。实践证明,经过优化设计的PLC控制系统运行安全,稳定,控制效果得到明显提高。     

沉箱重力式码头施工期间沉降位移观测与分析

介绍某码头工程3万吨级码头和5000吨级码头施工期间的沉降变位观测过程及对观测数据的分析,为类似工程提供参考。     

分油机系统模拟仿真设计

针对使用实际分油机系统进行教学与训练在安全和经济方面存在的制约因素.为帮助学员较快熟练掌握分油机系统的操控,采用VC++编程技术和数字仿真技术,结合数学建模,设计开发基于PC桌面的船舶分油机模拟仿真系统.仿真分析和应用结果表明:船舶分油机模拟仿真系统能够模拟实际分油机系统的操作控制过程,方便学员熟悉各种故障现象,熟练掌握船用燃油分油机的操作程序、操作要领和保养维护系统知识.