基于IP网络的多媒体指挥调度系统

介绍了在宽带IP网上依托H.323技术实现多媒体通信的特点。根据宽带网络不同构成情况,提出切实可行的基于IP网络技术的多媒体通信调度系统技术解决方案,并且分析系统的结构和所实现的功能。     

潜艇上方近场水下辐射噪声双峰特性的实验研究(英文)

The double-peak characteristic of underwater radiated noise in the near field on top of the target submarine was analyzed in depth on the basis of submarine test data on the sea. The contribution of three major noise sources to the radiated noise of a submarine were compared and analyzed, and emphasis was put on the original source, production mechanism, and their correlative characteristics. On the basis of analysis on underwater tracking and pass through characteristics of the target submarine, the double-peak phenomenon was reasonably interpreted. Furthermore, the correctness of the theoretical interpretation was verified adequately in real submarine tests. The double-peak phenomenon indicates that the space distributing character on submarine radiated noise are both asymmetrical with time and space, whereas that is provided with directivity. Studying the double-peak phenomenon in depth has important reference value and meaning in engineering practice for understanding the underwater radiated noise field of submarines.     

敷设抗冲瓦后舰船的阻力性能试验

抗冲瓦是一种能实现对水下非接触爆炸载荷整体冲击隔离同时又能隔离舰艇自身辐射噪声的新概念产品.但因其敷设于舰艇水线以下湿表面将对舰船的航行阻力产生影响.为此,在拖曳水池中对试验船模开展了敷设抗冲瓦前后的阻力性能对比试验.试验分析了抗冲瓦在水动力载荷作用下的弹性变形,探讨了敷设抗冲瓦后对不同阻力成分的影响.试验结果表明,舰...     

爆炸消除焊接残余应力的数值模拟

焊接残余应力及其控制技术是重大工程结构物(例如反应堆、潜艇等)建造中关注的核心问题之一。爆炸法消除残余应力是近年来发展起来的高效、低成本的1种新技术,但对其机理的研究仍然相当缺乏。本文利用非线性有限元软件ABAQUS对爆炸消除焊接残余应力技术进行了数值模拟,同时考察了焊缝中夹杂的裂纹缺陷对爆炸载荷的响应。研究对象为70 mm厚的超厚钢板对接焊缝,焊接坡口为X型。本文主要完成了以下2项研究工作。1)将盲孔法测得的焊接残余应力分布预置到模型中,计算了爆炸载荷作用下不同布药方式时焊接残余应力的再分布,并将其与对应的实测结果进行比较。研究结果表明,金属材料的塑性流动是爆炸消除焊接残余应力的根本因素。2)在模型的焊缝区引入面状裂纹来表征焊缝中的凝固裂纹,利用ABAQUS用户自定义子程序开发的基于虚拟裂纹闭合法的三维断裂单元,计算能量释放率对爆炸载荷的响应。研究结果表明,爆炸载荷并不一定会导致裂纹的扩展。因此,本文的研究方法和结果对于爆炸消除焊接残余应力在工程应用领域具有指导意义。     

水润滑轴承弹流动压润滑和摩擦特性数值计算分析

利用多重网格方法对水润滑径向轴承的弹性流体动力润滑性能,特别是摩擦性能进行分析,利用MATLAB软件编程求解,得到了水润滑径向轴承在稳态下的压力分布、液膜厚度和摩擦因数大小及变化趋势:在相同载荷下,随着转速的升高,局部最大压力减小,液膜厚度变大,摩擦因数减小,在相同转速下,随着载荷的升高,局部最大压力变大,液膜厚度减小,摩擦因数减小。     

体积噪声场和界面噪声场中声矢量传感器线阵阵增益分析

Acoustic vector sensor consists of pressure and particle velocity sensors,which measure the three-dimensional acoustic particle velocity,as well as the pressure at one location at the same time.By preserving the amplitude and phase information of the pressure and particle velocity,they possess a number of advantages over traditional scalar sensors.Signal-to-noise ratio (SNR) gain (which is often called array gain) is one of such advantages and is always interested by all of us.But it is not unchangeable if the spatial correlation of the noise field varies.Much more important,it is difficult to be given if the noise becomes complex.In this paper,spatial correlation of the vector field of isotropic volume-noise and surface-generated noise has been introduced briefly.Based on the results,the combined SNR output of a vector linear array is investigated and the maximum gain is given in the specified noise.Computer simulation shows that the output of one array in the same noise is not the same in different gestures.And then we find the best gesture through SNR calculation and obtain the biggest gain,which has important meaning to guide how to deploy an array in practice.We also should use the array with respect to the characteristics of the real ambient noise,especially in anisotropic noise field.     

新型企业业绩评价模式合EVA平衡记分卡

EVA综合平衡记分卡(BSC)就是将平衡记分卡在企业长期战略中的作用和EVA评价系统的导向作用相结合,利用BSC将公司的战略转化为具体的、可接受的目标,以EVA指标来检验企业战略或使命.本文将探讨如何将EVA和BSC合为一个综合的绩效评价体系,使EVA作为BSC财务维度的评估指标,从而克服各自的局限性,发挥最大效益,实现企业价值最大化目标.     

基于新型剖面设计的螺旋桨多目标性能权衡优化

利用Eppler方法进行新型抗空泡翼型剖面设计.设计的新型剖面其空泡斗比具有相同设计升力系数和厚度弦长比的NACA66 mod+a=0.8剖面要宽很多.将新设计的剖面用于螺旋桨敞水性能优化,以4个半径处的螺距为设计变量,以敞水效率和多个半径处的最小压力系数为目标函数,利用iSIGHT优化平台对其螺距分布进行优化,以改善其敞水性能,特别是空泡性能.计算结果表明,采用新型抗空泡剖面进行螺旋桨敞水性能优化是有效的.并比较不同优化算法对优化结果的影响.     

IMO成员国审核发现对我国履约借鉴作用分析

国际海事组织(IMO)成员国审核的目的之一是分享成功履约的经验,交流存在的不足,通过持续改进,促进全球海上安全、海洋环境保护及海事管理水平的共同提高。基于此,本文对IMO发布的涉及26个国家的9份《综合简要审核报告》进行了研究,旨在分析审核发现的问题,以期达到履约借鉴的作用。     

WMU关于人为因素和组织因素的研究介绍

为研究IMO成员国在事故调查开展过程中对人为因素和组织因素两类事故原因的反映,世界海事大学(WMU)选择了41份事故调查报告,采用人为因素分析与分类体系(HFACS)的研究方法对报告进行了深入回顾。研究结果表明,事故调查官们往往将更多的注意力集中在一些最基层的操作性错误即人为因素方面,而忽略重要的深层次组织因素。文中基于WMU向IMO船旗国履约分委会提交的报告对此项研究进行了介绍,以期为国内相关研究提供参考。