应用经验模态分解的拖船噪声信号重构及抵消方法

针对拖船干扰的时空特点,提出了将EMD(Empirical Mode Decomposition)应用于拖船噪声信号重构及抵消的方法。为了解决以往需要人工干预挑选EMD输出的多路IMF分量的缺点,提出了将多路IMF(Intrinsic Mode Function)分量与基元域信号按照线谱与连续谱分别做功率谱相关并以谱相关系数最大为准则的挑选算法。基于逆波束形成的理论,利用挑选后的IMF分量重构基元域信号,并与原始基元域信号谱减后再进行方位估计。拖曳声呐模拟器数据与实际海试数据验证结果表明,本文算法能够提高弱目标空间增益,尤其是对于靠近干扰盲区的弱目标空间增益提高明显,并且对拖船多途角扩展干扰也具有较好的抵消能力。     

OPTIMAL LOGISTICS FOR MULTIPLE JEEPS

We consider variations of the classical jeep problems： the optimal logistics for a caravan of jeeps which travel together in the desert. The main purpose is to arrange the travels for the one-way trip and the round trip of a caravan of jeeps so that the chief jeep visits the farthest destination. Based on the dynamic program principle, the maximum distances for the caravan when only part of the jeeps should return and when all drivers should return are obtained. Some related results such as the efficiency of the abandoned jeeps, and the advantages of more jeeps in the caravan are also presented.     

Lorentz变换的四元数表示——纪念李国平院士吴新谋教授诞辰100周年

为一般Lorentz变换给出了一种新的形式简单的四元数表示. 其特点是所用四元数的分量要么是实数, 要么是纯虚数. 与以往的向量-张量表示和八元数表示(双四元数)相比, 有其明显的优点.     

盲分离算法在听音波束净化中的性能分析

波束形成作为一种空域滤波技术,可以对听音信号进行净化,但效果不理想,盲分离技术的出现,给听音波束的净化带来新的方法,但由于受到水声环境的限制,盲分离算法在水声信号处理方面的应用还受到许多约束.对几种常用盲分离算法进行分析,并仿真检验其在听音波束净化方面的性能.     

A REMARK OF THE HLDER ESTIMATE OFSOLUTIONS OF SOME DEGENERATE PARABOLICEQUATIONS

1Intr0ducti0nWeconsiderthedegenerateparabolicequationswherejisasmo0thfunction.F0rgeneraldegenerateparab0licequati0nsoftype(1.1),therearealotofpaperscon-sideringtheeXistence,uniquenessandregUlarity0ftheweaksolutions.Mostoftheavailableresult8havetod0withlocalH5ldercontinuityofsolutionsandregularityupt0theb0undarywithboliciteXPonents.InthispaPer,westudytheH5lderesthoate0fthes0lutionforthedegenerateparab0licequati0nhionedimentionalcase,theekistence(1相似文献   

一种波束谱特征加权的水下弱目标检测方法

实际水下被动信号处理中,感兴趣的弱目标往往只在所处理频段的某些频率分量上表现出相对明显的谱特征,现有基于能量累加的后置处理方式存在谱能量小于噪声的目标被平滑的问题,最终导致目标无法被有效检测.针对该问题,本文提出一种新的自适应波束形成后置处理方法,通过Eckan最优滤波器从波束信号谱中提取感兴趣的频谱,从而求取波束谱加...     

一种新的低湖平原水系整治的动态规划模型与算法

本文以四湖地区为代表的低湖平原为研究对象，研究了该类地区的水利系统优化问题，尤其是汛期的涝水优化调度问题．应用大系统分解协调原理建立了具有两层结构的数学模型．在应用动态规划法对子系统进行动态寻优时，采用了一种很有特色的用混合进位制数描述系统状态的技巧，并对监利新兴垸的水利系统进行了实例计算，显示了该模型及算法的可行性和灵活性．     

THE AVALANCHE DYNAMICS IN RANDOM NEAREST NEIGHBOR MODELS OF EVOLUTION WITH INTERACTION STRENGTH

A generalized Bak-Sneppen model (BS model) of biological evolution with interaction strength θ is introduced in d-dimensional space, where the "nearest neighbors" are chosen among the 2d neighbors of the extremal site, with the probabilities related to the sizes of the fitnesses. Simulations of one- and two-dimensional models are given. For given θ > 0, the model can self-organize to a critical state, and the critical threshold fc(θ) decreases as θ increases. The exact gap equation depending on θ is presented, which reduces to the gap equation of BS model as θ tends to infinity. An exact equation for the critical exponent γ(θ) is also obtained. Scaling relations are established among the six critical exponents of the avalanches of the model.