Study on eliminating noises in short-period data of geomagnetic intensity by using numerical multichannel predictive filtering     

任熙宪  张玉敏  高金田 《地震学报(英文版)》1998,11(5):583-588

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VSP资料的程变反Q滤波     

安慧  黄德济  赵宪生 《物探化探计算技术》1998,(1)

因为ＶＳＰ（垂直地震剖面）可在井下不同深度直接观测震源子波的变化,因此被认为是能够提供唯一有价值的地震波衰减资源的来源。利用实际地层中波的衰减测量结果,可以对ＶＳＰ记录的地震波能量损失进行补偿。目前大多数ＶＳＰ的反Ｑ滤波都是直接套用地面地震资料的反Ｑ滤波方法,我们称之为ＶＳＰ资料的非程变反Ｑ滤波法。即对ＶＳＰ经过波场分离和静态时移后得到的上行波分别进行反Ｑ滤波。但是,ＶＳＰ并不像地面反射地震记录那样射线是双程路径的,它的下行直达波是单程走时,而上行反射波的走时介于单程和双程走时之间,因此,ＶＳＰ所记录的地震波衰减程度与地面地震资料所记录的地震波的衰减程度是不同的。本文根据ＶＳＰ上、下行波各自的波场特点,推导出ＶＳＰ特有的反Ｑ滤波数学表达式。该表达式与地面地震记录反Ｑ滤波的表达式所不同的是增加了一个校正因子,该校正因子是传播路程（或传播时间）和品质因子Ｑ的函数,我们称该方法为ＶＳＰ的程变反Ｑ滤波法。经过数值模拟计算表明,该方法对ＶＳＰ的地震波振幅和频率衰减的补偿具有明显的效果。  相似文献   

复杂多通道带乘性噪声系统的逆向滤波及单向反褶积算法     

褚东升  史政  王璐 《中国海洋大学学报(自然科学版)》2005,35(5):819-822

针对石油地震勘探、水下目标探测和语音处理等许多实际应用领域,在乘性噪声为一般随机矩阵的情形下,给出了在线性最小方差意义下的逆向最优滤波及单向最优反褶积算法.并对该算法进行了仿真研究,仿真结果表明了该算法的有效性.  相似文献   

1Bit极性重合相关器的研究   总被引：2，自引：0，他引：2  

戚海峰  陈孝桢 《海洋技术学报》2003,22(4):66-70

介绍一种应用于水声系统的接收电路：1Bit极性重合相关器。由于水下信号传输系统存在着：通道之间的频率间隔小、易受噪声干扰、用电池供电而要求长时间工作等问题，相应地，接受电路就必须具有窄带滤波能力，抗噪声性能良好，并且功耗极低。而普通的模拟滤波器或数字滤波器无法全面地满足这些要求。1Bit极性重合相关器极好地解决了这个问题，它不仅满足上述要求，而且有着结构简单、体积小、性能稳定等优点。作为水下信号传输系统的重要环节，1Bit极性重合相关器运行非常准确而且可靠，值得在水声系统中推广。  相似文献   

基于富里叶变换线性性的抗干扰时变滤波     

王宝升 《中国海洋大学学报(自然科学版)》1997,(4)

提出一种基于富里叶变换线性性实现时变滤波的方法，该方法可提高某些在传播过程中随着传播时间增加其高频成分逐渐减少的接收信号的信噪比。  相似文献   

Temporal significant wave height estimation from wind speed by perceptron Kalman filtering     

Abdüsselam Altunkaynak  Mehmet zger 《Ocean Engineering》2004,31(10):327-1255

Significant wave height estimates are necessary for many applications in coastal and offshore engineering and therefore various estimation models are proposed in the literature for this purpose. Unfortunately, most of these models provide simultaneous wave height estimations from wind speed measurements. However, in practical studies, the prediction of significant wave height is necessary from previous time interval measurements. This paper presents a dynamic significant wave height prediction procedure based on the perceptron Kalman filtering concepts. Past measurements of significant wave height and wind speed variables are used for training the adaptive model and it is then employed to predict the significant wave height amounts for future time intervals from the wind speed measurements only. The verification of the proposed model is achieved through the dynamic significant wave height and wind speed time series plots, observed versus predicted values scatter diagram and the classical linear significant wave height models. The application of the proposed model is presented for a station in USA.  相似文献   

Formulation, implementation and examination of vertical coordinate choices in the Global Navy Coastal Ocean Model (NCOM)   总被引：3，自引：3，他引：3  

Charlie N. Barron  A. Birol Kara  Paul J. Martin  Robert C. Rhodes  Lucy F. Smedstad 《Ocean Modelling》2006,11(3-4):347-375

A 1/8° global version of the Navy Coastal Ocean Model (NCOM) is described with details of its formulation, implementation, and configuration of the vertical coordinate. NCOM is a baroclinic, hydrostatic, Boussinesq, free-surface ocean model that allows its vertical coordinate to consist of σ coordinates for the upper layers and z-levels below a user-specified depth. This flexibility allows implementation of a hybrid σ–z coordinate system that is expected to mitigate some of the weaknesses that can be associated with either pure coordinate option. For the global NCOM application, the σ–z coordinate is used to allow terrain-following σ coordinates in the upper ocean, providing better resolution and topographic fidelity in shelf regions where flow is most sensitive to its representation. Including z coordinates for deeper regions efficiently maintains high near-surface vertical resolution in the open ocean. Investigation into the impact of the selected coordinate system focuses on differences between atmospherically-forced free-running (no assimilation) global solutions using σ–z and pure z coordinates. Comparisons with independent temperature observations indicate that global NCOM using the σ–z coordinate has improved skill relative to its z coordinate implementation. Among other metrics, we show that in comparison with time series of surface temperature from National Oceanic Data Center (NODC) buoys, mostly located in coastal regions, root mean squared differences (RMSD) improved for 63% and correlation improved for 71% of the stations when σ–z coordinates were used instead of pure z. For the exclusively open-ocean Tropical Atmosphere-Ocean (TAO) buoys, differences between the simulations were small, with the σ–z showing smaller RMSD for 45% of the stations and higher correlation for 65% of the stations. Additional comparisons using temperature profile observations further confirm a tendency for improved performance using the hybrid σ–z coordinates.  相似文献   

Elimination of Wind Wave Effects on Sub-Bottom Profiler Record     

刘秀娟  高抒杨旸 《中国海洋工程》2007,21(2):355-362

With the presence of wind waves, the swaying of survey vessel may effect the quality of sub-bottom profiler records and, therefore, it is necessary to correct the distortions induced by wave action. A major issue is to distinguish wind wave effect and real bedforms such as sand waves. In this paper, a bandstop filter is designed according to the frequency features of wind wave effect to treat the distortion of seabed topography by wind waves. The technique is used to correct the sub-bottom profile in order to eliminate the wave-induced distortions for the sub-bottom profile records from the Yangtze Estuary. This study shows that the undulate seabed record is resulted from wave action, rather than the presence of sand waves, and the filtration technique helps to eliminate the wave effect and recover the real morphology of seabed and the sediment sequence underneath. In addition, a method for data processing is proposed for the case that the record indeed represents a combination of wave effects and real bedforms.  相似文献   

四种营养盐对舟形藻(Navicula)BT001生长速率的影响          下载免费PDF全文

郑维发  王雪梅  王义琴  储成才 《海洋与湖沼》2007,38(2):157-162

以I.A.M.收集的培养基Ⅱ为基本培养基,采用单因子和L16(45)正交设计法,进行了舟形藻BT001对N、P、Fe、Si四种营养盐最适需求的研究,并在此基础上,研究了尿素对正交优化组合的影响以及以尿素作为氮源对正交优化组合的影响。结果表明,N、P、Fe、Si四种营养盐最佳单因子水平为:KNO3,300mg/L;Na2HPO4·12H2O,40mg/L;FeCl3,4mg/L;Na2SiO3·9H2O,200mg/L。四种营养盐正交组合水平为:KNO3,150mg/L;Na2HPO4·12H2O,40mg/L;FeCl3,4mg/L;Na2SiO3·9H2O,200mg/L。在正交组合水平基础上,添加16mg/LCO(NH2)2,可更好的促进该藻的生长和繁殖。在8天的培养中,最大细胞相对生长率可达0.1577。在等摩尔氮源的条件下,以CO(NH2)2代替正交优化水平组合中的KNO3对舟形藻BT001进行11天的培养。结果表明,以CO(NH2)2为氮源的藻细胞最大生长密度可达2.69×105cell/ml,明显地高于硝酸钾作为氮源培养的藻细胞密度。  相似文献   

On the design of a longitudinal motion control system of a fully-submerged hydrofoil craft based on the optimal preview servo system     

Sang-Hyun Kim  Hiroyuki Yamato 《Ocean Engineering》2004,31(13):1637-1653

The current control system of a fully-submerged hydrofoil craft based on optimal feedback control has several problems: it has no good performance of contouring waves and it cannot reduce the effect of wave disturbance. In this paper, we apply the optimal preview servo system to the longitudinal control system of a fully-submerged hydrofoil craft in order to settle the problems of current control system. The control system based on optimal preview servo system is composed of feedback controller and feedforward controller. Also in order to design the control system, the necessary prediction range of future information, the weight function in performance index, the future reference input and wave disturbance are determined. Finally, the validity of the proposed control system in this paper is confirmed by simulation. The simulation results show that the control system has good performance of contouring waves in following seas and is effective to settle the problems of current control system of a fully-submerged hydrofoil craft.  相似文献