小波变换多尺度分解系数阈值选择在一维去噪的应用

对小波变换理论进行了简单的介绍,并详细分析了基于小波变换对信号去噪处理的原理和实现,并对小波多重分解时选取不同的阈值对去噪效果进行详细的研究。最后结合理论分析和实验实例讨论了小波分析在信号去噪方面的作用,利用光滑性和相似性来评价去噪效果。     

A Technique for Jamming Bi- and Multistatic SAR Systems

Bi- and multistatic synthetic aperture radars (SARs) can achieve reduced vulnerability in military systems, especially in directional responsive jamming, and avoid physical attack to radar platforms. In this letter, a technique for jamming bi- and multistatic SAR systems is proposed, which is implemented with a novel transponder. This technique is based on a delayed retransmission of the received radar signal toward the scene. Unlike conventional delayed jamming, here, the jammer's delay time is random in the whole range interval. Moreover, the jamming signal is not retransmitted to the receiver directly but to the areas with targets that need to be protected against being imaged by radar. By this, it is then possible to jam the radar echoes independent of the receiver location     

Simulation of land use change using GIS-based stochastic model: the case study of <Emphasis Type="Italic">Shiqian</Emphasis> County,Southwestern China

This paper presents the GIS-based stochastic model and its application to simulate land use change in Shiqian County, Southwestern China. Transition probability of land use change with biophysical factors such as elevation, slope, distance to stream, distance to road and adjacent cells with the same land use are calculated and integrated into this model. Then the model simulated 2001 land use pattern based on 1988 land use pattern and the results are satisfactory. Finally, three different land use scenarios are simulated using this model. This study provides a new tool to predict land use pattern.     

GPS高程拟合转换正常高的研究

通过对GPS测高与水准测量理论及其异同分析的基础上,阐述了确定似大地水准面的原理与方法,分析了用数学模型法,用少量GPS与水准重合点将GPS大地高直接转换为具有cm量级正常高的实现方法。实验结合黑龙江省虎林地区的地形特点,提出了用线性内插法、平面模型法和二次曲面模型法等来转GPS高程,证明在黑龙江省虎林地区可以通过少量且分布合理的水准点来直接求出该地区具有cm量级的正常高,且精度可以达到四等水准测量的精度要求,满足一般工程的需要。     

柴达木地区耕地后备资源调查评价初步研究

通过介绍柴达木地区耕地后备资源分布、数量及评价的原则、分类体系,评价标准,总结了该地区耕地后备资源开发存在问题,提出了耕地后备资源开发对策建议。     

Disintegration characteristics of weak rocks using the Grey Prediction technique

The deterioration of weak rock subject to wetting impacts upon excavation and tunnelling for mine development. Based on a limited number of determinations at the XGZ Iron Mine, China, the Grey Prediction technique has been employed to assess susceptibility to deterioration. This has been compared to regression, suggesting that the Grey Prediction provides an effective approach where data are limited or inaccessible.     

NaClO法漂白江蓠时不同工艺对氯气浓度及漂白效果的影响

为解决NaClO法漂白江蓠时漂白空间氯气浓度过高导致环境的污染。对NaClO法漂白江蓠时影响漂白空间氯气浓度的几种主要因素进行了研究。通过改进生产工艺 ,对酸化后的江蓠进行水洗后再漂白 ,同时增加草酸作后处理 ,在保证江蓠漂白效果的前提下 ,使漂白空间氯气浓度从最高值 80 5 4mg m3 降低到约 0 0 5 0mg m3 ,车间及环境的氯气浓度远低于国家安全标准 ,解决了江蓠漂白中氯气污染的问题 ,达到了清洁生产的效果。     

A Short-Term Climate Prediction Model Based on a Modular Fuzzy Neural Network

In terms of the modular fuzzy neural network (MFNN) combining fuzzy c-mean (FCM) cluster and single-layer neural network, a short-term climate prediction model is developed. It is found from modeling results that the MFNN model for short-term climate prediction has advantages of simple structure, no hidden layer and stable network parameters because of the assembling of sound functions of the selfadaptive learning, association and fuzzy information processing of fuzzy mathematics and neural network methods. The case computational results of Guangxi flood season (JJA) rainfall show that the mean absolute error (MAE) and mean relative error (MRE) of the prediction during 1998 2002 are 68.8 mm and 9.78%, and in comparison with the regression method, under the conditions of the same predictors and period they are 97.8 mm and 12.28% respectively. Furthermore, it is also found from the stability analysis of the modular model that the change of the prediction results of independent samples with training times in the stably convergent interval of the model is less than 1.3 mm. The obvious oscillation phenomenon of prediction results with training times, such as in the common back-propagation neural network (BPNN) model, does not occur, indicating a better practical application potential of the MFNN model.     

Linguistic mechanism of hypermedia structure in multimedia electronic atlas

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广西钻孔压磁应力观测异常解释

对广西邕宁、灵山钻孔压磁观测资料进行了分析,结果发现,在广西及邻区几次中强地震前,两台钻孔压磁应力显示出一定程度的前兆异常。邕宁、灵山钻孔压磁应力观测曲线出现明显的压应力超差异常,应力测值下降速率较大,震后均显示缓慢的回升过程,特别是北部湾6．1级地震前,两台应力测点出现的方差限(异常限)幅度和时间跨度具有一致性,异常性质均为压性。