共查询到20条相似文献，搜索用时 453 毫秒
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《Journal of The Franklin Institute》2018,355(18):9245-9270
This paper deals with noise detection and threshold free on-line denoising procedure for discrete scanning probe microscopy (SPM) surface images using wavelets. In this sense, the proposed denoising procedure works without thresholds for the localisation of noise, as well for the stop criterium of the algorithm. In particular, a proposition which states a constructive structural property of the wavelets tree with respect to a defined seminorm has been proven for a special technical case. Using orthogonal wavelets, it is possible to obtain an efficient localisation of noise and as a consequence a denoising of the measured signal. An on-line denoising algorithm, which is based upon the discrete wavelet transform (DWT), is proposed to detect unavoidable measured noise in the acquired data. With the help of a seminorm the noise of a signal is defined as an incoherent part of a measured signal and it is possible to rearrange the wavelet basis which can illuminate the differences between its coherent and incoherent part. In effect, the procedure looks for the subspaces consisting of wavelet packets characterised either by small or opposing components in the wavelet domain. Taking real measurements the effectiveness of the proposed denoising algorithm is validated and compared with Gaussian FIR- and Median filter. The proposed method was built using the free wavelet toolboxes from the WaveLab 850 library of the Stanford University (USA). 相似文献
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针对基于四象限压力传感器阵列的迎角测量方法中传感器信号受到干扰的问题,讨论了在其预处理中应用小波包变换进行信号分离提取的方法。根据小波包分解理论,对信号进行小波包分解,信号中频率不同的部分落在不同的尺度上,剔除反映干扰的变换尺度,提取出有用信息。结果表明,该方法可很好地提取信号的主要特征信息,也有效地去除了确定性干扰和随机噪声,与传统的信号滤波方法相比较具有明显的优点,同时为后续的信号处理奠定了基础。 相似文献
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一种基于子波变换的语音增强方法 总被引：1，自引：0，他引：1
在分析了随机噪声的子波变换系数在不同尺度上的传递特性和噪声信号奇异性与子波模极大值的关系后,提出了用一尺度间变化的门限阈值来抑制带噪训音信号在不同尺度上噪声子波系数,从而实现了在重构信号中消除噪声的目的。文中还给出了不同信噪比语音信号的子波去噪的计算机仿真结果,从结果上看出,本文的方法有较好的语音去噪、增强效果。 相似文献
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基于小波滤波的信号处理方法 总被引：1，自引：0，他引：1
在信号处理中,噪声的存在往往影响分析的准确度,小波变换多分辨分析的特性使得它成为一种很好的滤噪方法.本文通过分析小波滤波的思想、计算过程以及幅频特性等问题,从而达到小波滤波的目的,并通过仿真来验证小波滤波的有效性. 相似文献
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目的:滤除心电信号中包含的基线漂移、工频干扰、肌电干扰三种主要噪声,获取干净有效的临床心电信号信息。方法:改进阈值处理函数的小波变换阈值去噪法。结论:改进阈值处理函数小波阈值去噪法能更好的弥补了软、硬阈值函数去噪法中存在的不足,得到的去噪效果更优。 相似文献
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《Journal of The Franklin Institute》2019,356(8):4601-4621
The stabilization problem concerning the user datagram protocol (UDP) for networked control systems (NCSs) is investigated in this paper. More specifically, both the state and control signal can be lost during transmission, and the networked induced delay occurs while the control signal delivered to the actuator. On the other hand, no communication channel can be accessed from the actuator to the estimator (no acknowledge signal). The innovations of this paper include: (1) Based on the modified Riccati-ZXL equations, the necessary and sufficient stabilization conditions are developed for the NCSs with packet losses and transmission delay (UDP case); (2) We have verified that the separation principle holds for the finite horizon optimal output feedback control problem; (3) For 1-dimensional case, the maximal delay bound and the maximal packet losses rate are derived. 相似文献
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重载的铁路货车滚动轴承极易出现损伤类故障,因故障的突发性使得振动信号具有非线性、非平稳的特性,且振动信号极易受非检测部位振动的干扰,而使得有效信号不易被提取,传统的基于傅里叶变换的检测方法无法有效将非平稳的振动信号中的干扰去除,造成最终的检测准确率不高的问题。为了提高检测准确率,提出基于小波包的检测方法,首先针对振动信号的非平稳特性采用小波滤波有效去除其中的干扰,然后通过最小二乘支持向量机提取出非平稳振动信号中的故障特征信号并完成故障检测。实验表明,这种方法能够有效去除振动信号中的干扰,并准确检测重载铁路货车上的滚动轴承损伤故障。 相似文献
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研发产业的产业关联与波及特点分析——以上海为例 总被引：1，自引：1，他引：1
运用投入产出理论，以上海2002年投入产出表为基础，对研发产业的投入结构、销路结构、中间需求率、中间投入率、影响力及影响力系数、感应度及感应度系数等重要指标进行量化分析，揭示了研发产业与相关产业间的关联效应和波及程度。 相似文献
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提出一种基于小波包与自适应预测器的音频隐写分析方法,主要用于检测加性噪声模型.利用加性噪声对音频高频部分比低频部分影响显著的特点,对音频信号进行小波包分解;然后利用最小均方(LMS)自适应预测器对高频小波包系数进行预测,选取预测误差的统计量作为统计特征;最后采用支持向量机分类.实验证明,对于常用的加性噪声隐写方法,即使在嵌入强度或嵌入率较低的情况下,也能达到较高的分类准确率. 相似文献
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Anubha Gupta Shiv Dutt Joshi Pushpendra Singh 《Journal of The Franklin Institute》2018,355(17):8989-9016
This paper establishes connection between discrete cosine transform (DCT) and the discrete-time fractional Brownian motion process (dfBm). It is proved that the eigenvectors of the auto-covariance matrix of a dfBm can be approximated by DCT basis vectors in the asymptotic sense. This shows that DCT basis acts as discrete Karhunen–Loève transform (DKLT) for these processes in the approximate sense. Analytic perturbation theory of linear operators is used to prove this result. This result will be of great practical significance in applications where one is looking for an appropriate basis to work with signals that can perhaps be modeled as belonging to fBm processes. The utility of the proposed work has been illustrated with two real-life data (a) on compressive sampling based reconstruction of financial time-series and (b) in denoising gravitational wave event GW150914 data obtained from a binary black hole merger. 相似文献
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为了解决心电图QRS波检测的问题,研究了一种基于自适应小波变换来检测QRS波的算法。该方法用心电信号的小波变换作为自适应白化滤波器的输入,然后对白化滤波后的输出进行匹配滤波和阈值检测来识别出QRS波。采用该方法,有利于减小检测的误检率以及提高运行速度。 相似文献
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规范多agent系统通过规范控制agent个体行为实现系统宏观目标。在自然语言描述的抽象规范和操作语言描述的具体规范之间存在巨大的语义鸿沟,采用分层规范模型将高层抽象规范逐级转换成底层具体规范是解决这一问题的有效手段。但是目前的分层规范模型存在着层次过多,层间界线模糊的问题,同时规范细化和层间规范转换完全依赖手工完成,不仅降低了系统可靠性和动态适应性,同时提高了规范系统开发成本。本文提出并实现了一种自治分层规范框架模型,该模型将规范系统分成三个层次,并且在形式化规范层建立概念语义蕴涵关系和行为责任关系实现了规范的自动细化,建立行为-操作映射模型实现不同层次的形式规范间的自动转化,提高了规范系统自治性,降低了规范系统开发成本,提高了系统可靠性和动态适应性。 相似文献
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《Journal of The Franklin Institute》2022,359(16):8621-8638
Networked systems using redundant channels to transmit data can effectively reduce the probability of data loss and improve system reliability and control margin. However, the structural complexity and economic cost of the system are also increased. To balance the redundancy and feasibility, the ratio of attraction domain to packet loss rate is defined as a balanced feasibility index. In this paper, single-channel packet loss is considered as Bernoulli distribution and a bounded packet loss network system control model is constructed as the arbitrary bounded packet loss control problem for redundant channel transmission network system. Therefore, the robust conditions of the closed-loop system and the constraints of the input and state are established under the framework of robust predictive control to construct the linear matrix inequality (LMI) optimization problem. Finally, to verify the effectiveness of the design method proposed in this paper, the discrete time-varying linear system and the main steam control system with redundant channels are used as study cases. 相似文献
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如何去除信号中的噪声．得到纯净的信号是信号处理过程中一个热点技术。本研究根据噪声与信号的小波变换模极大值点在多尺度空间上具有不同的特性，对信号进行了噪声消除。试验结果表明，使用傅里叶变换和coif2小波模极大值点法对信号去噪，都能够有效地去除信号中的噪声，且重构后的信号非常逼近原始信号．但coif2小波模极大值点法去噪效果更好。 相似文献
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提出了一种基于小波阈值去噪的语音增强算法。根据含噪语音中噪声、清音和浊音的不同特点,首先对它们进行检测区分,然后采用改进的Garrote阈值函数分别对噪声、清音和浊音运用不同的阈值方案进行处理。该方法在很大程度上抑制了噪声,又减少了语音段清音的损失,提高了信噪比,在MATLAB7.1中的仿真实验结果表明,该方法具有较好的增强效果。 相似文献