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Wavelet transform

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https://www.readbyqxmd.com/read/29792291/diurnal-variations-of-depression-related-health-information-seeking-case-study-in-finland-using-google-trends-data
#1
Jonas Christoffer Tana, Jyrki Kettunen, Emil Eirola, Heikki Paakkonen
BACKGROUND: Some of the temporal variations and clock-like rhythms that govern several different health-related behaviors can be traced in near real-time with the help of search engine data. This is especially useful when studying phenomena where little or no traditional data exist. One specific area where traditional data are incomplete is the study of diurnal mood variations, or daily changes in individuals' overall mood state in relation to depression-like symptoms. OBJECTIVE: The objective of this exploratory study was to analyze diurnal variations for interest in depression on the Web to discover hourly patterns of depression interest and help seeking...
May 23, 2018: JMIR Mental Health
https://www.readbyqxmd.com/read/29791354/improved-three-dimensional-reconstruction-algorithm-from-a-multifocus-microscopic-image-sequence-based-on-a-nonsubsampled-wavelet-transform
#2
Yingzhong Tian, Haoyang Cui, Zhiyan Pan, Jiaorong Liu, Shouchen Yang, Lilan Liu, Wenbin Wang, Long Li
In the multifocus microscopic image measurement method, the distortion of the three-dimensional (3D) reconstruction model has always been an important factor affecting the measurement result. In spatial domains, the focus measure algorithm is based on the gradient change of the pixel point to determine the degree of focus of the pixel. So it will be difficult to accurately extract the focus of the pixel in the areas where color difference is not obvious, resulting in 3D model distortion. According to the optical principle, the high-frequency coefficients of the clear image are larger than the high-frequency coefficients of the blurred image...
May 10, 2018: Applied Optics
https://www.readbyqxmd.com/read/29791344/analytical-performance-improvement-of-laser-induced-breakdown-spectroscopy-for-the-processing-degree-of-wheat-flour-using-a-continuous-wavelet-transform
#3
Ping Yang, Yining Zhu, Shisong Tang, Zhongqi Hao, Lianbo Guo, Xiangyou Li, Yongfeng Lu, Xiaoyan Zeng
Quality and safety of food are two of the most important matters in our lives. Wheat is one of the most important products in the modern agricultural processing industry. Issues of mislabeling and adulteration are of increasingly serious concern in the grain market. They threaten the credibility of producers and traders and the rights of the consumers. Therefore, it is very significant to guarantee the processing degree of wheat flour. In this work, two different spectral peak recognition methods, i.e., artificial spectral peak recognition and automatic spectral peak recognition, are carried out to study the adulteration problem in the food industry...
May 10, 2018: Applied Optics
https://www.readbyqxmd.com/read/29791308/optimal-level-and-order-detection-in-wavelet-decomposition-for-pcg-signal-denoising
#4
Mohamed Rouis, Abdelkrim Ouafi, Salim Sbaa
The recorded phonocardiogram (PCG) signal is often contaminated by different types of noises that can be seen in the frequency band of the PCG signal, which may change the characteristics of this signal. Discrete wavelet transform (DWT) has become one of the most important and powerful tools of signal representation, but its effectiveness is influenced by the issue of the selected mother wavelet and decomposition level (DL). The selection of the DL and the mother wavelet are the main challenges. This work proposes a new approach for finding an optimal DL and optimal mother wavelet for PCG signal denoising...
May 23, 2018: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/29790611/anesthesia-effects-on-the-low-frequency-blood-flow-oscillations-in-mouse-skin
#5
M E Astashev, D A Serov, A V Tankanag
BACKGROUND: When laboratory animals are used one needs to anesthetize them before recording. However, the influence of anesthesia on animal blood flow oscillations has not been studied. The effects of two ways of anesthesia, zoletil-xylazine, and zoletil-nitrous oxide mixtures, on mouse skin perfusion using laser Doppler flowmetry (LDF) technique were studied. METHODS: BALB/c mice were used. LDF probe was placed on the ventral surface of the left hind paw. Spectral analysis of LDF signals was performed with continuous adaptive wavelet transform to identify and describe peripheral blood flow oscillations in mouse skin...
May 23, 2018: Skin Research and Technology
https://www.readbyqxmd.com/read/29785154/detection-of-coronary-artery-disease-by-reduced-features-and-extreme-learning-machine
#6
Ram Sewak Singh, Barjinder Singh Saini, Ramesh Kumar Sunkaria
Objective: Cardiovascular diseases generate the highest mortality in the globe population, mainly due to coronary artery disease (CAD) like arrhythmia, myocardial infarction and heart failure. Therefore, an early identification of CAD and diagnosis is essential. For this, we have proposed a new approach to detect the CAD patients using heart rate variability (HRV) signals. This approach is based on subspaces decomposition of HRV signals using multiscale wavelet packet (MSWP) transform and entropy features extracted from decomposed HRV signals...
2018: Clujul Medical (1957)
https://www.readbyqxmd.com/read/29783139/inspection-of-baked-carbon-anodes-using-a-combination-of-multi-spectral-acousto-ultrasonic-techniques-and-principal-component-analysis
#7
Moez Ben Boubaker, Donald Picard, Carl Duchesne, Jayson Tessier, Houshang Alamdari, Mario Fafard
This paper reports on the application of an acousto-ultrasonic (AU) scheme for the inspection of industrial-size carbon anode blocks used in the production of primary aluminium by the Hall-Héroult process. A frequency-modulated wave is used to excite the anode blocks at multiple points. The collected attenuated AU signals are decomposed using the Discrete Wavelet Transform (DTW) after which vectors of features are calculated. Principal Component Analysis (PCA) is utilized to cluster the AU responses of the anodes...
May 17, 2018: Ultrasonics
https://www.readbyqxmd.com/read/29782490/an-optimized-digital-watermarking-algorithm-in-wavelet-domain-based-on-differential-evolution-for-color-image
#8
Xinchun Cui, Yuying Niu, Xiangwei Zheng, Yingshuai Han
In this paper, a new color watermarking algorithm based on differential evolution is proposed. A color host image is first converted from RGB space to YIQ space, which is more suitable for the human visual system. Then, apply three-level discrete wavelet transformation to luminance component Y and generate four different frequency sub-bands. After that, perform singular value decomposition on these sub-bands. In the watermark embedding process, apply discrete wavelet transformation to a watermark image after the scrambling encryption processing...
2018: PloS One
https://www.readbyqxmd.com/read/29780407/deep-learning-methods-for-underwater-target-feature-extraction-and-recognition
#9
Gang Hu, Kejun Wang, Yuan Peng, Mengran Qiu, Jianfei Shi, Liangliang Liu
The classification and recognition technology of underwater acoustic signal were always an important research content in the field of underwater acoustic signal processing. Currently, wavelet transform, Hilbert-Huang transform, and Mel frequency cepstral coefficients are used as a method of underwater acoustic signal feature extraction. In this paper, a method for feature extraction and identification of underwater noise data based on CNN and ELM is proposed. An automatic feature extraction method of underwater acoustic signals is proposed using depth convolution network...
2018: Computational Intelligence and Neuroscience
https://www.readbyqxmd.com/read/29772891/the-influence-of-urban-heat-islands-and-socioeconomic-factors-on-the-spatial-distribution-of-aedes-aegypti-larval-habitats
#10
Thiago S De Azevedo, Brian Patrick Bourke, Rafael Piovezan, Maria Anice M Sallum
We addressed the potential associations among the temporal and spatial distribution of larval habitats of Aedes (Stegomyia) aegypti, the presence of urban heat islands and socioeconomic factors. Data on larval habitats were collected in Santa Bárbara d'Oeste, São Paulo, Brazil, from 2004 to 2006, and spatial and temporal variations were analysed using a wavelet-based approach. We quantified urban heat islands by calculating surface temperatures using the results of wavelet analyses and grey level transformation from Thematic Mapper images (Landsat 5)...
May 8, 2018: Geospatial Health
https://www.readbyqxmd.com/read/29772820/effective-crack-detection-in-railway-axles-using-vibration-signals-and-wpt-energy
#11
María Jesús Gómez, Eduardo Corral, Cristina Castejón, Juan Carlos García-Prada
Crack detection for railway axles is key to avoiding catastrophic accidents. Currently, non-destructive testing is used for that purpose. The present work applies vibration signal analysis to diagnose cracks in real railway axles installed on a real Y21 bogie working on a rig. Vibration signals were obtained from two wheelsets with cracks at the middle section of the axle with depths from 5.7 to 15 mm, at several conditions of load and speed. Vibration signals were processed by means of wavelet packet transform energy...
May 17, 2018: Sensors
https://www.readbyqxmd.com/read/29768928/automated-daily-quality-control-analysis-for-mammography-in-a-multi-unit-imaging-center
#12
Veli-Matti Sundell, Teemu Mäkelä, Alexander Meaney, Touko Kaasalainen, Sauli Savolainen
Background The high requirements for mammography image quality necessitate a systematic quality assurance process. Digital imaging allows automation of the image quality analysis, which can potentially improve repeatability and objectivity compared to a visual evaluation made by the users. Purpose To develop an automatic image quality analysis software for daily mammography quality control in a multi-unit imaging center. Material and Methods An automated image quality analysis software using the discrete wavelet transform and multiresolution analysis was developed for the American College of Radiology accreditation phantom...
January 1, 2018: Acta Radiologica
https://www.readbyqxmd.com/read/29763824/use-of-continuous-wavelet-transform-approach-for-simultaneous-quantitative-determination-of-multicomponent-mixture-by-uv-vis-spectrophotometry
#13
Mahmoud Reza Sohrabi, Vahid Mirzabeygi, Mehran Davallo
In the present paper, a multicomponent analysis approach based on spectrophotometry method was developed for simultaneous determination of Guaifenesin (GU), Chlorpheniramine (CHL) and Pseudoephedrine (PSE) without any separation steps. The method under study is signal processing method based on Continuous Wavelet Transform (CWT) coupled with zero cross point technique. In this paper, CWT method was tested by synthetic ternary mixtures and was applied to the commercial cough syrup as a real sample and assessed by applying the standard addition technique...
May 8, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29763658/event-related-potential-analysis-techniques-for-autism-spectrum-disorders-a-review
#14
REVIEW
Priyalakshmi Sheela, Subha D Puthankattil
Autism Spectrum Disorders (ASD) comprise all pervasive neurodevelopmental diseases marked by deficits in social and communication skills, delayed cognitive development, restricted and repetitive behaviors. The core symptoms begin in early childhood, may continue life-long resulting in poor performance in adult stage. Event-related potential (ERP) is basically a time-locked electroencephalogram signal elicited by various stimuli, related to sensory and cognitive processes. The various ERP based techniques used for the study of ASD are considered in this review...
May 12, 2018: International Journal of Developmental Neuroscience
https://www.readbyqxmd.com/read/29761978/-synchronous-analysis-of-corticomuscular-coherence-based-on-gabor-wavelet-transfer-entropy
#15
Yuanyuan Zhang, Ce Zou, Xiaoling Chen, Yonghao Yin, Shengcui Cheng, Yingya Chen, Ping Xie
Synchronization analysis of electroencephalogram (EEG) and electromyogram (EMG) could reveal the functional corticomuscular coupling (FCMC) during the motor task in human. A novel method combining Gabor wavelet and transfer entropy (Gabor-TE) is proposed to quantitatively analyze the nonlinearly synchronous corticomuscular function coupling and direction characteristics under different steady-state force. Firstly, the Gabor wavelet transform method was used to acquire the local frequency-band signals of the EEG and EMG signals recorded from nine healthy controls simultaneously during performing grip task with four different steady-state forces...
December 1, 2017: Sheng Wu Yi Xue Gong Cheng Xue za Zhi, Journal of Biomedical Engineering, Shengwu Yixue Gongchengxue Zazhi
https://www.readbyqxmd.com/read/29761953/-epileptic-electroencephalogram-recognition-based-on-discrete-s-transform-and-permutation-entropy
#16
Jianzhao Zhang, Wei Jiang, Hui Yuan, Wei Shang, Shi Liu, Ping Jiao
Electroencephalogram(EEG) analysis has important reference value in the diagnosis of epilepsy. The automatic classification of epileptic EEG can be used to judge the patient's situation in time,which is of great significance in clinical application. In order to solve the problem that the recognition accuracy is not high by using the single feature of EEG signals and avoid the influence of wavelet basis function selection on recognition results,a method of automatic discrimination of epileptic EEG signals based on S transform and permutation entropy is proposed...
October 1, 2017: Sheng Wu Yi Xue Gong Cheng Xue za Zhi, Journal of Biomedical Engineering, Shengwu Yixue Gongchengxue Zazhi
https://www.readbyqxmd.com/read/29760518/theory-of-single-impact-atomic-force-spectroscopy-in-liquids-with-material-contrast
#17
Enrique A López-Guerra, Francesco Banfi, Santiago D Solares, Gabriele Ferrini
Scanning probe microscopy has enabled nanoscale mapping of mechanical properties in important technological materials, such as tissues, biomaterials, polymers, nanointerfaces of composite materials, to name only a few. To improve and widen the measurement of nanoscale mechanical properties, a number of methods have been proposed to overcome the widely used force-displacement mode, that is inherently slow and limited to a quasi-static regime, mainly using multiple sinusoidal excitations of the sample base or of the cantilever...
May 14, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29758974/emotion-recognition-from-multichannel-eeg-signals-using-k-nearest-neighbor-classification
#18
Mi Li, Hongpei Xu, Xingwang Liu, Shengfu Lu
BACKGROUND: Many studies have been done on the emotion recognition based on multi-channel electroencephalogram (EEG) signals. OBJECTIVE: This paper explores the influence of the emotion recognition accuracy of EEG signals in different frequency bands and different number of channels. METHODS: We classified the emotional states in the valence and arousal dimensions using different combinations of EEG channels. Firstly, DEAP default preprocessed data were normalized...
April 27, 2018: Technology and Health Care: Official Journal of the European Society for Engineering and Medicine
https://www.readbyqxmd.com/read/29756041/a-novel-method-of-identifying-motor-primitives-using-wavelet-decomposition
#19
Anton Popov, Erienne V Olesh, Sergiy Yakovenko, Valeriya Gritsenko
This study reports a new technique for extracting muscle synergies using continuous wavelet transform. The method allows to quantify coincident activation of muscle groups caused by the physiological processes of fixed duration, thus enabling the extraction of wavelet modules of arbitrary groups of muscles. Hierarchical clustering and identification of the repeating wavelet modules across subjects and across movements, was used to identify consistent muscle synergies. Results indicate that the most frequently repeated wavelet modules comprised combinations of two muscles that are not traditional agonists and span different joints...
March 2018: ... International Conference on Wearable and Implantable Body Sensor Networks
https://www.readbyqxmd.com/read/29752237/cross-comparison-of-motor-unit-potential-features-used-in-emg-signal-decomposition
#20
Mohsen Ghofrani Jahromi, Hossein Parsaei, Ali Zamani, Daniel W Stashuk
Feature extraction is an important step of resolving an electromyographic (EMG) signal into its component motor unit potential trains, commonly known as EMG decomposition. Until now, different features have been used to represent motor unit potentials (MUPs) and improve decomposition processing time and accuracy, but a major limitation is that no systematic comparison of these features exists. In an EMG decomposition system, like any pattern recognition system, the features used for representing MUPs play an important role in the overall performance of the system...
May 2018: IEEE Transactions on Neural Systems and Rehabilitation Engineering
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