Slope entropy (SlEn) is a time series complexity indicator proposed in recent years, which has shown excellent performance in the fields of medical and hydroacoustics. In order to improve the ability ...of SlEn to distinguish different types of signals and solve the problem of two threshold parameters selection, a new time series complexity indicator on the basis of SlEn is proposed by introducing fractional calculus and combining particle swarm optimization (PSO), named PSO fractional SlEn (PSO-FrSlEn). Then we apply PSO-FrSlEn to the field of fault diagnosis and propose a single feature extraction method and a double feature extraction method for rolling bearing fault based on PSO-FrSlEn. The experimental results illustrated that only PSO-FrSlEn can classify 10 kinds of bearing signals with 100% classification accuracy by using double features, which is at least 4% higher than the classification accuracies of the other four fractional entropies.
•Intrathecal injection DAPT suppressed Notch signaling and relieved vincristine-induced neuropathic pain.•Inactivated Notch signaling could suppress microglial CX3CR1/P38 MAPK pathway to effect pain ...formation.•Notch signaling pathway could be a potential therapeutic target to alleviate neuropathic pain.
Chemotherapy-induced peripheral neuropathy (CIPN) has a adverse impact to the living quality of cancer patients. This side effect of CIPN limit the dose of drug used in many chemotherapies, such as vincristine (VCR). The activation of microglia in the spinal dorsal horn is involved in the occurrence and development of neuropathic pain induced by VCR. Recent study has demonstrated that hypoxia induced microglia activation depends on Notch signaling, and it is involved in the release of many inflammatory related factors in microglia. In this work, we aimed to study that the role of Notch signaling pathway in microglia activation on a VCR-induced neuropathy rat model. Our results showed that the mechanical, thermal and cold pain threshold of rats was decreased by treatment of VCR, but N-N-(3,5-difluorophenacetyl)-l-alanyl-S-phenylglycine t-butyl ester (DAPT), a γ-secretase inhibitor, relieved the hyperalgesia. Molecular analysis showed that activation of Notch signaling pathway increased after nerve injury and that DAPT could significantly inhibit the upregulation of Notch signaling pathway, the activation of microglia, and the release of pro-inflammatory cytokines in the spinal. Taking together, Notch signaling pathway could be a potential therapeutic target to alleviate neuropathic pain.
Slope entropy (Slopen) has been demonstrated to be an excellent approach to extracting ship-radiated noise signals (S-NSs) features by analyzing the complexity of the signals; however, its ...recognition ability is limited because it extracts the features of undecomposed S-NSs. To solve this problem, in this study, we combined complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) to explore the differences of Slopen between the intrinsic mode components (IMFs) of the S-NSs and proposed a single-IMF optimized feature extraction approach. Aiming to further enhance its performance, the optimized combination of dual-IMFs was selected, and a dual-IMF optimized feature extraction approach was also proposed. We conducted three experiments to demonstrate the effectiveness of CEEMDAN, Slopen, and the proposed approaches. The experimental and comparative results revealed both of the proposed single- and dual-IMF optimized feature extraction approaches based on Slopen and CEEMDAN to be more effective than the original ship signal-based and IMF-based feature extraction approaches.
Warships play an important role in the modern sea battlefield. Research on the line spectrum features of warship radio noise signals is helpful to realize the classification and recognition of ...different types of warships, and provides critical information for sea battlefield. In this paper, we proposed a novel linear spectrum frequency feature extraction technique for warship radio noise based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN), duffing chaotic oscillator (DCO), and weighted-permutation entropy (W-PE). The proposed linear spectrum frequency feature extraction technique, named CEEMDAN-DCO-W-PE has the following advantages in comparison with other linear spectrum frequency feature extraction techniques; (i) as an adaptive data-driven algorithm, CEEMDAN has more accurate and more reliable decomposition performance than empirical mode decomposition (EMD) and ensemble EMD (EEMD), and there is no need for presetting parameters, such as decomposition level and basis function; (ii) DCO can detect the linear spectrum of narrow band periodical warship signals by way of utilizing its properties of sensitivity for weak periodical signals and the immunity for noise; and (iii) W-PE is used in underwater acoustic signal feature extraction for the first time, and compared with traditional permutation entropy (PE), W-PE increases amplitude information to some extent. Firstly, warship radio noise signals are decomposed into some intrinsic mode functions (IMFs) from high frequency to low frequency by CEEMDAN. Then, DCO is used to detect linear spectrum of low-frequency IMFs. Finally, we can determine the linear spectrum frequency of low-frequency IMFs using W-PE. The experimental results show that the proposed technique can accurately extract the line spectrum frequency of the simulation signals, and has a higher classification and recognition rate than the traditional techniques for real warship radio noise signals.
A new denoising algorithm and feature extraction algorithm that combine a new kind of permutation entropy (NPE) and variational mode decomposition (VMD) are put forward in this paper. VMD is a new ...self-adaptive signal processing algorithm, which is more robust to sampling and noise, and also can overcome the problem of mode mixing in empirical mode decomposition (EMD) and ensemble EMD (EEMD). Permutation entropy (PE), as a nonlinear dynamics parameter, is a powerful tool that can describe the complexity of a time series. NPE, a new version of PE, is interpreted as distance to white noise, which shows a reverse trend to PE and has better stability than PE. In this paper, three kinds of ship-radiated noise (SN) signal are decomposed by VMD algorithm, and a series of intrinsic mode functions (IMF) are obtained. The NPEs of all the IMFs are calculated, the noise IMFs are screened out according to the value of NPE, and the process of denoising can be realized by reconstructing the rest of IMFs. Then the reconstructed SN signal is decomposed by VMD algorithm again, and one IMF containing the most dominant information is chosen to represent the original SN signal. Finally, NPE of the chosen IMF is calculated as a new complexity feature, which constitutes the input of the support vector machine (SVM) for pattern recognition of SN. Compared with the existing denoising algorithms and feature extraction algorithms, the effectiveness of proposed algorithms is validated using the numerical simulation signal and the different kinds of SN signal.
(1) Background: Numerous meta-analyses have shown that a high intake of dietary fiber plays a protective role in preventing the development of various types of cancer. However, previous studies have ...been limited by focusing on a single type of dietary fiber and variations in outcome measures, which may not be effectively applied to provide dietary guidance for the general population. (2) Object: We summarized the meta-analysis of dietary fiber and cancer, and provided references for residents to prevent cancer. (3) Methods: Systematic search of relevant meta-analyses on the association between dietary fiber and cancer occurrence in PubMed, Web of Science and other databases was conducted from the time of database construction to February 2023. The method logical and evidence quality assessments were performed by applying the criteria in the "A Measurement Tool to Assess Systematic Reviews-2" (AMSTAR2) scale and the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) Expert Report, respectively. (4) Results: Our analysis included 11 meta-analyses, and the AMSTAR 2 assessment revealed that the overall methodological quality was suboptimal, with two key items lacking sufficient information. Nonetheless, our findings indicate that a high intake of dietary fiber is associated with a reduced risk of several types of cancer, including esophageal, gastric, colon, rectal, colorectal adenoma, breast, endometrial, ovarian, renal cell, prostate, and pancreatic cancers. The majority of these associations were supported by a "probable" level of evidence. (5) Conclusions: Dietary fiber intake has different protective effects on different cancers.
The fractal dimension (FD) is a classical nonlinear dynamic index that can effectively reflect the dynamic transformation of a signal. However, FD can only reflect signal information of a single ...scale in the whole frequency band. To solve this problem, we combine refined composite multi-scale processing with FD and propose the refined composite multi-scale FD (RCMFD), which can reflect the information of signals at a multi-scale. Furthermore, hierarchical RCMFD (HRCMFD) is proposed by introducing hierarchical analysis, which successfully represents the multi-scale information of signals in each sub-frequency band. Moreover, two ship-radiated noise (SRN) multi-feature extraction methods based on RCMFD and HRCMFD are proposed. The simulation results indicate that RCMFD and HRCMFD can effectively discriminate different simulated signals. The experimental results show that the proposed two-feature extraction methods are more effective for distinguishing six types of SRN than other feature-extraction methods. The HRCMFD-based multi-feature extraction method has the best performance, and the recognition rate reaches 99.7% under the combination of five features.
When leakage occurs for natural gas pipelines, acoustic waves generated at the leakage point will propagate to both ends of the pipe, which will be measured and processed to detect and locate the ...leakage. When acoustic waves propagate in the gas, the amplitude will attenuate and the waveform will spread, which decides the installation distance of acoustic sensors. Therefore, computational fluid dynamic (CFD) simulation research on the acoustic wave propagation model is accomplished and verified by experiments to provide the foundation for the acoustic leak location method. The propagation model includes two parts: amplitude attenuation model and waveform spreading model. Both can be obtained by the established CFD simulation model. Additionally, the amplitude attenuation model can be verified by the experiments. Then, the simulation method is applied to conclude the propagation model under variable conditions, including different flow directions, Reynolds numbers, and diameters. Finally, the experimental demonstration of the leak location based on the propagation model is given. The results indicate that not only the gas viscosity but also the gas flow can influence the propagation model, and the leak location method based on the propagation model is effective. Conclusions can be drawn that CFD simulation on the propagation model for natural gas pipelines is an efficient way to carry out research and provide the theoretical basis for acoustic leak location method application.
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Natural gas hydrates can readily form in deep-water oil production processes and pose a great threat to the oil industry. Moreover, the coexistence of hydrate and asphaltene can ...result in more severe challenges to subsea flow assurance. In order to study the effects of asphaltene on hydrate growth at the oil–water interface, a series of micro-experiments were conducted in a self-made reactor, where hydrates nucleated and grew on the surface of a water droplet immersed in asphaltene-containing oil. Based on the micro-observations, the shape and growth rate of the hydrate shell formed at the oil–water interface were mainly investigated and the effects of asphaltene on hydrate growth were analyzed. According to the experimental results, the shape of the water droplet and the interfacial area changed significantly after the formation of the hydrate shell when the asphaltene concentration was higher than a certain value. A mechanism related to the reduction of the interfacial tension caused by the absorption of asphaltenes on the interface was proposed for illustration. Moreover, the growth rate of the hydrate shell decreased significantly with the increasing asphaltene concentration under experimental conditions. The conclusions of this paper could provide preliminary insight how asphaltene affect hydrate growth at the oil–water interface.
Intermittent flow is one of the most complex flow patterns in gas-liquid two-phase flow in pipelines. The leakage of pipeline intermittent flow poses a threat to the operating safety. In order to ...improve the application of acoustic method to gas-liquid two-phase leakage detection, the amplitude characteristics and propagation velocity of dynamic pressure wave of intermittent flow for gas-liquid two-phase pipeline leakage were investigated. Experiments with conditions of superficial liquid velocity (vsL) from 0.57 m/s to 1.06 m/s, superficial gas velocity (vsG) from 0.3 m/s to 4.47 m/s, leakage aperture from 4 mm to 9 mm were carried out, and the characteristics were studied by time-domain analysis, frequency-domain analysis and time-frequency analysis. The propagation velocity formula of dynamic pressure wave in two-phase medium was fitted based on Levenberg-Marquardt algorithm, and the propagation velocity of straight pipe and elbow pipe was discussed. The experimental results indicate that the peak-to-peak value of dynamic pressure wave measured by sensor within 4.25 m increases during top or mid sustained leakage when leak aperture is larger than 4 mm in elongated bubble flow and 6 mm in slug flow. The amplitude of sustained leakage dynamic pressure increases as gas flow rate increases. The low frequency energy of signal increases immediately when leakage occurs, the energy of signal mainly concentrates at 0–15 Hz, the frequency amplitude of sustained leakage signal is much higher than normal flow signal and leak occur signal. As the gas volume fraction β increases from 0.23 to 0.75, the dynamic pressure propagation velocity decreases from 33.13 m/s to 26.5 m/s and then increases from 26.5 m/s to 66.25 m/s. The propagation velocity increases when it flows through an elbow pipe section. The results are meaningful for further study of two-phase pipeline slug flow leakage detection and location.
•Experiments of gas-liquid two-phase intermittent flow leak-detection based dynamic pressure is carried out.•Time-frequency analysis of leakage signal is performed based on generalized S-transformation.•Velocity propagation formula is fitted based on Levenberg-Marquardt algorithm.•Detecting method and dynamic pressure sensor arrangement suggestion is given for leak-detection.
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