Determinations of Stress Wave Velocity in a Timber Pole using Wavelet Transform

This paper presents an application of Wavelet Transfonn (WT) for determination of stress wave velocity for Non-destructive Testing of timber utility poles in service. For surface Non-destructive Testing (NDT), the hammer impact, which produces generally broadband frequency excitation, is used to generate stress wave. Moreover, due to practicality the impact location for field testing of a utility pole is on the side of the pole and 1.5 m above ground level. And the geometry of utility pole could not guarantee non-dispersive longitudinal wave. All of these issues have resulted in lack of accuracy and reliability of results from surface NDT in field testing. In recognition of such problem, this research explores methods to reliably calculate desired wave velocity by isolating wave mode and studying dispersive nature of utility pole. Fast Fourier Transform (FFT) is firstly conducted to determine the suitable frequency from a stress wave data. Then WT is applied on the wave data mentioned to perform time-frequency analysis. Velocity can be determined by time history data of desired frequency from WT results which will be compared with the available analytical solution for longitudinal wave velocity. The results of the investigation showed that wavelet transform analysis can be a reliable signal processing tool for non-destructive testing in terms of velocity determination, which in turn also helps to determine the embedded length of the timber pole

Condition assessment of timber utility poles based on a hierarchical data fusion model

© 2016 American Society of Civil Engineers. This paper proposes a novel hierarchical data fusion technique for the non-destructive testing (NDT) and condition assessment of timber utility poles. The new method analyzes stress wave data from multisensor and multiexcitation guided wave testing using a hierarchical data fusion model consisting of feature extraction, data compression, pattern recognition, and decision fusion algorithms. The researchers validate the proposed technique using guided wave tests of a sample of in situ timber poles. The actual health states of these poles are known from autopsies conducted after the testing, forming a ground-truth for supervised classification. In the proposed method, a data fusion level extracts the main features from the sampled stress wave signals using power spectrum density (PSD) estimation, wavelet packet transform (WPT), and empirical mode decomposition (EMD). These features are then compiled to a feature vector via real-number encoding and sent to the next level for further processing. Principal component analysis (PCA) is also adopted for feature compression and to minimize information redundancy and noise interference. In the feature fusion level, two classifiers based on support vector machine (SVM) are applied to sensor separated data of the two excitation types and the pole condition is identified. In the decision making fusion level, the Dempster-Shafer (D-S) evidence theory is employed to integrate the results from the individual sensors obtaining a final decision. The results of the in situ timber pole testing show that the proposed hierarchical data fusion model was able to distinguish between healthy and faulty poles, demonstrating the effectiveness of the new method

Behaviour of stress wave propagation in utility timber pole

Non-destructive testing has been used for many years to evaluate the in situ condition of timber piles. Longitudinal impact is usually applied on the top of piles to induce longitudinal wave to detect faults in piles due to the fact that the longitudinalwave has less dispersive nature at lowfrequency. On the other hand,when it comes to evaluation of poles in situ, it is different as poles are partly embedded in soil and it is more practical to produce bending waves, as the top of the pole is not easily accessible. However, bending wave is known for its highly dispersive nature; especially in the low frequency range which is usually induced in low strain integrity testing. As bending wave can be considered as a hybrid of longitudinal and shear waves, it will be helpful, if it could detect the component of these twowaves separately.To do so, components of displacements or accelerations along radial and longitudinal directions need to be determined. By applying Fast Fourier Transform (FFT) on the signals, the dominant frequencies can be obtained. It has been found that, the longitudinal component decreases along radial direction which indicates the presence of bending wave component and this finding allows to the application of ContinuousWavelet Transform (CWT) on the longitudinal component of wave signals in order to obtain phase velocity. Phase velocities at different frequencies are then determined to draw the dispersive curve and compare with analytical phase velocity curve. The dispersion curve matched well with the analytical curve. © 2013 Taylor & Francis Group

Analysis of the burden and economic impact of digestive diseases and investigation of research gaps and priorities in the field of digestive health in the European Region—White Book 2: Executive summary

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Automated health condition diagnosis of in situ wood utility poles using an intelligent non-destructive evaluation (NDE) framework

© 2020 World Scientific Publishing Company. Wood utility poles are widely applied in power transmission and telecommunication systems in Australia. Because of a variety of external influence factors, such as fungi, termite and environmental conditions, failure of poles due to the wood degradation with time is of common occurrence with high degree uncertainty. The pole failure may result in serious consequences including both economic and public safety. Therefore, accurately and timely identifying the health condition of the utility poles is of great significance for economic and safe operation of electricity and communication networks. In this paper, a novel non-destructive evaluation (NDE) framework with advanced signal processing and artificial intelligence (AI) techniques is developed to diagnose the condition of utility pole in field. To begin with, the guided waves (GWs) generated within the pole is measured using multi-sensing technique, avoiding difficult interpretation of various wave modes which cannot be detected by only one sensor. Then, empirical mode decomposition (EMD) and principal component analysis (PCA) are employed to extract and select damage-sensitive features from the captured GW signals. Additionally, the up-to-date machine learning (ML) techniques are adopted to diagnose the health condition of the pole based on selected signal patterns. Eventually, the performance of the developed NDE framework is evaluated using the field testing data from 15 new and 24 decommissioned utility poles at the pole yard in Sydney

Biogeographic history of the pantropical family Gesneriaceae with a focus on the Indian plate and diversification through the Old World

The Gesneriaceae consists of around 150 genera and c. 3750 species with a predominantly tropical and subtropical distribution across all continents. Although previous studies have proposed an American origin of Gesneriaceae, the biogeographic history of this pantropical plant family is still unclear, particularly in the Old World. To address this, we assembled the most comprehensively sampled matrix of Gesneriaceae with 143 Gesneriaceae genera and 355 species, including key samples from Sri Lanka analysed here for the first time. We generated molecular phylogenies based on four plastid gene regions (ndhF, matK, rps16 and trnL-F), obtained fossil-calibrated trees, and reconstructed ancestral areas and dispersal routes using Bayesian methods. Our results confirm the origin for the family in the Early Palaeocene (67. Ma) in the region of present-day Central America & Andean South America, and that diversity in the Old World originated from a long-distance dispersal event from South America around 59 Ma, most likely to the Indian plate, which was an island at the time. This lineage then dispersed to Malesia and later East Asia, which would ultimately become a major centre of diversity and source of many dispersals to other regions. Our results thus highlight the Indian plate as a likely key player in the early diversification of Old World Gesneriaceae, even though it is now more diverse elsewhere, and hence offer novel insights into this plant family’s dispersal routes and areas of diversification in the Old World

Transient Elastography in Community Alcohol Services: Can It Detect Significant Liver Disease and Impact Drinking Behaviour?

Introduction: Alcohol is the leading cause of cirrhosis in Western populations. The early identification of high-risk drinkers followed by intervention is an effective way to reduce harm. We aim to assess the feasibility of integrating transient elastography (TE) into community alcohol services, and to determine its impact on modifying drinking behaviours. Method: A prospective cohort study was conducted at a community alcohol clinic in Nottingham, UK (April 2012 to March 2014). Patients (>18 years) with a primary alcohol problem were recruited. Those known to liver services or those known to have chronic liver disease were excluded. Significant liver fibrosis was defined by a liver stiffness of >8 kilopascal (kPa). Follow-up was for a minimum of six months. Data were descriptively analysed for significant differences between patients with a normal liver stiffness versus raised liver stiffness. Results: 156 patients were invited; n = 87 attended and n = 86 underwent successful TE. The majority were male (n = 53, 70.0%), and the mean age was 46.3 years (SD ± 9.8). Median liver stiffness was 6.9 kPa (range 3.1–75.0kPa). Clinically significant liver fibrosis was identified in n = 33 (38.4%), of which n = 6 were in the cirrhotic range (≥15 kPa). The baseline median self-reported alcohol intake for normal stiffness was 126 units per week (range 24–378) and in raised stiffness was 149.0 units per week (range 39.0–420.0); this difference was nonsignificant (p = 0.338). The median reduction in self-reported alcohol intake in the whole cohort was 65.0 units per week (range 27.0–88.0, p < 0.001); in the normal liver stiffness group it was 25.0 units per week (range 18.0–75.0, p = 0.154), and in the raised liver stiffness group it was 78.5 units per week (range 36.0–126.0, p < 0.001). Conclusion: The study demonstrated that transient elastography is a feasible tool to stratify clinically significant liver disease in community alcohol services. It can stimulate a change in high-risk drinking behaviour and a normal liver stiffness result does not provide false reassurance to participants

Внедрение и принцип работы системы сейсмического мониторинга горного массива для работы в условиях ООО "Шахта "Усковская"

The status of the Silicon Microvertex Detector (SMD) and its installation into the LEP-L3 experiment are presented, highlighting novel features and sophisticated techniques. Preliminary results based on 1993 data are given and compared with Monte Carlo predictions, to understand the detector performances and its tracking capabilities

Genomic insights into rapid speciation within the world’s largest tree genus Syzygium

Species radiations, despite immense phenotypic variation, can be difficult to resolve phylogenetically when genetic change poorly matches the rapidity of diversification. Genomic potential furnished by palaeopolyploidy, and relative roles for adaptation, random drift and hybridisation in the apportionment of genetic variation, remain poorly understood factors. Here, we study these aspects in a model radiation, Syzygium, the most species-rich tree genus worldwide. Genomes of 182 distinct species and 58 unidentified taxa are compared against a chromosome-level reference genome of the sea apple, Syzygium grande. We show that while Syzygium shares an ancient genome doubling event with other Myrtales, little evidence exists for recent polyploidy events. Phylogenomics confirms that Syzygium originated in Australia-New Guinea and diversified in multiple migrations, eastward to the Pacific and westward to India and Africa, in bursts of speciation visible as poorly resolved branches on phylogenies. Furthermore, some sublineages demonstrate genomic clines that recapitulate cladogenetic events, suggesting that stepwise geographic speciation, a neutral process, has been important in Syzygium diversification