This paper proposes a new omni-directional electromagnetic acoustic transducer (EMAT) for the ultrasonic Lamb wave (ULW) tomography imaging (TI) of defects in metallic plates. The proposed EMAT is composed permanent magnet and coil with contra-flexure structure. structure used ULW transmission reception TI first time. theoretical background working principles this are presented analyzed. experimental results its use on 3 mm thick aluminum plate indicate that (CFC) can transmit receive pure...

As a typical fluid machine, the centrifugal pump system experiences impeller angular misalignment resulting from manufacturing and assembly errors. A new computational dynamics (CFD) simulation model is developed to investigate effect of angle on internal flow characteristics pump. The transient described by applying shear stress transport (SST) k- ω turbulence model. results reveal that an increase in exacerbates inhomogeneity instability. This failure can reduce head efficiency; it...

An omni-directional (OD) magnetostriction-based electromagnetic acoustic transducer (EMAT) is suitable for use in the guided wave (GW) tomography of steel plate defects. Because GW characterized by multiple modes and frequency dispersion, waveforms detected traditional OD EMATs are complex, which substantially reduces accuracy projection data extraction then decreases quality defect quantification. This paper proposes a new EMAT to generate shear-horizontal (SH) GWs special mode reduce...

The saddle pulse‐width modulation (PWM) that can be obtained by injecting third harmonic current into sampled three‐phase input currents is proposed to introduce in the conventional one‐cycle control (OCC) strategy‐based PWMrectifier on this study. In addition, for three‐level boost‐type neutral‐point‐clamped structure rectifiers such as Vienna rectifier, fluctuation neutral‐point‐potential (NPP) analysed under modified OCC strategy. scheme not only improve utilisation of DC bus voltage and...

This work proposes an EMD-based STFT flight time extraction method to recognize the different modes of overlapped Lamb wave detecting signals (OLWDS) in aluminum plate due its dispersion and multi-modes property. Firstly, empirical mode decomposit

Abstract In the present paper, a damage gradient model combing concept with theory of critical distance (TCD) is established to estimate fatigue lives notched metallic structures under multiaxial random vibrations. Firstly, kind structure designed, and biaxial vibration tests are carried out different correlation coefficients phase differences between two axes. Then, evaluated utilizing proposed numerical simulations. Finally, validated by experiment results tests. The comparison demonstrate...

Two characteristics of Chinese mixed traffic invalidate the conventional queuing delay estimates for western countries. First, driving drivers lead to different delays even though other conditions are same. Second, urban flow in China is often hindered by pedestrians at intersections, such that imported intelligent control systems do not work appropriately. Typical were obtained from data over 500 vehicle queues Beijing collected using charge coupled device (CCD) cameras. The results show...

Asymptomatic intracranial atherosclerotic stenosis (aICAS) is a major risk factor for cerebrovascular events. The study aims to construct and validate nomogram predicting the of aICAS. Participants who underwent health examinations at our center from September 2019 August 2023 were retrospectively enrolled. participants randomly divided into training set testing in 7:3 ratio. Firstly, set, least absolute shrinkage selection operator (LASSO) regression multivariate logistic performed select...

To explore the potential benefits of bus priority based on signal phasing strategy, this article proposes a simplified statistical sampling method to simulate vehicle delays at intersections instead using conventional microscopic traffic simulations. This greatly reduces calculation cost and time while maintaining estimation accuracy delay. research provides surrogate testing system tests intuitive strategies that shorten average waiting queuing vehicles by letting certain buses pass...

Modeling of headway/spacing between two consecutive vehicles has many applications in traffic flow theory and transport practice. Most known approaches only study the running on freeways. In this paper, we propose a model to explain spacing distribution queuing front signalized junction based random-matrix theory. We show that recently measured data well fit Gaussian symplectic ensemble (GSE). These results are also compared with observed for car parking problem. Why...

An inverse system method for multi-input multi-output stationary non-Gaussian random vibration test is proposed in the paper to control response characteristics both time-domain and frequency-domain simultaneously. Hence, objectives are not only traditional power spectral densities but also probability distributions. The of distributions more comprehensive reasonable than kurtoses order duplicate measured data because provide partial behaviors nonlinear transformation process introduced...

A new method of estimating the antepartum foetal electrocardiogram (ECG) signal by kernel principal component analysis (PCA) is presented. For ECG signals collected from body surface pregnant woman, powerful maternal most PC, compared with and other noises. Utilising correlation between components in different lead signals, can be removed abdominal to obtain estimation. However, it shows a strong non‐linearity every due diversity propagation path. Kernel PCA seen as non‐linear form which...

Noises always disturb the control effect of an environment test especially in multi-input multi-output (MIMO) systems. If frequency response function matrices are ill-conditioned, noises driving forces will be amplified and spectral lines may awfully exceed their tolerances. Most major biases between spectra reference produced by noises. However, ordinary algorithms can hardly reduce level The influences on both auto- cross-power analyzed this paper. As a conventional domain method inverse...

In the aircraft power systems with 360–800 Hz line frequency or medium‐ and high‐power three‐phase pulse‐width modulation (PWM) rectifier applications operating at utility (50/60 Hz), ratio of switching to will be reduced because increased low frequency. Therefore assumptions that average voltage drop across input inductor PWM rectifiers can neglected if conventional one‐cycle controlled (OCC) method had been adopted no longer true anymore, which deteriorate system factor (PF) dramatically....

This paper mainly studies about the road user's behavior when crossing urban intersection, including confliction patterns among motors, non-motors and pedestrians, influence on motor vehicles of non-motors' pedestrians' violating behavior, departure headways with without disturbance signalized intersection. Most researchers pay much attention to work planning method or control strategy, bring forward various simulating models, but no deeper researches vehicles, non-motor pedestrians are...

Facing the difficulty of carrying out optimum inspection defects and optimization design Kwun's magnetostrictive transducer, a new transducer configuration is proposed. The mutilple-belts coils are used as transmitting coil receiving coil. This kind often in electromagnetic ultrasonic (EMAT), but it for tansducer firstly. To verify performance several experiments were performed. results show that proposed not only could tune center frequency also improve amplitude signal-to-noise (SNR)...

This study describes an integrated approach for fetal heart beat detection from abdominal ECG signals. The signal is first processed by the first-order difference operation, and then, envelope of differentiated given Hilbert transform, which indicates both maternal beats. After that, non-linear state-space projections applied to remove beats, obtaining beats envelope. validity performance described method are confirmed through experiments on real data. A comparison with well-known...

A new method of estimating the heart rate (HR) from electrocardiogram (ECG) signals, which accurately estimates fundamental frequency heartbeat using iterative Fourier interpolation algorithm, is presented. This frequency‐domain has two advantages: (i) algorithm could improve estimation precision significantly without increasing recording signal length, monitor HR variability; (ii) low, usually between 1 and 2 Hz; thus, required ECG can be acquired at a low sampling frequency, such as 20–30...