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Background & aims: Polycystic ovary syndrome (PCOS) is a common endocrine syndrome, and obesity is the most common clinical manifestation of PCOS. Acupuncture therapy has shown great success in the treatment of PCOS, but the mechanism of acupuncture therapy in the treatment of patients with PCOS remains unclear. The biological mechanism of acupuncture therapy is vastly different from western drugs; thus, we aimed to compare the key metabolic pathways, including citric acid and glucose metabolism in acupuncture therapy. Methods Sixty patients with obese polycystic ovary syndrome were randomly distributed into three groups; patients receiving (1) acupuncture treatment alone, (2) conventional western medicine treatment, and (3) acupuncture combined with western medicine treatment. A targeted metabolomics approach was used to identify small molecules and metabolites related to glucose metabolism in the serum of each group, and ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was used to analyze different metabolic fractions. Results Acupuncture treatment reduced mitochondrial dysfunction and oxidative damage in the liver, and decreased insulin resistance in PCOS patients by reducing the production of many metabolites involved in the tricarboxylic acid cycle (TCA cycle), such as citric acid and succinic acid. Acupuncture therapy also regulated glycolysis and gluconeogenesis pathways upstream of the TCA cycle. Activating the enzymes involved in the key glycolytic pathways and reducing the production of lactate improved the pathological conditions (impaired energy metabolism, insulin resistance, and obesity) in patients with PCOS. Conclusions Acupuncture treatment improved the levels of sex hormones and energy metabolism by downregulating the TCA cycle activity and modulating glycolytic and gluconeogenic pathways. However, the intervention effects on the metabolic pathways were different between patients receiving combination therapy and patients receiving acupuncture therapy alone, suggesting that the dominant modulatory effect of western drugs may largely conceal the efficacy of acupuncture intervention.

Recently the direct TOF Lidar receivers employ cell averaging constant false alarm rate (CA-CFAR) technique to determine the threshold for the reflected pulses. CA-CFAR locally estimates the mean level of the noise from a predefined interval. The length of this interval is determined by a fixed number of reference cells. CA-CFAR with small number of reference cells fails to detect long distance objects. Conversely, setting reference cells to a large number can’t resolve closely spaced objects even at short distances. This paper presents an adaptive CA-CFAR adaptively determining the optimal number of reference cells. Simulation results show the capability of the proposed method to do both detecting long distance objects and resolving closely spaced objects at short distances.

Accurate average flow velocity determination is essential for flow measurement in many industries, including automotive, chemical, and oil and gas. The ultrasonic transit-time method is common for average flow velocity measurement, but current limitations restrict measurement accuracy, including fluid dynamic effects from unavoidable phenomena such as turbulence, swirls or vortices, and systematic flow meter errors in calibration or configuration. A new spatial averaging method is proposed, based on flexural ultrasonic array transducer technology, to improve measurement accuracy and reduce the uncertainty of the measurement results. A novel two-dimensional flexural ultrasonic array transducer is developed to validate this measurement method, comprising eight individual elements, each forming distinct paths to a single ultrasonic transducer. These paths are distributed in two chordal planes, symmetric and adjacent to a diametral plane. It is demonstrated that the root-mean-square deviation of the average flow velocity, computed using the spatial averaging method with the array transducer is 2.94%, which is lower compared to that of the individual paths ranging from 3.65% to 8.87% with an average of 6.90%. This is advantageous for improving the accuracy and reducing the uncertainty of classical single-path ultrasonic flow meters, and also for conventional multi-path ultrasonic flow meters through the measurement via each flow plane with reduced uncertainty. This research will drive new developments in ultrasonic flow measurement in a wide range of industrial applications. View Full-Text\ud

The calculation of the averaged flow velocity along an ultrasonic path is the core step in ultrasonic transit-time flow measurement. The conventional model for calculating the path-averaged velocity does not consider the influence of the flow velocity on the propagation direction of the ultrasonic wave and can introduce error when the sound speed is not much greater than the flow velocity. To solve this problem, a new mathematical model covering the influence of the flow velocity is proposed. It has been found that the same mathematical expressions of the path-averaged flow velocity, as a function of the absolute time-of-flight (ToFs) of ultrasonic waves travelling upstream and downstream, can be derived based on either of the models. However, the expressions as a function of the time difference (the relative ToF) between the ultrasonic waves travelling upstream and downstream derived by the two models are completely different. Flow tests are conducted in a calibrated flow rig utilising air as flowing medium. Experimental results demonstrate that the path-averaged flow velocities, calculated using either the relative or the absolute ToFs based on the new model, are much more consistent and stable, whereas those calculated based on the conventional model have shown evident and increasing discrepancy when the flow velocity exceeds 15 m/s. When the flow velocity is around 39.45 m/s, the discrepancy is as high as 0.38 m/s. As the relative ToF can be more accurately, reliably and conveniently measured in real applications, the proposed mathematical model has a great potential for the increase of the accuracy of the ultrasonic transit-time flowmeters, especially for the applications such as the measurement of fluids with high flow velocities.\ud

Increasing the inspection quality and speed is essential in manufacturing applications, especially for large structures (e.g. modern aircrafts). Traditional ultrasonic manual scanning can be comprehensive, but lacks repeatability and is time-consuming. Several robotic non-destructive testing systems have been developed in recent years. Although high inspection rates have been achieved by the use of robotic arms, there is the need to furtherly increase the inspection speeds, to cope with the current industrial demands. For systems delivering robotic ultrasonic inspection through phased array probes, the current bottleneck is given by the time required to electrically fire all elements of the phased array probes, which limits the maximum scanning speed of the automated manipulators. This paper discusses the development of a multi-aperture beamforming method to focus the beam with multiple focusing points at a single firing. This work investigates this approach and the influence of different aperture excitations on the data quality. Experiments have been carried out using a 5MHz 32-element phased array probe manipulated by a KUKA robot. The results highlight the possibility to significantly improve the speed of automated inspection compared to linear beamforming, without compromising the inspection quality.Increasing the inspection quality and speed is essential in manufacturing applications, especially for large structures (e.g. modern aircrafts). Traditional ultrasonic manual scanning can be comprehensive, but lacks repeatability and is time-consuming. Several robotic non-destructive testing systems have been developed in recent years. Although high inspection rates have been achieved by the use of robotic arms, there is the need to furtherly increase the inspection speeds, to cope with the current industrial demands. For systems delivering robotic ultrasonic inspection through phased array probes, the current bottleneck is given by the time required to electrically fire all elements of the phased array probes, which limits the maximum scanning speed of the automated manipulators. This paper discusses the development of a multi-aperture beamforming method to focus the beam with multiple focusing points at a single firing. This work investigates this approach and the influence of different aperture excitat...

In this study, three aluminium samples produced by wire + arc additive manufacture (WAAM) are inspected using ultrasonic phased array technology. Artificial defects are machined using a centre drill, ø 3 mm, and electrical discharge machining (EDM), ø 0.5-1 mm, in a cylindrical through-hole topology. The samples are first inspected using a single-element wheel probe mounted on a KUKA robot in order to investigate the feasibility of using a conventional ultrasonic transducer approach. Unfortunately, the wheel probe is found to be unsuitable for scanning the WAAM specimens and ultrasonic phased arrays are employed next. The set-up includes 5 MHz and 10 MHz arrays (128 elements) in direct contact with the sample surface using both the conventional and total focusing method (TFM) imaging techniques. Using an FIToolbox (Diagnostic Sonar, UK) as the controller, a phased array aperture of 32 elements is used to perform a focused B-scan with a range of settings for the transmit focal depth. All of the reflectors (including those located near the WAAM top surface) are successfully detected with a combination of conventional phased array and TFM, using a range of settings and set-ups, including bottom surface inspection, application through a plexiglass wedge and variation of the scanning frequency.

Specimens with intentionally embedded weld defects or flaws can be employed for training, ‎development and research into ‎procedures for mechanical property evaluation and ‎structural integrity assessment. It is critical that the artificial defects are ‎a realistic ‎representation of the flaws produced by welding. Cylindrical holes, which are usually ‎machined after welding, ‎are not realistic enough for our purposes as it is known that they ‎are easier to detect than the naturally occurring ‎imperfections and cracks. Furthermore, it is ‎usually impractical to machine a defect in a location similar to where the real ‎weld defects ‎are found. For example, electro-discharge machining can produce a through hole ‎‎(cylindrical reflector) which ‎neither represents the weld porosity (spherical voids) nor the ‎weld crack (planar thin voids).‎‏ ‏In this study, the aim is to ‎embed reflectors inside the weld intentionally, and then locate ‎them using ultrasonic phased array imaging. The specimen is ‎an 8 mm thick 080A15 ‎Bright Drawn Steel plate of length 300 mm. Tungsten rods (ø2.4-3.2 mm & length 20-25 ‎mm) and ‎tungsten carbide balls (ø4 mm) will be used to serve as reflectors simulating ‎defects within the weld itself. This study is ‎aligned to a larger research project investigating ‎multi-layer metal NDE found in many multi-pass welding and wire arc ‎additive ‎manufacturing (WAAM) applications and as such, there is no joint preparation as the first ‎layer is deposited over ‎the plate surface directly and subsequent layers contribute to the ‎specimen build profile, similar to the WAAM samples. A ‎tungsten inert gas welding torch ‎mounted on a KUKA robot is used to deposit four layers for each weld, with our process ‎‎using nine passes for the first layer, down to six passes for the last layer. During this procedure, ‎the tungsten artificial ‎reflectors are embedded in the weld, between the existing layers. The ‎sample is then inspected by a 10 MHz ultrasonic ‎phased array in direct contact with the ‎sample surface using both conventional and total focusing method (TFM) imaging ‎‎techniques. A phased array aperture of 32 elements has been used. The phased array ‎controller is FIToolbox (Diagnostic ‎Sonar, UK). Firstly, a focused B-scan has been ‎performed with a range of settings for the transmit focal depth. Secondly, a ‎full-aperture ‎TFM method has been processed. All the reflectors of interest were detected successfully ‎using this ‎combination of B-scan and TFM imaging approaches.‎

Increased demands in performance and production rates require a radical new approach to the design and manufacturing of aircraft wings. Performance of modern robotic manipulators has enabled research and development of fast automated non-destructive testing (NDT) systems for complex geometries. This paper presents recent outcomes of work aimed at removing the bottleneck due to data acquisition rates, to fully exploit the scanning speed of modern 6-DoF manipulators. The geometric assessment of the parts is carried out with a robotised dynamic laser scanner encoded through an absolute laser tracker. This method allows scanning speeds up to 330mm/s at 1mm pitch. State of the art ultrasonic instrumentation has been integrated into a large robot cell to enable fast data acquisition, high scan resolutions and accurate positional encoding. A fibre optic connection between the ultrasonic instrument and the server computer enables data transfer rates up to 1.6 GB/s. The robotic inspection system presented herein is currently being tested for industrial exploitation. The adopted system integration strategies allow traditional ultrasonic phased array scanning as well as full matrix capture (FMC) and other novel scanning approaches (e.g. multi-Tx phased array). Scan results, relative to a 1.2m x 3m carbon fibre sample, are presented. The system shows a reference scanning rate of 25.3m2/hour with an 8Tx/8Rx PA approach and an ultrasonically reachable scanning rate over 100m2/hour with the novel techniques.

The seamless integration of industrial robotic arms with server computers, sensors and actuators can revolutionize the way automated Non-Destructive Testing (NDT) is performed and conceived. Achieving effective integration and the full potential of robotic systems presents significant challenges, since robots, sensors and end-effector tools are often not necessarily designed to be put together and form a holistic system. This paper presents recent breakthroughs, opening up new scenarios for the inspection of product quality in advanced manufacturing. Many years of research have brought to software platforms the ability to integrate external data acquisition instrumentation with industrial robots for improving the inspection speed, accuracy and repeatability of NDT. Robotic manipulators have typically been operated by predefined tool-paths generated through off-line path-planning software applications. Recent developments pave the way to data-driven autonomous robotic inspections, enabling real-time path planning and adaptive control. This paper presents a toolbox with highly efficient algorithms and software functions, developed to be used through high-level programming languages (e.g. MATLAB, LabVIEW, Python) and/or integrated with low-level languages (e.g. C#, C++) applications. The use of the toolbox can speed-up the development and the robust integration of new robotic NDT systems with real-time adaptive capabilities and is compatible with all 6-DOF KUKA robots, which are equipped with Robot Sensor Interface (RSI) software add-on. The paper describes the architecture of the toolbox and shows two application examples, where performance results are provided. The concepts described in the paper are aligned with the emerging Industry 4.0 paradigms and have wider applicability beyond NDT.

The arrival time detection probability and the measurement range of transit-time ultrasonic flow meters are undermined by the sound drift effect. One solution to this problem is utilizing a phased-array beam steering technique to compensate the bend of the ultrasonic beams. The design, the fabrication and the characterization of two-dimensional flexural ultrasonic phased arrays is investigated in this paper. A meter body with an inner diameter of 146 mmis machined to accommodate the arrays, and flow tests are carried out at different flow rates ranging from 0 to 2500 m 3 /h. Experimental results indicate that, with the increase of flow rate, the optimum steering angle of arrays increases from 30° to 40.5° when ultrasonic beams travel upstream and decreases from 30° to 22.5° when ultrasonic beams travel downstream. This proof-of-concept design demonstrates the potential of the flexural ultrasonic phased array as an accurate, economic, efficient, and robust solution for gas flow measurement.

We present an ultrasonic transit-time gas flow meter (UFM) that features a 40-kHz 2D-phased array for transmitting ultrasonic sound waves up- and downstream to two single element receivers. This allows us to electronically compensate for the well-known parasitic sound drift effect, and, thus, increasing the measurement range by improving the signal-to-noise-ratio (SNR). A regular double-path UFM consists of at least two inclined sound paths to measure the propagation times up- and downstream. However, with increasing flow velocity the sound drift effect reduces the SNR and therefore limits the measurement range. Previous work used rotating [Mylvaganam, TUFFC, 1989] or shifting [Kupnik, IUS, 2006] the ultrasonic transducers to compensate for this parasitic effect. In this work, we consider whether an ultrasonic phased array as a transmitter can be utilized instead. For large diameter flowmeters with ultrasonic transducers, operating at lower frequencies for low attenuation, the array approach not only increases the measurement range but also allows new flowmeter operation modalities, such as adaptive beam steering and off-center measurements for more accurate meter factor determination.

A three-dimensional model for Rayleigh wave electromagnetic acoustic transducers operating on the Lorentz force mechanism has been established by combining the finite element method and analytical calculation. Rayleigh waves generated by the Lorentz forces due to the static magnetic field and the dynamic magnetic field are calculated. The ratio of wire width to spacing interval (RWWSI) between neighbouring wires is chosen to study the coil parameter influence of Lorentz forces in generating Rayleigh waves. The vibration amplitude of Rayleigh waves due to the dynamic magnetic field is almost proportional to the reciprocal of the RWWSI, whereas that due to the static magnetic field decreases slowly with the increase of the RWWSI. The divergence angles of Rayleigh waves due to the dynamic magnetic field remain invariable when the RWWSI is less than 0.5, and that due to static magnetic field reaches the minimum values and has better detectability when the RWWSI is 0.5. The critical excitation current, at which Rayleigh waves due to static and dynamic magnetic fields are equal, changes sharply when the RWWSI differs. The accuracy of this method is verified by experiment.

A design of a 4×4 ultrasonic phased array working in flexural mode is presented. The array consists of an elastic metal sheet, a baffle with 16 holes, a back plate and 16 piezoelectric discs. The active area of each flexural array element is defined by the diameter of the holes of the baffle and the back plate provides an additional clamped-edge-like boundary condition through the baffle for each flexural element. A finite element analysis is utilized to investigate the influence of the dimensions and the materials on the performance of the array. Optimal ratios of the radius of piezo disc to the radius of elastic element working at (0, 0) mode and (1, 0) mode are obtained. A direct comparison of the radiation patterns of the flexural transducers working at (0, 0) and (1, 0) modes proves that the (0, 0) mode is preferable as working mode for the array. The dimensions and the materials of the baffle and the back plate are chosen to effectively reduce the mechanical cross talk between the neighboring array elements. A flexural ultrasonic phased array prototype is fabricated and characterized. Experiments indicate that the ultrasonic beam of the array can be continuously steered from 0° to 50°. This proof-of-concept design demonstrates our low-cost flexural ultrasonic phased arrays design to be sufficiently robust for various fluid-coupled applications.

Typically, permanent magnets used in the electromagnetic acoustic transducers (EMATs), will cause the difficulty of mobility for on-line detection of ferromagnetic materials. In this paper, a pulsed electromagnet EMAT (PE-EMAT) with the effective magnetic field duration of 400 µs is designed. A 2-D finite element model for the bulk wave PE-EMAT is presented including both the electromagnetic field and the acoustic field analysis. The designed PE-EMAT has shown the effectiveness of bulk wave generation and detection compared with the permanent magnet EMAT, which is verified by experiments.

One of the main drawbacks of EMATs is their inefficiency in generating ultrasounds. To solve this problem, a new surface-wave EMAT design, whose magnet width is less than the coil, is proposed. The principle of the new EMAT is studied based on finite element simulation, which indicates that the EMAT is more efficient by taking advantage of both horizontal and vertical magnetic fields of the magnet. Experiment verified that the amplitude of the ultrasonic signal generated by the EMAT has been enhanced by about 53.7%. The potentials and limitations of the new design have also been discussed.

Lamb wave has been widely used for large structure inspection. Generally, piezoelectric transducers or electromagnetic acoustic transducers (EMATs) can be used to generate Lamb wave. The driving mechanism of EMATs includes Lorentz force, magnetization force and magnetostriction. A finite element model for magnetostrictive Lamb wave EMATs has been presented including the three mechanisms. The simulation result shows that magnetostriction is the main transduction mechanism under the horizontal magnetic field. The magnetic field dependence of EMATs has been evaluated by simulation and experiment on a 3mm thick low carbon steel plate.

The elastic waves generated by traditional meander- line coil electromagnetic acoustic transducers (EMATs) propagate in two directions, overlapping the echo signals from defects with the same distances, and the defect echo signal is hard to distinguish from the edge-reflected signal when the EMATs are near the edge of a specimen. In this paper, a unidirectional EMAT with two meander-line coils is proposed. A finite element model is used to simulate the directivity of the Rayleigh and shear vertical waves generated by these EMATs. Six transducers are fabricated using the printed circuit technique. The unidirectional Rayleigh wave and shear vertical wave are tested, and the results agree well with the simulation.

Electromagnetic acoustic transducer (EMAT) for Rayleigh wave has been widely used as a promising tool for flaw detection of metal plates due to its advantages such as high sensitivity to surface defects and low attenuation. Recently, numerous studies have focused on the unidirectional EMAT for Rayleigh wave as it can overcome the disadvantages such as low signal-to-noise ratio and existence of unfavorable received signals of typical EMAT. Since the unidirectional EMAT has been designed based on the principle of wave interference, its performance is sensitive to the parameters of the coil. In order to fully explore the influence of coil dimensions on the transduction performance of a unidirectional EMAT, a 2-D time domain finite model is established based on the Lorentz force mechanism. Using the model, the influence of coils on the transduction performance of a unidirectional EMAT for Rayleigh wave has been discussed. Experiments have been carried out to verify the validity of that model.

Currently, the finite element method (FEM) and analytical calculation are widely employed for the modeling of electromagnetic acoustic transducers (EMATs). However, it takes long time for finite element calculation. Previous analytical models for bulk wave EMATs are generally considered separately and incompletely, and expressions of radiated wave fields contain infinite integrations and multiple singular points, which result in complex numerical computation. A complete model containing the Lorentz force and radiated wave field calculation for the EMAT with a spiral coil and a NdFeB permanent magnet is established. By introducing a current loop instead of the permanent magnet and adopting the truncated region eigenfunction expansion (TREE) method, the distributions of static and dynamic magnetic fields and their generated Lorentz forces are calculated. A series expansion method is proposed for the computation of radiated wave fields, which replaces the integration by series operation and avoids the solutions of singular points effectively. The Lorentz forces and radiated wave fields of a typical transducer are computed. The validity of the model is verified by FEM and experiments. Their good agreements verify the accuracy and validity of the model.

In this study, three aluminium samples produced by wire + arc additive manufacture (WAAM) are inspected using ultrasonic phased array technology. Artificial defects are machined using a centre drill, ø3 mm, and electro-discharge machining (EDM), ø0.5-1 mm, in a cylindrical through hole topology. The sample was first inspected by a single element wheel probe mounted on a KUKA robot in order to investigate the feasibility of using a conventional ultrasonic transducer approach. Unfortunately, the wheel probe was found to be unsuitable for scanning of the WAAM specimens and ultrasonic phased arrays were employed next. The setup included 5 MHz and 10 MHz arrays (128 elements) in direct contact with the sample surface using both conventional and total focusing method (TFM) imaging techniques. Using FIToolbox (Diagnostic Sonar, UK) as the controller, a phased array aperture of 32 elements was used to perform a focussed B-scan with a range of settings for the transmit focal depth. All the reflectors (including those located near the WAAM top surface) were successfully detected by a combination of conventional phased array and TFM, using a range of settings and setups including bottom surface inspection, application through a Plexiglas wedge and variation of the scanning frequency.

Increased demands in performance and production rates require a radical new approach to the design and manufacturing of aircraft wings. Performance of modern robotic manipulators has enabled research and development of fast automated non-destructive testing (NDT) systems for complex geometries. This paper presents recent outcomes of work aimed at removing the bottleneck due to data acquisition rates, to fully exploit the scanning speed of modern 6-DoF manipulators. The geometric assessment of the parts is carried out with a robotised dynamic laser scanner encoded through an absolute laser tracker. This method allows scanning speeds up to 330mm/s at 1mm pitch. State of the art ultrasonic instrumentation has been integrated into a large robot cell to enable fast data acquisition, high scan resolutions and accurate positional encoding. A fibre optic connection between the ultrasonic instrument and the server computer enables data transfer rates up to 1.6 GB/s. The robotic inspection system presented herein is currently being tested for industrial exploitation. The adopted system integration strategies allow traditional ultrasonic phased array scanning as well as full matrix capture (FMC) and other novel scanning approaches (e.g. multi-Tx phased array). Scan results, relative to a 1.2m x 3m carbon fibre sample, are presented. The system shows a reference scanning rate of 25.3m2/hour with an 8Tx/8Rx PA approach and an ultrasonically reachable scanning rate over 100m2/hour with the novel techniques.