Recent advancements in Lorentz force eddy current testing

Lorentz Force Eddy Current Testing (LET) is a non-destructive testing technique based on induced eddy currents due to relative motion between a permanent magnet and a conductive, non-ferromagnetic device under test which has been recently introduced. The Lorentz force acting on the magnet is measured and perturbations in conductivity change the Lorentz force profile along the conductor. The permanent magnet is placed in a lift-off distance above the specimen moving with a constant velocity relative to the magnet. The design of the magnet is the most crucial element to improve the technique. Therefore, we present new developments in LET: the optimization of an innovative magnetic structure enhancing the Lorentz force and an uncertainty analysis to identify most important sources of variance. Futhermore, in a defect depth study a detection limit for LET was determined. A new cylindrical magnetic Halbach structure has been designed to concentrate and magnify the magnetic field below the structure. For internal defects a multi-objective, non-linear optimization to maximize the defect response of the drag force is performed. The optimized magnet shape depends on the geometrical parameters of the experimental setup and therefore the optimal shape is highly problem-specific. Secondly, we investigate the uncertainties in our existing experimental setup quantified by a non-intrusive polynomial chaos expansion to determine the impact of multiple unknown input parameters. The experimentally determined statistics of velocity, magnetic remanence of the permanent magnet, conductivity of the specimen and the lift-off distance are modeled as uniform and beta-distributed random variables. The numerically predicted force profiles were validated by experiments. The included analysis of variance of the Lorentz force enables the enhancement of defect detection capability. Finally, experiments with a specimen containing a quasi-infinite crack were performed. By variation of the defect depth a detection limit for LET for drag- and lift-force components of the Lorentz force was determined. It showed the compatibility of LET compared with traditional eddy current testing

Motion-induced eddy current testing of composite materials

Modern composite materials are gaining more and more importance in mechanical engineering. Due to the complex structure of most of these materials, traditional NDT methods do not satisfy the measurement requirements. In this paper we address the capabilities and limitations of the non-destructive testing method of motion-induced eddy currents for (non-ferromagnetic) composite materials. The specimen moves with constant velocity through a magnetic field, which is created by a fixed permanent magnet. The interaction of induced eddy currents and the primary magnetic field re-sults in the Lorentz force acting on the specimen. Due to the third Newton law, the reaction force acts on the magnet system itself and is measured in all three spatial dimensions. Every force component has a characteristic profile for a certain defect-free specimen. Anomalies in the specimen affect the eddy currents due to variations of local conductivity. These deviations influence the measured force profiles from which the location, size and type of the defect in the specimen may be determined. Two types of magnet systems have been applied: a cylindrical magnet and a radial Halbach array with a ferromagnetic disc. The cylindrical magnet produces a dipole-like field, whereas the Halbach array with the additional disc creates a field concentrated right below the magnet system. Experiments show, that the Halbach array is very well suited for thin speci-mens. The defect response signal is higher due to the stronger eddy currents caused by the focused magnetic field. Two different types of composite materials have been experimentally tested: Carbon fiber reinforced plastic (CFRP) and glass laminate aluminum reinforced epoxy (GLARE). For CFRP four samples were fabricated, whereas one was tested. For GLARE two samples were used with defects in different depth

Detection and attribution of aerosol-cloud interactions in large-domain large-eddy simulations with the ICOsahedral Non-hydrostatic model

Clouds and aerosols contribute the largest uncertainty to current estimates and interpretations of the Earth’s changing energy budget. Here we use a new-generation large-domain large-eddy model, ICON-LEM (ICOsahedral Non-hydrostatic Large Eddy Model), to simulate the response of clouds to realistic anthropogenic perturbations in aerosols serving as cloud condensation nuclei (CCN). The novelty compared to previous studies is that (i) the LEM is run in weather prediction mode and with fully interactive land surface over a large domain and (ii) a large range of data from various sources are used for the detection and attribution. The aerosol perturbation was chosen as peak-aerosol conditions over Europe in 1985, with more than fivefold more sulfate than in 2013. Observational data from various satellite and ground-based remote sensing instruments are used, aiming at the detection and attribution of this response. The simulation was run for a selected day (2 May 2013) in which a large variety of cloud regimes was present over the selected domain of central Europe. It is first demonstrated that the aerosol fields used in the model are consistent with corresponding satellite aerosol optical depth retrievals for both 1985 (perturbed) and 2013 (reference) conditions. In comparison to retrievals from ground-based lidar for 2013, CCN profiles for the reference conditions were consistent with the observations, while the ones for the 1985 conditions were not. Similarly, the detection and attribution process was successful for droplet number concentrations: the ones simulated for the 2013 conditions were consistent with satellite as well as new ground-based lidar retrievals, while the ones for the 1985 conditions were outside the observational range. For other cloud quantities, including cloud fraction, liquid water path, cloud base altitude and cloud lifetime, the aerosol response was small compared to their natural variability. Also, large uncertainties in satellite and ground-based observations make the detection and attribution difficult for these quantities. An exception to this is the fact that at a large liquid water path value (LWP > 200 g m−2), the control simulation matches the observations, while the perturbed one shows an LWP which is too large. The model simulations allowed for quantifying the radiative forcing due to aerosol–cloud interactions, as well as the adjustments to this forcing. The latter were small compared to the variability and showed overall a small positive radiative effect. The overall effective radiative forcing (ERF) due to aerosol–cloud interactions (ERFaci) in the simulation was dominated thus by the Twomey effect and yielded for this day, region and aerosol perturbation −2.6 W m$^{-2}$. Using general circulation models to scale this to a global-mean present-day vs. pre-industrial ERFaci yields a global ERFaci of −0.8 W m$^{-2}$

University of Queensland vital signs dataset: Development of an accessible repository of anesthesia patient monitoring data for research

Data recorded from the devices used to monitor a patient's vital signs are often used in the development of displays, alarms, and information systems, but high-resolution, multiple-parameter datasets of anesthesia monitoring data from patients during anesthesia are often difficult to obtain. Existing databases have typically been collected from patients in intensive care units. However, the physical state of intensive care patients is dissimilar to those undergoing surgery, more frequent and marked changes to cardiovascular and respiratory variables are seen in operating room patients, and additional and highly relevant information to anesthesia (e.g., end-tidal agent monitoring, etc.) is omitted from these intensive care databases. We collected a set of high-quality, high-resolution, multiple-parameter monitoring data suitable for anesthesia monitoring research.Vital signs data were recorded from patients undergoing anesthesia at the Royal Adelaide Hospital. Software was developed to capture, time synchronize, and interpolate vital signs data from Philips IntelliVue MP70 and MP30 patient monitors and Datex-Ohmeda Aestiva/5 anesthesia machines into 10 millisecond resolution samples. The recorded data were saved in a variety of accessible file formats.Monitoring data were recorded from 32 cases (25 general anesthetics, 3 spinal anesthetics, 4 sedations) ranging in duration from 13 minutes to 5 hours (median 105 min). Most cases included data from the electrocardiograph, pulse oximeter, capnograph, noninvasive arterial blood pressure monitor, airway flow, and pressure monitor and, in a few cases, the Y-piece spirometer, electroencephalogram monitor, and arterial blood pressure monitor. Recorded data were processed and saved into 4 file formats: (1) comma-separated values text files with full numerical and waveform data, (2) numerical parameters recorded in comma-separated values files at 1-second intervals, (3) graphical plots of all waveform data in a range of resolutions as Portable Network Graphics image files, and (4) graphical overview plots of numerical data for entire cases as Portable Network Graphics and Scalable Vector Graphics files. The complete dataset is freely available online via doi:102.100.100/6914 and has been listed in the Australian National Data Service Collections Registry.The present dataset provides clinical anesthesia monitoring data from entire surgical cases where patients underwent anesthesia, includes a wide range of vital signs variables that are commonly monitored during surgery, and is published in accessible, user-friendly file formats. The text and image file formats let researchers without engineering or computer science backgrounds easily access the data using standard spreadsheet and image browsing software. In future work, monitoring data should be collected from a wider range and larger number of cases, and software tools are needed to support searching and navigating the database

Effect of preoperative warming on intraoperative hypothermia: a randomized-controlled trial

Purpose: The purpose of this study was to evaluate the effects of preoperative forced-air warming on intraoperative hypothermia. Methods: In this randomized-controlled trial, adult patients scheduled for elective, non-cardiac surgery under general anesthesia were stratified by scheduled surgical duration ( \u3c 2.5 hr or ≥ 2.5 hr) and then randomized to a pre-warming group using a BairPaws™ forced-air warming system for at least 30 min preoperatively or to a control group with warmed blankets on request. All patients were warmed intraoperatively via convective forced-air warming blankets. Perioperative temperature was measured using the SpotOn™ temperature system consisting of a single-use disposable sensor applied to the participant\u27s forehead. The primary outcome was the magnitude of intraoperative hypothermia calculated as the area under the time-temperature curve for core temperatures \u3c 36°C between induction of general anesthesia and leaving the operating room. Secondary outcomes included surgical site infections, packed red blood cell requirements, and 24 hr postoperative opioid consumption. Results: Two hundred participants were analyzed (101 control; 99 pre-warmed). Pre-warmed participants had a lower median [interquartile range] magnitude of hypothermia than controls (0.00 [0.00-0.12] °C·hr −1 vs 0.05 [0.00-0.36] °C·hr −1 , respectively; median difference, −0.01°C·hr −1 ; 95% confidence interval, −0.04 to 0.00°C·hr −1 ; P = 0.005). There were no between-group differences in the secondary outcomes. Conclusion: A minimum of 30 min of preoperative forced-air convective warming decreased the overall intraoperative hypothermic exposure. While redistribution hypothermia still occurs despite pre- and intraoperative forced-air warming, their combined application results in greater preservation of intraoperative normothermia compared with intraoperative forced-air warming alone. Trial registration: www.clinicaltrials.gov(NCT02177903). Registered 25 June 2014

High precision hyperfine measurements in Bismuth challenge bound-state strong-field QED

Electrons bound in highly charged heavy ions such as hydrogen-like bismuth 209Bi82+ experience electromagnetic fields that are a million times stronger than in light atoms. Measuring the wavelength of light emitted and absorbed by these ions is therefore a sensitive testing ground for quantum electrodynamical (QED) effects and especially the electron–nucleus interaction under such extreme conditions. However, insufficient knowledge of the nuclear structure has prevented a rigorous test of strong-field QED. Here we present a measurement of the so-called specific difference between the hyperfine splittings in hydrogen-like and lithium-like bismuth 209Bi82+,80+ with a precision that is improved by more than an order of magnitude. Even though this quantity is believed to be largely insensitive to nuclear structure and therefore the most decisive test of QED in the strong magnetic field regime, we find a 7-σ discrepancy compared with the theoretical prediction