Table of contents

Cosmic-ray muon radiography has the potential to reveal the density structure of gigantic objects. It utilizes the strong penetration ability of high-energy muons. By measuring the number of muons that travel through a target object, the average density can be calculated along the muon path. Since muons travel in straight paths through matter, specially designed detectors can generate density maps with higher spatial resolution than those obtained with conventional geophysical methods. However, this technique has a few notable limitations in that it can only be applied to near-surface structures above the muon sensor and strongly depends on the characteristics of the local topography. This is due to the fact that almost all cosmic-ray muons arrive only from the upper hemisphere. Geological structures, e.g. volcanoes, that allow for muon detectors to be placed on a slope directly below the point of interest are thus the best candidates for this technique. The drawback of muon radiography that only the horizontally integrated density above the sensor is measured with a time resolution larger than several weeks may be partly remedied by combining its results with gravity data, as they are both sensitive to target density while complementary to each other in several aspects. An example of such a combination is presented: real-time monitoring of magma head height in a volcano conduit.

In this work, it is shown that dc voltages may be measured via a capacitive interface, provided that the capacitance between the measurement system and the dc voltage source being measured is nonlinearized. This nonlinearization is achieved by the addition of a nonlinear capacitor in series with the coupling capacitance. Two types of nonlinear capacitor are used—multilayer ceramics and varicap diodes. Currently available multilayer ceramics have a larger value than desired but prove the concept, while the small capacitance of the varicap diode allows measurement on real wires. Results show that over a low voltage range (−8 V to +8 V), the voltage on a conductor can be measured if the coupling capacitance between source and electrode is larger than 20 pF, which equates to an electrode length of 5 cm when wire compliant with MIL-W-81044-22 is used. Detection is performed by momentarily applying a voltage at a node within the measurement system, then measuring the time it takes for this voltage to decay to a threshold level—the capacitive nonlinearity causes this time delay to be dependent upon the dc input voltage whose value is being measured.

As a novel tool for quantitative 3D internal deformation measurement throughout the interior of a material or tissue, digital volume correlation (DVC) has increasingly gained attention and application in the fields of experimental mechanics, material research and biomedical engineering. However, the practical implementation of DVC involves important challenges such as implementation complexity, calculation accuracy and computational efficiency. In this paper, a least-squares framework is presented for 3D internal displacement and strain field measurement using DVC. The proposed DVC combines a practical linear-intensity-change model with an easy-to-implement iterative least-squares (ILS) algorithm to retrieve 3D internal displacement vector field with sub-voxel accuracy. Because the linear-intensity-change model is capable of accounting for both the possible intensity changes and the relative geometric transform of the target subvolume, the presented DVC thus provides the highest sub-voxel registration accuracy and widest applicability. Furthermore, as the ILS algorithm uses only first-order spatial derivatives of the deformed volumetric image, the developed DVC thus significantly reduces computational complexity. To further extract 3D strain distributions from the 3D discrete displacement vectors obtained by the ILS algorithm, the presented DVC employs a pointwise least-squares algorithm to estimate the strain components for each measurement point. Computer-simulated volume images with controlled displacements are employed to investigate the performance of the proposed DVC method in terms of mean bias error and standard deviation error. Results reveal that the present technique is capable of providing accurate measurements in an easy-to-implement manner, and can be applied to practical 3D internal displacement and strain calculation.

The machining accuracy is an important index to evaluate the machine tool characteristics, and error measurement and compensation are effective methods to improve the machining accuracy with low cost. Error measurement is a prerequisite and basis for error compensation, so how to quickly and accurately measure the machine error is particularly important. To quickly and accurately detect the geometric error of multi-axis NC machine tool, a new method with laser tracker based on the sequential multi-lateration measurement principle is proposed in the paper. The laser tracker is used to measure the same motion trajectory of the linear axis and rotary axis of machine tool at different base stations. Based on the GPS principle, the space coordinates of each measuring point can be determined by large amount of measured data. Then according to the error model of the linear axis and rotary axis, each error can be separated. In the paper, the principles of sequential multi-lateration measurement are analyzed in depth. By establishing the mathematical model of sequential multi-lateration measurement for the linear axis and rotary axis, the algorithms for linear axis measurement and rotary axis measurement are derived and proved feasible by simulations, respectively. Meanwhile, the error separation algorithm is also deduced. The results of experiments show that this method can achieve quick and accurate detection of errors in multi-axis NC machine tool.

A method for measurement of resistivity of flat samples and thin layers complementary to the well-known van der Pauw technique has been proposed. The method is based on the application of the Thompson–Lampard theorem of electrostatics used in metrology for the realization of calculable capacitor, according to which a large variety of electrode systems can be designed. A prototypic electrode arrangement is shown on which the practical performance of the method was tested.

Numerical simulation of complex-shaped devices for contactless electromagnetic flow measurement in metallurgy is a challenge for computational magnetohydrodynamics. We report a series of numerical simulations which demonstrate for the first time that it is possible to predict the calibration constant of a generic Lorentz force flowmeter (LFF) with an uncertainty close to the requirements of real-life industrial applications. Our simulations involve both magnetostatic computations of a complex-shaped magnet system and magnetohydrodynamic computations of the flow of a liquid metal in a nozzle under the influence of a predominantly transverse magnetic field. In order to assess the role of turbulence, the simulations have been performed both for laminar and for turbulent flows using Reynolds-averaged Navier–Stokes equations in the latter case. In addition to the numerical simulations we have measured the calibration constant of the considered LFF using room-temperature liquid metal instead of liquid aluminum. A comparison between the numerically predicted and the measured values of the calibration constant shows that they differ by only 3.4%. This result suggests that numerical calibration of a LFF may become an economic alternative to expensive full-scale experimental calibration.

The end-tooth indexing table (EIT) is widely used as angular reference in precision measurement or precision manufacturing fields. In order to improve the pitch accuracy of ultra-precision master gears, we designed an automatic end-tooth indexing system on a specific gear grinder. Theoretically, the indexing accuracy of an EIT can reach ±0.2'' or even more, which can meet the machining requirements of ultra-precision gears with pitch deviation up to grade 0 (ISO1328-1:1995). However, the axial and radial misalignment of an EIT to the spindle will decrease the indexing accuracy of the gear grinder. In order to solve this difficulty, precision measurement and lapping on the datum face of an EIT will be necessary. How to measure the parallelism deviation correctly at the datum of the mating face of the EIT will be another difficulty. Using the closure measuring technique which allows error separation, in this paper the measurement platform is set up, the data acquisition and handling method are presented and an experimental measurement is carried out. The maximum parallelism deviation, which is between the target face of an EIT and its mating face, was reduced from about 4 to 0.29 µm by adopting the closure measuring technique and precision lapping. It confirms that the closure measuring technique can implement precision measurement of dimensional measurands for an axisymmetric part.

An improved denoising algorithm based on wavelet transform modulus maxima (WTMM) is proposed for processing non-intrusive measurement signals in pneumatic systems. Combined with the adaptive BayesShrink threshold and Witkin's scale space tracking theory, the process of tracing the evolution of WTMM over scales has been optimized. Thus, the signal and the noise can be identified and isolated effectively. Additionally, to improve the computational efficiency, a fast method based on a piecewise cubic Hermite interpolating polynomial is applied to reconstruct the signal. Numerical experiments confirm the advantages of the improved denoising algorithm: compared with the classical algorithm of WTMM, the improved denoising algorithm not only increases the signal to noise ratio by over 10% but also reduces the processing time by over 90%. More generally, the algorithm has better performance than that of several typical algorithms in its denoising quality, adaptability and practicality.

An original software system for in-process Bayesian estimation is presented with application to a vector of time-varying measurands. The estimation algorithm, mainly based on the Kalman filter technique, is an innovative application to in-process metrology. The programmed strategy, data flow, system/operator interfaces and implemented routines are illustrated and supported by numerical examples. The system performance is demonstrated by reporting and discussing results of simulation trials of metrological interest. The algorithm proves convergent even in severe trials.

This paper presents a single reflective grating-based fiber optic accelerometer that can monitor the low-frequency acceleration of civil engineering structures. A simpler sensor structure was realized by employing a single reflective grating panel and two optical fibers as transceivers rather than the moiré fringe fiber optic accelerometer, which is composed of two gratings and four optical fibers. The simplified layout contributes to resolving the issues of space restraints during installation and complex cabling problems in transmission of fiber optic accelerometers. The measured oscillated displacement and sinusoidal acceleration from the proposed fiber optic sensor demonstrated good agreement with those of a commercial laser displacement sensor and an accelerometer without electromagnetic interference. The developed fiber optic accelerometer can be used in frequency ranges below 4 Hz within a 5% error margin and high sensitivity of 33.33 rad G⁻¹. Furthermore, in comparison with the conventional transmission fiber optic accelerometer design, the proposed scheme's cable design is simplified by 50%.

A capacitive sensor has been developed for the purpose of measuring the permittivity of a cylindrical dielectric that coats a conductive core cylinder. The capacitive sensor consists of two identical curved patch electrodes that are exterior to and coaxial with the cylindrical test piece. The permittivity of the cylinder is determined from measurements of capacitance by means of a physics-based model. In the model, an electroquasistatic Green function due to a point source exterior to a dielectric-coated conductor is derived, in which the permittivity of the dielectric material may take complex values. The Green function is then used to set up integral equations that relate the unknown sensor surface charge density to the imposed potentials on the electrode surfaces. The method of moments is utilized to discretize the integral equation into a matrix equation that is solved for the sensor surface charge density and eventually the sensor output capacitance. This model enables the complex permittivity of the dielectric coating material, or the geometry of the cylindrical test-piece, to be inferred from the measured sensor capacitance and dissipation factor. Experimental validation of the numerical model has been performed on three different cylindrical test-pieces for two different electrode configurations. Each of the test-pieces has the structure of a dielectric coated brass rod. A good agreement between measured and calculated sensor capacitance (to an average of 7.4%) and dissipation factor (to within 0.002) was observed. Main sources of uncertainty in the measurement include variations in the test-piece geometry, misalignment of sensor electrodes, strain-induced variation in the test-piece permittivity and the existence of unintended air gaps between electrodes and the test-piece. To demonstrate the effectiveness of the sensor, measurements of capacitance have been made on aircraft wires and the permittivity of the insulation inferred. A significant change in permittivity was observed for thermally degraded wires.

The thermal conductivity of molten copper was measured by the periodic laser-heating method, in which a static magnetic field was superimposed to suppress convection in an electromagnetically levitated droplet, to extend the measurement range of the method up to a relatively high thermal conductivity. Before measuring the thermal conductivity, the optimum conditions for static magnetic field, the laser frequency of periodic heating and sample diameter were investigated by numerical simulation both for the flow and thermal fields in an electromagnetically levitated droplet and for the periodic laser heating of the droplet in the presence of melt convection. As a result, the temperature dependence of the thermal conductivity of molten copper was proposed in the temperature range between 1383 and 1665 K. In addition, by comparing our results with those of previous studies, it was demonstrated that the present method of measuring thermal conductivity is also available for molten materials with a relatively high thermal conductivity, such as molten copper.

Quasi-distributed optical fibre sensor arrays containing luminescent sensor molecules can be read out spatially resolved utilizing optical time-of-flight detection (OTOFD) methods, which employ pulsed laser interrogation of the luminosensors and time-resolved detection of the sensor signals. In many cases, sensing is based on a change in sensor luminescence intensity; however, sensing based on luminescence lifetime changes is preferable because it reduces the need for field calibration. Because in OTOFD detection is time-resolved, luminescence-lifetime information is already available through the signal pulses, although in practise applications were restricted to sensors with long luminescence lifetimes (hundreds of ns). To implement lifetime-based sensing in crossed-optical-fibre-sensor arrays for sensor molecules with lifetimes less than 10 ns, two time-domain methods, time-correlated single photon counting and stroboscopic detection, were used to record the pH-dependent emission of a fluorescein derivative covalently attached to a highly-porous polymer. A two-term nonexponential decay function yielded both a good fit for experimental lifetime data during reconvolution and a pH response that matches Henderson–Hasselbalch behaviour, yielding a sensor accuracy of 0.02 pH units. Moreover, strong agreement was obtained for the two lifetime determination methods and with intensity-based measurements taken previously.

A novel surface plasmon resonance setup is introduced in this paper. By applying a galvo scanner to modulate the incident beam, the interference noise caused by the coherent light source and mismatching optical interfaces can be reduced significantly and a wide measurement range can be acquired meanwhile. In order to calculate the tiny shift of the resonance angle, a new algorithm called the phase shift algorithm based on discrete Fourier transform is proposed. The method measures the angle shift by detecting the signal phase shift in the frequency domain. According to the simulation and experimental results, this method has better resolution, good immunity of light source drift and fast computation speed. The experimental results demonstrate that a resolution of 1.8 × 10⁻⁶ RIU (3 standard derivations) is finally acquired with a measurement range from 1.33 to 1.385. It suggests a good potential value in small molecule interaction detection.

Venturi meters are playing an increasingly important role in wet gas metering in natural gas and oil industries. Due to the effect of liquid in a wet gas, the differential pressure over the converging section of a Venturi meter is higher than that when a pure gas flows through with the same flow rate. This phenomenon is referred to as over-reading. Thus, a correction for the over-reading is required. Most of the existing wet gas models are more suitable for higher pressure (>2 MPa) than lower pressure (<1 MPa). Much attention has been paid on higher quality (>0.5) than lower quality (<0.5) in recent years. However, conditions of lower pressure and lower quality also widely exist in the gas and oil industries. By comparing the performances of eight existing wet gas models in low-pressure range of 0.26–0.86 MPa and low-quality range of 0.07–0.36 with a vertically mounted Venturi meter of diameter ratio 0.45, de Leeuw's model was proven to perform best. Derived from de Leeuw's model, a modified model with better performance for the low-pressure and low-quality ranges was obtained. Experimental data showed that the root mean square of the relative errors of the over-reading was 2.30%.

In this work a methodology is proposed for measurement and analysis of gaseous emissions and particle size distributions emitted by a diesel city bus during its typical operation under urban driving conditions. As test circuit, a passenger transportation line at a Spanish city was used. Different ways for data processing and representation were studied and, derived from this work, a new approach is proposed. The methodology was useful to detect the most important uncertainties arising during registration and processing of data derived from a measurement campaign devoted to determine the main pollutant emissions. A HORIBA OBS-1300 gas analyzer and a TSI engine exhaust particle spectrometer were used with 1 Hz frequency data recording. The methodology proposed allows for the comparison of results (in mean values) derived from the analysis of either complete cycles or specific categories (or sequences). The analysis by categories is demonstrated to be a robust and helpful tool to isolate the effect of the main vehicle parameters (relative fuel–air ratio and velocity) on pollutant emissions. It was shown that acceleration sequences have the highest contribution to the total emissions, whereas deceleration sequences have the least.

A pressure-sensitive paint (PSP) system capable of measuring the global, unsteady pressure distribution on a rotating surface without resorting to phase averaging is applied to a two-bladed model propeller in edgewise freestream flow. A gated lifetime-based technique captures the paint luminescence after a single pulse of high-energy laser excitation, yielding a signal-to-noise ratio sufficient to avoid image averaging. The selection of a porous polymer/ceramic matrix base with platinum tetra(pentafluorophenyl) porphyrin (PtTFPP) as the luminophore afforded high frequency response and pressure sensitivity, but the long lifetime of PtTFPP caused blurring in the long-exposure image of the rotating blade. An approach to deblurring based on the lifetime of the paint and surface motion is described and validated by results obtained from a disc of 17.8 cm diameter spinning at 70 Hz. An infrared camera recorded wind-on and -off temperature maps to provide a temperature correction for the PSP. The single-shot PSP technique with motion deblurring and temperature correction is then applied to a vertically mounted model propeller with a 25.4 cm diameter and 10.2 cm pitch. Surface pressure maps for the advancing and retreating blades are presented for a spin rate of 70 Hz and advance ratio of 0.3. The higher suction peak and other features on the advancing blade due to its larger effective velocity are detected by the paint system, while the retreating blade shows a qualitatively different distribution.

We demonstrate the non-destructive measurement of the stiffness of single-beam, monocrystalline silicon cantilevers with a trapezoidal cross-section and tips as used for atomic force microscopy from the knowledge of cantilever dimensions, eigenfrequencies and material parameters. This yields stiffness values with an uncertainty of ±25% as the result critically depends on the thickness of the cantilever that is experimentally difficult to determine. The uncertainty is reduced to ±7% when the measured fundamental eigenfrequency is included in the calculation and a tip mass correction is applied. The tip mass correction can be determined from the eigenfrequencies of the fundamental and first harmonic modes. Results are verified by tip destructive measurements of the stiffness with a precision instrument recording a force–bending curve yielding an uncertainty better than ±5%.

It is very important to evaluate thermal protective performance (TPP) in laboratory-simulated fire scenes as accurately as possible. For this paper, to thoroughly understand the effect of fabric deformation on basic physical properties and TPP of flame-retardant fabrics exposed to flash fire, a new modified TPP testing apparatus was developed. Different extensions were employed to simulate the various extensions displayed during different body motions. The tests were also carried out with different air gaps. The results showed a significant decrease in air permeability after deformation. However, the change of thickness was slight. The fabric deformation had a complicated effect on thermal protection with different air gaps. The change of TPP depended on the balance between the surface contact area and the thermal insulation. The newly developed testing apparatus could be well employed to evaluate the effect of deformation on TPP of flame-resistant fabrics.

Direct methanol fuel cells (DMFCs) are promising candidates for energy supply based on renewable sources. They provide a high power density and the possibility of an easy recharge. Moreover, the fuel storage is significantly easier than it is for hydrogen fuel cells. However, in continuous operation, supplying the anode with a constant concentration of methanol is the key to achieving stable and optimal performance. Hence, developing a method for measuring the methanol content of the fuel online is desirable for advanced monitoring of the fuel cell. In this work, we report the combined application of Raman spectroscopy, chronoamperometry and gravimetry for the simultaneous determination of the methanol concentration and the Faradaic efficiency in a DMFC. Raman spectroscopy is used to measure the actual methanol concentration supplied to the anode. The chronoamperometric and gravimetric measurements allow the theoretical methanol concentration, i.e. assuming that methanol is only consumed by electro-oxidation, to be determined. The full set of data ultimately facilitates the calculation of the Faradaic efficiency.

Feature extraction is always a crucial step for fault diagnosis in rotating machinery. When faults occur, rotating machinery always manifests nonlinear dynamic behavior. It is necessary to extract the nonlinear features hidden in the vibration signal for more accurate diagnosis. Approximate entropy (ApEn) is the nonlinear parameter identification method for measuring the irregularity of the stochastic signal or the stochastic process. In this paper, ApEn is used as a nonlinear feature parameter to measure the irregularity of the vibration signals for fault diagnosis in rotating machinery. Four typical faults are considered, which are imbalance, misalignment, shaft rubbing and oil whirl. To improve the distinguishability of the ApEn values of the different faults, the empirical mode decomposition (EMD) method is used to remove the basic frequency component from the signals of the various faults. The experimental study results demonstrate that EMD can separate the basic frequency component from the original signals satisfactorily. After removing the basic frequency component, the distinguishability of the ApEn values of the residual signals is improved greatly. The proposed strategy for the ApEn calculation of the various faults is proved effective. In addition, the simulation study is presented to investigate some characteristics of ApEn, which will benefit better application of ApEn in the field of fault diagnosis.

Risers are flexible multilayered pipes formed by an inner flexible metal structure surrounded by polymer layers and spiral wound steel ligaments, also known as armor wires. Since these risers are used to link subsea pipelines to floating oil and gas production installations, and their failure could produce catastrophic consequences, some methods have been proposed to monitor the armor integrity. However, until now there is no practical method that allows the automatic non-destructive detection of individual armor wire rupture. In this work we show a method using magnetic Barkhausen noise that has shown high efficiency in the detection of armor wire rupture. The results are examined under the cyclic and static load conditions of the riser. This work also analyzes the theory behind the singular dependence of the magnetic Barkhausen noise on the applied tension in riser armor wires.

Analysis of the main parameters affecting the fundamental vibrating frequency of film/substrate bilayer beams of rectangular cross-section is discussed based on modeling and testing. Initially, the limits of validity of two analytical models to obtain the fundamental frequency of perfectly-bonded bilayer beams in cantilever configuration are determined by comparing the predicted frequencies to a finite element model developed herein. Using a selected analytical formulation, a modeling-assisted methodology is employed to investigate the parameters that are most influential on the determination of the elastic modulus of the film using a vibratory technique. Modeling suggests the use of thin compliant substrates for extracting the modulus of stiff (metallic) films. If the substrate is stiffer than the film, a thicker film is required to yield measurable shifts in the resonant frequency. The elastic modulus of a millimeter-thick thermosetting polymer extracted by this method agrees with the results obtained from conventional tensile testing of the polymer. Measurements carried out on a gold (100 nm)/polysulfone (130 µm) system yield an average elastic modulus of the gold film similar to the values reported in the literature.

A method is presented for characterizing particle centres, particle size and crystal symmetries with sub-pixel resolution from 8-bit digital images of colloidal thin films taken with a scanning electron microscope (SEM). Digital images are converted to xyz data points by converting colour contrast to a numerical intensity. The data are then passed through a modified form of a Savitzky–Golay filter which allows particle centres to be determined. A subsequent routine is presented that, by analysing the weighted standard deviation and average intensity of the pixels along shifting rings, improves the accuracy of the detected particle centres and provides the radius of each particle. Obtaining the particle centres allows the symmetry of each particle (with respect to its neighbours) along with the mean crystal orientation to be obtained, all in one cohesive package. A key advantage of the method presented here is that it is very robust and works with both low- and high-resolution images—enabling, for example, routine quantitative analysis of SEM images. Because of the low level of user input, the method can be used to process a batch of images in order to characterize the evolution of samples.

Parameters that vary monotonically with damage propagation are useful in condition monitoring. However, it is not easy to find such parameters especially for complex systems like pumps. A method using half and full spectra, fuzzy preference-based rough sets and principal component analysis (PCA) is proposed to generate such an indicator for tracking impeller damage in a centrifugal slurry pump. Half and full spectra are used for extracting features related to pump health status. A fuzzy preference-based rough set model is employed in the process of selecting features reflecting the damage propagation monotonically. PCA is used to condense the features and generate an indicator which represents the damage propagation. The effectiveness of the proposed method is tested using laboratory experimental data. Results show that the indicator generated by the proposed method can clearly and monotonically distinguish the health status of the pump impeller.

Rotating machinery fault detection is significant to avoid serious accidents and huge economic losses effectively. However, due to the vibration signal with the character of non-stationarity and nonlinearity, the detection and extraction of the fault feature turn into a challenging task. Therefore, a novel method called improved spectral kurtosis (ISK) with adaptive redundant multiwavelet packet (ARMP) is proposed for this task. Spectral kurtosis (SK) has been proved to be a powerful tool to detect and characterize the non-stationary signal. To improve the SK in filter limitation and enhance the resolution of spectral analysis as well as match fault feature optimally, the ARMP is introduced into the SK. Moreover, since kurtosis does not reflect the actual trend of periodic impulses, the SK is improved by incorporating an evaluation index called envelope spectrum entropy as supplement. The proposed method is applied to the rolling element bearing and gear fault detection to validate its reliability and effectiveness. Compared with the conventional frequency spectrum, envelope spectrum, original SK and some single wavelet methods, the results indicate that it could improve the accuracy of frequency-band selection and enhance the ability of rotating machinery fault detection.

The technique of ultraviolet reflection ratio measurement is modified from the traditional albedo measurement in order to compensate for unusual inflation of the reflection ratio found previously in non-horizontal surface ultraviolet reflection studies. Data collected to test this method of reflection ratio collection show that there is significant reduction in the inflation. In order to collect UV reflection ratio data on non-horizontal surfaces that can be comparable to differently oriented planar surfaces, the sun and the sensor's positions during the measurement process are equally important, which leads to this new method of reflection measurement for non-horizontal surfaces.

Our research goal is to carry out two-dimensional (2D) and three-dimensional (3D) measurements of the velocity distribution within a single vessel. We modified a non-invasive beam laser Doppler velocimeter using near-infrared light, and linearized the laser to carry out simultaneous multipoint measurements. We also scanned the measurement line in the direction of depth to allow 3D imaging of vascular blood flow in opaque areas in vivo. We used micro multipoint laser Doppler velocimetry (LDV) and a device with improved spatial resolution from 250 to 125 µm. We compared actual and calculated values using a rotating disk with an attached microwire. To demonstrate the effectiveness of the proposed system, blood flowing at a constant rate through a glass capillary and the velocity distribution of flow in the capillary were measured and mapped. The average flow velocity was calculated from the cross-sectional area and flow rate in the glass capillary, and we compared the calculated and measured values. To obtain an image of blood flow velocity in vivo, we measured both 2D and 3D flow velocity distributions in mouse mesenteric vessels.

In this paper, we describe a magnetic resonance method of measuring material elasticity using a single-sided magnet with a permanent static field gradient. This method encodes sample velocity in a reciprocal space using Hahn spin-echoes with variable timing. The experimental results show a strong correlation between magnetic resonance signal attenuation and elasticity when an oscillating force is applied on the sample. This relationship in turn provides us with information about the displacement velocity experienced by the sample, which is inversely proportional to Young's modulus. The proposed method shows promise in offering a portable and cost-effective magnetic resonance elastography system.

Thermal therapy is emerging as an effective treatment option for benign localized tumors. However, lack of reliable intraoperative monitoring techniques of the thermal lesion impedes more widespread application of thermal therapy in clinical settings. In order to address this challenge, a thermometry technique using temperature dependent fluorescence of quantum dots was proposed and its feasibility was also demonstrated with an in vitro cell system. In the present study, light–tissue interaction relevant to applying this quantum dot (QD) thermometry to a tissue system was characterized both experimentally and computationally. In the experiments, QD fluorescence was quantified through tissue phantom while varying QD temperature and phantom thickness. The results showed that QD fluorescence became diffused due to light–tissue interaction, but the QD fluorescence was still correlated to the temperature at any given phantom thickness studied. In the computations, an inverse solution algorithm was developed to estimate the QD fluorescence underneath the tissue phantom from the fluorescence through the phantom. This algorithm is to inversely solve the diffusion approximation of the radiative transfer equation. The developed algorithm was verified using the experimental results. In addition, the effects of relevant optical and thermal parameters on the accuracy of the inverse solution were characterized. The results suggest that the developed algorithm is capable of estimating the QD fluorescence considering light–tissue interaction in the range of tissue phantom thickness studied. The results were further discussed for implications to the application of QD thermometry in vivo.

A signal degradation feature in pre-launch irradiance calibration of space UV remote sensing instrument (SURSI) in vacuum has been identified. We discuss the possible degradation factors, degradation mechanisms and degradation rules, and then demonstrate that the irradiance degradation of the deuterium lamp as the calibration source is the significant cause of the signal degradation. A liquid nitrogen cooled device (LNCD) has been developed and the irradiance degradation is reduced to 1% during the radiometric calibration. On the basis of this LNCD, a high-accuracy irradiance calibration of the SURSI in vacuum from 160 to 250 nm has been performed and the calibration uncertainty is ±4.5%. Finally, the extraterrestrial solar spectrum from 170 to 250 nm measured by the SURSI is compared with the one derived from the NOAA-11 SBUV/2, showing an agreement of better than ±3.2%.

To capture the full spectrum of the fluctuating wall pressure beneath a turbulent boundary layer (TBL) provides a unique challenge in transducer design. This paper discusses the design, construction and testing of an array of surface-mounted piezoelectric ceramic elements with the goal of having both the spatial resolution and the frequency bandwidth to accurately sense the low-frequency, low-wavenumber events beneath a TBL at moderately low Reynolds numbers. The array is constructed from twenty 1.27 cm tall prismatic rods with 0.18 cm × 0.16 cm cross-section made of Navy type II piezoelectric ceramic material. Calibration was performed by comparing the response of a Navy H56 precision-calibrated hydrophone to the outputs of each element on the array for a given input from a Navy J9 projector. The elements show an average sensitivity of −184 dB (re: 1 V μPa⁻¹) and are assembled with a centre-to-centre spacing of 0.2 cm. Measurements of the fluctuating wall pressure below a 2d TBL with Reynolds numbers (based on momentum thickness) ranging from 2100 to 4300 show that the dimensions of the elements are between 64 and 107 viscous length units, respectively. A spatial and temporal footprint of the fluctuating wall pressure reveals convective speeds averaging 75% of the free stream velocity.

This paper describes the VESUVIO electron volt neutron spectrometer at the ISIS pulsed neutron source and its data analysis routines. VESUVIO is used primarily for the measurement of proton momentum distributions in condensed matter systems, but can also be used to measure the kinetic energies of heavier masses and bulk in-situ sample compositions. A series of VESUVIO runs on the same zirconium hydride sample over the past two years show that (1) kinetic energies of protons can be measured to an absolute accuracy of ∼1%. (2) Measurements of the proton momentum distribution n(p) are highly reproducible from run to run. This shows that small changes in kinetic energy and the detailed shape of n(p) with parameters such as temperature, pressure and sample composition can be reliably extracted from VESUVIO data. (3) The impulse approximation (IA) is well satisfied on VESUVIO. (4) The small deviations from the IA due to the finite momentum transfer of measurement are well understood. (5) There is an anomaly in the magnitude of the inelastic neutron cross-section of the protons in zirconium hydride, with an observed reduction of 10% ± 0.3% from that given in standard tables. This anomaly is independent of energy transfer to within experimental error. Future instrument developments are discussed. These would allow the measurement of n(p) in other light atoms, D, ³He, ⁴He, Li, C and O and measurement of eV electronic and magnetic excitations.

An improved curve-fitting method for a simultaneous measurement of the real and imaginary parts of the complex refractive index of turbid media is demonstrated. Based on an introduction of angle-dependent light penetration into turbid media by Calhoun et al (2010 Opt. Lett.35 1224), the fitting is performed on the rapid change part of the measured curve around the critical angle. Moreover, a technology to locate this part of the curve by differentiation is introduced. Experimental results on Intralipid solutions show that this method can significantly reduce the computation time as well as the fitting error between the measured curve and theoretical one.

The ENGIN-X beamline is a dedicated engineering science facility at ISIS optimized for the measurement of strain, and thus stress, deep within crystalline materials using the atomic lattice planes as an atomic 'strain gauge'. Internal stresses in materials have a considerable effect on material properties including fatigue resistance, fracture toughness and strength. The growing interest in properties of materials at high temperatures may be attributed to the dynamic development in technologies where materials are exposed to a high-temperature environment for example in the aerospace industry or fission and fusion nuclear reactors. This article describes in detail the design and construction of a furnace for neutron scattering measurements of internal stress in engineering materials under mechanical load and in elevated temperature environments, designed to permit a range of gases to provide a non-oxidizing atmosphere for hot samples.