457 research outputs found
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Welcome by the President of IMEKO, Professor Kenneth Grattan
The XXII World Congress of the International Measurement Confederation (IMEKO) is held in the UK in 2018 for the first time in over 40 years. Hosted by the Institute of Measurement and Control, the UK's specialist Professional Engineering Institute in the fields of measurement, automation and control and supported by the Institute of Physics, the World Congress covers all aspects of current research in the field of measurement and attracts some of the worlds' largest companies from the sensor, instrumentation, automation and 'Internet of Things' (IoT) industries.
Belfast, the capital city of Northern Ireland, sees delegates from across the world come together for an interesting and scientifically challenging World Congress, bringing together leading experts from many countries to report on the latest exciting developments in their fields. The city is also an excellent centre to explore the beautiful countryside and historic landmarks to be seen across Ireland
List of Co-located conferences, Keynote Speakers and Committees are available in this PDF
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Recognition of Microseismic and Blasting Signals in Mines Based on Convolutional Neural Network and Stockwell Transform
The microseismic monitoring signals which need to be determined in mines include those caused by both rock bursts and by blasting. The blasting signals must be separated from the microseismic signals in order to extract the information needed for the correct location of the source and for determining the blast mechanism. The use of a convolutional neural network (CNN) is a viable approach to extract these blast characteristic parameters automatically and to achieve the accuracy needed in the signal recognition. The Stockwell Transform (or S-Transform) has excellent two-dimensional time-frequency characteristics and thus to obtain the microseismic signal and blasting vibration signal separately, the microseismic signal has been converted in this work into a two-dimensional image format by use of the S-Transform, following which it is recognized by using the CNN. The sample data given in this paper are used for model training, where the training sample is an image containing three RGB color channels. The training time can be decreased by means of reducing the picture size and thus reducing the number of training steps used. The optimal combination of parameters can then be obtained after continuously updating the training parameters. When the image size is 180 × 140 pixels, it has been shown that the test accuracy can reach 96.15% and that it is feasible to classify separately the blasting signal and the microseismic signal based on using the S-Transform and the CNN model architecture, where the training parameters were designed by synthesizing LeNet-5 and AlexNet
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Fluorescent optical fibre chemosensor for the detection of mercury
This work aims to develop a stable, compact and portable fibre optic sensing system which is capable of real time detection of the mercury ion (II), Hg2+. A novel fluorescent polymeric material for Hg2+ detection, based on a coumarin derivative (acting as the fluorophore) and an azathia crown ether moiety (acting as the mercury ion receptor), has been designed and synthesized. The material was covalently attached to the distal end of an optical fibre and exhibited a significant increase in fluorescence intensity in response to Hg2+ in the μM concentration range via a photoinduced electron transfer (PET) mechanism. The sensor has also demonstrated a high selectivity for Hg2+ over other metal ions. A washing protocol was identified for sensor regeneration, allowing the probe to be re-used. The approach developed in this work can also be used for the preparation of sensors for other heavy metals
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Generation of periodic surface structures on silica fibre surfaces using 405 nm CW diode lasers
Periodic surface structures have been observed on the end surfaces of synthetic silica fibres when they are exposed to long-term irradiation with light from a 405 nm CW diode laser. The surface structures are generated when the laser power is at a level which is three magnitudes of order lower than that of the damage threshold. They exhibit multiple bends, break-ups and bifurcations, unlike interference patterns but rather like the effect caused by short-pulsed laser irradiation on wide band-gap insulators. The detailed investigation undertaken in this work has concluded that the key parameters that contribute to the generation of the surface structures are power density, surface roughness, polarisation direction and the presence of ultraviolet defect centres
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Fast response time fiber optical pH and oxygen sensors
While fluorescence-based fiber optic sensors for measuring both pH and oxygen concentration (O2) are well known, current sensors are often limited by their response time and drift, which limits the use of existing fiber optic sensors of this type in wider applications, for example in physiology and other fields. Several new fiber optical sensors have been developed and optimized, with respect to key features such as tip shape and coating layer thickness. In this work, preliminary results on the performance of a suite of pH sensors with fast response times, < 3 second and oxygen sensors (O2) with response times < 0.2 second. The sensors have been calibrated and their performance analyzed using the Henderson–Hasselbalch equation (pH) and classic Lehrer-model (O2)
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Advances in test and measurement of the interface adhesion and bond strengths in coating-substrate systems, emphasising blister and bulk techniques
In this paper, recent advances in the minimum-destructive testing of the adhesion of coating-substrate systems are reviewed, focusing on key techniques such as micro- and nano-scale levels of indentation, scratching, laser-induced wave shock, as well as the blister and buckle approach. Along with adhesion failure tests, the latest and most extensive applications of the adhesion test methods in nano-, micro- and bulk-coating technology and the associated techniques to determine the minimum damage defects left on the coatings are discussed and their use reviewed
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Investigation of the Viscoelastic Effect on Optical- Fiber Sensing and Its Solution for 3D-Printed Sensor Packages
Viscoelasticity is an effect seen in a wide range of materials and it affects the reliability of static measurements made using Fiber Bragg Grating-based sensors, because either the target structure, the adhesive used, or the fiber itself could be viscoelastic. The effect of viscoelasticity on FBG-based sensing has been comprehensively researched through theoretical analysis and simulation using a finite-element approach and a further data processing method to reconstruct the graphical data has been developed. An integrated sensor package comprising of an FBG-based sensor in a polymer host and manufactured by using three-dimensional printing was investigated and examined through tensile testing to validate the approach. The application of the 3D-printed FBG-based sensor package, coupled to the data process method has been explored to monitor the height of a railway pantograph, a critical measurement requirement to monitor elongation, employing a method that can be used in the presence of electromagnetic interference. The results show that the effect of viscoelasticity can be effectively eliminated, and the graphical system response allows results that are sufficiently precise for field use to be generated
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TDLAS Detection of propane and butane gas over the near-infrared wavelength range from 1678nm to 1686nm
It is important in the petrochemical industry that there are high sensitivity, high accuracy, low-power consumption and intrinsically safe methods for the detection of propane, butane and their gas mixtures, to provide early warning of potential explosion hazards during both storage and transportation of oil and gas. This paper proposes a 'proof of principle' method for the detection of propane and butane using a Tunable Diode Laser Absorption Spectroscopy (TDLAS) technique over the near-infrared wavelength range from 1678nm to 1686nm. This method is relatively inexpensive to implement and is thus more practical, compared with detection methods using wavelengths further into the infra-red, near 3.3μm. The minimum detectable concentration was found to be low as 300ppm for propane or butane. Importantly, the relative measurement errors were all below 3% LEL, which meets the requirements from the petrochemical and oil-gas storage and transportation industries for a field-based system for monitoring of combustible gases
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Suppression of subsidiary fringes in white light interferometry utilising two-wavelength light source
This paper analyzes and compares the two methods for suppressing the subsidiary fringes in white-light correlograms with two-wavelength light source. One of the methods adds the intensities of the two wavelength components and the other multiplies them. Peak intensity difference between the central fringe and the subsidiary fringes is investigated. A mathematical expression for a rapid estimation of the optimum wavelength difference between the two wavelengths is given for suppressing the subsidiary fringes. The effects of the intensities of the two wavelength components have also been investigated
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Uncertainty evaluation of trigonometric method for vertical angle calibration of the total station instrument
The total station is an instrument, widely used in civil and environmental engineering, for flat and vertical angle as well as distance measurements. Typically, routine calibration of such an instrument is obligatory, and depending on the local regulations, is performed typically annually or bi-annually. Analysis of previous research shows that undertaking flat angle calibration under laboratory conditions is more common than calibration of vertical angle measuring systems. This paper deals with a trigonometric vertical angle calibration method and research into determining the main sources of uncertainty is described in the paper. The principle of the method is explained, as well as the uncertainty evaluation based on GUM and the advantages as well as the weaknesses of the setup are discussed
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