Advanced Measurement Techniques Research Articles

International Conference on Hydrotransport special issue section: Preface

AbstractSelected papers presented at the 19th International Conference on Hydrotransport (HYDROTRANSPORT 19, Golden, CO, 24–26 September 2014) are published as a special section in this issue. The transport of solid‐liquid mixtures (or slurries) in pipelines or in open‐channel flow is ubiquitous in Canada's mining, mineral processing, and oil sands industries. In particular, processes designed to produce dewatered waste tailings, which are crucial components in any strategy to reduce land disturbance and minimize water usage, involve the transport and deposition of complex, highly non‐Newtonian, settling mixtures. The specific focus of each study in this special issue section varies quite widely, ranging from a historical perspective on slurry flow modelling to fluid‐structure interactions during pump operation. The papers presented, though, are united in that they contribute to step‐change improvements in the ability to understand slurry flow behaviour through model development and advanced measurement techniques.

Integration of optical measurement methods with flight parameter measurement systems

During the AIM (advanced in-flight measurement techniques) and AIM2 projects, innovative modern techniques were developed. The purpose of the AIM project was to develop optical measurement techniques dedicated for flight tests. Such methods give information about aircraft elements deformation, thermal loads or pressure distribution, etc. In AIM2 the development of optical methods for flight testing was continued. In particular, this project aimed at the development of methods that could be easily applied in flight tests in an industrial setting. Another equally important task was to guarantee the synchronization of the classical measuring system with cameras. The PW-6U glider used in flight tests was provided by the Rzeszów University of Technology. The glider had all the equipment necessary for testing the IPCT (image pattern correlation technique) and IRT (infrared thermometry) methods. Additionally, equipment adequate for the measurement of typical flight parameters, registration and analysis has been developed. This article describes the designed system, as well as presenting the system’s application during flight tests. Additionally, the results obtained in flight tests show certain limitations of the IRT method as applied.

Interface and grain boundary resistance of a lithium lanthanum titanate (Li3xLa2/3−xTiO3, LLTO) solid electrolyte

Advanced experimental setups and measurement techniques are crucial for investigating and systematically improving interface characteristics. In this study we introduce an interface-cell, which allows the systematic analysis of liquid/solid electrolyte interfaces via four-point measurements. The functionality of this setup is demonstrated by analysing the impact of parameter variations on the aqueous interface of lithium lanthanum titanate (Li3xLa2/3−xTiO3, LLTO) solid electrolytes as used in Lithium–air batteries.By variation of real operating conditions their impact on cycling performance is highlighted. Examples include temperature (0 to +25 °C) and state of charge (SoC), which induces an alteration of pH (here pH ≈ 6–14) and Li+-concentration (here 0.057 mol L−1 to 10.62 mol L−1). Interestingly, a change of the polarization resistance greater than two orders of magnitude (250 Ωcm2–25,000 Ωcm2) could be identified.The proven dependency of the interface to both the pH and Li+-concentration is explained by an H+/Li+-exchange reaction at the LLTO/H2O-interface. Additionally, we were able to determine the solely grain boundary resistance (∼250 Ωcm2 at 25 °C) of the LLTO samples, without the impact of blocking electrodes. A temperature variation revealed the activation energies of the processes to be 0.4 eV (grain boundary) and 0.46 eV (interface).These results were then critically evaluated in the context of aqueous Lithium–air batteries.

A new linear back projection algorithm to electrical tomography based on measuring data decomposition

As an advanced measurement technique of non-radiant, non-intrusive, rapid response, and low cost, the electrical tomography (ET) technique has developed rapidly in recent decades. The ET imaging algorithm plays an important role in the ET imaging process. Linear back projection (LBP) is the most used ET algorithm due to its advantages of dynamic imaging process, real-time response, and easy realization. But the LBP algorithm is of low spatial resolution due to the natural ‘soft field’ effect and ‘ill-posed solution’ problems; thus its applicable ranges are greatly limited. In this paper, an original data decomposition method is proposed, and every ET measuring data are decomposed into two independent new data based on the positive and negative sensing areas of the measuring data. Consequently, the number of total measuring data is extended to twice as many as the number of the original data, thus effectively reducing the ‘ill-posed solution’. On the other hand, an index to measure the ‘soft field’ effect is proposed. The index shows that the decomposed data can distinguish between different contributions of various units (pixels) for any ET measuring data, and can efficiently reduce the ‘soft field’ effect of the ET imaging process. In light of the data decomposition method, a new linear back projection algorithm is proposed to improve the spatial resolution of the ET image. A series of simulations and experiments are applied to validate the proposed algorithm by the real-time performances and the progress of spatial resolutions.

Kinetic Mie ellipsometry to determine the time-resolved particle growth in nanodusty plasmas

The growth of nanometer-sized particles in a reactive argon-acetylene plasma is investigated by means of kinetic single-wavelength Mie ellipsometry from the change of the polarization state of scattered light. This requires advanced measurement techniques as well as complex methods for the analysis of the measured data. Today commercial devices reduce the metrological effort, but the data analysis is still a challenging topic. We present a scheme to gain time-resolved information about the size evolution of monodisperse spherical particles and to determine their optical properties, represented by the complex refractive index N, without limiting assumptions concerning the evolution of the particle size or the need for additional ex situ diagnostics. The method is applied on typical particle growth processes at varying optical depth and compared to ex situ SEM measurements. It is shown that more complex processes, including particle etching, can be analyzed. This demonstrates the applicability of the analysis on a strongly non-linear process.

Comparison of particle velocity measurement techniques in a fluidized bed operating in the square-nosed slugging flow regime

The novel “travelling fluidized bed” (TFB), operated under identical conditions, was deployed to compare alternate experimental measurement techniques for the investigation of solid motion in gas-fluidized beds operating in the square-nosed slugging regime. Measurements of particle velocity obtained by radioactive particle tracking (RPT — non-invasive at the Ecole Polytechnique de Montréal), positron emission particle tracking (PEPT — non-invasive at University of Birmingham), optical fibre probes (invasive at UBC) and borescopic high speed particle image velocimetry (invasive at PSRI) are compared for sand particles of mean diameter of 292μm. Significant differences between the time-average radial profiles of particle velocity are observed in many cases. The results provide valuable insights into the merits and challenges of advanced particle velocity measurement techniques.

Evaluation of a numerical model for tapered threaded connections subjected to combined loading using enhanced experimental measurement techniques

Threaded connections used in the oil and gas industry have to withstand ever-increasing axial and pressure loads. The structural behavior of these joints can be predicted using numerical models, provided these are soundly validated. Within this article, a finite element model of tapered, shoulderless connections containing a trapezoidal thread type is experimentally validated conducting a test load envelope experiment and a tensile failure test. The evaluation is performed using both conventional and advanced measurement techniques. Surface strains are validated by comparing digital image correlation and strain gage results with the numerical output. An almost perfect quantitative match between the numerically predicted axial strains and the experimentally measured strain gage data is obtained. In addition, a qualitative match can also be observed when considering the axial strains obtained by digital image correlation. Furthermore, infrared thermography measurements are compared to the numerical deformation energy, assuming that temperature is an additional, but indirect parameter to evaluate the validity of the model. From the results, the proposed model has proven to be reliable when a combination of axial tension and internal pressure is applied. While the model is originally designed to predict the connection’s structural behavior for loads up to the yield strength, it is possible to estimate this behavior for higher loads by modifying the contact area.

Materials used to simulate physical properties of human skin.

For many applications in research, material development and testing, physical skin models are preferable to the use of human skin, because more reliable and reproducible results can be obtained. This article gives an overview of materials applied to model physical properties of human skin to encourage multidisciplinary approaches for more realistic testing and improved understanding of skin-material interactions. The literature databases Web of Science, PubMed and Google Scholar were searched using the terms 'skin model', 'skin phantom', 'skin equivalent', 'synthetic skin', 'skin substitute', 'artificial skin', 'skin replica', and 'skin model substrate.' Articles addressing material developments or measurements that include the replication of skin properties or behaviour were analysed. It was found that the most common materials used to simulate skin are liquid suspensions, gelatinous substances, elastomers, epoxy resins, metals and textiles. Nano- and micro-fillers can be incorporated in the skin models to tune their physical properties. While numerous physical skin models have been reported, most developments are research field-specific and based on trial-and-error methods. As the complexity of advanced measurement techniques increases, new interdisciplinary approaches are needed in future to achieve refined models which realistically simulate multiple properties of human skin.

Measurement and analysis of the internal flow field in the hydrodynamic torque converter with adjustable guide vanes

This article presents a particle-tracking velocimetry experiment for studying internal flows of hydrodynamic torque converter whose guide vanes are adjustable. The torque converter in which the flow region is an enclosed space with multiple impellers has a complicated geometry of impellers. Complex flows in adjustable stator are experimentally analyzed using particle-tracking velocimetry, and some advanced measurement technique has been successfully applied. Under each opening, using the single-frame and triple-exposure method, images of the flow fields in the adjustable stator were recorded at three typical working conditions as the speed ratios were equal to 0 (stall), 0.5 (design), and 1 (idle). According to particle trajectories on the images, the displacements and corresponding velocity vectors were obtained. The internal flow pattern of the hydrodynamic torque converter with adjustable guide vanes were acquired and analyzed in two cases: the changing conditions under the same opening and the changing openings under the same condition.

MECHANICAL CHARACTERIZATION OF ORTHOTROPIC ELASTIC PARAMETERS OF A FOAM BY THE MIXED EXPERIMENTAL-NUMERICAL ANALYSIS

Different kind of foams, usually made from polymers, metals, ceramics, glass, etc. have been widely used in various branches of civil engineering since the 80s. The most common are polyurethane foams. Since their role in construction nowadays is not only to act as a thermal barrier but also to take some of loads, the engineers need to know also their mechanical properties. This implies that manufacturers or designers must perform a number of laboratory tests in order to find a set of substantial parameters of this particular material. Due to noticeable orthotropic behavior of foams, one needs to carry out several laboratory tests to identify elastic properties only. Here, an enhanced testing methodology is proposed to reduce the number of tests required for characterization of elastic orthotropic properties of foams. By combining the advanced measurement techniques, non-traditional experimental setup, numerical modeling and inverse analysis one can capture all nine elastic properties from just two or three tests. In the paper, full experimental and numerical procedures are presented and validated by noisy pseudo-experimental data.

Cavitation Bubble Measurement in Tribological Contacts Using Digital Holographic Microscopy

The use of advanced measurement techniques such as the digital holography method described in this paper improves the understanding of the cavitation phenomenon in tribological contacts such as the sliding contact of the piston ring–cylinder liner conjunction. The paper describes the use of digital holography measurement technique to measure cavitation bubble formation and thickness. The position of observed lubricant film rupture preceding the cavitation region is compared with some commonly predicted boundary often used with Reynolds equation. The experimental results indicate that the Reynolds and Elrod boundary conditions are the most suitable for the investigated sliding contact conditions.

Evaluation of hydraulic conductivity in shallow groundwater formations: a comparative study of the Csókás’ and Kozeny–Carman model

The Kozeny–Carman equation has achieved widespread use as a standard model for estimating hydraulic conductivity of aquifers. An empirically modified form applicable in shallow formations called Csókás’ formula is discussed, which is based on the relation between the effective grain-size and formation factor of freshwater-bearing unconsolidated sediments. The method gives a continuous estimate of hydraulic conductivity along a borehole by using electric and nuclear logging measurements without the need of grain-size data. In the first step, synthetic well-logging data sets of different noise levels are generated from an exactly known petrophysical model to test the noise sensitivity of the Csókás’ method and to assess the degree of correlation between the results of Csókás’ and Kozeny–Carman model. In the next step, borehole logs acquired from Hungarian sites are processed to make a comparison between the Csókás’ formula and the Kozeny–Carman equation including grain-size data measured on rock samples. The hydraulic conductivity logs derived separately from the Csókás’ and Kozeny–Carman formulae show reliable interpretation results, which are also validated by the Hazen’s formula and statistical factor analysis. The fundamental goal of Professor Csókás’ research was to derive some useful hydraulic parameters solely from well-logging observations. This idea may be of importance today since the input parameters can be determined more accurately by advanced measurement techniques. Hence, the Csókás’ formula may inspire the hydrogeophysicists to make further developments for a more efficient exploration of groundwater resources.

Experimental Verification of a Benchmark Forming Simulation

Forming of near-net-shaped and load-adapted functional components, as it is developed in theTransregionalCollaborative Research Centreon Sheet-Bulk Metal FormingSFB/TR73, causes different problems, which lead to non-optimal manufacturing results. For these high complex processes the prediction of forming effects can only be realized by simulations. A stamping process of pressing eight punches into a circular blank is chosen for the considered investigations. This reference process is designed to reflect the main aspects, which strongly affect the final outcome of forming processes. These are the orthotropic material behaviour, the optimal design of the initial blank and the influences of different contact and friction laws. The aim of this work is to verify the results of finite element computations for the proposed forming process by experiments. Evaluation methods are presented to detect the influence of the anisotropy and also to quantify the optimal blank design, which is determined by inverse form finding. The manufacturing accuracy of the die plate and the corresponding roughness data of the milled surface are analysed, whereas metrological investigations are required. This is accomplished by the help of advanced measurement techniques like a multi-sensor fringe projection system and a white light interferometer. Regarding the geometry of the punches, micromilling of the die plate is also a real challenge, especially due to the hardness of the high-speed steelASP2023(approx. 63 HRC). The surface roughness of the workpiece before and after the forming process is evaluated to gain auxiliary data for enhancing the friction modelling and to characterise the contact behaviour.

Accuracy of Numerical Algorithms for Satellite Orbit Propagation and Gravity Field Determination

The orbit determination process, such as that used for the Gravity Recovery and Climate Experiment, known as GRACE, is highly dependent upon the comparison of measured observables with computed values, derived from mathematical models relating the satellites’ numerically integrated state to the observable. Significant errors in the computed state corrupt this comparison and induce errors in the least-squares estimate of the satellites’ states, as well as the gravity field. Due to the high accuracy of the intersatellite ranging measurements from GRACE, numerical computations must mitigate errors to maintain a similar level of accuracy. One error source is the presence of roundoff errors in the computed intersatellite range-rate when integrating continuous, smoothly varying accelerations with double-precision arithmetic. These errors occur at approximately root mean square and limit the accuracy of numerically integrating background gravity field models to degrees/orders 260 and 410 for satellite pairs flying at altitudes of 500 and 300 km respectively. In addition, the integration of filtered, transient accelerations, which occur on timescales much smaller than the integration step size, induce errors at an approximately in range-rate, becoming a limitation as more advanced intersatellite measurement techniques approach this level of accuracy.

Room Acoustical Parameters as Predictors of Room Acoustical Impression: What Do We Know and What Would We Like to Know?

Room acoustical parameters are audio features, usually extracted from monaural or binaural measurements of room acoustical environments, and used to predict different aspects of the ‘room acoustical impression’. The paper takes a closer look at the nature of this perceptional construct and at different approaches to develop a psychological measuring instrument for the multidimensional perceptional profile of room acoustical environments. Even after several decades of research, there is no satisfactory solution available for this purpose. The reasons for this lie in methodological deficits with respect to test development and item analysis as well as in a much too small sample of stimuli used in previous studies. Prospects for progress are opened up by state-of-the-art technologies for room acoustical simulation and auralization, which may be used to provide a large and representative sample of room acoustical environments as well as an authentic presentation in experimental studies. The fundamental perceptional components delivered by this approach will, most likely, not be predictable by traditional room acoustical parameters, but require advanced measurement techniques based on spherical arrays of transducers for both source and receiver characteristics, as well as new auditory models for feature extraction. The physical and psychological aspects of the problem are, in any case, inextricably linked with each other.

Modeling of Discharge Distribution in Bend of Ganga River at Varanasi

Dynamics of river behavior plays a great role in meandering, sediment transporting, scouring, etc. of river at bend, which solely depends on hydraulics properties such as horizontal and vertical stress, spatial and temporal variation of discharge. Therefore understanding of discharge distribution of river Ganga is essential to apprehend the behavior of river cross section at bend particularly. The measurement of discharge is not very simple as there is no instrument that can measure the discharge directly, but velocity measurement at a section can be made. Velocity distribution at different cross sections at a time is also not easy with single measurement with the help of any instrument and method, so it required repetitions of the measurement. Velocity near the end of bank, top and bottom layer of natural streams is difficult to be measured, yet velocity distribution at these regions plays important role in characterizing the behavior of river. This paper deals with the new advanced discharge measurement technique and measured discharge data has been used for modelling at river bend. To carry out the distribution of discharge and velocity with depth in river Ganga, the length of river in study area was distributed into 14 different cross sections, M-1 to M-14, measured downstream to upstream and the measurement was done by using of ADCP (Acoustic Doppler Current Profiler). At each cross section, profiles were measured independently by an ADCP and data acquired from ADCP were further used for the regression modeling. A multiple linear regression model was developed, which showed a high correlation among the discharge, depth and velocity parameters with the root mean square error (R2) value of 0.8624.

BUBBLE DYNAMICS IN 2D BUBBLE COLUMN: COMPARISON BETWEEN HIGH-SPEED CAMERA IMAGING ANALYSIS AND 4-POINT OPTICAL PROBE

Two-dimensional (2D) bubble columns have been used in the literature to study the detailed flow field for evaluation and validation of computational fluid dynamics (CFD) and for developing the needed closures and interfacial forces models for gas-water systems. Hence, this work focuses on investigating the bubble dynamics (i.e., local gas holdup, bubble velocity, bubble chord length, and frequency) in a 2D bubble column. Two advanced measurement techniques were implemented in this work, high-speed video camera imaging and a four-point optical probe. A new method for analysis of video camera imaging was employed. The results of both techniques were compared. The results show good overall agreement between the two methods for the horizontal profile of both bubble size and gas holdup. The findings revealed a strong positive correlation between bubble size and gas holdup. It was found that video image analysis could become an accurate, noninvasive alternative to fiber optical probes, at least in 2D systems, although the technique needs more refinement.

Application of the tracer combination TEA/acetone for multi-parameter laser-induced fluorescence measurements in IC engines with exhaust gas recirculation

The present study introduces an advanced measurement technique for multi-parameter imaging in optically accessible IC engines which is based on two planar laser-induced fluorescence (PLIF) techniques. A LIF tracer mixture consisting of triethylamine (TEA) and acetone is used to investigate the simultaneous determination of air/fuel-ratio, temperature and exhaust gas/air concentration in a direct-injection spark-ignition (DISI) engine with exhaust gas recirculation (EGR). The approach is based on applying a two-wavelength excitation scheme of acetone for temperature and concentration measurement and employing single-wavelength excitation of TEA for the determination of AFR utilizing the effect of oxygen quenching. At first the spectral properties of the tracer mixture are studied to show the separability of the fluorescence signals of both tracers and to identify possible tracer interactions. For calibration and IC engine measurements the focus is put on the tracer acetone for the determination of temperature and air concentration. Fluorescence calibration at IC engine conditions is conducted with pure acetone and with an acetone/TEA mixture to visualize possible interactions. The tracer mixture is then applied in an optically accessible IC engine for temperature determination, which is compared with results of the commonly used successive application of the two individual techniques. The results suggest the suitability of this measurement technique for the simultaneous determination of air/fuel-ratio, air concentration and temperature in combustion devices like IC engines, which helps in the optimization of mixture formation and the subsequent processes such as ignition and pollutant formation.

Digital image correlation techniques to investigate strain fields and cracking phenomena in asphalt materials

This paper is the outcome of a specific task group of the RILEM Technical Committee 241-MCD “Mechanisms of Cracking and Debonding in Asphalt and Composite Pavements”. The group on “Advanced Measurement Techniques” was established in 2011 to investigate DIC applications for non-destructive and non-contact measurements of strain fields during laboratory testing. The paper illustrates different DIC/optical flow applications in measuring strain distribution during laboratory testing. Specific applications of DIC for evaluating crack initiation and crack propagation in asphalt materials are presented.

R-curve evaluation of pipeline girth welds using advanced measurement techniques

A strain-based flaw assessment procedure is recommended for girth welded pipelines subjected to large deformations. To evaluate the allowable defect dimensions, the tearing resistance needs to be characterized. This paper investigates the effect of weld metal strength mismatch on the resistance curve using Single Edge Notched Tension (SENT) specimens. Several advanced measurement techniques are applied during the tests in order to obtain a continuous measurement of crack extension and to visualize the deformation fields near the crack. The resistance curves are determined using a single specimen technique. The unloading compliance method and the potential drop method result in similar predictions of ductile crack extension, yielding similar resistance curves. Next to these measurements, the full field deformations are determined using digital image correlation. The experiments indicate that the position of the applied notch in the weld has the potential to influence the strain fields.