Showing papers in "Measurement Science and Technology in 2003"
TL;DR: In this paper, the authors reviewed recent research on fiber optic long-period gratings (LPGs) with emphasis placed upon the characteristics of LPGs that make them attractive for applications in sensing strain, temperature, bend radius and external index of refraction.
Abstract: Recent research on fibre optic long-period gratings (LPGs) is reviewed with emphasis placed upon the characteristics of LPGs that make them attractive for applications in sensing strain, temperature, bend radius and external index of refraction. The prospect of the development of multi-parameter sensors, capable of simultaneously monitoring a number of these measurands will be discussed.
1,203 citations
TL;DR: In this article, a review of existing image reconstruction algorithms for electrical capacitance tomography (ECT) is presented, including linear back-projection, singular value decomposition, Tikhonov regularization, Newton-Raphson, steepest descent method, Landweber iteration, conjugate gradient method, algebraic reconstruction techniques, simultaneous iterative reconstruction techniques and model-based reconstruction.
Abstract: Electrical capacitance tomography (ECT) is used to image cross-sections of industrial processes containing dielectric material. This technique has been under development for more than a decade. The task of image reconstruction for ECT is to determine the permittivity distribution and hence material distribution over the cross-section from capacitance measurements. There are three principal difficulties with image reconstruction for ECT: (1) the relationship between the permittivity distribution and capacitance is non-linear and the electric field is distorted by the material present, the so-called 'soft-field' effect; (2) the number of independent measurements is limited, leading to an under-determined problem and (3) the inverse problem is ill posed and ill conditioned, making the solution sensitive to measurement errors and noise. Regularization methods are needed to treat this ill-posedness. This paper reviews existing image reconstruction algorithms for ECT, including linear back-projection, singular value decomposition, Tikhonov regularization, Newton–Raphson, iterative Tikhonov, the steepest descent method, Landweber iteration, the conjugate gradient method, algebraic reconstruction techniques, simultaneous iterative reconstruction techniques and model-based reconstruction. Some of these algorithms are examined by simulation and experiment for typical permittivity distributions. Future developments in image reconstruction for ECT are discussed.
1,082 citations
TL;DR: A detailed description of the methodology used to determine residual stresses can be found in this paper, which contains 20 chapters contributed by 23 authors, divided into five major parts: the overall layout is very logical, with the first part giving a general introduction to the use of neutrons and x-rays for materials research and summarizing the methods used for their production.
Abstract: The presence of residual stresses within engineering components is often a key feature in determining their usable lifetimes and failure characteristics. Residual surface compression can, for example, restrict the propagation of surface cracks through the bulk. As a consequence, it is essential to characterize the magnitude and spatial distribution of residual stresses and, at least for non-destructive testing, this is most widely achieved using diffraction of neutron and high energy synchrotron radiations. This book aims to provide a detailed description of the methodology used to determine residual stresses. The major emphasis is placed on the neutron method, this being the more widely established approach at present. It contains 20 chapters contributed by 23 authors, divided into five major parts. The overall layout is very logical, with the first part giving a general introduction to the use of neutrons and x-rays for materials research and summarizing the methods used for their production. Part 2 considers the more specific aspects of extracting the residual stress distribution within a bulk sample and includes some valuable comments on a number of potential experimental problems, such as the determination of the stress-free lattice parameter and the effects of broadening of the Bragg peaks. The experimental facilities currently available or under development are described in part 3, with the remaining two parts devoted to general and specific applications of the residual stress measurement technique. As expected with such a large number of different authors, there is some variation in style and quality. However, the text is generally easy to follow and, more importantly, it is largely free of the problems of inconsistent notation and dupication of material that can afflict multi-authored texts. My only negative comment concerns the latter portion of the book devoted to specific applications of the technique, which is illustrative rather than comprehensive. In particular, there is no clear justification for the particular choice of topics included. Chapters devoted to the more important areas of residual stresses in aerospace components and within the chemical industry would probably have more general interest than, for example, the one devoted nuclear fusion reactors. The publication of this book is rather timely, with a current expansion in the experimental facilities available for the measurement of residual stresses, including dedicated diffractometers for the study of engineering components. To the best of my knowledge, there is no comparable text currently available. In my opinion, this book provides both an accessible introduction to the topic for new students in this particular area and a useful reference text on the current status of the field to more established researchers. Stephen Hull
315 citations
TL;DR: In this article, the water vapour spectrum in the 1-2 µm near-infrared region is systematically analyzed to find the best absorption transitions for sensitive measurement of H2O concentration and temperature in combustion environments using a single tunable diode laser with typical distributed feedback single-mode scanning range (1 cm−1).
Abstract: The water vapour spectrum in the 1–2 µm near-infrared region is systematically analysed to find the best absorption transitions for sensitive measurement of H2O concentration and temperature in combustion environments using a single tunable diode laser with typical distributed feedback single-mode scanning range (1 cm−1) The use of a single laser, even with relatively narrow tuning range, can offer distinct advantages over wavelength-multiplexing techniques The strategy and spectroscopic criteria for selecting optimum wavelength regions and absorption line combinations are discussed It should be stressed that no single figure of merit can be derived to simplify the selection process, and the optimum line pair should be chosen case by case Our investigation reveals that the 18 µm spectral region is especially promising, and we have identified 10 of the best water line pairs in this spectral region for temperature measurements in flames Based on these findings, a pair of H2O transitions near 18 µm was targeted for the design and development of an initial single-laser sensor for simultaneously measuring H2O concentration and temperature in atmospheric-pressure flames As part of the sensor development effort, fundamental spectroscopic parameters including the line strength, line-centre frequency and lower state energies of the probed transitions were measured experimentally to improve the current databases We conclude with demonstration results in a steady and a forced atmospheric-pressure laboratory combustor
238 citations
TL;DR: Neutron activation analysis is a powerful quantitative analytical technique with application in a broad range of disciplines such as agriculture, archaeology, geochemistry, health and human nutrition, environmental monitoring and semiconductor technology as mentioned in this paper.
Abstract: Neutron activation analysis is a powerful quantitative analytical technique with application in a broad range of disciplines such as agriculture, archaeology, geochemistry, health and human nutrition, environmental monitoring and semiconductor technology. Due to its excellent sensitivity, great accuracy and precision, and versatility, the technique is a suitable method for analysing many different types of samples. Archaeologists, in particular, have made extensive use of neutron activation analysis for the purpose of characterizing archaeological materials and determining their provenance. This paper presents a brief history of the technique and its application to archaeology, describes the physics behind the analytical method, and explains how the method is generally employed to determine the sources of archaeological materials.
190 citations
TL;DR: In this paper, a further developed evaluation procedure was described to determine cp and h as temperature dependent values which was not the case in Yinping's method, based on the same experimental procedure.
Abstract: The temperature-history method, proposed by Yinping et al, is a simple and economic way to determine the main thermophysical properties of materials used in thermal energy storage based on solid–liquid phase change. It is based on comparing the temperature history of a phase-change material sample and a sample of a well known material upon cooling down. In this paper we describe a further developed evaluation procedure to determine cp and h as temperature dependent values which was not the case in Yinping's method, based on the same experimental procedure. Given the suitability of these properties to calculate thermal energy storage using these materials, the method is proposed to present the results obtained in the form of enthalpy–temperature curves. A discussion about the errors produced by this method and an experimental improvement are proposed too.
190 citations
TL;DR: A simple optical humidity sensor with fast response and high sensitivity, which is based on the plastic optical fiber structure change from leaky to guided, was easily fabricated and could be used for real-time humidity monitoring as mentioned in this paper.
Abstract: Certain kinds of cellulose, such as a hydroxyethylcellulose, swell in a humid atmosphere and show a decrease in refractive index. Using this effect, a simple optical humidity sensor with fast response and high sensitivity, which is based on the plastic optical fibre structure change from leaky to guided, was easily fabricated and could be used for real-time humidity monitoring.
183 citations
TL;DR: In this paper, a self-mixing interference effect in a laser diode is used for a new type of laser vibrometer based on the self mixing interference effect, which can operate on nearly any kind of rough surface.
Abstract: The principle and the experimental realization of a new type of laser vibrometer based on the self-mixing interference effect in a laser diode are presented. The self-mixing configuration allows for a practical set-up that is simpler by far than conventional laser vibrometer schemes. The vibrometer relies on locking of the system to half the interferometric fringe, and on active phase-nulling by wavelength modulation. This allows an extended dynamic range to be achieved, whilst retaining a good sensitivity to sub-wavelength vibrations. We have designed and built a prototype of the vibrometer that can operate on nearly any kind of rough surface, covering the 0.1 Hz–70 kHz frequency range of vibration. The noise floor is less than 100 pm Hz−1/2, and the maximum measurable vibration amplitude is 180 µm peak to peak. The proposed method can find application in modal analysis and noise and vibration measurements in industrial and scientific environments.
177 citations
TL;DR: In this article, the authors present a system including a vector network analyser, horn/lens antennas, holder for grain and oilseed samples and a radiation absorbing enclosure that was used for such measurements, and the techniques and procedures followed to obtain reliable permittivity data for wheat, shelled corn (maize) and soybeans are outlined.
Abstract: Principles of dielectric property measurement by microwave free-space transmission measurements are presented, and the important sources of errors in such measurements are discussed. A system, including a vector network analyser, horn/lens antennas, holder for grain and oilseed samples and a radiation absorbing enclosure that was used for such measurements is described, and the techniques and procedures followed to obtain reliable permittivity data for wheat, shelled corn (maize) and soybeans are outlined. Data illustrating linear relationships between microwave attenuation and phase shift per unit sample thickness, each divided by the bulk density of the granular materials, and frequency and moisture content are presented graphically. The linear dependence of calculated permittivity components, dielectric constant and loss factor, on bulk density is also shown, and permittivity components for wheat, corn and soybeans are listed for reference at frequencies from 5 to 17 GHz at different densities and moisture levels at about 23 °C. Permittivity values are also listed for the same three commodities, adjusted to a medium density value through use of the Landau and Lifshitz, Looyenga dielectric mixture equation, for the total range of moisture contents at 10 GHz and at the same temperature.
160 citations
TL;DR: In this paper, the authors measured the water vapour permeability and evaporative resistance of 26 different waterproof, windproof and breathable shell fabrics using five standard test methods, including the ASTM E 96 upright and inverted cup tests with water, the JIS L 1099 desiccant inverted cup test and the new ASTM F 2298 standard using the dynamic moisture permeation cell (DMPC).
Abstract: It is difficult for outdoor apparel manufacturers to interpret the technical information provided by fabric suppliers concerning fabric 'breathability' properties because different methods and test conditions are used. In addition, fabrics with hydrophilic components change their properties under different humidity conditions. The purpose of this study was to measure the water vapour permeability and evaporative resistance of 26 different waterproof, windproof and breathable shell fabrics using five standard test methods. The water vapour transmission rate (WVTR) was measured using the ASTM E 96 upright and inverted cup tests with water, the JIS L 1099 desiccant inverted cup test and the new ASTM F 2298 standard using the dynamic moisture permeation cell (DMPC). The evaporative resistance was measured using the ISO 11092 sweating hot plate test. The WVTRs were consistently highest when measured with the desiccant inverted cup, followed by the inverted cup, DMPC and upright cup. The upright cup was significantly correlated with the DMPC (0.97), and the desiccant inverted cup was correlated to the sweating hot plate (?0.91).
139 citations
TL;DR: In this article, techniques and methods used in the C2RMF laboratory for manganese oxide pigments are presented and several conclusions are drawn concerning the technical level of Palaeolithic artists.
Abstract: Archaeologists have attempted the interpretation of rock art, but have often disregarded the technical aspects of paints. Analysing paint samples for preparation techniques and studying the various compounds used, allows us to determine the technology of early painters. Palaeolithic artists used two main colours: red (iron oxide: natural hematite or heated goethite) and black (charcoal or manganese oxides). These pigments could be prepared in different ways (grinding, mixing with extender and/or binder or by heating) in order to enhance the properties of the paints. Analyses attempt to determine the physicochemical nature of the matter and its preparation mode, and to get an idea of its geographic origin. This paper presents techniques and methods used in the C2RMF laboratory for manganese oxide pigments. Distinction between manganese oxides with or without other cations is made and heat treatment of manganese oxide minerals is described. Results obtained for black pigment in Lascaux and Ekain caves are presented and discussed. From paint analyses, several conclusions are drawn concerning the technical level of Palaeolithic artists.
TL;DR: In this article, the authors describe the process of depositing gold-black on thin, freestanding pyroelectric detector substrates and compare this with previous work documented in the literature.
Abstract: We describe the process of depositing gold-black on thin, freestanding pyroelectric detector substrates and compare this with previous work documented in the literature. We have evaluated gold-black coatings on thin, freestanding pyroelectric detector substrates by means of scanning electron microscope, Fourier transform infrared spectrophotometer reflectance, and spectral responsivity measurements. Spectrophotometric measurements indicate that reflectance at normal incidence varies by less than 1% at wavelengths shorter than 2.5 µm and by less than 10% at 10 µm. These results are correlated with the spectral responsivity of the detector and demonstrate that radiation not reflected by the gold-black is absorbed by the detector element. We have evaluated gold-black coatings as a function of position at two wavelengths and found variations of less than 1% at 1.25 µm and less than 5% at 10.3 µm, which demonstrates that spatial uniformity can be coating dependent. Gold-black coatings exposed to a 193 nm wavelength excimer laser were evaluated by visual inspection for damage and determined to have a damage threshold of approximately 38 mJ cm−2.
TL;DR: In this paper, the precision measurements of 240 nm-pitch one-dimensional grating standards were carried out using an atomic force microscope (AFM) with a high-resolution three-axis laser interferometer (nanometrological AFM).
Abstract: Precision measurements of 240 nm-pitch one-dimensional grating standards were carried out using an atomic force microscope (AFM) with a high-resolution three-axis laser interferometer (nanometrological AFM). Laser sources of the three-axis laser interferometer in the nanometrological AFM were calibrated with an I2-stabilized He–Ne laser at a wavelength of 633 nm. The results of the precision measurements using the nanometrological AFM have direct traceability to the length standard. The uncertainty in the pitch measurements was estimated in accordance with the Guide to the Expression of Uncertainty in Measurement. The primary source of uncertainty in the measurements was derived from interferometer nonlinearity, and its value was approximately 0.115 nm. Expanded uncertainty (k = 2) of less than 0.31 nm was obtained. It is suggested that the nanometrological AFM is a useful instrument for the nanometrological standard calibration.
TL;DR: A review of the engineering theory and the sensing element applications of the magnetostrictive delay line (MDL) technique is presented in this article, where the state of the art of magnetic materials and effects used in sensor design is overviewed and the operation of MDLs and their basic engineering properties are discussed.
Abstract: A review of the engineering theory and the sensing element applications of the magnetostrictive delay line (MDL) technique is presented. The state of the art of magnetic materials and effects used in sensor design is overviewed and the operation of MDLs and their basic engineering properties are discussed. The resulting position, stress and field sensors based on this technique as well as their most significant applications are demonstrated. Finally, the industrialization process and the integration of the sensors with electronic circuitry as well as their evaluation with respect to the state of the art are discussed.
TL;DR: In this article, a theory of diffraction-limited spot size for infinity-corrected microscope optics is developed for all numerical apertures and all immersion media, and a new theory is developed that estimates the effective numerical aperture of an oil-immersion lens when imaging into fluid of a lower refractive index, such as water.
Abstract: A theory of diffraction-limited spot size is developed for infinity-corrected microscope optics. Previously reported formulae were originally derived using a single-lens system. In addition, the previously reported relationship between f-number and numerical aperture assumed a paraxial approximation and was limited to air-immersion lenses. Here, a new relationship between f-number and numerical aperture is developed, and is valid for all numerical apertures and all immersion media. In addition, a new theory is developed that estimates the effective numerical aperture of an oil-immersion lens when imaging into fluid of a lower refractive index, such as water. The results indicated that when imaging into water, high numerical aperture NA = 1.0 or 1.2 water-immersion lenses provide comparable and sometimes better diffraction-limited resolution than NA = 1.4 oil-immersion lenses. In addition, when imaging into water, water-immersion lenses may provide superior image quality, because they are corrected for aberrations resulting from the water/glass interface.
TL;DR: The first International PIV Challenge was held in Gottingen (Germany) on 14 and 15 September 2001 as discussed by the authors, which was linked to the PIV01 International Symposium which was held the same place the week after.
Abstract: The aim of this paper is to present the main results of the First International PIV Challenge which took place in Gottingen (Germany) on 14 and 15 September 2001. This workshop was linked to the PIV01 International Symposium which was held in the same place the week after. The present contribution gives the objectives of the challenge, describes the test cases and the algorithms used and presents the main results obtained together with some discussion and conclusions on the accuracy and robustness of both PIV and PTV algorithms. As it is not possible to detail all the results obtained, this contribution should serve as a guide for the use of the full database of images and results which is available at http://www.pivchallenge.org.
TL;DR: This paper shows that a high resolution ECG can be acquired using two of these sensors mounted wristwatch style, one on each wrist, and predicts that these new devices will rapidly find application in the areas of clinical medicine and ambulatory monitoring.
Abstract: In this paper we describe the application of an electric potential sensor to the ambulatory monitoring of the human electrocardiogram (ECG). We show that a high resolution ECG can be acquired using two of these sensors mounted wristwatch style, one on each wrist. These sensors, which do not require a real current conducting path in order to operate, are used non-invasively without making electrical contact to the subject. Furthermore, their sensitivity and low noise floor have made it possible to detect a peak which corresponds, in timing, to the His bundle depolarization?a feature not normally seen in conventional surface ECGs. We predict that these new devices will rapidly find application in the areas of clinical medicine and ambulatory monitoring.
TL;DR: In this paper, the authors presented an application of a low-cost commercially available NIR spectrometer for the estimation of ripeness of Chilean wine grapes using two configurations for the spectra acquisition (diffuse transmittance and interactance), using a custom-designed contact probe.
Abstract: Near-infrared (NIR) spectroscopy has become a very popular technique for the non-invasive assessment of intact fruit. This work presents an application of a low-cost commercially available NIR spectrometer for the estimation of ripeness of Chilean wine grapes. Two configurations for the spectra acquisition were used (diffuse transmittance and interactance), using a custom-designed contact probe. Samples of Chardonnay, Carmenere and Cabernet Sauvignon, collected over the 2002 harvest and pre-harvest seasons, were analysed for total soluble solids content (°Brix). Partial least squares calibration models, obtained from several preprocessing techniques (smoothing, multiplicative signal correction, standard normal variate, etc), were compared. Also, two spectral regions were used, one without the red part of the visible spectrum (just the short-wave (SW–NIR) region) and the other including it. Performance of different models was assessed in terms of root mean square of cross-validation, root mean square of prediction (RMSEP) and R2 for a validation set of samples. RMSEPs of 1.06 with R2 = 0.942 indicate that it is possible to estimate wine grape ripeness (°Brix value), by using a CCD portable spectrometer. The red grape models performed better than the white grape models.
TL;DR: In this paper, the authors used white-light interferometry surface profiling for material characterization and device inspection, and showed that residual stress may be determined by using electrostatic actuation to pull fixed fixed-fixed beams towards the substrate, and inter-ferometry to record the beam deflection profile.
Abstract: As microelectromechanical systems (MEMS) move rapidly towards commercialization, the issue of mechanical characterization has emerged as a major consideration in device design and fabrication. It is now common to include a set of test structures on a MEMS wafer for extraction of thin film material properties (in particular, residual stress, stress gradient and Young's modulus), and for process and device monitoring. These structures usually consist of micromachined beams and strain gauges. Measurement techniques include tensile testing, scanning electron microscopy (SEM) imaging, atomic force microscopy (AFM) analysis, surface profiling and Raman spectroscopy. However, these tests are often destructive and may be difficult to carry out at the wafer scale. Instead of these methods, this paper uses white-light interferometry surface profiling for material characterization and device inspection. Interferometry is quick, non-destructive, non-contact, and can offer a high density lateral resolution with extremely high sensitivities to the surface in the z-direction—all essential requirements for high volume manufacturing. A range of devices is employed to illustrate the capabilities of white-light interferometry as a measurement and process characterization tool.It is shown that residual stress may be determined by using electrostatic actuation to pull fixed–fixed beams towards the substrate, and interferometry to record the beam deflection profile. Finite-element simulation software is employed to model this deflection, and to estimate the material properties which minimize the difference between the measured and simulated profiles. The results agree well with blanket film measurements.
TL;DR: In this article, a tunable optical filter for selecting different bands of wavelength in the UV, visible and IR regions is presented, which consists of a ferrofluid-based emulsion cell (emulsion sandwiched between two transparent sheets), a miniature solenoid and a variable direct current source.
Abstract: We present the details of a new tunable optical filter, suitable for selecting different bands of wavelength in the UV, visible and IR regions. The filter comprises a ferrofluid-based emulsion cell (emulsion sandwiched between two transparent sheets), a miniature solenoid and a variable direct current source for changing the magnetic field inside the solenoid. By varying the magnetic field, one can tune the filter and select the desired wavelength. We discuss the working principle of the new tunable optical filter with a few examples.
TL;DR: In this article, a pig tendon was studied by the use of the conventional fibre-based optical coherence tomography (OCT) systems. And the results demonstrate that conventional OCT can be used to monitor the tissue birefringence.
Abstract: This paper addresses whether conventional fibre-based optical coherence tomography (OCT) is capable of obtaining birefringence information of well-organized tissues. For this purpose, a highly organized tissue, pig tendon, is studied by the use of the conventional fibre-based OCT systems. It is found that the tendons result in well-defined banded OCT images. The observed bands in the OCT images are sensitive to the wavelength of light source applied and phase retardation. The results demonstrate that conventional OCT can be used to monitor the tissue birefringence.
TL;DR: In this paper, the wavelength of the radiation which interacts with wood was selected for the description of the measurement techniques and the most relevant technique for the imaging of the cross section of the specimen under test will depend upon the particular application and material being studied: trees, logs, timber and wood-based composites.
Abstract: High resolution imaging of wood requires the development of measurement techniques for nondestructive characterization of this material. The techniques, ranging from ionizing radiation to thermal techniques, microwaves, ultrasonics and nuclear magnetic resonance, provide excellent means of obtaining information about the internal structure of wood. High resolution images of wood structure can be obtained from a complete set of projections of relevant physical parameters such as x-ray attenuation, ultrasonic velocities, dielectric properties, etc. In this article the criterion selected for the description of the measurement techniques is the wavelength of the radiation which interacts with wood. The most relevant technique for the imaging of the cross section of the specimen under test will depend upon the particular application and material being studied: trees, logs, timber and wood-based composites.
TL;DR: In this paper, an electronic nose (EN) based system, which employs an array of four inexpensive commercial tin-oxide odour sensors, has been used to analyse the state of freshness of eggs.
Abstract: An electronic nose (EN) based system, which employs an array of four inexpensive commercial tin-oxide odour sensors, has been used to analyse the state of freshness of eggs. Measurements were taken from the headspace of four sets of eggs over a period of 20-40 days, two 'types of egg data' being gathered using our EN; one type of 'data' related to eggs without a hole in the shells and the other type of 'data' related to eggs wherein we made tiny holes in the shells. Principal component analysis, fuzzy C means, self-organizing maps and 3D scatter plots were used to define regions of clustering in multisensor space according to the state of freshness of the eggs. These were correlated with the 'use by date' of the eggs. Then four supervised classifiers, namely multilayer perceptron, learning vector quantization, probabilistic neural network and radial basis function network, were used to classify the samples into the three observed states of freshness. A comparative evaluation of the classifiers was conducted for this application. The best results suggest that we are able to predict egg freshness into one of three states with up to 95% accuracy. This shows good potential for commercial exploitation.
TL;DR: In this paper, a combination of complementary elemental and structural analyses (particle-induced x-ray emission, particle-induced γ-ray emissions, scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX), electron microprobe, xray diffraction, infrared spectroscopy, TEM with EDX), microscopic observations, and porosity measurements are performed.
Abstract: Bone remains play an important role in archaeology as a source of information about the past. However, they alter over time. Alteration occurs at all scales from the macroscopic to nanoscopic level. The evaluation of information extracted on palaeodiets, ages and palaeoclimates from their chemical and isotopic composition requires the study of diagenetic modifications by means of different complementary analytical methods. Diagenetic parameters that quantify the post-mortem alteration of bone are bone histology, porosity, protein content, crystallinity of bone apatite, carbonate content, enrichment and leaching of chemical species in general. The investigation of these features can be performed by a combination of complementary elemental and structural analyses (particle-induced x-ray emission, particle-induced γ-ray emission, scanning electron microscopy (SEM) coupled with energy dispersive x-ray (EDX), electron microprobe, x-ray diffraction, infrared spectroscopy, transmission electron microscopy (TEM) with EDX), microscopic observations (optical, SEM, TEM) and porosity measurements.The study of animal bones from the Neolithic site of Bercy, France (4000 BC) from the same archaeological layer within different local depositional, hydrological and redox environments illustrates the possible information that can be extracted from the diagenetic study on the processes affecting the state of bone preservation. The main characteristic of the bone buried in the waterlogged zone is a high level of preservation of the organic matter and a low level of porosity inhibiting major structural or chemical modifications. The bone sample from the zone with a fluctuating hydrological regime shows a low level of organic matter and high porosity. Knowledge of the diagenetic patterns enables an estimation of the reliability of information obtained from bone analyses.
TL;DR: In this paper, a method for evaluating the dynamic response of force transducers to a step force is proposed, where the inertial forces acting on an object, which is suddenly put on a force transducer under test, are used as the reference force.
Abstract: A method is proposed for evaluating the dynamic response of force transducers to a step force. In the method, gravitational and inertial forces acting on an object, which is suddenly put on a force transducer under test, are used as the reference force. At the beginning of the evaluation, the object is suspended using a wire just above the transducer. The object is then made to fall on to the transducer by cutting the wire. To realize perpendicular motion with sufficiently small friction, a pneumatic linear bearing is used. The inertial force acting on the object is measured highly accurately by measuring the velocity of the mass using an optical interferometer.
TL;DR: In this paper, a luminescence dating method for single aliquots and single grains has been proposed, which can not only identify and date mixed deposits but also provide valuable information on site formation processes.
Abstract: With improvements in methodology and instrumentation, luminescence dating is becoming a much more useful chronometric tool in archaeology. Procedures for dating ceramics are relatively routine and their accuracy has been demonstrated in a number of studies. Research is aimed at applying ceramic dating in situations where other methods lack the direct dating ability of luminescence to resolve chronological problems. Sediment dating is more difficult because of uncertainty in the extent of zeroing or because of mixtures of different aged deposits. These problems have been addressed by isolating signals most likely to be zeroed and by dating single aliquots, and ultimately single grains. Single-grain dating now has the potential not only to identify and date mixed deposits but to provide valuable information on site formation processes. This is particularly critical for judging site integrity at controversial sites.
TL;DR: In this paper, the authors used optical fibres to detect hairline cracks and ultimate failure crack in civil engineering structures and highlight their ability to monitor crack propagation up to ultimate failure, in addition to detecting the initiation of a crack, good agreement between the sensor output and crack progression during loading was obtained in these concrete beams.
Abstract: Plastic optical fibres have been employed to detect initial cracks, monitor post-crack vertical deflection and detect failure cracks in concrete beams subjected to flexural loading conditions. The intensity-based sensor system relies on monitoring the modulation of light intensity within the optical fibre as the sensor is loaded. The sensor design offers good signal stability and sensitivity to the monitored parameter and represents a cost-effective alternative to other more sophisticated health-monitoring systems currently used in civil engineering structures. Here, a series of three- and four-point bend tests was conducted on a range of structures. Initially, the optical fibres were attached to scale-model concrete samples (without reinforcement) to evaluate their ability to monitor beam deflection and detect cracks. Similar tests were subsequently conducted on life-size concrete beams containing reinforcing steel bars. The location and subsequent trajectory of cracks during the loading regime were marked and then compared to the sensor signal to assess the sensor's ability to monitor crack development. The results demonstrate the possibility of using optical fibres to detect hairline cracks and ultimate failure crack in civil engineering structures and highlight their ability to monitor crack propagation up to ultimate failure. In addition to detecting the initiation of a crack, good agreement between the sensor output and crack progression during loading was also obtained in these concrete beams.
TL;DR: In this article, a force transducer is connected to a mass by a spring, which generates the oscillating force after the mass is manually hit using a hammer, and a pneumatic linear bearing is used to realize linear motion with sufficiently small friction acting on the mass.
Abstract: A method for evaluating the dynamic response of force transducers against an oscillation force is proposed. In the method, a force transducer is connected to a mass by a spring, which generates the oscillating force after the mass is manually hit using a hammer. A pneumatic linear bearing is used to realize linear motion with sufficiently small friction acting on the mass, which is the moving part of the bearing. The inertial force acting on the mass is determined highly accurately by measuring the velocity of the mass using an optical interferometer.
TL;DR: In this article, a novel measurement technique using fluorescent dye in combination with microresolution particle image velocimetry (micro-PIV) has been devised to investigate convective mixing in microspace.
Abstract: A novel measurement technique using fluorescent dye in combination with microresolution particle image velocimetry (micro-PIV) has been devised to investigate convective mixing in microspace. Tris(bipyridine)ruthenium(II), whose fluorescent intensity when excited by ultraviolet light is strongly temperature dependent, was applied to the bottom surface of a cover glass, that served as the upper boundary surface of a flow channel. This set-up thus realized a two-dimensional temperature measurement of the microflow channel. A spatial resolution of 5 µm × 5 µm and a temperature resolution of 0.26 K were achieved by using a cooled CCD camera and a 10× objective lens of a microscope. Pure water at differing temperatures was injected into opposite inlets of a T-shaped microchannel bound by cover glass and PDMS. The mixing process in the junction area was visualized by the present temperature and the micro-PIV techniques. The convective heat flux was calculated from measurement of velocity and temperature and compared to the heat conduction. It is found that the heat flux due to conduction was larger than that due to convection, thus it is noted that heat conduction may be an important factor in the design process of microfluidic devices.
TL;DR: In this paper, a comparison of measurements and numerical simulation results of the transfer function performed on a medium-voltage transformer winding is described, and a quantitative analysis of deformation detection and winding dislocation by means of transfer function method is described.
Abstract: Improvement of diagnostic methods for both power and distribution transformers is crucial considering the part they play in electrical networks as well as their cost. Transfer function based testing of transformers is one of the methods that has been introduced recently. This method enables the identification of winding deformations resulting from the short circuit currents and winding dislocations occurring during transportation, and can also be used to assess the state of electrical insulation. The methods of measurement of the transfer functions as well as the numerical simulations are aiming at determining the sensitivity of this method and to develop recognition criteria with regard to the type and range of the deformations. This paper presents a comparison of measurements and numerical simulation results of the transfer function performed on a medium-voltage transformer winding. A quantitative analysis of deformation detection and winding dislocation by means of the transfer function method is described.