Embedded fibre Bragg grating array sensors in aluminium alloy matrix by ultrasonic consolidation

Fibre Bragg Grating (FBG) array sensors have been successfully embedded in aluminium alloy matrix by ultrasonic consolidation (UC) technique. The temperature and loading responses of the embedded FBG arrays have been systematically characterised. The embedded grating sensors exhibit an average temperature sensitivity of ~36pm/°C, which is three times higher than that of normal FBGs, and a loading responsivity of ~0.1nm/kg within the dynamic range from 0kg to 3kg. This initial experiment clearly demonstrates that FBG array sensors can be embedded in metal matrix together with other passive and active fibres to fabricate smart materials to monitor the operation and health of engineering structures.

Ultrasonic field and temperature sensor based on short in-fibre Bragg gratings

The authors demonstrate that in-fibre Bragg gratings may be successfully used to measure megahertz acoustic fields if the grating length is sufficiently short and the optical fibre is appropriately desensitised. A noise-limited pressure resolution of 4.5 × 10 –3 atm vHz was found. The capability to simultaneously act as a temperature sensor is also demonstrated.

An energy-efficient route to the rapid synthesis of organically-modified SBA-15 via ultrasonic template removal

A low energy route for the removal of Pluronic P123 surfactant template during the synthesis of SBA-15 mesoporous silicas is explored. The conventional reflux of the hybrid inorganic-organic intermediate formed during co-condensation routes to Pr-SOH-SBA-15 is slow, utilises large solvent volumes, and requires 24 h to remove ∼90% of the organic template. In contrast, room temperature ultrasonication in a small methanol volume achieves the same degree of template extraction in only 5 min, with a 99.9% energy saving and 90% solvent reduction, without compromising the textural, acidic or catalytic properties of the resultant Pr-SOH-SBA-15. © 2014 The Royal Society of Chemistry.

Ultrasonic hydrophone based on short in-fiber Bragg gratings

We investigate the feasibility of using in-fiber Bragg gratings for measuring acoustic fields in the megahertz range. We found that the acoustic coupling from the ultrasonic field to the grating leads to the formation of standing waves in the fiber. Because of these standing waves, the system response is complex and, as we show, the grating does not act as an effective probe. However, significant improvement in its performance can be gained by use of short gratings coupled with an appropriate desensitization of the fiber. A noise-limited pressure resolution of ˜4.5 × 10-3 atm/vHz was found.

Embedded fibre Bragg grating array sensors in aluminium alloy matrix by ultrasonic consolidation

Fibre Bragg Grating (FBG) array sensors have been successfully embedded in aluminium alloy matrix by ultrasonic consolidation (UC) technique. The temperature and loading responses of the embedded FBG arrays have been systematically characterised. The embedded grating sensors exhibit an average temperature sensitivity of ~36pm/°C, which is three times higher than that of normal FBGs, and a loading responsivity of ~0.1nm/kg within the dynamic range from 0kg to 3kg. This initial experiment clearly demonstrates that FBG array sensors can be embedded in metal matrix together with other passive and active fibres to fabricate smart materials to monitor the operation and health of engineering structures.

Ultrasonic measurement of anisotropic reflectivity from Water-Phenolic CE Interface

In this contribution, we experimentally test the effects of azimuth and tilt angle on the acoustic reflectivity of a liquid- anisotropic solid interface. For this study, we are using a large source transducer, and acquired data for samples with different tilt angles. We use Phenolic CE material, which is known to have orthorhombic symmetry. Our results show that changes of the tilt angle produce important variations on the reflectivity that are larger as the tilt increases. The most remarkable feature is the change of the critical angle with the azimuth, which shows a larger spread for larger tilts. The spectral components of the acquired waveforms also show characteristic features linked to the location of the critical angle, we particularly observed a drop in the peak frequency. These observations suggest that care must be taken about the interpretation and inversion of observed incidence and azimuth dependent seismic reflectivities and critical angles in obtaining information on a formation's anisotropy. Zip archive contains four segy files: - LAB_TI00, is not tilted sample in contact with water, - LAB_TI30, is 30degrees tilted sample in contact with water, - LAB_TI45, is 45 degrees tilted sample in contact with water, - LAB_TI90, is 90 degrees tilted sample in contact with water.

The effect of ultrasonic waves on the phase behavior of a surfactant-brine-oil system

Acknowledgements The authors would like to gratefully acknowledge and appreciate the School of Engineering, University of Aberdeen, Aberdeen, Scotland, UK, for the provision of the laboratory facilities necessary for completing this work.

The effect of ultrasonic waves on the phase behavior of a surfactant-brine-oil system

Acknowledgements The authors would like to gratefully acknowledge and appreciate the School of Engineering, University of Aberdeen, Aberdeen, Scotland, UK, for the provision of the laboratory facilities necessary for completing this work.

Family giving dog a bath

Inscriptions: Verso: [stamped] Photograph by Freda Leinwand. [463 West Street, Studio 229G, New York, NY 10014].

New Bivariate Lifetime Distributions Based on Bath-Tub Shaped Failure Rate

A class of lifetime distributions which has received considerable attention in modelling and analysis of lifetime data is the class of lifetime distributions with bath-tub shaped failure rate functions because of their extensive applications. The purpose of this thesis was to introduce a new class of bivariate lifetime distributions with bath-tub shaped failure rates (BTFRFs). In this research, first we reviewed univariate lifetime distributions with bath-tub shaped failure rates, and several multivariate extensions of a univariate failure rate function. Then we introduced a new class of bivariate distributions with bath-tub shaped failure rates (hazard gradients). Specifically, the new class of bivariate lifetime distributions were developed using the method of Morgenstern’s method of defining bivariate class of distributions with given marginals. The computer simulations and numerical computations were used to investigate the properties of these distributions.

Numerical Simulation Of Ultrasonic Wave Propagation In Elastically Anisotropic Media

The ultrasonic non-destructive testing of components may encounter considerable difficulties to interpret some inspections results mainly in anisotropic crystalline structures. A numerical method for the simulation of elastic wave propagation in homogeneous elastically anisotropic media, based on the general finite element approach, is used to help this interpretation. The successful modeling of elastic field associated with NDE is based on the generation of a realistic pulsed ultrasonic wave, which is launched from a piezoelectric transducer into the material under inspection. The values of elastic constants are great interest information that provide the application of equations analytical models, until small and medium complexity problems through programs of numerical analysis as finite elements and/or boundary elements. The aim of this work is the comparison between the results of numerical solution of an ultrasonic wave, which is obtained from transient excitation pulse that can be specified by either force or displacement variation across the aperture of the transducer, and the results obtained from a experiment that was realized in an aluminum block in the IEN Ultrasonic Laboratory. The wave propagation can be simulated using all the characteristics of the material used in the experiment evaluation associated to boundary conditions and from these results, the comparison can be made.

Ultrasonic Spectral Analysis for Nuclear Fuel Characterization

Ceramic materials have been widely used for various purposes in many different industries due to certain characteristics, such as high melting point and high resistance to corrosion. Concerning the areas of applications, automobile, aeronautics, naval and even nuclear, the characteristics of these materials should be strictly controlled. In the nuclear area, ceramics are of great importance once they are the nuclear fuel pellets and must have, among other features, a well controlled porosity due to mechanical strength and thermal conductivity required by the application. Generally, the techniques used to characterize nuclear fuel are destructive and require costly equipment and facilities. This paper aims to present a nondestructive technique for ceramic characterization using ultrasound. This technique differs from other ultrasonic techniques because it uses ultrasonic pulse in frequency domain instead of time domain, associating the characteristics of the analyzed material with its frequency spectrum. In the present work, 40 Alumina (Al2O3) ceramic pellets with porosities ranging from 5% to 37%, in absolute terms measured by Archimedes technique, were tested. It can be observed that the frequency spectrum of each pellet varies according to its respective porosity and microstructure, allowing a fast and non-destructive association of the same characteristics with the same spectra pellets.

Evaluation of Two Ultrasonic Systems for Analysis of Porosity in Ceramic

The Ultrasound Laboratory of the Nuclear Engineering Institute (LABUS / IEN) has developed an ultrasonic technique to measure porosity in nuclear fuel pellets (UO2). By difficulties related to the handling of UO2 pellets, Alumina (Al2O3) pellets have been used in preliminary tests, until a methodology for tests with pellets of UO2 could be defined. In a previous work, in which a contact ultrasonic technique was used, good results were obtained to measure the porosity of Alumina pellets. In the current studies, it was found that the frequency spectrum of an ultrasonic pulse is very sensitive to the porosity of the medium in which it propagates. In order to define the most appropriate experimental apparatus for using immersion technique in future tests, two ultrasonic systems, available in LABUS, which permit to work with the ultrasonic pulse in the frequency domain were evaluated . One system was the Explorer II (Matec INSTRUMENTS) and the other the ultrasonic pulse generator Epoch 4 Plus (Panametrics) coupled with an oscilloscope TDS 3032B (Tektronix). For this evaluation, several frequency spectra were obtained with the two equipment, by the passage of the ultrasonic wave in the same pellet of Alumina. This procedure was performed on four different days, on each day 12 ultrasonic signals were acquired, one signal every 10 minutes, with each apparatus. The results were compared and analyzed as regard the repeatability of the frequency spectra obtained.

Analysis of Ultrasonic Techniques for the Characterization of Microfiltration Polymeric Membranes

The use of polymeric membranes is extremely important in several industries such as nuclear, biotechnology, chemical and pharmaceutical. In the nuclear area, for instance, systems based on membrane separation technologies are currently being used in the treatment of radioactive liquid effluent, and new technologies using membranes are being developed at a great rate. The knowledge of the physical characteristics of these membranes, such as, pore size and the pore size distribution, is very important to the membranes separation processes. Only after these characteristics are known is it possible to determine the type and to choose a particular membrane for a specific application. In this work, two ultrasonic non destructive techniques were used to determine the porosity of membranes: pulse echo and transmission. A 25 MHz immersion transducer was used. Ultrasonic signals were acquired, for both techniques, after the ultrasonic waves passed through a microfiltration polymeric membrane of pore size of 0.45 μm and thickness of 180 μm. After the emitted ultrasonic signal crossed the membrane, the received signal brought several information on the influence of the membrane porosity in the standard signal of the ultrasonic wave. The ultrasonic signals were acquired in the time domain and changed to the frequency domain by application of the Fourier Fast Transform (FFT), thus generating the material frequency spectrum. For the pulse echo technique, the ultrasonic spectrum frequency changed after the ultrasonic wave crossed the membrane. With the transmission technique there was only a displacement of the ultrasonic signal at the time domain.

Big Bath and Impairment of Goodwill : A study of the European telecommunications industry

Income decreasing strategies conducted by management could be harmful for various stakeholders. One example is big bath accounting, which could be accomplished in numer- ous ways. This study focus on big baths achieved by recognising impairments of goodwill. Purpose - The purpose of this study is to examine patterns of association between big bath accounting and impairment of goodwill within the telecommunication service industry in Europe. Further, this study aim at contributing to the discussion regarding utilisation of big baths through impairments of goodwill, and takes the perspective of an external stakehold- er. Delimitations - The study is restricted to European telecommunication entities comprised in STOXX Europe 600 Index. Method - This study was conducted using a hybrid of qualitative and quantitative research strategy with a deductive approach. The five indicators used to identify various big bath behaviours were inspired and derived from theory and previous research. Data from 2009 to 2015 was collected from the companies’ annual reports and websites, and analysed by the help of codification of each fulfilled indicator where 2009 merely served as a compara- tive year for 2010. By the use of a scoreboard the collected data was summarised on an ag- gregated yearly basis as the industry, not the specific companies, were analysed. Empirical findings - The results of this study suggests that big baths are executed among tele- communication companies within Europe. These are conducted simultaneously as impair- ments of goodwill are present, facilitated by earning management. A possible explanation is considered to be the room for interpretation inherent in IAS 36, enabling goodwill impair- ments to be recognised on managers’ command. Thereby an impairment could be “saved” for better or worse circumstances, or recognised when there exist an opportunity to max- imise (the manager's) wealth in the future. This study reveal the co-occurrence of goodwill impairments and big bath-indications, however a review of causal relationships are not en- abled by the limitations of the chosen method.