Brillouin scattering properties in partially chlorinated plastic optical fibers estimated with ultrasonic pulse-echo technique

In this article, the analysis of the acoustic path during the ultrasonic pulse echo testing of the rail head in production is carried out. The influence of the parameters of the applied piezoelectric transducers on the distribution of sensitivity for the sounding scheme used in the existing installations is estimated and the real sensitivity of detecting defects of the «non-metallic inclusion» type is estimated.

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Signal Processing Enhanced Fiber Vibration Sensors

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.543.302 ◽

2013 ◽

Vol 543 ◽

pp. 302-305

Author(s):

Daniele Tosi ◽

Massimo Olivero ◽

Alberto Vallan ◽

Guido Perrone

Keyword(s):

Signal Processing ◽

Optical Fibers ◽

Adaptive Filters ◽

Spectral Estimation ◽

Cost Effective ◽

Fiber Sensors ◽

High Frequencies ◽

Vibration Sensors ◽

Signal Processing Algorithms ◽

Plastic Optical Fibers

The paper analyzes the feasibility of cost-effective fiber sensors for the measurement of small vibrations, from low to medium-high frequencies, in which the complexity of the measurement is moved from expensive optics to cheap electronics without losing too much performance thanks to signal processing algorithms. Two optical approaches are considered: Bragg gratings in standard telecom fibers, which represent the most common type of commercial fiber sensors, and specifically developed sensors made with plastic optical fibers. In both cases, to keep the overall cost low, vibrations are converted into variations of the light intensity, although this makes the received signal more sensitive to noise. Then, adaptive filters and advanced spectral estimation techniques are used to mitigate noise and improve the sensitivity. Preliminary results have demonstrated that the combined effect of these techniques can yield to a signal-to-noise improvement of about 30 dB, bringing the proposed approaches to the level of the most performing sensors for the measurement of vibrations.

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X-ray Diffraction Analysis and Williamson-Hall Method in USDM Model for Estimating More Accurate Values of Stress-Strain of Unit Cell and Super Cells (2 × 2 × 2) of Hydroxyapatite, Confirmed by Ultrasonic Pulse-Echo Test

Materials ◽

10.3390/ma14112949 ◽

2021 ◽

Vol 14 (11) ◽

pp. 2949

Author(s):

Marzieh Rabiei ◽

Arvydas Palevicius ◽

Amir Dashti ◽

Sohrab Nasiri ◽

Ahmad Monshi ◽

...

Keyword(s):

Young’S Modulus ◽

Young's Modulus ◽

Ultrasonic Pulse ◽

High Accuracy ◽

Unit Cell ◽

Deformation Model ◽

X Ray Diffraction ◽

Uniform Deformation ◽

X Ray ◽

Pulse Echo

Taking into account X-ray diffraction, one of the well-known methods for calculating the stress-strain of crystals is Williamson-Hall (W–H). The W-H method has three models, namely (1) Uniform deformation model (UDM); (2) Uniform stress deformation model (USDM); and (3) Uniform deformation energy density model (UDEDM). The USDM and UDEDM models are directly related to the modulus of elasticity (E). Young’s modulus is a key parameter in engineering design and materials development. Young’s modulus is considered in USDM and UDEDM models, but in all previous studies, researchers used the average values of Young’s modulus or they calculated Young’s modulus only for a sharp peak of an XRD pattern or they extracted Young’s modulus from the literature. Therefore, these values are not representative of all peaks derived from X-ray diffraction; as a result, these values are not estimated with high accuracy. Nevertheless, in the current study, the W-H method is used considering the all diffracted planes of the unit cell and super cells (2 × 2 × 2) of Hydroxyapatite (HA), and a new method with the high accuracy of the W-H method in the USDM model is presented to calculate stress (σ) and strain (ε). The accounting for the planar density of atoms is the novelty of this work. Furthermore, the ultrasonic pulse-echo test is performed for the validation of the novelty assumptions.

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A Nanoplasmonic-Based Biosensing Approach for Wide-Range and Highly Sensitive Detection of Chemicals

Nanomaterials ◽

10.3390/nano11081961 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1961

Author(s):

Francesco Arcadio ◽

Luigi Zeni ◽

Aldo Minardo ◽

Caterina Eramo ◽

Stefania Di Di Ronza ◽

...

Keyword(s):

Optical Fibers ◽

Limit Of Detection ◽

Slab Waveguide ◽

Grating Pattern ◽

Transparent Substrate ◽

Synthetic Receptor ◽

Sensing Applications ◽

Wide Range ◽

Plastic Optical Fibers ◽

Highly Sensitive Detection

In a specific biosensing application, a nanoplasmonic sensor chip has been tested by an experimental setup based on an aluminum holder and two plastic optical fibers used to illuminate and collect the transmitted light. The studied plasmonic probe is based on gold nanograting, realized on the top of a Poly(methyl methacrylate) (PMMA) chip. The PMMA substrate could be considered as a transparent substrate and, in such a way, it has been already used in previous work. Alternatively, here it is regarded as a slab waveguide. In particular, we have deposited upon the slab surface, covered with a nanograting, a synthetic receptor specific for bovine serum albumin (BSA), to test the proposed biosensing approach. Exploiting this different experimental configuration, we have determined how the orientation of the nanostripes forming the grating pattern, with respect to the direction of the input light (longitudinal or orthogonal), influences the biosensing performances. For example, the best limit of detection (LOD) in the BSA detection that has been obtained is equal to 23 pM. Specifically, the longitudinal configuration is characterized by two observable plasmonic phenomena, each sensitive to a different BSA concentration range, ranging from pM to µM. This aspect plays a key role in several biochemical sensing applications, where a wide working range is required.

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