Static and dynamic weighing of rolling stocks by mean of a customized FBG-Sensorized-Patch

The structural health monitoring (SHM) of an infrastructure is of fundamental importance for the structure and people safety. Fiber Bragg Grating (FBG) sensors allow to design for each application, a tailored array of quasi-distributed sensors integrated to the infrastructure. To ensure the structural integrity of the railways is crucial to verify that the infrastructures comply with safety requirements to carry out their task. Railways rolling stock must comply with speed limits, the maximum number of wagons, maximum weight limit distributed on each axis of the wagons and the allowed number of trains on specific routes. The identification of the vertical load acting on each wheel is fundamental for the safety of a rolling-stock moving on a railway line. This paper presents the results of a test campaign on sensitive smart patches for static and dynamic weighing of trains. The system aims to generate a gripping system based on the magnetic force of a plastoferrite patch, taking advantage of the peculiarity that the rails are made of ferritic steel. This solution has the benefit of simplifying and speeding up the installation process and enabling a fast and easy removal or change in the configuration of the sensors array on the rail

Critical issues of double-metal layer coating on FBG for applications at high temperatures

Use of fiber Bragg gratings (FBGs) to monitor high temperature (HT) applications is of great interest to the research community. Standard commercial FBGs can operate up to 600 ∘ C. For applications beyond that value, specific processing of the FBGs must be adopted to allow the grating not to deteriorate. The most common technique used to process FBGs for HT applications is the regeneration procedure (RP), which typically extends their use up to 1000 ∘ C. RP involves a long-term annealing of the FBGs, to be done at a temperature ranging from 550 to 950 ∘ C. As at that temperature, the original coating of the FBGs would burn out, they shall stay uncoated, and their brittleness is a serious concern to deal with. Depositing a metal coating on the FBGs prior to process them for RP offers an effective solution to provide them with the necessary mechanical strengthening. In this paper, a procedure to provide the FBG with a bimetallic coating made by copper and nickel electrodeposition (ED) is proposed, discussing issues related to the coating morphology, adherence to the fiber, and effects on the grating spectral response. To define the processing parameters of the proposed procedure, production tests were performed on dummy samples which were used for destructive SEM-EDS analysis. As a critical step, the proposed procedure was shown to necessitate a heat treatment after the nickel ED, to remove the absorbed hydrogen. The spectral response of the FBG samples was monitored along the various steps of the proposed procedure and, as a final proof test for adherence stability of the bimetallic coating, along a heating/cooling cycle from room temperature to 1010 ∘ C. The results suggest that, given the emergence of Kirkendall voids at the copper-nickel interface, occurring at the highest temperatures (700-1010 ∘ C), the bimetallic layer could be employed as FBG coating up to 700 ∘ C

Efecto de caucho reciclado en las propiedades de mezclas de caucho reciclado y polipropileno reciclado

This study evaluates the influence of recycled rubber (RR) with a specific particle size in the properties of blends, blended recycled polypropylene/polyethylene (RPP) and RR (RPP/RR) -- The proportions of RPP/RR employed to obtain the blends were as follows: 90/10 (PP90), 75/25 (PP75), 60/40 (PP60) and 45/55 (PP45) -- The particle size of the RR employed was 850 µm -- The properties of the blends were evaluated by rheometric, thermogravimetric (TGA), differential scanning calorimetric (DSC), scanning electronic microscopy (SEM), density, melt flow index and tensile analysis -- The maximum torque increased with the RPP content -- By DSC analysis, it was observed that the RPP exhibited two melting temperatures, the first corresponded to low density polyethylene (LDPE) and the second to polypropylene (PP) -- Furthermore, the RR affected the crystallinity of the RPP -- By using SEM and TGA analyses, it was determined that the RPP as well as RR contained fillers -- The blend densities were higher than those of RPP -- The melt flow index exhibited a trend with the amount of RR.PACS: 61.25.hk, 83.80.Va, 81.05.LgEste estudio evalúa la influencia de caucho reciclado (RR) con un tamaño de partícula específico en las propiedades de mezclas, mezclas de polipropileno reciclado/polietileno (RPP) y RR (RPP/RR) -- Las proporciones de RPP/RR para obtener los compósitos fueron como sigue: 90/10 (PP90), 75/25 (PP75), 60/40 (PP60) and 45/55 (PP45) -- El tamaño de partícula empleado del RR fue 850 µm -- Las propiedades de las mezclas, fueron evaluadas por análisis reométrico, termogravimétrico (TGA), calorimetría diferencial de barrido (DSC), microscopia de barrido electrónica (SEM), densidad, índice de fluidez y ténsil -- El torque máximo incrementó con el contenido de RPP -- Por análisis DSC se observó que el RPP exhibió dos temperaturas de fusión, la primera correspondió al polietileno de baja densidad (LDPE) y la segunda al polipropileno (PP) -- Además, el RR afectó la cristalinidad del RPP -- Por análisis de SEM y TGA, se determinó que el RR y el RPP contenían rellenos -- Las densidades de las mezclas fueron más altas que la del RPP -- El índice de fluidez exhibió una tendencia con la cantidad de RR.PACS: 61.25.hk, 83.80.Va, 81.05.L

Railway overhead contact wire monitoring system by means of FBG sensors

Safety of infrastructures represents one of the most significant concerns for governments and service providers to preserve people's well-being. One of the main ways to keep in safe facilities (buildings, bridges, railways, etc.) involves the use of monitoring sensor systems in charge of measuring critical operating conditions. Those measurements together with periodical maintenance, contribute to minimize potential risks that the infrastructure faces. The paper aims at designing, developing, and testing a monitoring system for mechanical stresses acting on the overhead contact wire (OCW) to ensure the operational safety of the railway network. In this regard, the paper proposes two Fiber Bragg Grating (FBG) sensors-based solutions, relying on the ability of these sensors to allow real-time and continuous data acquisition. The first one consists in a polyimide-coated sensor bonded on an OCW clamp, the second one is a copper-coated sensor hanging between the two separated halves of an OCW clamp. Significant results have been obtained mechanically testing both solutions, trying to simulate the operative conditions

Elaboración de un cemento óseo de fosfato de calcio con una adición de biovidrio

Bone cement is synthesized using CaCO3 and CaHPO4, in a thermal treatment at 1400 °C. The mixture was rapidly cooled with a stream of forced air; bone cement was mixed with 10%wt. Bioglass (BC-10BG) later milled and characterized milled and characterized by Particle Size Distribution (PSD), X-ray diffraction and fluorescence (XRD and XRF). The mixing (Bone cement-Bioglass) and bone cement alone were characterized physic- mechamically through testing compressive strength, microhardness, cohesive and setting times; in order to see precipitation trends were carried out in-vitro tests. Additionally, two compositions more of bioglass (5 and 15% wt.) were evaluated by XRD, SEM and FTIR-ATR.The crystalline phases of α-TCP y β-TCP, Ca2P2O7 y CaHPO4 were related to bone cement and whitlockita phase was in agreement with bioglass in one part of its crystalline structure. Physically handling times and the mechanical properties correspond to bone cement for filling cavities. The in-vitro tests showed a progressive bioactive effect with increase the exposition time

Elaboración de un cemento óseo de fosfato tricalcico Α en un tratamiento térmico a 1400°C a partir de CaCO3 y CAHPO4

RESUMEN: Las cerámicas de fosfatos de calcio buscan dar solución al relleno de una cavidad y a su futura colonización por nuevo tejido óseo. Estas cerámicas son biocompatibles y osteoconductoras. En general, cualquier cemento está formado por dos fases, una sólida en forma de polvo y otra líquida, que al mezclarse forman una pasta que se endurece con el tiempo. El objetivo principal de este trabajo es la elaboración de un cemento óseo de fosfato tricálcico alfa (α-TCP) a partir de hidrógeno fosfato de calcio (CaHPO4) y carbonato de calcio (CaCO3). Para obtener la fase α- TPC, fueron mezclados estequiométricamente estos dos polvos de alta pureza (CaHPO4 y CaCO3), en un molino centrífugo marca S1000 Tesch, con cuerpos moledores de zirconia (ZrO2) por un periodo de 7 min a 175 rpm. Luego se utilizó un horno de alta temperatura llevando la muestra hasta 1400°C, e inmediatamente se realizó un enfriamiento forzado con aire, con el fin de evitar la formación de fases no deseadas como el β-TCP. Fueron elaboradas 7 síntesis, cuya granulometría se acondicionó en un molino, por un período de 10 min a 250 rpm. Para identificar las fases obtenidas, se realizaron pruebas por difracción de rayos X (DRX) a cada una de las síntesis. Los resultados de las pruebas de DRX mostraron que siguiendo los procedimientos establecidos, es posible obtener la fase α, indispensable un cemento óseo.ABSTRACT: Calcium phosphate ceramics seek to solve the filling of a cavity and its future colonization by new bone. These ceramics are biocompatible and osteoconductive. In general, any cement is formed by two phases; a solid powder and a liquid, which when are mixed form a paste that hardens over time. The main objective of this work is to develop a bone cement alpha tricalcium phosphate (α-TCP) from calcium hydrogen phosphate (CaHPO4) and calcium carbonate (CaCO3). For α-TPC phase were mixed steichiometrically these two high purity powders (CaHPO4 and CaCO3) in a centrifugal mill Tesch S1000 mark with grinding media of zirconium (ZrO2) for a period of 7 min at 175 rpm. Then was used a high temperature furnace taking the sample to 1400 ° C, follow by a forced cooling with air, in order to avoid formation of undesirable phases such as β-TCP. Seven syntheses were prepared, whose particle size was conditioned in a mill, for a period of 10 min at 250 rpm. To identify the phases obtained, tests were conducted by X-ray diffraction (XRD) to each synthesis. The results of XRD tests howed that following established procedures, it is possible to obtain the α phase, essential bone cement

Kinetics and thermodynamic study of the indium electrowinning process using different metal cathodic supports: operative conditions optimization and deposit characterization

The excessive indium demand in the existing markets for the manufacture of indium based high-tech devices (solar panels, optoelectronic systems and liquid-crystal display (LCD) units) has promoted a shortage scenario of indium from primary supply routes. With emerging indium supply restrictions, the spotlight is on determining painful secondary sources and their respective efficient and eco-friendly treatments. Wet electrometallurgy, combined with separation/leaching /enrichment stages, has been highlighted as one of the most useful methodologies to recover indium from electronic waste (obsolete LCD screens) due to the operative parameter adaptation and high occupational and environmental safety. To date, chloride electrolytes have been widely used for indium electrowinning without considering critical challenges. In contrast, sulfate electrolyte shows lower environmental impact and higher efficiencies than conventional acidic solutions. This solution has been disregarded to carry out the indium electrowinning. In this doctoral investigation, the indium electrowinning process is studied from sulfate solutions considering the kinetic features of the indium reduction reaction near the cathodic surface. Also, the influence of operative parameters on productivity and energy consumption has been analyzed. Initially, a critical outlook of the indium processing was performed considering different sources, electrolytes and methodologies to determine the main strengths, drawbacks, and targeting concerns that should be studied. Apart from this, the kinetic study of the indium reduction reaction near the cathodic surface was carried out using copper, titanium, aluminum, nickel and stainless-steel cathodes (Cu, Ti, Al, Ni and AISI 316L) as cathodic supports. These metal cathodes were assessed by cyclic voltammetry (CV) and chronoamperometry (CA) techniques. CVs described features of the indium cathodic curve and the hydrogen evolution reaction (HER) influence. Since HER is a parasitic reaction, kinetic parameters, such as heterogeneous charge transfer rate constant (k0), charge transfer coefficient values (α), diffusion coefficient (D0), roughness factor (φ) and the exchange current density (i0), were calculated without HER interference. In the case of the i0, the values were equal to 1.20 mA/cm2, 0.30 mA/cm2 and 0.075 mA/cm2 for Cu cathode Ti and Al cathodes, respectively. Further correlations for previous parameters were held using both CV and CA. In fact, the k0 values for Cu, Ti and Al cathodes were 7.1·10-5 cm/s, 6.2·10-5 cm/s and 5.4·10-5 cm/s. Once indium reaction reduction kinetics near the cathodic support were analyzed, the indium electrowinning process was performed in long lasting tests to achieve high and low energy consumption. In addition, operative conditions were optimized using five different metal supports. Therefore, the indium electrowinning was evaluated by varying operative conditions (current density, electrolyte composition, pH and temperature) using different metal supports (AISI 316L, Ni, Cu, Ti and Al). The optimization of the indium electrowinning process was focused on achieving high current Efficiency (CE) and low specific energy consumption (SEC). The performance of AISI 316L, Ni and Cu supports were significantly influenced by the electrolyte composition, while Al and Ti showed better results using merely the indium sulfate solution. Comparing AISI 316L, Ni and Cu support, nickel showed a significant increase in productivity (around 83% and 2.4 kWh/kg) working at 100 A/m2 with respect to AISI 316L and Cu supports, that can efficiently operate at 25 and 50 A/m2, respectively. Otherwise, Ti and Al depicted high CEs above 80% and reasonable SEC values using an etched cathode to improve the adhesion conditions between cathode and deposit. These electrowinning outputs for both cathodes demonstrated that the surface pretreatment improved the productivity in terms of high CE and low SEC for the indium recovery. The deposit showed very-well defined polygonal grains covered by a lamellar morphology. While in most cases, temperature increases negatively affect the crystallographic features of indium deposits

FBG Spectrum Regeneration by Ni-Coating and High-Temperature Treatment

FBG sensors are used in many scientific and industrial fields for assessing the structural integrity of mechanical components and in very high (above 600 °C) or very low (cryogenic) temperature applications. The main concerns with the use of such sensors in applications involving extreme temperatures are related partly to the instability of the reflected spectrum, which tends to dissolve into the noise floor, and partly to the degradation of the mechanical properties of the optical fiber, which tends to worsen the inherent brittleness. All of this raises the need for a robust nickel protective coating to ensure the grating’s integrity in high-temperature environments. In addition, the inherent brittleness of fiber-optic gratings leaves one to wonder whether it is possible to recover a broken, seemingly unusable sensor. In this way, a single-peak commercial FBG was intentionally broken in the middle of the grating length and re-spliced, inducing a strongly asymmetric chirped-like spectrum; then, a nickel coating was electrodeposited on its surface. The most important outcome achieved by this work is the regeneration of a highly distorted reflected spectrum through three thermal cycles performed from room temperature up to 500, 750, and 800 °C, respectively. After reaching a temperature of at least 700 °C, the spectrum, which has been drastically altered by splicing, becomes stable and restores its single peak shape. A further stabilization cycle carried out at 800 °C for 80 min led to an estimation of the stabilizing time of the new single-peak reflected spectrum