We demonstrate a fiber optics sensing structure for the measurement of the refractive index of liquid samples at multiple spatial locations simultaneously. The sensing architecture is all-fiber and consists of standard single-mode–multimode-single-mode multimodal interference (MMI) devices working in parallel. The spectral response of each MMI device is carefully engineered to have nonoverlapping responses, such that the entire system can be interrogated with a single broadband light source and single optical spectrum analyzer. In proof-of-concept experiments, we tested the proposed system with aqueous saline solutions and binary solutions of water–glycerol and water–ethylene glycol. Our results validate the use of the proposed platform for the simultaneous monitoring of the refractive index of liquid samples at different locations.
This paper reports on the refractometric detection of water-adulterated milk using an optical fiber sensor whose principle of operation is based on multimode interference (MMI). The device is manufactured in a simple way by splicing a segment of coreless multimode fiber (NC-MMF) between two single-mode fibers (SMFs); neither functionalization nor deposition of a sensing material is required. MMI takes place in the NC-MMF and, when fed with a broadband spectrum, a transmission peak appears at the output of the MMI device due to its inherent filter-like response, whose position depends on the effective refractive index (RI) of the medium surrounding the NC-MMF. Therefore, when the sensor is immersed in different milk–water mixtures, the peak wavelength shifts according to the RI of the mixture. In this way, adulterated milk can be detected from the wavelength shift of the transmission peak. The system was tested with two commercial brands of milk, and adulterations were clearly distinguished in both cases. In the range of interest, from no dilution up to 50% dilution, the sensor exhibits a linear response with a sensitivity of −0.04251 and −0.03291 nm/%, respectively, for the two samples tested. The measurement protocol is repeatable and allows for locating the peak wavelength within <0.34 nm over several repetitions using different samples with the same concentration. A thermal sensitivity of 0.85 nm/°C was obtained, which suggests that the temperature needs to be maintained as fixed during the measurements. The approach presented can be extended to other scenarios as a quality control tool in beverages for human consumption, showing the advantages of simple construction, high sensitivity, and the potential for real-time monitoring.
The aim of this paper is to show the results about the design and implementation of a strategic management model based on the Balanced Scorecard (BSC) methodology applied to a company in the automotive activity which allows it to have greater competitiveness. The developed methodology allowed a review of the vision, mission and objectives of the company in order to align the objectives of the supplier quality department, in such a way that the indicators obtained directly impact the KPI of the company and this generates a strategic map for the development of suppliers. These indicators allow measuring the performance of companies, establishing metrics with greater impact, which is of great importance in worldwide. The BSC is linked to the Toyota Production Systems (TPS), where one of its pillars is the Just in Time and therefore the importance of having an OTD metric (Delivery Compliance). The implementation of this methodology, we obtained the following indicator to evaluate the suppliers: Defective Material, OTD, Process of Approval of Production Parts and Defects per Million. These results allowed improving the efficiency in the company and that of the suppliers because they directly impacted the KPI, OTD and CONC metrics.
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