The purpose of this paper is to provide an overview of the current state of research and the key aspects and implications of the relationships between Information and Digital Technologies (IDT) of ...

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Information and digital technologies of Industry 4.0 and Lean supply chain management: a systematic literature review

In this paper, we report a design of high sensitivity Photonic Crystal Fiber (PCF) sensor with high birefringence and low confinement losses for liquid analyte sensing applications. The proposed PCF structures are designed with supplementary elliptical air holes in the core region vertically-shaped V-PCF and horizontally-shaped H-PCF. The full vectorial Finite Element Method (FEM) simulations performed to examine the sensitivity, the confinement losses, the effective refractive index and the modal birefringence features of the proposed elliptical air hole PCF structures. We show that the proposed PCF structures exhibit high relative sensitivity, high birefringence and low confinement losses simultaneously for various analytes.

https://www.mdpi.com/1424-8220/15/12/29891/pdf

PCF Based Sensor with High Sensitivity, High Birefringence and Low Confinement Losses for Liquid Analyte Sensing Applications

\n This study presents an analytical model analysis of reflection/transmission characteristics of long-period fiber Bragg grating (LPFBG) by using coupled mode theory. Reflected signal power is deeply studied against grating length at the optimum operating signal wavelength of 1550 nm for the proposed and previous models. Reflectivity and transmission coefficient are also clarified versus operating wavelength for the previous model and proposed a model with a central wavelength of 1550 nm, Δn = 0.003 and optimum grating length of 30 mm. In the same way, the reflectivity and transmission coefficient are outlined against relative refractive grating difference step at the optimum wavelength of 1550 nm and optimum grating length of 30 mm. The optimum LPFBG can be achieved with the optimum grating length of 30 mm, operating wavelength of 1550 nm and relative refractive grating difference step of 0.3 %.

Analytical Model Analysis of Reflection/Transmission Characteristics of Long-Period Fiber Bragg Grating (LPFBG) by Using Coupled Mode Theory

Study on temperature error processing technique for fiber optic gyroscope

Freezing of gait (FOG) is a leading cause of falls and fractures in Parkinson’s disease (PD). The episodic and rather unpredictable occurrence of FOG, coupled with the variable response to L-Dopa of this gait disorder, makes the objective evaluation of FOG severity a major clinical challenge in the therapeutic management of patients with PD. The aim of this study was to examine and compare gait, clinically and objectively, in patients with PD, with and without FOG, by means of a new wearable system. We also assessed the effect of L-Dopa on FOG severity and specific spatio-temporal gait parameters in patients with and without FOG. To this purpose, we recruited 28 patients with FOG, 16 patients without FOG and 16 healthy subjects. In all participants, gait was evaluated clinically by video-recordings and objectively by means of the wearable wireless system, during a modified 3-m Timed Up and Go (TUG) test. All patients performed the modified TUG test under and not under dopaminergic therapy (ON and OFF therapy). By comparing instrumental data with the clinical identification of FOG based on off-line video-recordings, we also assessed the performance of the wearable system to detect FOG automatically in terms of sensitivity, specificity, positive and negative predictive values, and finally accuracy. TUG duration was longer in patients than in controls and the amount of gait abnormalities was prominent patients with FOG compared with those without FOG. L-Dopa improved gait significantly in patients with PD and particularly in patients with FOG mainly by reducing FOG duration and increasing specific spatio-temporal gait parameters. Finally, the overall wireless system performance in automatic FOG detection was characterized by excellent sensitivity (93.41%), specificity (98.51%), positive predictive value (89.55 %), negative predictive value (97.31 %), and finally accuracy (98.51%). Our study overall provides new information on the beneficial effect of L-Dopa on FOG severity and specific spatio-temporal gait parameters as objectively measured by a wearable sensory system. The algorithm here reported potentially opens to objective long-time sensing of FOG episodes in patients with PD.

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l-DOPA and Freezing of Gait in Parkinson's Disease: Objective Assessment through a Wearable Wireless System

In this paper, we investigate the birefringence of polarization maintaining photonic crystal fibers (PM-PCFs) under thermal effect. Modeling and simulation of PM-PCFs under thermal effect are conducted. Birefringence in a PM-PCF as a function of the temperature is measured experimentally. The experimental results are in agreement with theoretical calculation, and show that the relative temperature dependent birefringence coefficient of the PM-PCF, dΔ n /d T /Δ n , is 2.93×10 −5 /°C, which is typically ∼35 times less than that of conventional panda fibers. The insensitivity of polarization properties in PM-PCFs to temperature is demonstrated. These findings have important benefits in fiber optic systems and sensors, especially in fiber optic gyroscopes (FOG) where it translates into a lower polarization error and thus a higher measurement precision.

Birefringence sensitivity to temperature of polarization maintaining photonic crystal fibers

A small-diameter polarization-maintaining photonic crystal fiber (PM-PCF) for mini coils of spaceborne miniature fiber-optic gyroscopes is proposed in this paper. To ensure the strength of the small-diameter PM-PCF, a four-ring air holes structure is adopted. Using the full vector finite element method, dependence studies of modal field distribution, birefringence, and confinement loss on several key structure parameters are numerically investigated. The optimized parameter region is obtained. An optimized PM-PCF is fabricated, which can achieve similar to or even better optical properties than that of commercial PM-PCFs. The coating and cladding diameters of the optimized PM-PCF are 135 μm and 100 μm, respectively. Meanwhile, the optimized small-diameter PM-PCF shows a proof test level of 0.5%. The attenuation of the PM-PCF at 1550 nm is ∼2  dB/km. Typical volume of a mini coil wound with 300 m optimized PM-PCF is 5.9  cm3, which is decreased by ∼60% compared with a commercial PM-PCF coil of the same length. The bias stability of this coil is comparable with that of a conventional PMF coil of comparable length. Thus, the optimized small-diameter PM-PCF is suitable for mini coils of spaceborne miniature fiber-optic gyroscopes.

Structure optimization of small-diameter polarization-maintaining photonic crystal fiber for mini coil of spaceborne miniature fiber-optic gyroscope.

Thermal analysis of the effects of thermally induced nonreciprocity in fiber optic gyroscope sensing coils

A compact quad interferometric fiber optic gyroscope (IFOG) is demonstrated for attitude determination in space application, which combines efficiently multiplexing technology with redundancy technology. Compared with existing typical three-axis and four-axis systems, the IFOG not only reduces greatly the size, weight, power consumption and cost, but also improves dramatically the reliability. Based on the configuration, a multiplexing modulation method and a control method are proposed. A prototype is manufactured, which achieves the angle random walk of less than 0.025 deg/√h and the bias instability of less than 0.15 deg/h. The weight and power consumption of the prototype are 3.5 times and 2.6 times less than the existing system with roughly the same performance, respectively. The fault injection experiments are conducted and verify that the control method is available for fault recovery.

Jing Jin

Papers

Birefringence sensitivity to temperature of polarization maintaining photonic crystal fibers

Structure optimization of small-diameter polarization-maintaining photonic crystal fiber for mini coil of spaceborne miniature fiber-optic gyroscope.

Thermal analysis of the effects of thermally induced nonreciprocity in fiber optic gyroscope sensing coils

A Compact Four-Axis Interferometric Fiber Optic Gyroscope Based on Multiplexing for Space Application

A novel interferometric fiber optic gyroscope with random walk fault diagnosis for space application