Environmental Sensitivity of Fiber Bragg Grating Sensors for Aerospace Prognostics

Optical sensors have recently gained interest due to the many advantages they offer over traditional electrical sensors commonly used in aerospace applications. In particular, their total insensitivity to electromagnetic interference (EMI), the ease of multiplexing of different signals on a single line, the excellent resilience to hostile environments, the very compact dimensions, and the considerable overall weight savings resulting from the signal cables reduction, make technological solutions based on optical fibers a compelling alternative to traditional sensing elements. In this work, authors consider optical sensors based on Fiber Bragg Gratings (FBGs), which can reflect a very narrow band of wavelengths, called the Bragg wavelength, but are almost transparent for the other signals. This behaviour is obtained by realizing local variations of the refractive index of the FBG core. The Bragg wavelength, nominally defined in the production phase by the grating etching process, can vary as a function of physical changes in the sensor itself or environmental conditions (physical stresses applied to the grating or variations of temperature or humidity). The correlation of the Bragg wavelength variation with the physical variations of the sensor is essential to guarantee satisfactory levels of accuracy and reliability. In particular, using FBGs as mechanical strain sensors, it is crucial to estimate with proper accuracy the disturbance generated by environmental conditions and conceive an effective compensation method. Hence, this work studies the effects of environmental temperature and humidity variations on measurements, examining possible non-linear, time-dependent phenomena arising from the FBGs bonding. For this purpose, the authors developed a dedicated test bench to simultaneously detect the various physical measures (FBG deformation, temperature, humidity, Bragg wavelength variation), analyse their correlations, and formulate the said compensation strategy

Medical tattooing, the new frontiers: a case of nail bed reconstruction.

The primary objective of medical tattooing is to restore part of a patient’s physical integrity. Moreover, the procedure seeks to assist in psychological recovery from the physical and/or psychological consequences of disease, surgery or trauma. The method described in this brief note marks a step forward in the field of such tattooing. The treatment simulates reconstruction of the nail bed, as the nails of the big toes had previously been removed through a surgical avulsion procedure. This treatment, agreed with the physician and performed by a tattooist with proven experience in medical tattooing, also involved the use of specific colour nuances that resulted in an extremely realistic outcome

Creation of a Support Software for the Development of a System for Sending and Visualizing FBG Sensor Data for Aerospace Application

Optical fiber-based sensors have rapidly increased their application fields across multiple engineering sectors. Their physical characteristics, including low weight, electrical passivity, immunity to electromagnetic disturbances, and high sensitivity, make them highly suitable for aerospace applications. A flying test bench was recently developed at the Politecnico di Torino to evaluate the performance of optical sensors applied to an aircraft model. To allows their fruition in near real-time, it was necessary to develop a pipeline of software capable of transmitting, saving, and displaying them on the ground. To carry out in-depth tests on their reliability it is necessary to carry out more tests with different sensors and configurations. However, doing flight tests for the sole purpose of testing the data acquisition system is too expensive and impractical. Therefore, it was developed an emulator software that can generate data like that obtained from the real system, saving time and resources. Thanks to it, it is now possible to exploit the complete test bench on the aircraft for the final verification campaign only. The results are therefore very positive and demonstrate the potential of the emulator also for the most recent applications

A New Method for Friction Estimation in EMA Transmissions

The increasing interest for adopting electromechanical actuators (EMAs) on aircraft demands improved diagnostic and prognostic methodologies to be applied to such systems in order to guarantee acceptable levels of reliability and safety. While diagnostics methods and techniques can help prevent fault propagation and performance degradation, prognostic methods can be applied in tandem to reduce maintenance costs and increase overall safety by enabling predictive and condition-based maintenance schedules. In this work, a predictive approach for EMAs friction torque estimation is proposed. The algorithm is based on the reconstruction of the residual torque in mechanical transmissions. The quantity is then sampled and an artificial neural network (ANN) is used to obtain an estimation of the current health status of the transmission. Early results demonstrate that such an approach can predict the transmission health status with good accuracy

Fiber Bragg Grating Sensor Networks Enhance the In Situ Real-Time Monitoring Capabilities of MLI Thermal Blankets for Space Applications

The utilization of Fiber Bragg Grating (FBG) sensors in innovative optical sensor networks has displayed remarkable potential in providing precise and dependable thermal measurements in hostile environments on Earth. Multi-Layer Insulation (MLI) blankets serve as critical components of spacecraft and are employed to regulate the temperature of sensitive components by reflecting or absorbing thermal radiation. To enable accurate and continuous monitoring of temperature along the length of the insulative barrier without compromising its flexibility and low weight, FBG sensors can be embedded within the thermal blanket, thereby enabling distributed temperature sensing. This capability can aid in optimizing the thermal regulation of the spacecraft and ensuring the reliable and safe operation of vital components. Furthermore, FBG sensors offer sev eral advantages over traditional temperature sensors, including high sensitivity, immunity to electromagnetic interference, and the ability to operate in harsh environments. These properties make FBG sensors an excellent option for thermal blankets in space applications, where precise temperature regulation is crucial for mission success. Nevertheless, the calibration of temperature sensors in vacuum conditions poses a significant challenge due to the lack of an appropriate calibration reference. Therefore, this paper aimed to investigate innovative solutions for calibrating temperature sensors in vacuum conditions. The proposed solutions have the potential to enhance the accuracy and reliability of temperature measurements in space applications, which can enable engineers to develop more resilient and dependable spacecraft systems

Analysis of navigation pattern in the sport of rowing

The effect of weather and environmental conditions on sports has been extensively studied over the last few years (Pezzoli et al., 2010). Based upon the studies of Lobozewicz (1981) and of Kay and Vamplew (2002), Pezzoli and Cristofori (2008) have studied the impact of some specific environmental parameters over different sports using a particular impact index divided into five classes. This analysis clearly shows that most of the outdoor sport activities are strongly influenced by the variation of meteorological parameters. However the impact of meteorological conditions on outdoor sport activities has not yet been extensively studied. The aim of this research is to show that an accurate assessment of wind and wave parameters enables decisive improvements in both training and race strategy planning. Furthermore this analysis provide a very innovative working method for the applied sport research. The work has been based on in-situ measurements of both environmental and performance parameters (wind direction, wind velocity, boat speed and stroke rate) made over different classes and in different race conditions during the 2009 FISA World Championship (Poznan, Poland). In particular a detailed environmental analysis was performed by measuring the wind direction, the wind speed and by evaluating the significant wave height and the wave peak period for each class during the semi-final phase and the final phase. It should be noted that, since wind is a key parameter affecting not only the boat speed but also the race strategy, the assessment of the wind velocity and of the wind direction has been made in connection with the boat movement. The comparison between coupled wind-wave data, boat speed and stroke rate evidently demonstrates that only crews that managed the adaption to changing in the environmental conditions from semi-final to final phase of the race, were able to get better results. References Kay, J., & Vamplew, W. (2002) Weather beaten: sport in the British climate. London: Ed. Mainstream Publishing. Lobozewicz, T. (1981) Meteorology in sport. Frankfurt: Ed. Sportverlag. Pezzoli, A,, Moncalero, M., Boscolo, A., Cristofori, E., Giacometto, F., Gastaldi, S., & Vercelli, G. (2010) The meteo-hydrological analysis and the sport performance: which are the connections? The case of the XXI Winter Olympic Games, Vancouver 2010, Journal of Sports Medicine and Physical Fitness, 50: 19-20. Pezzoli, A., & Cristofori, E. (2008) Analisi, previsioni e misure meteorologiche applicate agli sport equestri, in: 10th Congress "New findings in equine practices, Druento: Centro Internazionale del Cavallo Ed., p.38-4

THE H2020 PROJECT REDSHIFT: OVERVIEW, FIRST RESULTS AND PERSPECTIVES

The ReDSHIFT (Revolutionary Design of Spacecraft through Holistic Integration of Future Technologies) project has been approved by the European Community in the framework of the H2020 Protec 2015 call, focused on passive means to reduce the impact of Space Debris by prevention, mitigation and protection. In ReDSHIFT these goals will be achieved through a holistic approach that considers, from the outset, opposing and challenging constraints for the space environment preservation, the spacecraft survivability in the harsh space environment and the safety of humans on ground. The main innovative aspects of the project concern a synergy between theoretical and experimental aspects, such as: long term simulations, astrodynamics, passive de-orbiting devices, 3D printing, design for demise, hypervelocity impact testing, legal and normative issues. The paper presents a quick overview of the first ReDSHIFT results in an effort to highlight the holistic approach of the project covering different aspects of the space debris mitigation field. De- tailed reports on the results of the single Work Packages can be found in other papers in this same volume

Tissue engineering approaches for the construction of a completely autologous tendon substitute

Tissue engineering is a multidisciplinary field that involves the application of the principles and methods of engineering and life sciences towards i) the fundamental understanding of structure-function relationships in normal and pathological mammalian tissues and ii) the development of biological substitutes that restore, maintain or improve tissue function. The goal of tissue engineering is to surpass the limitations of conventional treatments based on organ transplantation and biomaterial implantation. The field of tendon tissue engineering is relatively unexplored due to the difficulty in in vitro preservation of tenocyte phenotype. Only recently has mechanobiology allowed us to gain a better understanding of the fundamental role of in vitro mechanical stimuli in maintaining the phenotype of tendinous tissue. This review analyzes the techniques used so far for in vitro regeneration of tendinous tissue

Tissue engineering approaches for the construction of a completely autologous tendon substitute

Tissue engineering is a multidisciplinary field that involves the application of the principles and methods of engineering and life sciences towards i) the fundamental understanding of structure-function relationships in normal and pathological mammalian tissues and ii) the development of biological substitutes that restore, maintain or improve tissue function. The goal of tissue engineering is to surpass the limitations of conventional treatments based on organ transplantation and biomaterial implantation. The field of tendon tissue engineering is relatively unexplored due to the difficulty in in vitro preservation of tenocyte phenotype. Only recently has mechanobiology allowed us to gain a better understanding of the fundamental role of in vitro mechanical stimuli in maintaining the phenotype of tendinous tissue. This review analyzes the techniques used so far for in vitro regeneration of tendinous tissue