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de Fazio, R., Giannoccaro, N. I., Carrasco, M., Velazquez, R., & Visconti, P. (2021). Wearable devices and IoT applications for symptom detection, infection tracking, and diffusion containment of the COVID-19 pandemic: a survey. Front. Inf. Technol. Electron. Eng., 22(11), 1413–1442.
Abstract: Until a safe and effective vaccine to fight the SARS-CoV-2 virus is developed and available for the global population, preventive measures, such as wearable tracking and monitoring systems supported by Internet of Things (IoT) infrastructures, are valuable tools for containing the pandemic. In this review paper we analyze innovative wearable systems for limiting the virus spread, early detection of the first symptoms of the coronavirus disease COVID-19 infection, and remote monitoring of the health conditions of infected patients during the quarantine. The attention is focused on systems allowing quick user screening through ready-to-use hardware and software components. Such sensor-based systems monitor the principal vital signs, detect symptoms related to COVID-19 early, and alert patients and medical staff. Novel wearable devices for complying with social distancing rules and limiting interpersonal contagion (such as smart masks) are investigated and analyzed. In addition, an overview of implantable devices for monitoring the effects of COVID-19 on the cardiovascular system is presented. Then we report an overview of tracing strategies and technologies for containing the COVID-19 pandemic based on IoT technologies, wearable devices, and cloud computing. In detail, we demonstrate the potential of radio frequency based signal technology, including Bluetooth Low Energy (BLE), Wi-Fi, and radio frequency identification (RFID), often combined with Apps and cloud technology. Finally, critical analysis and comparisons of the different discussed solutions are presented, highlighting their potential and providing new insights for developing innovative tools for facing future pandemics.
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Dreyer, M. J., Weisse, B., Raggio, J. I. C., Zboray, R., Taylor, W. R., Preiss, S., et al. (2023). The influence of implant design and limb alignment on in vivo wear rates of fixed-bearing and rotating-platform knee implant retrievals. J. Orthop. Res., Early Access.
Abstract: Analysis of polyethylene (PE) wear in knee implants is crucial for understanding the factors leading to revision in total knee arthroplasty. Importantly, current experimental and computational methods for predicting insert wear can only be validated against true in vivo measurements from retrievals. This study quantitatively investigated in vivo PE wear rates in fixed-bearing (FB) (n = 21) and rotating-platform (n = 53) implant retrievals. 3D surface geometry of the retrievals was measured using a structured light scanner. Then, a reference surface that included the deformation, but not the wear that the retrievals had experienced in vivo, was constructed using a fully automatic surface reconstruction algorithm. Finally, wear volume was calculated from the deviation between the worn and reconstructed surfaces. The measurement and analysis techniques were validated and the algorithm was found to produce errors of only 0.2% relative to the component volumes. In addition to quantifying cohort-level wear rates, the effect of mechanical axis limb alignment on mediolateral wear distribution was examined for a subset of the retrievals (n = 14 + 26). Our results show that FB implants produce significantly (p = 0.04) higher topside wear rates (24.6 +/- 10.1 mm3/year) than rotating-platform implants (15.3 +/- 8.0 mm3/year). This effect was larger than that of limb alignment, which had a smaller and nonsignificant influence on overall wear rates (+4.5 +/- 11.6 mm3/year, p = 0.43). However, increased varus alignment was associated significantly with greater medial compartment wear in both the FB and rotating-platform designs (+1.7 +/- 1.3%/degrees and +1.8 +/- 1.6%/degrees). Our findings emphasize the importance of implant design and limb alignment on wear outcomes, providing reference data for improving implant performance and longevity.
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Martinez, C., Briones, F., Rojas, P., Ordonez, S., Aguilar, C., & Guzman, D. (2017). Microstructure and Mechanical Properties of Copper, Nickel and Ternary Alloys Cu-Ni-Zr Obtained by Mechanical Alloying and Hot Pressing. MRS Adv., 2(50), 2831–2836.
Abstract: Elemental powders of Cu and Ni, binary alloys (Cu-Ni and Cu-Zr) and ternary alloy (Cu-Ni-Zr) obtained by mechanical alloying and uniaxial compaction hot microstructure and mechanical properties were investigated. The alloys studied were: pure Cu, pure Ni, binary alloys (Cu-Ni; Cu-Zr) and ternary alloys (Cu-Ni-Zr) under the same mechanical milling and hot pressing conditions. The samples were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM); the mechanical properties were studied by compression tests and hardness in Vickers scale (HV0.5) on polished surfaces at room temperature. According to XRD results, hot pressing process crystallite size increase and microstrain decreases in the compact samples due to the release of crystalline defects. The compacted samples have porosity of approximately 20%. The milling powder samples have a higher hardness than the unmilled samples, this because during milling crystal defects are incorporated together with the microstructural refinement. Ternary alloy is the one with the highest hardness of all systems studied, reaching 689 HV0.5. In compression tests determined a strain 5 %, Zr-containing samples become more fragile presenting the lowest values of compressive strength. In contrast, samples of Ni and Cu-Ni binary alloy are more resistant to compression.
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Velazquez, R., Pissaloux, E., Rodrigo, P., Carrasco, M., Giannoccaro, N. I., & Lay-Ekuakille, A. (2018). An Outdoor Navigation System for Blind Pedestrians Using GPS and Tactile-Foot Feedback. Appl. Sci.-Basel, 8(4), 15 pp.
Abstract: This paper presents a novel, wearable navigation system for visually impaired and blind pedestrians that combines a global positioning system (GPS) for user outdoor localization and tactile-foot stimulation for information presentation. Real-time GPS data provided by a smartphone are processed by dedicated navigation software to determine the directions to a destination. Navigational directions are then encoded as vibrations and conveyed to the user via a tactile display that inserts into the shoe. The experimental results showed that users were capable of recognizing with high accuracy the tactile feedback provided to their feet. The preliminary tests conducted in outdoor locations involved two blind users who were guided along 380-420 m predetermined pathways, while sharing the space with other pedestrians and facing typical urban obstacles. The subjects successfully reached the target destinations. The results suggest that the proposed system enhances independent, safe navigation of blind pedestrians and show the potential of tactile-foot stimulation in assistive devices.
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Velazquez-Guerrero, R., Pissaloux, E., Del-Valle-Soto, C., Carrasco-Zambrano, M. A., Mendoza-Andrade, A., & Varona-Salazar, J. (2021). Mobility of blind people using the smartpho-ne's GPS and a wearable tactile display. Dyna, 96(1), 98–104.
Abstract: This paper presents a novel wearable system devoted to assist the mobility of blind and visually impaired people in urban environments with the simple use of a smartphone and tactile feedback. The system exploits the positioning data provided by the smartphone's GPS sensor to locate in real-time the user in the environment and to determine the directions to a destination. The resulting navigational directions are encoded as vibrations and conveyed to the user via an on-shoe tactile display. To validate the pertinence of the proposed system, two experiments were conducted. The first one involved a group of 20 voluntary normally sighted subjects that were requested to recognize the navigational instructions displayed by the tactile-foot device. The results show high recognition rates for the task. The second experiment consisted of guiding two blind voluntary subjects along public urban spaces to target destinations. Results show that the task was successfully accomplished and suggest that the system enhances independent safe navigation of people with visually impairments. Moreover, results show the potentials of smartphones and tactile-foot devices in assistive technology.
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