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  • Open access
  • 83 Reads
ARC Knee Brace: neoprene knee brace with active control using wearable sensors

Remote monitoring of physical rehabilitation process of a patient that has undergone knee surgery is important in particular in the cases like pandemic in which patients may not have the opportunity to receive continuous postoperative treatment due to the measures taken. Currently, there is no available wearable knee brace that keeps track of knee posture during such a rehabilitation process while simultaneously giving users active control and knee posture feedback regarding users’ activity. To solve this problem, ARC (Active Rotation Control) knee brace was developed to guide and facilitate physical therapy movements of patients with knee injuries in an actively controlled manner. The system is able to trigger a visual feedback mechanism when the subject performs various knee postures. Through the Internet, caregivers could obtain patients’ overall knee related rehabilitation metrics. ARC Knee Brace employs inertial motion tracking technology which is based on low-cost inertial sensors and data processing algorithms to capture user's knee posture in real-time during rehabilitation process. The inertial measurement units (IMUs) containing a combination of accelerometer and gyroscope are used as motion sensors to measure accelerations and rotational rates of knee. The sensors track data including acceleration, rotation and temperature. The processing system handles calculating various metrics from the posture of knee. The filtration algorithms aid in collecting correct data in real time. Through data processing, the physician dictated knee movements of a patient are recorded for analysis. Future prospective researches with the subjects from various age ranges and genders are needed to improve the effectiveness as well as design of the ARC Knee Brace.

  • Open access
  • 115 Reads
A Numerical Analysis on the Cyclic Behavior of 316 FR Stainless Steel and Fatigue Life Prediction

Many components in the nuclear power plant sector, such as liquid metal cooled fast breeders, are designed to function at severe temperature loading conditions, causing thermal stresses to occur simultaneously with repeated mechanical loads. As a result, low cycle fatigue is one of the most common damage mechanisms that leads to the failure of these components. Hence, in this study, the low cycle fatigue behavior of smooth cylindrical specimens made of 316 FR austenitic stainless steel, a typical material used for fatigue and creep loading applications, is investigated. The specimens have been first modeled using finite element analysis, with nominal mechanical strain amplitudes ranging from ±0.4 to ±1.2%, at 650 °C, and the numerical models have been validated against experimental hysteresis loops. The fatigue life has been then calculated, for various strain amplitudes levels, using several low cycle fatigue prediction equations, including the Coffin-Manson model, Ostergren's damage function, and Smith-Watson-Topper (SWT) damage model. The obtained results reveal that the numerically generated hysteresis loops are in good agreement with those provided in the literature. Furthermore, the fatigue lifetimes predicted using the aforementioned low cycle fatigue life models and based on the present study suggested material parameters at 650 °C, have been compared with the experimental fatigue life data available in the literature. Overall, considering the current research proposed material constants, the estimated fatigue lifetimes from the Coffin-Manson model, Ostergren damage function, and Smith-Watson-Topper equation are all in good agreement with the experimental findings and all fall within a factor of one

  • Open access
  • 103 Reads
The contribution of port-related emissions and meteorology in the air quality of Igoumenitsa port

Among the most important trade bridges for Western Europe and the Balkans is the Port of Igoumenitsa in Western Greece that experiences heavy traffic of goods and passengers. This study primarily aimed to investigate the effect of shipping and port activity on air quality in the Port of Igoumenitsa comparing two representative seasons of air quality measurement campaigns. The first, high activity season, ranges from 25/8/2018 to 31/08/2018, and the second, the low activity season, ranges from 17/5/2018 to 25/5/2018. A mobile air quality monitoring system was used to perform the analysis. To investigate the air quality differences between the two seasons, the wind speed rose diagrams, the correlation analysis as well as the hourly variations in concentrations of pollutants and meteorological parameters, were studied. In addition, the impact of meteorology and atmospheric circulation on local air quality were investigated. For study implementation, various types of data, obtained from NASA Worldview application, Barcelona Supercomputing Center (BSC) and Giovanni online system (NASA-GES-DISC) were included. The results indicate that port operations affect the air quality in the Port of Igoumenitsa, as the high season showed higher concentrations of air pollutants compared to the low season. A notable exception was the concentration of PMs which was affected by an African dust transfer event during the low season. Finally, the analysis shows that meteorology affects air quality, and emphasizes the importance of developing a green and sustainable management system within the port.

  • Open access
  • 58 Reads

Needles are the most important stitch formation elements of the knitting process and they are exposed to variable and repetitive loads and forces during fabric production. Stresses that are obtained due to these forces are smaller than the material yield and tensile strength. However, after a while the material cannot carry these dynamic loading they are exposed and finally broken. This is regarded as the fatigue of the needles. Any abraded or fracture of these needles cause unwanted and irrecoverable faults on fabric like uneven loop structure, holes and dropped stitches, which cause huge cost loss. Considering that the number of needles on circular knitting machines (varying from 1000 to 2800 averages depending on machine type) and the average price of 6 Euro/per needle, it is very important to estimate the needle deformation to avoid fabric production faults and reduce the operating costs by extending needle life. From this point, the study was designed to predict the fatigue lives of needles under certain production conditions. To do so, a model using finite element method was developed to determine the forces acting on the needles during knitting production process. The stress values obtained were imported to nCode Designlife program in order to estimate the fatigue damage of circular knitting needle. The model showed that by changing production data, the fatigue lives of the needles, can be determined very quickly at low cost.

  • Open access
  • 37 Reads
Partial differential equations of motion for a single-link flexible manipulator

Robot manipulators have played an enormous role in the industry during the twenty-one century. Due to the advances in materials science, lightweight manipulators have emerged with low energy consumption and positive economic aspect regardless of their complex mechanical model and control techniques problems. This paper presents a dynamic model of a single link flexible robot manipulator with a payload at its free end based on the Euler-Bernoulli beam theory with a complete second-order deformation field that generates a complete second-order elastic rotation matrix. The beam experiences an axial stretching, horizontal and vertical deflections, and a torsional deformation ignoring the shear due to bending, warping due to torsion, and viscous air friction. The deformation and its derivatives are assumed to be small. The application of the extended Hamilton principle while taking into account the viscoelastic internal damping based on the Kelvin-Voigt model expressed by the Rayleigh dissipation function yields both the boundary conditions and the coupled partial differential equations of motion that can be decoupled when the manipulator rotates with a constant angular velocity. Equations of motion solutions are still under research, as it is required to study the behavior of flexible manipulators and develop novel ways and methods for controlling their complex movements.

  • Open access
  • 67 Reads
The Influence of Sample Preparation Techniques on Aluminium Alloy AA2024-T3 Substrates for Sol-Gel Coating
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Sol-gel coatings provide environmentally friendly surface protection of metals and can replace toxic pre-treatments such as those based on hexavalent chromium on metal alloys. the project ultimately aims to develop silica-based organic-inorganic sol-gel derived thin film coatings possessing anti-corrosion and anti-fouling properties on aluminium alloys substrates. As with any coating, sample preparation plays a significant role in the performance of a sol-gel coating. It was, therefore, necessary to define a preparation method that combines removal of contaminants, surface roughening to improve adhesion and reproducibility. Four techniques were investigated: abrasive cleaning, acetone degreasing and cleaning with an industrial-available alkaline cleaner for 5 minutes and 30 minutes.

  • Open access
  • 52 Reads
First results for the selection of repeating earthquakes in the Eastern Tien Shan (China)

This geophysics research in repeating earthquakes (EQs) is aimed at the possible influence of space weather parameters on the seismic process. I give attention to the behavior of specific faults and tectonic active zones, where strong EQs are expected in the medium to long term. Repeating EQs were found in the Eastern Tien Shan (region of China), on the border with Kazakhstan and Kyrgyzstan. In this work, an earthquake catalog (NEIC) of 400 earthquakes with 2.5+ magnitude from 2000 to 2020 was used. The areas of shear zones with small nucleating are found. These droplets could lead to the process before the nucleation of the macroscopic phase. I examine repeater families to check the probability of a change in the recurrence rate of earthquakes under the influence of strong magnetic storms with Kp = 8-9. An example of co-located earthquakes (repeaters) was found and examined. Especially, to detect slip faults areas, the Google Earth tools are effective.

The results showed the presence of repeating seismic events in the area, that represent important components of interplate slip processes in addition to major earthquakes.

  • Open access
  • 63 Reads
Development of a curd cake for patients with type 2 diabetes: Influence of replacing sugar with sweetener on nutritional value

A main message of modern nutritional science is that nutrition plans should be individualized and flexible to meet the specific needs of the people with diabetes(PWD), in consideration of their ability to implement the changes. Many people, even those who want to correct conditions associated with excess weight or diabetes,are not ready to completely abandon their usual foods, for example, desserts. Non-nutritive sweeteners such as sucralose are used to create desserts with a lowglycemic index and calorie content.
The subject of the research was the technology of low-calorie curd cake. Calorie content was reduced by replacing 50% of the sugar in the formulation with sucralose.A worsening of Maillard browning reaction was noted with substitution of more than 50% sugar. Sucralose was introduced as a sweetener TM Splenda®. The amount ofadded sucralose was calculated so that the sweetness of the new product did not diff er from the sweetness of the control product. In the production of reducedcalorie muff ins by partially replacing sugar with sucralose, there is a problem of creating the structure of the product and replenishing the mass of the derived sugar,which is approximately 30% of the total weight of the original ingredients. To solve this problem, it was proposed to introduce skimmed curd cheese (fat content 0.6%)into the cake recipe, the weight of which in the new recipe corresponded to the weight of sugar derived from the original recipe. As a result, a curd cake was obtainedwith a calorie content of 14% lower than that of the analogue product, which in its sensory characteristics and structure does not diff er from the analogue productand contains 26% more protein.

  • Open access
  • 46 Reads
Developing a Benzimidazole Silica-Based Hybrid Sol-gel Coating with Significant Corrosion Protection on Aluminum Alloys 2024-T3
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The inherent reactivity of the Al-Cu-Mg alloys is such that their use for building structural, maritime, and aeroplane components with great strength/weight ratio, it would not be possible without good anti-corrosion systems. These systems could be considered as imitations of the protection mechanism found with the conventional hexavalent chromium-based system, but also limiting the environmental impact, precisely without toxic or carcinogenic effect, and should also be eco-friendly. Silica-based hybrid protective coatings have been shown to exhibit excellent chemical stability combined with the ability to reduce the corrosion of metal substrates. However, research shows that sol-gel has some limitation in term of the period of anti-corrosive properties. Therefore, this work reports the performance of a silica-based hybrid sol-gel coating encapsulated with Benzimidazole (BZI) that can be applied to light alloys to form a crack-free coating. This coating was applied on AA 2024-T3 and cured at 80ºC. The high corrosion resistance performance results from the combination of good adhesion, the hydrophobic property of the silica-based hybrid coating and the presence of the encapsulated (BZI) film-forming volatile corrosion inhibitor, which will be released at pores within the coating system resulting in film-forming, reducing the cathodic reaction at cathodic sites. The evaluation of this mechanism is based upon using electrochemical testing techniques. The anti-corrosion properties of the coatings were studied immersed within 3.5% NaCl by using electrochemical impedance spectroscopy (EIS) and Potential-dynamic polarization scanning (PDPS). The chemical confirmation was done by infrared spectroscopy (ATR-FTIR). supported by analyzing the morphology of the surface before and after the immersion testing by using scanning electron microscopy (SEM). The Benzimidazole-silica-based hybrid coating exhibited excellent anti-corrosion properties, providing an adherent protection film on the aluminium alloy 2024-T3 samples compared to sol-gel-only and bare material, with cost-effective and as an eco-friendly system.

  • Open access
  • 91 Reads
A wearable temperature sensor network to address the COVID-19 pandemic emergency

To reduce the infections of the SARS-CoV-2 virus, several types of body temperature sensors have been used to monitor the access of people to enclosed spaces, e.g. thermal imaging cameras and infrared thermometers. However, these approaches cause the concentration of the people flows in checkpoints, increasing the risk of exposure for the people. Moreover, in buildings where the people are located for several hours, e.g. schools, universities, or industries, these approaches cannot reduce the pandemic risk. So, we have proposed and tested a body temperature sensor network in three schools based on wearable temperature sensors monitored via Bluetooth 5.0 by smartphones and/or custom gateways (with a maximum of about one hundred per gateway and about fifty per smartphone). The data collected are transmitted on a server via the internet. The wearable sensor system is a small-size chip with an accuracy of +/- 0.1 °C that can be inset into a specific rubber bracelet for continuous and real-time body temperature monitoring. The sensor system is waterproof and does not present a display, to reduce battery consumption, whereas the communication system and other components have been integrated onboard. The gateway transmits the data via the internet to a server directly. In contrast, the smartphone app (available for IoS and Android) transmits the data and can display the temperature of all the sensors connected to it. For constant and safe monitoring, the developed software is used to analyse the database present on the server to control the measured temperature and produce warning automatically.