This paper aims to reveal the characteristics of thermal energy release in a solar water heater (SWH) tank involving phase change materials (PCM) as thermal energy storage material. A bundle of cylindrical capsules wa...
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This paper presents the results of the research stage focused on applications of composite materials in aviation, carried on by an international team of European Project Semester students at the National Institute for...
This paper presents the results of the research stage focused on applications of composite materials in aviation, carried on by an international team of European Project Semester students at the National Institute for Aerospace Research "Elie Carafoli" – INCAS, as Research Partner of the University POLTEHNICA of Bucharest, as Organizer and EUROPEAN PROJECT SEMESTER Provider. The study case is a light aircraft wheel cover. The objectives are set to the determination of the body geometry by reverse engineering techniques, modeling and numerical simulations for aerodynamics and structural analysis. A scale reduced demonstrator was obtained through 3D printing.
Most current hand exoskeletons have been designed specifically for rehabilitation, assistive or haptic applications to simplify the design requirements. Clinical studies on post-stroke rehabilitation have shown that a...
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With the growing number of discovered exoplanets, the Gaia concept finds its second wind. The Gaia concept defines that the biosphere of an inhabited planet regulates a planetary climate through feedback loops such th...
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With the growing number of discovered exoplanets, the Gaia concept finds its second wind. The Gaia concept defines that the biosphere of an inhabited planet regulates a planetary climate through feedback loops such that the planet remains habitable. Crunching the “Gaia” puzzle has been a focus of intense empirical research. Much less attention has been paid to the mathematical realization of this concept. In this paper, we consider the stability of a planetary climate system with the dynamic biosphere by linking a conceptual climate model to a generic population dynamics model with random parameters. We first show that the dynamics of the corresponding coupled system possesses multiple timescales and hence falls into the class of slow-fast dynamics. We then investigate the properties of a general dynamical system to which our model belongs and prove that the feedbacks from the biosphere dynamics cannot break the system's stability as long as the biodiversity is sufficiently high. That may explain why the climate is apparently stable over long time intervals. Interestingly, our coupled climate-biosphere system can lose its stability if biodiversity decreases; in this case, the evolution of the biosphere under the effect of random factors can lead to a global climate change.
This work marks the first use of a quasi-static electrical measurement method on graphene field effect transistors (FET) to characterize sub-ppm level of toxic gases in air at room temperature. Compared with the state...
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This paper presents the results of the research stage focused on applications of composite materials in aviation, carried on by an international team of European Project Semester students at the National Institute for...
This paper presents the results of the research stage focused on applications of composite materials in aviation, carried on by an international team of European Project Semester students at the National Institute for Aerospace Research "Elie Carafoli" – INCAS, as Research Partner of the University POLTEHNICA of Bucharest, as Organizer and EUROPEAN PROJECT SEMESTER Provider. The study case is a light aircraft wheel cover. The objectives are set to the laboratory experiments in case of a light aircraft composite wheel cover.
Powder bed fusion of metals with laser beam (PBF-LB/M) using Ti-6Al-4V (Ti64) has enabled delicate fabrication of biocompatible medical implants. This research focuses on how the spatial uniformity of laser irradiatio...
Powder bed fusion of metals with laser beam (PBF-LB/M) using Ti-6Al-4V (Ti64) has enabled delicate fabrication of biocompatible medical implants. This research focuses on how the spatial uniformity of laser irradiation affects material under continuous wave (CW) and pulse width modulated (PWM) laser conditions, using a self-developed PBF-LB/M system. The volumetric energy density (VED) was used as a reference parameter in order to accurately compare the effects of CW and PWM lasers, but limitations of VED, which does not include spatial and kinetic factors, which are reinforced in the PWM laser process, were also considered. Results revealed that the uniform distribution of energy irradiation across the entire region brought similar porosities and Vickers hardness tendencies for CW and PWM laser processes. In contrast, the spatially nonuniform energy transfer resulted in a significantly higher porosity in the specimen fabricated using the PWM laser than that produced using the CW laser at the same VED, reducing compressive yield strength. The electron backscattered diffraction analysis showed no significant differences in the average grain size, phase distribution, and misorientation angle of the samples produced using CW and PWM lasers under the same VED. However, sharper grains with an aspect ratio of less than 0.3 were 7 % higher in specimens produced using the PWM laser. This study highlights the possibility of controlling the microstructure and mechanical properties in a wider range when using the PWM laser with spatially nonuniform irradiation.
Line following robots are becoming increasingly popular both in industrial and in domestic applications. In these real world environments, noisy or inaccurate measurements lead to ambiguous conclusions about the robot...
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We report light-driven levitation of macroscopic polymer films whose bottom surface is engineered to maximize the thermal accommodation coefficient. Specifically, we levitated centimeter-scale disks made of commercial...
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This investigation aims to study heat transfer rates and temperature changes within a 5 litter cold box enveloped with water-salt solution as phase change material (PCM). The study begins with design and fabrication o...
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