1,406 research outputs found
UniquID: A Quest to Reconcile Identity Access Management and the Internet of Things
The Internet of Things (IoT) has caused a revolutionary paradigm shift in
computer networking. After decades of human-centered routines, where devices
were merely tools that enabled human beings to authenticate themselves and
perform activities, we are now dealing with a device-centered paradigm: the
devices themselves are actors, not just tools for people. Conventional identity
access management (IAM) frameworks were not designed to handle the challenges
of IoT. Trying to use traditional IAM systems to reconcile heterogeneous
devices and complex federations of online services (e.g., IoT sensors and cloud
computing solutions) adds a cumbersome architectural layer that can become hard
to maintain and act as a single point of failure. In this paper, we propose
UniquID, a blockchain-based solution that overcomes the need for centralized
IAM architectures while providing scalability and robustness. We also present
the experimental results of a proof-of-concept UniquID enrolment network, and
we discuss two different use-cases that show the considerable value of a
blockchain-based IAM.Comment: 15 pages, 10 figure
Tuned liquid dampers simulation for earthquake response control of buildings
This paper is focused on the study of an earthquake protection system, the Tuned Liquid Damper (TLD), which
can, if adequately designed, reduce earthquake demands on buildings. This positive effect is accomplished taking
into account the oscillation of the free surface of a fluid inside a tank (sloshing). The behaviour of an isolated
Tuned Liquid Damper, subjected to a sinusoidal excitation at its base, with different displacement amplitudes,
was studied by finite element analysis. The efficiency of the TLD in improving the seismic response of an existing building, representative of modern architecture buildings in southern European countries was also evaluated based on linear dynamic analyses
Evolutionary Implications of a Peroxidase with High Affinity for Cinnamyl Alcohols from Physcomitrium patens, a Non-Vascular Plant
[Abstract] Physcomitrium (Physcomitrella) patens is a bryophyte highly tolerant to different stresses, allowing survival when water supply is a limiting factor. This moss lacks a true vascular system, but it has evolved a primitive water-conducting system that contains lignin-like polyphenols. By means of a three-step protocol, including ammonium sulfate precipitation, adsorption chromatography on phenyl Sepharose and cationic exchange chromatography on SP Sepharose, we were able to purify and further characterize a novel class III peroxidase, PpaPrx19, upregulated upon salt and H2O2 treatments. This peroxidase, of a strongly basic nature, shows surprising homology to angiosperm peroxidases related to lignification, despite the lack of true lignins in P. patens cell walls. Moreover, PpaPrx19 shows catalytic and kinetic properties typical of angiosperm peroxidases involved in oxidation of monolignols, being able to efficiently use hydroxycinnamyl alcohols as substrates. Our results pinpoint the presence in P. patens of peroxidases that fulfill the requirements to be involved in the last step of lignin biosynthesis, predating the appearance of true lignin.Xunta de Galicia; INCITE08PXIB103182PRPortugal. Fundaçao para a Ciência e a Tecnologia; SFRH/BPD/112587/2015This research was funded by Xunta de Galicia (Spain), grant number INCITE 08PXIB103182PR. E.N.-U. holds an FCT postdoctoral fellowship (SFRH/BPD/112587/2015)
Processing conditions and properties of continuous fiber reinforced GF/PP thermoplastic matrix composites manufactured from different pre-impregnated materials
The aim of the present work was to study and compare the processing conditions and final mechanical properties of continuous glass-fiber reinforced polypropylene composites (GF/PP) manufactured by using available thermoplastic preimpregnated materials produced by different methods.To assess the quality of the three different GF/PP pre-impregnated materials, final manufactured composite parts were submitted to mechanical testing and microscopy analysis. The obtained properties were compared between each other and to those theoretical ones that can be predicted by using the Classical amination Theory (CLT).Fundação para a Ciência e a Tecnologia (FCT
Effect of Agrobacterium rhizogenes infection on in vitro rooting of Vitis vinifera
Agrobacterium rhizogenes is known to induce the proliferation of rapid growing, highly branching roots (hairy roots) in most dicotyledonous plants. We report here the effect of in vitro infection of Vitis vinifera with two A. rhizogenes strains (b-glucuronidase transgenic A4 and wild type LBA), with regard to an increase of root mass. In vitro-grown V. vinifera explants were infected with two A. rhizogenes strains. Both strains induced a significant increase in the number of the developed roots, and of their weight and length. Root number was increased by a factor of 2.9 (strain A4) and 2.7 (strain LBA), length increased 1.9 and 1.6 times (strains A4 and LBA, respectively), while the root weight was more affected by strain A4 (2.8 times increasing) than by LBA strain (1.9 times increasing). The transformation status of the developed roots was assessed by two different methods: PCR detection of rolB gene in LBA strain-derived roots and quantification of â-glucuronidase activity in A4 strain-derived roots.
Optimizing the production and processing of fibre reinforced thermoplastic pre-impregnated materials
The aim of this work is to optimize the production of new continuous carbon fibres reinforced polypropylene matrix pre-impregnated materials (towpregs) continuously processed by dry deposition of polypropylene (PP) powder. The processing of the produced towpregs by pultrusion using a prototype equipment was also optimized. The method of Taguchi/DOE (Design of Experiments) was used to achieve this goal allowing improved choices of processing windows. Towpregs were characterized by scanning electron microscopy (SEM), visual analysis and their polymer mass contents were also determined. The final pultruded composite profiles were also submitted to tensile, interlaminar, flexural, calcination and optical microscopy tests.(undefined
Processing of carbon reinforced thermoplastic composites
The aim of this work is to produce and optimize the processing of carbon fibres thermoplastic matrix pre-impregnated materials (towpregs and PCT´s) using the dry powder coating equipment from our own laboratories. Pultrusion was the selected manufacturing method for processing all carbon fibres thermoplastic matrix pre-impregnated materials into composite parts.
The optimization of the pultrusion processe was made by studying the influence of the most relevant processing parameters in the final properties of the produced carbon fibres thermoplastic matrix pre-impregnated materials and composites.
The composite relevant mechanical properties were determined and studied. The final composites were also submitted to Scanning Electron Microscopy (SEM), optical microscopy and calcination tests.
The determination of the fiber volume fraction of a composite with a high melting temperature thermoplastic polymer used as matrix was obtained comparing the results of thermogravimetric analysis (TGA) with the calcination tests.info:eu-repo/semantics/publishedVersio
Processing of carbon reinforced thermoplatic pre-impregnated materials
The aim of this work is to produce and optimize the processing of carbon fibres thermoplastic matrix pre-impregnated materials (towpregs and PCT´s). Pultrusion and heated compression moulding were the selected manufacturing methods for processing all carbon fibres thermoplastic matrix pre-impregnated materials into composite parts.
The optimization of those processes was made by studying the influence of the most relevant processing parameters in the final properties of the produced carbon fibres thermoplastic matrix pre-impregnated materials and composites. The method of Taguchi / DOE (Design of Experiments) was used to achieve this aim as it allowed making more rational choices of processing windows.
The composite relevant mechanical properties were determined and studied. The final composites were also submitted to SEM microscopy analysis
Advanced thermoplastic carbon fibre reinforced pultruded composites
The aim of this work is to optimize the production of new continuous carbon fibers reinforced thermoplastic matrix pre-impregnated materials (towpregs) continuously processed by dry deposition of polymer powders in a new equipment developed by the Institute for Polymers and Composites (IPC). The processing of the produced towpregs by pultrusion, in a developed prototype equipment existing in the Engineering School of the Polytechnic Institute of Porto (ISEP), was also optimized.
Two different thermoplastic matrices were studied: one for commercial applications (polypropylene) and an-other for advanced markets (Primospire®).
The optimization was made by studying the influence of the most relevant processing parameters in the final properties of the produced towpregs and composites. The final pultruded composite profiles were submitted to mechanical tests in order to obtain relevant properties.FCT projeto UID/CTM/50025/20
Advances in thermoplastic pultruded composites
Pultrusion is a versatile continuous high speed production technology allowing the production of fibre
reinforced complex profiles. Thermosetting resins are normally used as matrices in the production of
structural constant cross section profiles. Although only recently thermoplastic matrices have been used in long and continuous fibre reinforced composites replacing with success thermosetting matrices, the number of their applications is increasing due to their better ecological and mechanical performance. Composites with thermoplastic matrices offers increased fracture toughness, higher impact tolerance, short processing cycle time and excellent environmental stability. They are recyclable, post-formable and can be joined by welding. The use of long/continuous fibre reinforced thermoplastic matrix composites involves, however, great technological and scientific challenges since thermoplastics present much higher viscosity than thermosettings, which makes much difficult and complex the impregnation of reinforcements and consolidation tasks.
In this work continuous fibres reinforced thermoplastic matrix towpregs were produced using equipment developed by the Institute for Polymers and Composites (IPC). The processing of the towpregs was made by pultrusion, in a developed prototype equipment existing in the Engineering School of the Polytechnic Institute of Porto (ISEP).
Different thermoplastic matrices and fibres raw-materials were used in this study to manufacture
pultruded composites for commercial applications (glass and carbon fibre/ polypropylene) and for
advanced markets (carbon fibre/Primospire®). To improve the temperature distribution profile in heating die, different modifications were performed. In order to optimize both processes, towpregs production and pultruded composites profiles were analysed to determine the influence of the most relevant processing arameters in the final properties. The final pultruded composite profiles were submitted to mechanical tests to obtain the relevant properties.(undefined
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