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- Brinkfeldt, Klas, et al.
(author)
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Failure mechanism assessment of TO-247 packaged SiC power devices
- 2018
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In: ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems, InterPACK 2018. - 9780791851920
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Conference paper (peer-reviewed)abstract
- As the automotive industry shifts towards the electrification of drive trains, the efficiency of power electronics becomes more important. The use of silicon carbide (SiC) devices in power electronics has shown several benefits in efficiency, blocking voltage and high temperature operation. In addition, the ability of SiC to operate at higher frequencies due to lower switching losses can result in reduced weight and volume of the system, which also are important factors in vehicles. However, the reliability of packaged SiC devices is not yet fully assessed. Previous work has predicted that the different material properties of SiC compared to Si could have a large influence on the failure mechanisms and reliability. For example, the much higher elastic modulus of SiC compared to Si could increase strain on neighboring materials during power cycling. In this work, the failure mechanisms of packaged Si- and SiC-based power devices have been investigated following power cycling tests. The packaged devices were actively cycled in 4.5 s heating and 20 s cooling at ΔT = 60 - 80 K. A failure analysis using micro-focus X-ray and scanning acoustic microscopy (SAM) was carried out in order to determine the most important failure mechanisms. The results of the analysis indicate that the dominant failure mechanism is wire bond liftoff at the device chip for all of the SiC-based devices. Further analysis is required to determine the exact failure mechanisms of the analyzed Si-based devices. In addition, the SiC-based devices failed before the Si-based devices, which could be a result of the different properties of the SiC material.
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- Büki, Andras, 1966-, et al.
(author)
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Baleseti agysérültek ellátásának irányelvei -2017 : [GUIDELINES FOR THE TREATMENT OF TRAUMATICBRAIN INJURY – 2017]
- 2017
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In: Ideggyógyászati szemle. - : Literatura Medica Kiado. - 0019-1442 .- 2498-6208. ; 70:7-8, s. 223-245
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Research review (peer-reviewed)abstract
- Traumatic brain injury (TBI) is recognized to be the main cause of death and disability in the first four decades representing a major socio-economical problem worldwide. Recent communications revealed a particularly worrying image about the quality of care for TBI in Hungary. For any improvement a systematic approach characterized by utilization of scientific evidence based guidelines forming the basis for close monitoring of the actual care are considered a prerequisite. In Hungary the first evidence based guidelines in the field of TBI have been issued by the National Society for Anesthesiology and Intensive Care more than two decades ago followed by joint guidelines of the Hungarian Neurosurgical Society and the Hungarian College of Neurosurgeons. These publications were primarily based on the work of the European Brain Injury Consortium as well as guidelines issued by the Brain Trauma Foundation. Recent renewal of the latter and a need to refresh the outdated national guidelines was met by a call from regulatory authorities to issue the updated version of the Hungarian TBI-guidelines. The present review is aimed to briefly summarize the most fundamental elements of the national head injury guidelines that would hopefully be officially issued in a far more detailed format soon.
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- Chauhan, Tanya, et al.
(author)
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Synthesis, characterization, and challenges faced during the preparation of zirconium pillared clays
- 2022
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In: Arabian Journal of Chemistry. - : Elsevier BV. - 1878-5352. ; 15:4
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Journal article (peer-reviewed)abstract
- In this study, Zr-pillared montmorillonite clays (Zr-PILCs) were synthesized using two different precursor materials: raw montmorillonite (CM) and sodium ion-saturated montmorillonite (Na-CM) at different Zr/clay ratios (2.5, 5 and 10 mmol/g). To study the effect of Zr concentration and clay pre-treatment with NaCl on pillaring, the modified clay samples were characterized in detail using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy (STEM-EDX). The XRD analysis showed the increase of basal spacing of Zr-PILCs prepared from both precursor materials: from 1.26 to 1.74 nm in the case of CM, and from 1.13 to 1.93 nm for Na-CM. Results from FT-IR revealed new bands ascribed to Zr-O bonds in the range of 400–500 cm−1 in Zr-pillared samples obtained from Na-CM at Zr/clay ratios of 2.5 and 5 mmol/g. The distribution and nature of Zr species in between the silicate layers were studied using STEM-EDX and HAADF imaging. They were found to be separated by a distance of 1.5–3 nm and their thickness lies in the range of 1–2 nm. Pillared clays prepared from pre-treatment with NaCl were more thermally stable at higher temperatures.
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- Claesson, A, et al.
(author)
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District nurses' perceptions of osteoporosis management: a qualitative study
- 2015
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In: Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA. - : Springer Science and Business Media LLC. - 1433-2965. ; 26:7, s. 1911-1918
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Journal article (peer-reviewed)
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- Fooladgar, Ehsan, et al.
(author)
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CFD modeling of pyrolysis oil combustion using finite rate chemistry
- 2021
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In: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 299
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Journal article (peer-reviewed)abstract
- This paper reports the first Computational Fluid Dynamics (CFD) model developed for biomass pyrolysis oil spray combustion using Finite-Rate Chemistry (FRC) approach. To make the CFD calculations feasible, a reduced mechanism for modeling the combustion of biomass Fast Pyrolysis Oil (FPO) based on the POLIMI 1412 mechanism and a model for eugenol oxidation was developed. The reduced mechanism consisted of 200 reactions and 71 species. This level of complexity was found to be a good tradeoff between predictive power and computational cost such that the reduced model could be used in CFD modeling. The predictive power of the reduced mechanism was demonstrated via 0D (adiabatic, premixed, constant pressure reactor), 1D (laminar counterflow flame) and 3D (CFD of a methane-air flat-flame piloted FPO spray flame) calculations. Results from CFD were compared against experimental data from non-intrusive optical diagnostics. The reduced model was successfully used in CFD calculations—the computational cost was approximately 2 orders of magnitude higher than that of a simplified model. Using the reduced mechanism, the concentration of pollutants, minor combustion products, and flame radicals could be predicted—this is added capability compared to already existing models. The CFD model using the reduced mechanism showed quantitative predictive power for major combustion products, flame temperature, some pollutants and temperature, and qualitative predictive power for flame radicals and soot.
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- Garami, Attila, et al.
(author)
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Reaction zone monitoring in biomass combustion
- 2018
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In: Control Engineering Practice. - : Elsevier Ltd. - 0967-0661 .- 1873-6939. ; 74, s. 95-106
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Journal article (peer-reviewed)abstract
- In this work we demonstrate the utilization of a machine vision-based combustion monitoring system in biomass combustion. The proposed system monitored the location of the reaction zone in a 3 MW, grate-fired biomass boiler operated at varying loads and with fluctuating fuel quality. The system can help guarantee equal primary air supply to different regions of the grate and avoid the elutriation of fly ash by providing information on the location of the reaction zone. Strong correlation was found between the reaction zone boundary location and most process parameters, indicating that the location of the reaction zone can be a useful metric in monitoring and control by providing supplementary measurements to already existing monitoring to avoid over-emissions and improve economics.
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