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Sven Kalker,Johannes Holz,Isabel Austrup,Rik W. De Doncker 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-
The increasing reliability requirements of power electronic components demands for a better understanding of their application-dependent aging progression. Active power cycling is a commonly used accelerated-aging method for invoking degradation effects in the thermal path of power devices. For aging diagnosis during power cycling, usually step-response thermal impedance spectroscopy is applied utilizing a temperature-sensitive parameter for thermal sensing. This approach has multiple limitations: Degradation detection close to the power semiconductor is limited since the load step over-proportionally excites low-frequency components. The temperature-sensitive parameter is by itself prone to aging, leading to reduced accuracy or necessitates repeated calibration. To overcome these limitations, this paper proposes online thermal impedance spectroscopy in frequency domain for aging diagnosis during active power cycling. By doing so, aging effects in the thermal path can be detected and localized more robustly and with higher accuracy without testing interruption. Furthermore, by using a near-chip NTC sensor for thermal sensing, calibration effort can be reduced significantly. This paper evaluates the online thermal impedance spectroscopy using data from the active power cycling of an IGBT lead-frame power module with a near-chip NTC.
Comparison of mass operator methods considering test uncertainties
Olympio, K.R.,Blender, F.,Holz, M.,Kommer, A.,Vetter, R. Techno-Press 2018 Advances in aircraft and spacecraft science Vol.5 No.2
In the space industry, structures undergo several vibration and acoustic tests in order to verify their design and give confidence that they will survive the launch and other critical in-orbit dynamic scenarios. At component level, vibration tests are conducted with the aim to reach local or global interface loads without exceeding the design loads. So, it is often necessary to control and limit the input based on a load criterion. This means the test engineer should be able to assess the interface loads, even when load cannot be measured. This paper presents various approaches to evaluate interface loads using measured accelerations and by referring to mass operators. Various methods, from curve fitting techniques to finite element-based methods are presented. The methods are compared using signals with known imperfection to identify strengths and weaknesses of each mass operator definition.
Synthesis and characterization of H2V3O8 nanorods for electrochemical devices
V.S. Reddy Channu,Rudolf Holze,B. Rambabu 한국물리학회 2013 Current Applied Physics Vol.13 No.1
Vanadium oxide hydrate (H2V3O8) nanorods to be used as cathode material in secondary batteries were synthesized using a hydrothermal method without templates and reducing agents. The obtained pristine product was characterized using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. Cyclic voltammetry and charge/discharge studies were conducted to examine the electrochemical performance of cathodes made of these vanadium oxide hydrate nanorods. The specific capacity of the vanadium oxide hydrate nanorods is 292 mAh/ g, the columbic efficiency is about 95%. The calculated capacities are 42.8 F/g at 5 mV/s and 39.2 F/g at 10 mV/s scan rate.
Dubal, Deepak P.,Gund, Girish S.,Holze, Rudolf,Jadhav, Harsharaj S.,Lokhande, Chandrakant D.,Park, Chan-Jin The Royal Society of Chemistry 2013 Dalton Transactions Vol.42 No.18
<P>Copper oxide (CuO) thin films are successfully synthesized using a surfactant assisted chemical bath deposition method for application in supercapacitors. The effect of organic surfactants such as Triton X-100 and polyvinyl alcohol (PVA) on structural, morphological, surface areas and electrochemical properties of CuO thin films is investigated. The films deposited using organic surfactants exhibit different surface morphologies. It is observed that the organic surfactants play important roles in modifying the morphology, surface area and pore size distribution. Electrochemical analysis confirms that the nanostructures of the electrode material play a vital role in supercapacitors. The cyclic voltammetry studies show a considerably improved high rate pseudocapacitance of CuO samples synthesized using organic surfactants. The maximum specific capacitance of 411 F g<SUP>−1</SUP> at 5 mV s<SUP>−1</SUP> is obtained for the CuO sample prepared using an organic surfactant (Triton X-100). Furthermore, all the CuO nanostructures exhibit high power performance, excellent rate as well as long term cycling stability. The Ragone plot ascertains better power and energy densities of CuO nanostructured samples. This is an easy and simple way to tune the morphology using surfactants which can be applied for other energy storage materials.</P> <P>Graphic Abstract</P><P>Copper oxide (CuO) thin films are successfully synthesized using a surfactant assisted chemical bath deposition method for application in supercapacitors. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3dt50275a'> </P>
A Standard for Map Data Representation: IEEE 1873-2015 Facilitates Interoperability Between Robots
Amigoni, Francesco,Yu, Wonpil,Andre, Torsten,Holz, Dirk,Magnusson, Martin,Matteucci, Matteo,Moon, Hyungpil,Yokotsuka, Masashi,Biggs, Geoffrey,Madhavan, Raj IEEE 2018 IEEE robotics & automation magazine Vol.25 No.1
<P>The availability of environment maps for autonomous robots enables them to complete several tasks. A new IEEE standard, IEEE 1873-2015, Robot Map Data Representation for Navigation (MDR) [15], sponsored by the IEEE Robotics and Automation Society (RAS) and approved by the IEEE Standards Association Standards Board in September 2015, defines a common representation for two-dimensional (2-D) robot maps and is intended to facilitate interoperability among navigating robots. The standard defines an extensible markup language (XML) data format for exchanging maps between different systems. This article illustrates how metric maps, topological maps, and their combinations can be represented according to the standard.</P>