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    NachhaltigElektrotechnik und MedientechnikMaschinenbau und Mechatronik

    Zeitschriftenartikel

    L. Larcher, F. Puglisi, L. Jiang, Jonas Weber, Günther Benstetter, P. Pavan, M. Lanza, Werner Frammelsberger

    Understanding Current Instabilities in Conductive Atomic Force Microscopy

    Materials, vol. 12, no. 3

    2019

    DOI: 10.3390/ma12030459

    Abstract anzeigen

    Conductive atomic force microscopy (CAFM) is one of the most powerful techniques in studying the electrical properties of various materials at the nanoscale. However, understanding current fluctuations within one study (due to degradation of the probe tips) and from one study to another (due to the use of probe tips with different characteristics), are still two major problems that may drive CAFM researchers to extract wrong conclusions. In this manuscript, these two issues are statistically analyzed by collecting experimental CAFM data and processing them using two different computational models. Our study indicates that: (i) before their complete degradation, CAFM tips show a stable state with degraded conductance, which is difficult to detect and it requires CAFM tip conductivity characterization before and after the CAFM experiments; and (ii) CAFM tips with low spring constants may unavoidably lead to the presence of a ~1.2 nm thick water film at the tip/sample junction, even if the maximum contact force allowed by the setup is applied. These two phenomena can easily drive CAFM users to overestimate the properties of the samples under test (e.g., oxide thickness). Our study can help researchers to better understand the current shifts that were observed during their CAFM experiments, as well as which probe tip to use and how it degrades. Ultimately, this work may contribute to enhancing the reliability of CAFM investigations.

    NachhaltigTC Freyung

    Zeitschriftenartikel

    Javier Valdés, Luis Ramirez Camargo, Y. Masip Macia, A. Poque González

    Cogeneración en Chile: Capacidades, desarrollo y perspectivas

    [Status: In Press]

    Avances en Energías Renovables y Medio Ambiente (AVERMA)

    2019

    Abstract anzeigen

    RESUMEN: En Chile, el proyecto de cogeneración más antiguo data de 1930 y operó hasta el año 1997. Sin embargo, pese a que la tecnología lleva introducida largo tiempo, pocos son los estudios que han analizado el potencial de CHP y su evolución. Un primer paso para el estudio del potencial del país es la creación de un catastro que incluya la capacidad instalada. El interés de este ejercicio radica en el potencial de integración de mayores cantidades de CHP en el sistema eléctrico con el objetivo de hacer frente a la intermitencia de fuentes de energía no convencionales. Además, las plantas CHP pueden ayudar a alcanzar los objetivos de eficiencia energética gracias a la posibilidad de los generadores de volcar a la red tanto la electricidad como calor no consumido en los procesos productivos. Sin embargo, para que esto ocurra es necesario el desarrollo de un marco regulatorio acorde a las capacidades y características de las plantas de CHP. El objetivo de este artículo es precisamente identificar las características de las instalaciones en industrias específicas, así como su evolución, con el objetivo de extrapolar los datos al resto de la economía y obtener un potencial de CHP para el país. Para ello, se han hecho consultas de catastros anteriores, así como entrevistas con empresas para conocer el estado actual del parque de plantas de CHP en el país. Palabras clave: cogeneración, eficiencia energética, flexibilidad del sistema eléctrico 1.

    NachhaltigElektrotechnik und Medientechnik

    Zeitschriftenartikel

    J. Michalicka, S. Li, Z. Bi, Y. Zhang, Ondrej Man, Y. Hong, Y. Wu, W. Ni, H. Fan, Günther Benstetter, L. Liu, Q. Yang, D. Liu

    The effect of O2 impurity on surface morphology of polycrystalline W during low-energy and high-flux He+ irradiation

    Fusion Engineering and Design, vol. 139, pp. 96-103

    2019

    DOI: 10.1016/j.fusengdes.2019.01.003

    Abstract anzeigen

    The interaction between the impurities (such as carbon, nitrogen, oxygen) and the plasma-facing materials (PFMs) can profoundly influence the performance and service of the PFMs. In this paper, we investigated the influence of oxygen (O2) impurity in the helium radio frequency (RF) plasma on the surface morphology of polycrystalline tungsten (W) irradiated at the surface temperature of 1450 ± 50 K and the ion energy of 100 eV. The pressure ratio of O2 to He (R) in RF source varied from 4.0 × 10−6 to 9.0 × 10-2. The total irradiation flux and fluence were ˜1.2 × 1022 ions·m-2·s-1 and ˜1.0 × 1026 ions·m-2, respectively. After He+ irradiation, the specimen surface morphology was observed by scanning electron microscopy. It was found that with increasing R from 4.0 × 10−6 to 9.0 × 10-2 the thickness of nano-fuzz layer at the W surface was thinner and thinner, accompanied by the formation of rod-like structures. The erosion yield increased from 5.2 × 10-4 to 2.3 × 10-2 W/ion when R varied from 4.0 × 10-6 to 9.0 × 10-2. The X-ray diffraction analysis shows that tungsten oxides were formed at the near surface of specimens when R exceeded 1.8 × 10-2. The erosion yield measurements revealed that in addition to surface physical sputtering process, the chemical erosion process could occur due to the interaction between oxygen-containing species and W at the surface. The results indicated that the presence of O2 impurity in He plasma can obviously affect the surface microstructure of W. The study suggested that O2 impurity can effectively reduce the growth of nano-fuzz structures.

    NachhaltigElektrotechnik und MedientechnikTC Freyung

    Beitrag (Sammelband oder Tagungsband)

    Javier Valdés, Luis Ramirez Camargo, Y. Masip Macia, A. Poque González

    Cogeneración en Chile: Capacidades, desarrollo y perspectivas

    Memorias de la XLI Reunión de Trabajo de la ASADES (Nov 5-10, 2018; Cordoba, Argentina)

    2019

    ISBN: 978-987-29873-1-2

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    A. Rineiski, S. Gianfelici, W. Maschek, B. Vezzoni, Rui Li, C. Matzerath Boccaccini, F. Gabrielli, M. Flad

    Probabilistic evaluation of the energetics upper bound during the transition phase of an unprotected loss of flow accident for a sodium cooled fast reactor by using a Phenomenological Relationship Diagram

    Nuclear Engineering and Design, vol. 341, no. 146-154

    2019

    DOI: 10.1016/j.nucengdes.2018.11.004

    Abstract anzeigen

    One of the main research goals of the GEN-IV systems is enhancing their safety compared with the former Sodium-Cooled Fast Reactor (SFR) designs. A key issue is the capability of accidents prevention as well as of demonstrating that their consequences do not violate the safety criteria. In order to fulfill such requirements, risk analyses of severe core disruptive accidents are performed. Since the beginning of the SFR development, Hypothetical Core Disruptive Accidents (HCDAs) have played an outstanding role. Numerous safety analyses have been performed for developing and licensing past SFR designs and nowadays a large database of results is available. In particular, a large amount of results of the mechanistic SIMMER-II and SIMMER-III/IV analyses for various core designs and different power classes is available at the Karlsruhe Institute of Technology (KIT). The current paper describes the probabilistic approach based on the Phenomenological Relationship Diagram (PRD), which is used to evaluate the Probability Distribution Function (PDF) of the thermal energy release during the transition phase of an unprotected loss of flow accident scenario for a SFR. The technique allows taking into account the mechanistic nature of the accident scenario. In fact, the available results of the mechanistic analyses of HCDAs in SFRs are used to assess the PDFs of the dominant phenomena affecting the thermal energy release, which are propagated in the PRD by employing a Monte Carlo method.

    NachhaltigTC Freyung

    Beitrag (Sammelband oder Tagungsband)

    Javier Valdés, Luis Ramirez Camargo, Y. Masip Macia, Wolfgang Dorner

    Assessment of on-site steady electricity generation from renewable energy sources in Chile

    Energy Procedia (Contributions to the 10th International Conference on Applied Energy ICAE 2018), vol. 158

    2019

    DOI: 10.1016/j.egypro.2019.01.266

    Abstract anzeigen

    Chile has an immense renewable energy potential but their integration in the energy system constitutes a major challenge. The complex topography of the country, the isolation of the different electric grids and the variability of renewable energy sources, makes energy transmission from locations with high variable renewable power generation potential to the demand centres not an easy task. The present study aims at assessing the potential of combining solar power, wind power and storage systems to provide steady loads already from the source. Such a combination should take advantage of complementarity between variable renewable sources and serves to simplify their integration in the energy system. The analysis relies on an optimization model to size hybrid renewable energy systems and 10 years of weather data from the brand new ERA-5 reanalysis. Necessary system sizes to constantly generate 1 MWh of electricity for every hour during the period 2008-2017 are calculated for all possible locations across the country. The results show that the necessary generation and storage capacities to provide a steady energy output are very high even for areas with exceptionally high renewable energy potential.

    NachhaltigTC Freyung

    Beitrag (Sammelband oder Tagungsband)

    Luis Ramirez Camargo, Wolfgang Dorner, K. Gruber, F. Nitsch

    Hybrid renewable energy systems to supply electricity to self-sufficient residential buildings in Central Europe

    Energy Procedia (Contributions to the 10th International Conference on Applied Energy ICAE 2018), vol. 158

    2019

    DOI: 10.1016/j.egypro.2019.01.096

    Abstract anzeigen

    This work evaluates potentials of photovoltaic and battery systems with additional micro-generation wind turbines (10.5 kW) to cover electricity demand of residential users in two countries in Central Europe. It relies on high-resolution regional reanalysis data and a techno-economical optimization model. Maps showing the number of wind turbines, photovoltaic and battery systems sizes necessary to supply electricity for clusters of electricity self-sufficient single-family houses across Germany and the Czech Republic are generated. No general trends that apply for the two countries concerning the relation between the sizes of the different technologies were identified. However, it was possible to determine several large areas where the inclusion of small wind turbines decreases the total system costs and considerably reduces the required storage capacities. Results are discussed and compared to previous work on self-sufficient single-family houses.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTC Weißenburg

    Beitrag (Sammelband oder Tagungsband)

    Gerhard, R., Dmitry Rychkov, Wang, J.

    Influence of Charge Density on Charge Decay in Chemically Modified Polypropylene Films

    Proceedings of the IEEE 2nd International Conference on Dielectrics, Budapest, Hungary

    2018

    ISBN: 978-1-5386-6389-9

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTC Weißenburg

    Beitrag (Sammelband oder Tagungsband)

    F. He, Gerhard, R., Schulze, M., Wirges, W., Dmitry Rychkov, Wang, J.

    Senskin deformable silicone-elastomer sensors for structural health monitoring: assessment of strain sensitivity and correction for thermal expansion

    Proceedings of the 8th International Conference on Electromechanically Active Polymer (EAP) Transducers & Artificial Muscles , Valpré Ecully - Lyon, France

    2018

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTC Weißenburg

    Beitrag (Sammelband oder Tagungsband)

    F. He, G. Gidion, Gerhard, R., Schulze, M., Wirges, W., Dmitry Rychkov, Wang, J.

    Soft Stretchable All-Silicone Sensor for Transport-Infrastructure Monitoring

    Sensoren und Messsysteme 2018 19. ITG-/GMA-Fachtagung

    2018

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTC Weißenburg

    Beitrag (Sammelband oder Tagungsband)

    Kuznetsov, A., Dmitry Rychkov, V. Stojharov, Rychkov, A. A.

    The Influence of Recrystallization Regimes on Electret Charge Stability in Low-Density Polyethylene Films

    Proceedings of the IEEE 2nd International Conference on Dielectrics, Budapest, Hungary

    2018

    ISBN: 978-1-5386-6389-9

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTC Weißenburg

    Zeitschriftenartikel

    Damigos, Y., Kourousis, D., Frankenstein, B., Gerhard, R., Amditis, A., Cheilakou, E., Dmitry Rychkov, Bouklas, C., Tsopelas, N., Anastasopoulos, A.

    Strain monitoring system for steel and concrete structures

    Procedia Structural Integrity, vol. 10, pp. 25-32

    2018

    DOI: 10.1016/j.prostr.2018.09.005

    Abstract anzeigen

    The present work is part of a collaborative H2020 European funded research project called SENSKIN, that aims to improve Structural Health Monitoring (SHM) for transport infrastructure through the development of an innovative monitoring and management system for bridges based on a novel, inexpensive, skin-like sensor. The integrated SENSKIN technology will be implemented in the case of steel and concrete bridges, and tested, field-evaluated and benchmarked on actual bridge environment against a conventional health monitoring solution developed by Mistras Group Hellas. The main objective of the present work is to implement the autonomous, fully functional strain monitoring system based on commercially available off-the-shelf components, that will be used to accomplish direct comparison between the performance of the innovative SENSKIN sensors and the conventional strain sensors commonly used for structural monitoring of bridges. For this purpose, the mini Structural Monitoring System (mini SMS) of Physical Acoustics Corporation, a comprehensive data acquisition unit designed specifically for long-term unattended operation in outdoor environments, was selected. For the completion of the conventional system, appropriate foil-type strain sensors were selected, driven by special conditioners manufactured by Mistras Group. A comprehensive description of the strain monitoring system and its peripheral components is provided in this paper. For the evaluation of the integrated system’s performance and the effect of various parameters on the long-term behavior of sensors, several test steel pieces instrumented with different strain sensors configurations were prepared and tested in both laboratory and field ambient conditions. Furthermore, loading tests were performed aiming to validate the response of the system in monitoring the strains developed in steel beam elements subject to bending regimes. Representative results obtained from the above experimental tests have been included in this paper as well.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTC Weißenburg

    Zeitschriftenartikel

    Dmitry Rychkov, Altafim, R.A.P.

    Template-based fluoroethylenepropylene ferroelectrets with enhanced thermal stability of piezoelectricity

    Journal of Applied Physics, vol. 124, no. 17

    2018

    DOI: 10.1063/1.5041374

    Abstract anzeigen

    In ferroelectrets, the piezoelectricity stems from the charges of both polarities trapped on the inner surfaces of the cavities in the material, so that its thermal stability is defined by the stability of the respective charges. In the present work, a template-based lamination technique has been employed to fabricate tubular-channel ferroelectrets from fluoroethylenepropylene (FEP) films. It has been shown that the piezoelectricity in FEP ferroelectrets decays at relatively low temperatures due to the inherently lower thermal stability of the positive charge. In order to improve charge trapping, we have treated both FEP films and inner surfaces of the ferroelectret cavities with titanium-tetrachloride vapor, using the atomic-layer-deposition technique. Using surface-potential-decay measurements on FEP films, we have found that the charge-decay curves shift by more than 100 ∘C to the higher temperatures as a result of the surface treatment. Direct measurements of piezoelectric d33 coefficients as a function of temperature have shown that the piezoelectric stability is likewise improved with the d33-decay curves shifted by 60 ∘C to the right. The improvement of electret/ferroelectret properties can be attributed to the formation of the deeper traps on the chemically modified FEP surface. SEM micrographs and EDS analysis reveal island-like structures with titanium- and oxygen-containing species that can be responsible for the deeper trapping of the electret charges.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTC Weißenburg

    Zeitschriftenartikel

    Gerhard, R., Kuznetsov, A., Dmitry Rychkov, Rychkov, A. A.

    Influence of Charge Density on the Trap-Energy Spectrum in Fluoroethylenepropylene Copolymer Films with Chemically Modified Surfaces

    IEEE Transactions on Dielectrics and Electrical Insulation, vol. 25, no. 3, pp. 840-844

    2018

    DOI: 10.1109/TDEI.2018.007437

    Abstract anzeigen

    Tetrafluoroethylene-hexafluoropropylene copolymer (FEP) films were treated with titanium-tetrachloride vapor by means of molecular-layer deposition. The treatment leads to considerable improvements of the electret-charge stability on positively charged films. A slight improvement is also observed for negatively charged films. In line with our previous findings, we attribute the improvement in electret properties to the formation of deeper traps on the chemically modified polymer surfaces. Here, we investigate the influence of the charge density on electret stability of FEP films with modified surfaces. Trap-energy spectra obtained from thermally-stimulated-discharge measurements indicate that the charge stability on modified FEP films depends on how the surface traps are populated and on the availability of additional deeper traps.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    A. Theodoridis, S. Detscher, Sascha Kreiskott, M. Handschuh, C. Glöckner

    Mit AAA-Vertrieb innovative Energielösungen verkaufen

    Sales Excellence, vol. 27, no. 11, pp. 16-19

    2018

    DOI: 10.1007/s35141-018-0178-5

    Abstract anzeigen

    Neue Ansätze sind nötig, um den Verkauf innovativer Energielösungen zu beschleunigen und zu vereinfachen. Bereits heute stehen vielfältige leistungsstarke Anwendungen basierend auf Analytik, Automatisierung und Artifizieller Intelligenz (AAA) bereit. Die Weichen für zukünftige Markterfolge werden jetzt gestellt. ...

    DigitalNachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach

    Beitrag (Sammelband oder Tagungsband)

    O. Fähnle, M. Doetz, Christian Vogt, O. Dambon, Rolf Rascher, E. Langenbach

    Enlarging process window of ductile mode machining of WC molds

    Proceedings of EOSAM 2018 (European Optical Society Biennial Meeting; October 2018; Delft, The Netherlands): Optical System Design, Tolerancing, and Fabrication

    2018

    DigitalNachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach

    Beitrag (Sammelband oder Tagungsband)

    O. Fähnle, Christian Vogt, Rolf Rascher, Christian J. Trum, Sebastian Sitzberger

    First experiences with Filled-Up-Microscopy (FUM) to evaluate the depth of sub-surface damages on ground surfaces

    Proceedings of EOSAM 2018 (European Optical Society Biennial Meeting; October 2018; Delft, The Netherlands): Optical System Design, Tolerancing, and Fabrication

    2018

    DigitalNachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach

    Beitrag (Sammelband oder Tagungsband)

    O. Fähnle, M. Doetz, Christian Vogt, Rolf Rascher

    Standardized evaluation of grinding tools for brittle and ductile mode grinding

    Invited Paper

    Proceedings of EOSAM 2018 (European Optical Society Biennial Meeting; October 2018; Delft, The Netherlands): Optical System Design, Tolerancing, and Fabrication

    2018

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach

    Beitrag (Sammelband oder Tagungsband)

    O. Fähnle, Christian Vogt, Rolf Rascher, E. Langenbach

    In situ monitoring of laser polishing

    DGaO Proceedings (119. Jahrestagung in Aalen, 22.-26.05.2018)

    2018