NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenZeitschriftenartikel
A. Hamid, J. Sun, H. Zhang, Thomas Stirner
Molecular dynamics simulation analysis of helium cluster growth conditions under tungsten surfaces
Computational Materials Science, vol. 186, no. January
2021
DOI: 10.1016/j.commatsci.2020.109994
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Molecular dynamics simulations have been performed to study the effects of helium fluxes on helium cluster size underneath tungsten surfaces under bombardment of helium atoms with incident energy 30 100 eV at temperature 300 2100 K. The simulation results show that the helium cluster size depends on the magnitude of the helium flux: at a higher flux, the helium clusters on average form in smaller size in tungsten but with larger number; while the clusters form further away from the surface at a lower flux. The coalescence of He atoms and helium bubbles depends on the tungsten temperature: at elevated temperatures around 2000 K, the incident He atoms in tungsten slow down more rapidly than at 1000 K but the number of vacancies per He cluster is smaller. The incident energy has a strong effect on the retention of helium atoms: The helium retention rate increases with the incident energy, and the helium retention depends weakly on temperature in the low energy range of interest. It is also found that the surface orientation plays an important role not only in determining the depth distribution but also in determining the helium retention and cluster size: at the surface {1 1 0}, the retention rate of helium atoms is the lowest, and at the surface {1 1 1}, the clusters grow easily in the lateral direction. The present simulation results suggest that the {0 0 1} surface is favorable for fuzz growth. The results obtained in the present work provide insight to the reasons why the fuzz only grows within a certain parameter range at the atomic level.
NachhaltigTC WeißenburgZeitschriftenartikel
Wang, J., D. Rychkov, Q. Nguyen, Gerhard, R.
Unexpected bipolar space-charge polarization across transcrystalline interfaces in polypropylene electret films
Journal of Applied Physics, vol. 128, no. 13
2020
DOI: 10.1063/5.0022071
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A double-layer transcrystalline polypropylene (PP) film with a flat central interface layer between its two transcrystalline layers is obtained by recrystallization from the melt between two polytetrafluoroethylene (PTFE) surfaces on both sides of the PP film. Its electret properties are studied and compared with those of a single-layer transcrystalline PP film re-crystallized in contact with only one PTFE surface. Within experimental uncertainty, the two types of transcrystalline films exhibit the same thermal properties and crystallinities. After thermal poling, however, two hetero-charge layers of opposite polarity are found on the internal interfaces of the double-layer transcrystalline films and may together be considered as micrometer-sized dipoles. The unexpected phenomenon does not occur in single-layer transcrystalline samples without a central interface layer, suggesting that the interfaces between the transcrystalline layers and the micrometer-thick central interface layer may be the origin of deeper traps rather than the crystalline structures in the transcrystallites or the spherulites. The origin of the interfacial charges was also studied by means of an injection-blocking charging method, which revealed that intrinsic charge carriers introduced during recrystallization are most likely responsible for the interfacial charges. It is fascinating that a material as familiar as PP can exhibit such intriguing properties with a special bipolar space-charge polarization across the central interface layer after quasi-epitaxial surface moulding into a double-layer transcrystalline form. In addition to applications in electret (micro-)devices for electro-mechanical transduction, the highly ordered structures may also be employed as a new paradigm for studying charge storage and transport in polymer electrets and in dielectrics for DC electrical insulation.
NachhaltigAngewandte InformatikTC FreyungZeitschriftenartikel
Javier Valdés, A. Poque González, Y. Masip Macia, Wolfgang Dorner, Luis Ramirez Camargo
Unveiling the potential for combined heat and power in Chilean industry-A policy perspective
Energy Policy, vol. 140, no. May
2020
DOI: 10.1016/j.enpol.2020.111331
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Combined Heat and Power (CHP) has again become a key element in international energy and environmental policy, since it is one of the most promising methods of ensuring grid stability, making an energy system more flexible and environmentally friendly. This is particularly true in the case of Chile, which has an energy system that progressively introduced volatile renewable energy sources such as wind and solar energy. This scenario has led to the development of a new regulatory strategy and CHP flagship projects throughout the country. Despite this interest, there has been no analysis of CHP development or the impact of the latest regulatory changes on its evolution. This study presents an updated cadastre of the CHP facilities as of 2018, together with an analysis of its evolution in terms of an energy policy. From this cadastre, interviews with experts, and a review of the regulations and incentives, the study identifies the main policy barriers for CHP development in Chile. Furthermore, this study presents a series of challenges and recommendations for the country.
NachhaltigAngewandte InformatikTC FreyungZeitschriftenartikel
Javier Valdés, Y. Masip Macia, Wolfgang Dorner, Luis Ramirez Camargo
Unsupervised grouping of industrial electricity demand profiles: synthetic profiles for demand-side management applications
Energy, no. Available online 1 October 2020
2020
DOI: 10.1016/j.energy.2020.118962
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Demand side management is a promising alternative to offer flexibility to power systems with high shares of variable renewable energy sources. Numerous industries possess large demand side management potentials but accounting for them in energy system analysis and modelling is restricted by the availability of their demand data, which are usually confidential. In this study, a methodology to synthetize anonymized hourly electricity consumption profiles for industries and to calculate their flexibility potential is proposed. This combines different partitioning and hierarchical clustering analysis techniques with regression analysis. The methodology is applied to three case studies in Chile: two pulp and paper industry plants and one food industry plant. A significant hourly, daily and annual flexibility potential is found for the three cases (15% to 75%). Moreover, the resulting demand profiles share the same statistical characteristics as the measured profiles but can be used in modelling exercises without confidentiality issues.
NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenZeitschriftenartikel
H. Zhang, J. Sun, Y. Wang, Thomas Stirner, A. Hamid, C. Sang
Study of lattice thermal conductivity of tungsten containing bubbles by molecular dynamics simulation
Fusion Engineering and Design, vol. 161, no. December
2020
DOI: 10.1016/j.fusengdes.2020.112004
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Exposed to high fluxes of helium/hydrogen isotope particles and heat, tungsten divertor plates will suffer damage thus degrading its performance such as its thermal conductivity. This paper presents a study on the effect of bubbles on the lattice thermal conductivity of tungsten at the atomic level using molecular dynamics simulations. The present study finds that empty bubbles in tungsten lead to a decrease in the lattice thermal conductivity of tungsten. Furthermore, He/D filled bubbles aggravate this decrease. The physical origin of this behavior is discussed. It is also found that the decrease in lattice thermal conductivity depends strongly on both the impurity density in the bubbles and the bubble size.
DigitalTC FreyungBeitrag (Sammelband oder Tagungsband)
Anja Braehmer, Wolfgang Dorner
Museum Uploaded. Digitale Technologie für crossmediale grenzüberschreitende Museumskooperationen.
Online-Erweiterung zum Band 84 (2019) der Museumskunde
2020
Abstract anzeigen
Zusammen mit Projektpartnern entwickelt die TH Deggendorf digitale Technologien für eine neue stadtgeschichtliche Dauerausstellung im Stadtmuseum Deggendorf. Konkret handelt es sich hierbei um drei digitale Teilprojekte: ein Content Management System (CMS), das erlaubt die festinstallierten Medienstationen der Ausstellung zentral zu verwalten, einen digitalen Museumsbegleiter, der die Geschichten der Exponate erzählt und Zugang zu Vertiefungsebenen bietet und eine barrierefreie digitale Anwendung zur Verknüpfung von Museums-und Stadtraum.
NachhaltigTC FreyungZeitschriftenartikel
Roland Zink, Javier Valdés, Jane Wuth
Prioritizing the Chicken or Egg? Electric Vehicle Purchase and Charging Infrastructure Subsidies in Germany
Politics and Governance, vol. 8, no. 3, pp. 185-198
2020
DOI: 10.17645/pag.v8i3.3025
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To meet current targets for greenhouse gas emissions in Europe, emissions, especially those originating from the road transport sector, need to be reduced. Plans are to achieve this goal by substituting fossil fuel vehicles with electric vehicles (EVs). This article first discusses conceptually the impact of an increasing share of EVs on the electricity grid and suitable locations for charging stations with examples from a Case Study in Lower Bavaria. Secondly, the impact of purchase subsidies on EV purchases in Germany, a high-income country characterized by an important automotive industry and an increasing share of private vehicles is examined. To achieve this, yearly information on EV purchases were analyzed by applying the Synthetic Control Method. Combining data from different sources including the European Alternative Fuels Observatory, Eurostat, and the European Automobile Manufacturers' Association, an overall picture was developed. Results indicate a difference between private, semi-public, and public charging infrastructures. Its spatial distribution does not correspond to a specific development strategy. Moreover, EV subsidies have a limited effect in Germany when controlling for market size. Limiting the discussion to a trade-off between subsidizing infrastructures or EV purchases obviates the multidimensionality of the problem as neither of them may be sufficient to accelerate the transition per se. Furthermore, if electricity provided for EVs comes mainly from fossil carriers, the changes in the road transport sector will not yield the expected emission reductions. The transition towards renewables is directly intertwined with the effects of EVs on emission reductions in the road transport sector.
DigitalAngewandte InformatikInstitut ProtectITZeitschriftenartikel
Amar Almaini, A. Al Dubai, I. Romdhani, Martin Schramm, A. Alsarhan
Lightweight edge authentication for software defined networks
Computing (Special Issue), no. 8 August 2020
2020
DOI: 10.1007/s00607-020-00835-4
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OpenFlow is considered as the most known protocol for Software Defined Networking (SDN). The main drawback of OpenFlow is the lack of support of new header definitions, which is required by network operators to apply new packet encapsulations. While SDN’s logically centralized control plane could enhance network security by providing global visibility of the network state, it still has many side effects. The intelligent controllers that orchestrate the dumb switches are overloaded and become prone to failure. Delegating some level of control logic to the edge or, to be precise, the switches can offload the controllers from local state based decisions that do not require global network wide knowledge. Thus, this paper, to the best of our knowledge, is the first to propose the delegation of typical security functions from specialized middleboxes to the data plane. We leverage the opportunities offered by programming protocol-independent packet processors (P4) language to present two authentication techniques to assure that only legitimate nodes are able to access the network. The first technique is the port knocking and the second technique is the One-Time Password. Our experimental results indicate that our proposed techniques improve the network overall availability by offloading the controller as well as reducing the traffic in the network without noticeable negative impact on switches’ performance.
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