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    NachhaltigAngewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Zeitschriftenartikel

    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

    Abstract anzeigen

    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.

    NachhaltigTSZ Weißenburg

    Zeitschriftenartikel

    Y.A.O. Assagra, Altafim, R.A.P., J. do Carmo, R.A.C. Altafim, Dmitry Rychkov, Wirges, W., Gerhard, R.

    A new route to piezo-polymer transducers: 3D printing of polypropylene ferroelectrets

    IEEE Transactions on Dielectrics and Electrical Insulation, vol. 27, no. 5, pp. 1668-1674

    2020

    DOI: 10.1109/TDEI.2020.008461

    Abstract anzeigen

    Here, a promising approach for producing piezo-polymer transducers in a one-step process is presented. Using 3D-printing technology and polypropylene (PP) filaments, we are able to print a two-layered film structure with regular cavities of precisely controlled size and shape. It is found that the 3D-printed samples exhibit piezoelectric coefficients up to 200 pC/N, similar to those of other PP ferroelectrets, and their temporal and thermal behavior is in good agreement with those known of PP ferroelectrets. The piezoelectric response strongly decreases for applied pressures above 20 kPa, as the pressure in the air-filled cavities strongly influences the overall elastic modulus of ferroelectrets.

    DigitalAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach

    Zeitschriftenartikel

    Felix Sepaintner, Andreas Scharl, Franz Xaver Röhrl, Werner Bogner, Stefan Zorn

    Characterization and Production of PCB Structures With Increased Ratio of Electromagnetic Field in Air

    IEEE Transactions on Microwave Theory and Techniques, vol. 68, no. 6, pp. 2134-2143

    2020

    DOI: 10.1109/TMTT.2020.2983934

    Abstract anzeigen

    Producing passive printed circuit board (PCB) structures in the millimeter-wave range includes some fundamental challenges, such as low manufacturing costs and high fabrication accuracy. These aspects, in general, have to be combined with low signal attenuation, precise simulation models, and a reliable producibility. This article shows a new method to manufacture different kinds of passive RF waveguides with reduced attenuation and decreased electrical length on low-cost PCB substrates. First, the complex material parameters of the used substrate and the used copper foil are extracted from 10 to 100 GHz to have accurate simulation models in CST Microwave Studio. This is necessary because the parameters provided by the manufacturer are often no longer generally valid in this frequency range. In addition, PCB materials have a significantly higher surface roughness compared with conventional materials for millimeter-wave applications. Therefore, the correct determination and the correct modeling of surface roughness is particularly important. Next, laminate is removed partially on the outer layer of the PCB to increase the electromagnetic field ratio in air. The undesired substrate is removed by a CO2 laser drilling machine by setting narrow drills sequentially. The RF performance of these waveguides is compared with those manufactured in conventional PCB technology according to attenuation and producibility.

    DigitalAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach

    Zeitschriftenartikel

    E. Hassan, B. Scheiner, F. Michler, M. Berggren, E. Wadbro, Franz Xaver Röhrl, Stefan Zorn, R. Weigel, F. Lurz

    Multi-Layer Topology Optimization of Wideband SIW-to-Waveguide Transitions

    IEEE Transactions on Microwave Theory and Techniques, vol. 68, no. 4, pp. 1326-1339

    2020

    DOI: 10.1109/TMTT.2019.2959759

    Abstract anzeigen

    This article utilizes a topology optimization approach to design planar multilayer transitions between substrate integrated waveguides (SIWs) and rectangular waveguides (RWGs). The optimization problem is formulated based on the modal field analyses and Maxwell's equations in the time domain solved by the finite-difference time-domain (FDTD) method. We present a time-domain boundary condition based on the Klein-Gordon equation to split traveling waves at homogeneous waveguide ports. We employ the boundary condition to compute portal quantities and to devise an adjoint-field system that enabled an efficient computation of the objective function gradient. We solve design problems that include more than 105 000 design variables by using less than 400 solutions of Maxwell's equations. Moreover, a new formulation that effectively combats the development of in-band resonances in the design is presented. The transition configuration allows the direct mount of conventional RWG sections on the circuit board and aims to cover the entire K-band. The guiding structure of the optimized transition requires blind vias, which is realized by a simple and cost-efficient technique. In addition, the transition is optimized for three different setups that can be used to provide different field polarizations. The proposed transitions show less than 1-dB insertion loss and around 15-dB return loss over the frequency interval 18-28 GHz. Several prototypes are fabricated with an excellent match between the simulation and measurement results.

    Angewandte Wirtschaftswissenschaften

    Zeitschriftenartikel

    Hanjo Allinger

    Ehegattensplitting: Besteuerung nach Leistungsfähigkeit und Arbeitsanreizneutralität sind kein Widerspruch - Eine Replik zum Gutachten des wissenschaftlichen Beirats im Bundesfinanzministerium zur Reform der Besteuerung von Ehegatten

    ORDO Jahrbuch für die Ordnung von Wirtschaft und Gesellschaft, vol. 70, pp. 188-214

    2020

    DOI: 10.1515/ordo-2020-0010

    Abstract anzeigen

    Der wissenschaftliche Beirat im Bundesfinanzministerium schlägt in einem Gutachten materiell die Neuinterpretation, bzw. die teilweise Einschränkung des Leistungsfähigkeitsprinzips bei der Besteuerung von Ehegatten vor, um Arbeitsanreize für verheiratete Zweitverdiener zu erhöhen. Dagegen wendet sich dieser Beitrag. Es wird herausgearbeitet, dass eine ungleiche Verteilung von Haus- und Erwerbsarbeit auch in einer Welt ohne Steuern der Regelfall ist. Es wird deutlich, dass nicht der Beibehalt, sondern die vom Beirat vorgeschlagenen Modifikationen des Splittingverfahrens die Arbeitsanreizentscheidung des Zweitverdieners verzerren würden und darüber hinaus verfassungsrechtlich fragwürdig sind.

    NachhaltigTSZ Weißenburg

    Zeitschriftenartikel

    Wang, J., Dmitry 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

    Abstract anzeigen

    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 Freyung

    Zeitschriftenartikel

    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

    Abstract anzeigen

    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 Freyung

    Zeitschriftenartikel

    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

    Abstract anzeigen

    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 Wirtschaftsingenieurwesen

    Zeitschriftenartikel

    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

    Abstract anzeigen

    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.

    DigitalAngewandte GesundheitswissenschaftenInstitut für Existenzgründung

    Zeitschriftenartikel

    Thomas Bartscher

    Was macht der digitale Wandel mit Menschen und Unternehmen?

    Magazin hoch³, no. 4 (Juli), pp. 12-15

    2020

    NachhaltigTC Freyung

    Zeitschriftenartikel

    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

    Abstract anzeigen

    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 ProtectIT

    Zeitschriftenartikel

    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

    Abstract anzeigen

    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.

    DigitalNachhaltigTC Grafenau

    Zeitschriftenartikel

    S. Goisser, S. Wittmann, Michael Fernandes, H. Mempel, C. Ulrichs

    Comparison of colorimeter and different portable food-scanners for non-destructive prediction of lycopene content in tomato fruit

    Postharvest Biology and Technology, vol. 167, no. September

    2020

    DOI: 10.1016/j.postharvbio.2020.111232

    Abstract anzeigen

    Lycopene, the red colored carotenoid in tomatoes, has various health benefits for humans due to its capability of scavenging free radicals. Traditionally, the quantification of lycopene requires an elaborate extraction process combined with HPLC analysis within the laboratory. Recent studies focused simpler methods for determining lycopene and utilized spectroscopic measurement methods. The aim of this study was to compare non-destructive methods for the prediction of lycopene by using color values from colorimeter measurements and Vis/NIR spectra recorded with three commercially available and portable Vis/NIR spectrometers, so called food-scanners. Tomatoes of five different ripening stages (green to red) as well as tomatoes stored up to 22 days after harvest were used for modeling. After measurement of color values and collection of Vis/NIR spectra the corresponding lycopene content was analyzed spectrophotometrically. Applying exponential regression models yielded very good prediction of lycopene for color values L*, a*, a*/b* and the tomato color index of 0.94, 0.90, 0.90 and 0.91, respectively. Color value b* was not a suitable predictor for lycopene content, whereas the (a*/b*)² value had the best linear fit of 0.87. In comparison to color measurements, the cross-validated prediction models developed for all three food-scanners had coefficients of determination (r²CV) ranging from 0.92 to 0.96. Food-scanners also can be used for additional measurements of internal fruit quality, and therefore have great potential for fruit quality assessment by measuring a multitude of important fruit traits in one single scan.

    Angewandte Wirtschaftswissenschaften

    Zeitschriftenartikel

    Marcus Dittrich, S. Städter

    Regulating executive pay: Incentive contracts and non-binding bonus caps

    Journal of Institutional and Theoretical Economics, vol. [To be published]

    2020

    NachhaltigTSZ Weißenburg

    Zeitschriftenartikel

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

    The influence of orthophosphoric-acid surface modification on charge-storage enhancement in polypropylene electrets

    Journal of Applied Physics, vol. 128, no. 3

    2020

    DOI: 10.1063/5.0013805

    Abstract anzeigen

    Bipolar electrets from polypropylene (PP) are essential, e.g., in electret air filters and in cellular-foam ferroelectrets. Therefore, the mechanism of surface-charge stability enhancement on PP electrets via orthophosphoric-acid surface treatment is investigated in detail. It is shown that the significant charge-stability enhancement can be mainly attributed to deeper surface traps originating from deposited chemicals and topographic features on the modified surfaces. Thermally stimulated discharge of chemically treated and non-treated PP films with different surface-charge densities is used to test the limits of the newly formed deep traps in terms of the capacity for hosting surface charges. When the initial surface-charge density is very high, more charges are forced into shallower original traps on the surface or in the bulk of the treated PP samples, reducing the effect of the deeper surface traps brought by the surface modification. The well-known crossover phenomenon (of the surface-charge decay curves) has been observed between modified PP electrets charged to ±2 kV and to ±3  kV. Acoustically probed charge distributions in the thickness direction of PP electrets at different stages of thermal discharging indicate that the deep surface trapping sites may have preference for negative charges, resulting in the observed asymmetric charge stability of the modified PP films.

    GesundAngewandte GesundheitswissenschaftenInstitut Betriebliches Gesundheitsmanagement u. Arbeitssicherheit

    Zeitschriftenartikel

    Stephan Gronwald, Jasmin Weber

    Betriebliches Gesundheitsmanagement in der Pflegeausbildung. Eine Chance für nachhaltige Veränderungen in Pflegeeinrichtungen

    PADUA - Die Fachzeitschrift für Pflegepädagogik, Patientenedukation und -bildung, vol. 15, no. 1, pp. 38-42

    2020

    DOI: 10.1024/1861-6186/a000533

    Abstract anzeigen

    Die Arbeitsbedingungen in der Pflege frühzeitig in die richtigen Wege zu leiten, beginnt bereits bei der Ausbildung des Pflegefachpersonals. Sowohl Lehrende als auch Auszubildende brauchen grundlegende Kenntnisse, wie sie die Arbeit mitgestalten können. Die Erweiterung des Curriculums um die Kompetenzen eines systemischen Prozessberaters für betriebliches Gesundheitsmanagement bringt dabei für beide Seiten Vorteile.

    DigitalNachhaltigFraunhofer AWZ CTMTMaschinenbau und Mechatronik

    Zeitschriftenartikel

    Gabriel Herl, Jochen Hiller, A. Maier

    Scanning trajectory optimisation using a quantitative Tuybased local quality estimation for robot-based X-ray computed tomography

    Nondestructive Testing and Evaluation, vol. (Published 21 June 2020), no. 6

    2020

    DOI: 10.1080/10589759.2020.1774579

    Abstract anzeigen

    Robotic CT systems allow complex scanning trajectories. This work presents a workflow to automatically calculate optimised scanning trajectories for robotic CT systems. In particular, as a local quality estimation, this work introduces a quantitative measure to quantify local reconstruction quality based on the Tuy conditions. The proposed method is tested in two summation experiments using an STL model of a motorcycle. In both experiments, a trajectory is calculated using a quantitative Tuy-based local quality estimation and the reconstruction result is then compared to reconstructions using conventional scanning trajectories. The comparison results indicate that the proposed approach automatically finds trajectories that enable 3D reconstructions with high image quality using much less projection data, which allows a significant reduction of scanning time.

    DigitalNachhaltigFraunhofer AWZ CTMTMaschinenbau und Mechatronik

    Zeitschriftenartikel

    A. Stock, Gabriel Herl, T. Sauer, Jochen Hiller

    Edge-preserving compression of CT scans using wavelets

    Insight - Non-Destructive Testing and Condition Monitoring (The British Institute of Non-Destructive Testing), vol. 62, no. 6, pp. 345-351

    2020

    DOI: 10.1784/insi.2020.62.6.345

    Abstract anzeigen

    This work addresses the subject of efficient storage of computed tomography (CT) data with an emphasis on the quality of surfaces. Industrial dimensional metrology often requires high measurement accuracy and it is shown that this is retained using wavelet-based compression methods. The applied techniques include a tensor product wavelet transform and soft wavelet shrinkage. In these tests, performed on real objects, dimensional CT measurements of compressed and uncompressed volumes were compared. The necessary storage space was reduced significantly with a negligible loss of accuracy. The storage space required for a multi-sphere phantom was decreased to 4.7% (from 638 MB to 30 MB), with an average deviation below 1 μm from the original volume.

    DigitalNachhaltigExtern

    Zeitschriftenartikel

    Anton Schmailzl, Johannes Käsbauer, J. Martan, P. Honnerová, F. Schäfer, Maximilian Fichtl, T. Lehrer, L. Prušáková, J. Tesař, J. Skála, M. Honner

    Measurement of core temperature through semi-transparent polyamide 6 using scanner-integrated pyrometer in laser welding

    International Journal of Heat and Mass Transfer, vol. 146, no. January

    2020

    DOI: 10.1016/j.ijheatmasstransfer.2019.118814

    Abstract anzeigen

    Predicting the core temperature during welding is an ambitious aim in many research works. In this work, a 3D-scanner with integrated pyrometer is characterized and used to measure the temperature during quasi-simultaneous laser transmission welding of polyamide 6. However, due to welding in an overlap configuration, the heat radiation emitted from the joining zone of a laser transmission weld has to pass through the upper polymer, which is itself a semi-transparent emitter. Therefore, the spectral filtering of the heat radiation in the upper polymer is taken into account by calibrating the pyrometer for the measurement task. Thermal process simulations are performed to compare the temperature field with the measured temperature signal. The absorption coefficients of the polymers are measured, in order to get precise results from the computation. The temperature signals during welding are in good agreement with the computed mean temperature inside the detection spot, located in the joining area. This is also true for varying laser power, laser beam diameter and the carbon black content in the lower polymer. Both, the computed mean temperature and the temperature signal are representing the core temperature. In order to evaluate the spatial sensitivity of the measurement system, the emitted heat radiation from both polymers is calculated on basis of the computed temperature field. Hereby it is found, that more than 90 percent of the detected heat radiation comes from the joining area, which is a crucial information for contact-free temperature measurement tasks on semi-transparent polymers.

    DigitalNachhaltigExtern

    Zeitschriftenartikel

    Johannes Käsbauer, Anton Schmailzl, J. Prehm, T. Loose, S. Hierl

    Simulation of Quasi-Simultaneous Laser Transmission Welding of Plastics: Optimization of Material Parameters in Broad Temperature Range

    [Accepted for publication]

    Procedia CIRP

    2020