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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.

    DigitalNachhaltigAngewandte InformatikTC Plattling MoMo

    Vortrag

    Markus Eider, Andreas Berl

    Requirements for prescriptive recommender systems extending the lifetime of EV batteries

    2020 10th International Conference on Advanced Computer Information Technologies (ACIT), Deggendorf

    2020

    DigitalNachhaltigAngewandte InformatikTC Plattling MoMo

    Vortrag

    Nicki Bodenschatz, Markus Eider, Andreas Berl

    Mixed-Integer-Linear-Programming model for the charging scheduling of electric vehicle fleets

    2020 10th International Conference on Advanced Computer Information Technologies (ACIT), Deggendorf

    2020

    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

    Beitrag (Sammelband oder Tagungsband)

    Javier Valdés, Luis Ramirez Camargo, Wolfgang Dorner

    Generating consumer load profiles to assess demand-side management potential of industries

    Paper ID: 1063

    Energy Proceedings 2020 - Proceedings of 11th International Conference on Applied Energy (12-15 August 2019; Västerås, Sweden)

    2020

    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.

    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.

    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.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach

    Beitrag (Sammelband oder Tagungsband)

    Simon Killinger, Johannes Liebl, Rolf Rascher

    First steps towards an automated polishing process chain using one robot

    Proceedings of SPIE 11478 (Seventh European Seminar on Precision Optics Manufacturing [8 July 2020; Teisnach]), Bellingham, WA, USA

    2020

    DOI: 10.1117/12.2564840

    Abstract anzeigen

    Manufacturing precision optics is a complex process chain, which requires many operations on different machines. This is combined with operator-dependent steps such as manual cleaning, loading and measuring. In order to realize this process chain on a smaller shop area and to achieve a higher level of automation we build an operator-independent polishing cell. In this cell, an ABB robot serves as the actuator handling the workpiece. We positioned the robot in the center of the polishing cell to operate several workstations, so the whole process chain works with one single actuator. This arrangement allows a smaller and cheaper system, since no additional handling is required.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach

    Beitrag (Sammelband oder Tagungsband)

    Michael Benisch, O. Fähnle, Rolf Rascher, Werner Bogner

    Force and pressure analysis during overarm polishing

    Proceedings of SPIE 11478 (Seventh European Seminar on Precision Optics Manufacturing [8 July 2020; Teisnach]), Bellingham, WA, USA

    2020

    DOI: 10.1117/12.2564903

    Abstract anzeigen

    The Preston-equation implies, that, besides the relative speed υrel and a specific constant KP, the pressure p plays a significant role for the removal rate when polishing an optical component. This paper demonstrates a possibility for a qualitative evaluation of the pressure distribution before the polishing process. A pressure-sensitive foil is used as a gauge for pressure measurement. The effectiveness of this measuring method is explained. Specific weaknesses and limitations in the use of these foils are discussed. A method for an integrated evaluation of the pressure on different spots of the polishing pad is proposed at the end of the paper.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach

    Beitrag (Sammelband oder Tagungsband)

    M. Pohl, R. Börret, Olga Kukso, Rolf Rascher

    Mid spatial frequency error prevention strategies for the grinding process

    Proceedings of SPIE 11478 (Seventh European Seminar on Precision Optics Manufacturing [8 July 2020; Teisnach]), Bellingham, WA, USA

    2020

    DOI: 10.1117/12.2565261

    Abstract anzeigen

    This research is focused on the link between manufacturing parameters and the resulting mid-spatial frequency error in the manufacturing process of precision optics. The goal is to understand the generation mechanisms of mid-spatial frequency errors and avoid their appearance in the manufacturing process. Also, a simulation which is able to predict the resulting mid spatial frequency error from a manufacturing process is desired.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach

    Beitrag (Sammelband oder Tagungsband)

    Jessica Stelzl, Christine Wünsche, S. Höfer

    Influencing factors for a continuous wave UV-laser component

    Proceedings of SPIE 11478 (Seventh European Seminar on Precision Optics Manufacturing [8 July 2020; Teisnach]), Bellingham, WA, USA

    2020

    DOI: 10.1117/12.2564916

    Abstract anzeigen

    During the development of an optical system, one comes to the point where you have to build the optically active element into a mechanical device that becomes part of the system. At this point you come across the well-known question that it is not only necessary to consider and ensure the quality of the individual element. It is also important to look at the entire component in order to identify potential influencing factors on the performance of the optical system. At the beginning of a two-year project at Technologiecampus Teisnach the polishing process of a nonlinear crystal as the crucial component of the optical system was being explored. This system is designed to create continuous wave laser beams in the deep UV range. The crystal has to be embedded between two prisms. Roughness and shape of the crystal is ensured via the polishing process which alone has many influencing factors and was examined at the beginning of the project. The quality of the crystal can be as good as it can be, but if the contacting prisms do not fit, the whole prism-coupled device will become unusable in the overall optical laser system. The performance of the laser can only be achieved by harmonizing all elements of the PCD and the PCD itself into the laser set-up. In the current phase of the project this question will be dealt with. The prism-coupled device is split up into its individual parts, which are the nonlinear crystal, the prisms as optical auxiliary components, micro screws and mechanical support. Going through the requirements to the properties of the crystal and their limitations, the influence of the PCD on the optical performance of the crystal is presented. Here, the main focus is placed on the mode of fixing the crystal between the prisms and on putting the stack of crystal and prisms in the laser beam. The influencing factors between the crystal, the prisms and the method of fixing the PCD are described.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach

    Beitrag (Sammelband oder Tagungsband)

    Michael Wagner, Gerald Fütterer

    Computer-aided beam path generation and assessment for Stevick-Paul telescopes

    Proceedings of SPIE 11478 (Seventh European Seminar on Precision Optics Manufacturing [8 July 2020; Teisnach]), Bellingham, WA, USA

    2020

    DOI: 10.1117/12.2564852

    Abstract anzeigen

    At Deggendorf Institute of Technology a student project is currently under way to build a Stevick-Paul telescope for astrophotography. An important step in the overall development procedure of each telescope is the design of a beam-path and ensuring its suitability under optical and engineering aspects. The students performed this process in a sequential manner by using several different computer programs (e.g. MATLAB, Zemax, Creo Parametric). To accelerate the beam path design process, a Python program to automate the major part of the design process with minimum human supervision was created. The input data of the python program consists of ranges of the desired characteristics of the Stevick-Paul telescope, such as focal lengths, primary mirror diameters and tilts etc., mirror thickness and mount geometries, as well as the specific type of camera. After setting the input, the program creates 2D cross-sections of beam paths according to the formulas of D. Stevick and may introduce a flat fold mirror to reduce the overall system size as well as improve the accessibility of the focus plane. The subsequent assessment routine checks against the susceptibility for stray light and performs a complex analysis of the available installation space to ensure sufficient mechanical tolerances. In this way, collisions between mirrors, mounts and cameras are avoided and obstructions of the beam path are prevented. At any stage, the program can produce graphical representations of the beam paths. In this paper the computer-aided design of a telescope beam path with a focal length of 2400 mm is demonstrated. During development of the software, a subset of folded Stevick-Paul telescopes, in which certain components are parallel, was found. This subset may be useful to simplify the alignment procedure. In conclusion, further refinement of the software is necessary, although the program is already a useful aid for certain aspects when creating a beam path design.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach

    Beitrag (Sammelband oder Tagungsband)

    Olga Kukso, Rolf Rascher, M. Pohl, R. Börret

    On the metrology and analysis of MSF error

    Proceedings of SPIE 11478 (Seventh European Seminar on Precision Optics Manufacturing [8 July 2020; Teisnach]), Bellingham, WA, USA

    2020

    DOI: 10.1117/12.2566251

    Abstract anzeigen

    The aim of our research was to study middle spatial frequency errors (MSFE) on optical surfaces. We investigate the surfaces after manufacturing processes to find out the main affecting factors and to choose the proper processing parameters to minimize the size of the errors. To find an appropriate parameter window we have to be able not only to define the factors, which lead to MSFE, but also to analyze the change of the error after next following production steps.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach

    Beitrag (Sammelband oder Tagungsband)

    M. Jung, Christian J. Trum, Beate Schmidbauer, E. Willenborg, Rolf Rascher

    Non-ablative removal of sub surface damages in ground optical glass substrates by controlled melting of thin surface layers using CO2-laser radiation

    Proceedings of SPIE 11478 (Seventh European Seminar on Precision Optics Manufacturing [8 July 2020; Teisnach]), Bellingham, WA, USA

    2020

    DOI: 10.1117/12.2564801

    Abstract anzeigen

    The form generation of optical surfaces by grinding and mechanical polishing results in small sub surface damages in the form of micro cracks that conventionally have to be removed by further removal of the damaged surface layers. In order to reduce process time and material cost non-ablative methods for removal of micro cracks are desired. Utilising the low optical penetration depths of less than 10 μm for CO2-laser radiation in glass, the laser energy can be used to heat up and melt thin surface layers. Using a 1.5 kW CO2-laser, a quasi-line focus formed by a scanner unit and a constant feed speed, it is possible to close all micro cracks present in the rough grinded test surfaces (max. SSD-depth ~ 63 μm), while achieving a process time of less than 2 seconds for a Ø 30 mm N-BK7 lens, respectively 7.5 seconds for fused silica. With a Sa as low as 50 nm and low distortion from the original shape the surfaces can directly be conventionally polished, further reducing the process chain complexity.

    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.

    NachhaltigElektrotechnik und MedientechnikIQMA

    Vortrag

    Fabian Kühnel, Christoph Metzke, Günther Benstetter

    Thermal conductivity measurements of thin films using 3ω method

    7. Tag der Forschung, Deggendorf

    2020