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  • 550.724  (18)
  • 548  (13)
  • ddc:330  (12)
  • Englisch  (43)
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  • 2020-2022  (43)
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  • 1
    Publikationsdatum: 2021-04-14
    Beschreibung: Pyrroloquinoline quinone (PQQ) is an important cofactor of calcium‐ and lanthanide‐dependent alcohol dehydrogenases, and has been known for over 30 years. Crystal structures of Ca–MDH enzymes (MDH is methanol dehydrogenase) have been known for some time; however, crystal structures of PQQ with biorelevant metal ions have been lacking in the literature for decades. We report here the first crystal structure analysis of a Ca–PQQ complex outside the protein environment, namely, poly[[undecaaquabis(μ‐4,5‐dioxo‐4,5‐dihydro‐1H‐pyrrolo[2,3‐f]quinoline‐2,7,9‐tricarboxylato)tricalcium(II)] dihydrate], {[Ca3(C14H3N2O8)2(H2O)11]·2H2O}n. The complex crystallized as Ca3PQQ2·13H2O with Ca2+ in three different positions and PQQ3−, including an extensive hydrogen‐bond network. Similarities and differences to the recently reported structure with biorelevant europium (Eu2PQQ2) are discussed.
    Beschreibung: Pyrroloquinoline quinone (PQQ) is an important cofactor of calcium‐ and lanthanide‐dependent alcohol dehydrogenases. The crystal structure of a Ca–PQQ complex (Ca3PQQ2·13H2O) is reported for the first time outside a protein environment. image
    Beschreibung: research
    Schlagwort(e): 548 ; pyrroloquinoline quinone ; calcium ; PQQ ; methanol dehydrogenase ; crystal structure ; FID-GEO-DE-7
    Sprache: Englisch
    Materialart: article , publishedVersion
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  • 2
    Publikationsdatum: 2021-08-10
    Beschreibung: During evaporation of natural and synthetic K–Mg–Cl brines, the formation of almost square plate-like crystals of potassium carnallite (potassium chloride magnesium dichloride hexahydrate) was observed. A single-crystal structure analysis revealed a monoclinic cell [a = 9.251 (2), b = 9.516 (2), c = 13.217 (4) Å, β = 90.06 (2)° and space group C2/c]. The structure is isomorphous with other carnallite-type compounds, such as NH4Cl·MgCl2·6H2O. Until now, natural and synthetic carnallite, KCl·MgCl2·6H2O, was only known in its orthorhombic form [a = 16.0780 (3), b = 22.3850 (5), c = 9.5422 (2) Å and space group Pnna].
    Schlagwort(e): 548 ; crystallization ; metastable ; monoclinic ; potassium carnallite ; crystal structure ; potash ; fertilizer
    Sprache: Englisch
    Materialart: article
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  • 3
    Publikationsdatum: 2021-07-23
    Beschreibung: MgCO3·MgCl2·7H2O is the only known neutral magnesium carbonate containing chloride ions at ambient conditions. According to the literature, only small and twinned crystals of this double salt could be synthesised in a concentrated solution of MgCl2. For the crystal structure solution, single-crystal diffraction was carried out at a synchrotron radiation source. The monoclinic crystal structure (space group Cc) exhibits double chains of MgO octahedra linked by corners, connected by carbonate units and water molecules. The chloride ions are positioned between these double chains parallel to the (100) plane. Dry MgCO3·MgCl2·7H2O decomposes in the air to chlorartinite, Mg2(OH)Cl(CO3)·nH2O (n = 2 or 3). This work includes an extensive characterization of the title compound by powder X-ray diffraction, thermal analysis, SEM and vibrational spectroscopy.
    Schlagwort(e): 548 ; magnesium ; carbonate ; chloride ; hydrate ; synchrotron ; twinning ; crystal structure
    Sprache: Englisch
    Materialart: article
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  • 4
    Publikationsdatum: 2021-07-24
    Beschreibung: Relativistic electron diffraction depends on linear and quadratic terms in the electric potential, the latter being neglected in the frequently used relativistically corrected Schrödinger equation. The quadratic electric potential term modifies atomic scattering amplitudes in particular for large-angle scattering and backscattering. The respective correction increases with increasing scattering angle, increasing atomic number and increasing kinetic energy. Conventional tabulations for electron scattering and its large-angle extrapolations can be amended in closed form by a universal correction based on the screened Coulomb potential squared.
    Schlagwort(e): 548 ; electron diffraction ; atomic scattering factors ; relativity theory ; Schrödinger equation
    Sprache: Englisch
    Materialart: article
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  • 5
    Publikationsdatum: 2021-08-06
    Beschreibung: Energy poverty is high up on national and European Union policy agendas. A number of possible indicators to measure the issue have been identified in the literature, but comparable data with European coverage is scarce. The EU Commission thus proposes four independent indicators on the "EU Energy Poverty Observatory" based on self-reported items from the pan-European surveys on income and living conditions (SILC) and household budgets (HBS). It is of increasing public interest to analyse social impacts of energy policies, and quantify energy poverty indicators also from modelling. This paper first shortly outlines how the expenditure-based indicators using HBS micro data may be directly linked to existing macroeconomic models through their defining variables (energy expenditure and income). As endogenous modelling based on micro data is difficult, the link may be country-specific elasticities. The main contribution of the paper is a systematic in-depth sensitivity analysis of the two indicators to changes in income and energy expenditure following varying patterns in the underlying distributions of the micro data. The results may be used by future soft links to models. The results display sometimes counterintuitive effects. We find that whether these indicators increase/decrease after a change of income or energy expenditure largely depends on the specific country-wise income and energy expenditure distribution between households on a micro-level. Due to their definition, the examined indicators are especially sensitive, when income changes alter the indicator threshold values, which in these cases are the median values in underlying distributions. We discuss these findings and relate them to several indicator shortcomings and potential remedies through changes in indicator definition.
    Schlagwort(e): ddc:330
    Repository-Name: Wuppertal Institut für Klima, Umwelt, Energie
    Sprache: Englisch
    Materialart: article , doc-type:article
    Format: application/pdf
    Format: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
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  • 6
    Publikationsdatum: 2021-08-06
    Beschreibung: In order to calculate the financial return of energy efficiency measures, a cost-benefit analysis (CBA) is a proven tool for investors. Generally, however, most CBAs for investors have a narrow focus, which is - simply speaking - on investment costs compared with energy cost savings over the life span of the investment. This only provides part of the full picture. Ideally, a comprehensive or extended CBA would take additional benefits as well as additional costs into account. The objective of this paper is to reflect upon integrating into a CBA two important cost components: transaction costs and energy efficiency services - and how they interact. Even though this concept has not been carried out to the knowledge of the authors, we even go a step further to try to apply this idea. In so doing, we carried out a meta-analysis on relevant literature and existing data and interviewed a limited number of energy experts with comprehensive experience in carrying out energy services. Even though data is hardly available, we succeeded in constructing three real-world cases and applied an extended CBA making use of information gathered on transaction costs and energy services costs. We were able to show that, despite these additional cost components, the energy efficiency measures are economically viable. Quantitative data was not available on how energy services reduce transaction costs; more information on this aspect could render our results even more positive. Even though empirical and conceptual research must intensify efforts to design an even more comprehensive CBA, these first-of-its-kind findings can counterargue those that believe energy efficiency is not worth it (in monetary terms) due to transaction costs or energy services costs. In fact, this is good news for energy efficiency and for those that seek to make use of our findings to argue in favor of taking up energy efficiency investments in businesses.
    Schlagwort(e): ddc:330
    Repository-Name: Wuppertal Institut für Klima, Umwelt, Energie
    Sprache: Englisch
    Materialart: article , doc-type:article
    Format: application/pdf
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  • 7
    facet.materialart.
    Unbekannt
    Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publikationsdatum: 2021-05-18
    Beschreibung: The European Union (EU) has established that the goal of achieving climate neutrality by 2050 as a key driver of innovation and growth for industry and the economy in the EU. In addition to offering great opportunities, this also poses considerable challenges for the European economy and, for the most part, for basic industries, which are particularly emission-intensive and face strong international competition. An integrated climate and industry strategy is of central importance to protecting the climate, since the production of steel, cement, basic chemicals, glass, paper, and other materials in the EU and worldwide accounts for roughly one fifth of total greenhouse gas emissions. Even in a greenhouse gas-neutral future, we will not be able to fully eliminate our need for these materials. At the same time, it is particularly challenging to produce these materials without creating emissions given the state of technology and the necessary infrastructures. This applies above all to the question of how large amounts of green energy, including electricity and hydrogen, can be produced at competitive prices. Analyses show that despite the considerable costs involved in process changeover, the costs of transforming the raw materials industry are acceptable to society as a whole, given that the additional costs usually only increase the price of the end products by a few percentage points. However, in the case of crude steel or cement, the price would increase by between one third and 100 per cent. Since almost all raw materials manufacturers face strong global market competition, in most cases they are not able to bankroll the investments in climate-neutral production and the required energy infrastructure without outside support. This paper outlines an integrated climate industrial policy package that allows the EU to utilise its existing technological leadership in many of these industries to build a greenhouse gas-neutral raw materials industry.
    Schlagwort(e): ddc:330
    Repository-Name: Wuppertal Institut für Klima, Umwelt, Energie
    Sprache: Englisch
    Materialart: workingpaper , doc-type:workingPaper
    Format: application/pdf
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  • 8
    Publikationsdatum: 2021-05-06
    Beschreibung: In the light of Germany's chosen path towards the energy transition, the regulatory framework has changed considerably. New players have succeeded in entering the market, and renewable energies have become increasingly competitive. Greater electrification of the transport and heating sectors will be needed in the future to achieve national climate targets. Against this background, Germany's big energy companies need to be sure that their sales will increase. However, they were unable to anticipate this development, and made strategic mistakes in the past. The development of sustainable business models in line with the energy transition failed to materialize. Now it is becoming increasingly clear that companies must create new business models to survive in the long term. These business models have to keep with the tradition, whilst meeting the needs of low-carbon power supplies. In this paper, we will examine the past and future challenges of the four energy companies and develop a proposal for evaluating sustainable business models. For this purpose, we use the multi-level perspective to categorize developments in the electricity market over the last 50 years, and then apply a multi-criteria analysis to derive five suitable business models from the results.
    Schlagwort(e): ddc:330
    Repository-Name: Wuppertal Institut für Klima, Umwelt, Energie
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 9
    Publikationsdatum: 2021-05-04
    Schlagwort(e): ddc:330
    Repository-Name: Wuppertal Institut für Klima, Umwelt, Energie
    Sprache: Englisch
    Materialart: bookpart , doc-type:bookPart
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  • 10
    facet.materialart.
    Unbekannt
    Oxford : Oxford University Press
    Publikationsdatum: 2021-07-05
    Beschreibung: This chapter turns to the measurement of performance in delivering corporate and ecosystem purposes. The metrics are designed to capture the pain points in the ecosystem that need to be addressed and the success of the intervention in addressing them. This requires measures of non-financial as well as financial performance. The chapter provides an overview of measurements of non-financial forms of capital: natural, human, and social. In examining natural capital, it contrasts input measures that record the amount of natural resources that are used in the production process and output measures that examine the impact of the inputs on products, emissions, waste, etc. It notes that measuring inputs is in general more straightforward than outputs and it therefore argues that natural capital metrics should be constructed around inputs rather than outputs.
    Schlagwort(e): ddc:330
    Repository-Name: Wuppertal Institut für Klima, Umwelt, Energie
    Sprache: Englisch
    Materialart: bookpart , doc-type:bookPart
    Format: application/pdf
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  • 11
    Publikationsdatum: 2021-05-18
    Beschreibung: In this paper, we aim to present a comprehensive analysis on the emerging phenomenon of distributed innovation in commons-based peer production (CBPP) platforms. Starting with the exploration of the widely held belief on value-creation confined to industrial settings, we raise several questions regarding the feasibility of, and a need for, an inclusive innovation process that can tap grassroots capacity into both traditional (industrial research and development) and emerging (peer-to-peer) innovation models to yield sustainable solutions. In particular, we explore the emergence and structuration of digital innovations in the maker movement, as it presents an alternative construct of innovation wherein access to and sharing of knowledge is predominantly distributed. With innovation outcomes often freely revealed, its very structuration could pose a principal challenge to our conceptualizations of value creation and competitive advantage in the current economic model. Drawing from responses received from 200 collaborative innovation platforms, six semi‐structured interviews focusing on socio-technical innovation cases, as well as four in-depth narrative interviews with maker turned entrepreneurs, we present a detailed analysis on the topology of network, typology of actors, as well as the underlying innovation ecosystem in CBPP networks in Germany. In doing so, we contribute to the conceptualization of peer-to-peer distributed innovations in collaborative platforms.
    Schlagwort(e): ddc:330
    Repository-Name: Wuppertal Institut für Klima, Umwelt, Energie
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 12
    Publikationsdatum: 2021-07-05
    Beschreibung: The data centre industry (DCI) has grown from zero in the 1980s, to enabling 60% of the global population to be connected in 2021 via 7.2 million data centres. The DCI is based on a linear economy and there is an urgent need to transform to a Circular Economy to establish a secure supply chain and ensure an economically stable and uninterrupted service, which is particularly difficult in an industry that is comprised of ten insular subsectors. This paper describes the CEDaCI project which was established to address the challenge in this unique sector; this ground-breaking project employs a whole systems approach, Design Thinking and the Double Diamond methods, which rely on people/stakeholder engagement throughout. The paper reviews and assesses the impact of these methods and project to date, using quantitative and qualitative research, via an online sectoral survey and interviews with nine data centre and IT industry experts. The results show that the project is creating positive impact and initiating change across the sector and that the innovative output (designs, business models, and a digital tool) will ensure that sectoral transformation continues; the project methods and structure will also serve as an exemplar for other sectors.
    Schlagwort(e): ddc:330
    Repository-Name: Wuppertal Institut für Klima, Umwelt, Energie
    Sprache: Englisch
    Materialart: article , doc-type:article
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    Format: application/pdf
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  • 13
    Publikationsdatum: 2021-09-27
    Beschreibung: It is shown that it is possible to perform combined X-ray and neutron single-crystal studies in the same diamond anvil cell (DAC). A modified Merrill–Bassett DAC equipped with an inflatable membrane filled with He gas has been developed. It can be used on laboratory X-ray and synchrotron diffractometers as well as on neutron instruments. The data processing procedures and a joint structural refinement of the high-pressure synchrotron and neutron single-crystal data are presented and discussed for the first time.
    Schlagwort(e): 548 ; single-crystal X-ray diffraction ; single-crystal neutron diffraction ; high pressure ; diamond anvil cells
    Sprache: Englisch
    Materialart: map
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  • 14
    Publikationsdatum: 2021-09-27
    Beschreibung: White-beam X-ray topography has been performed to provide direct evidence of micro-voids in dislocation-free high-purity germanium single crystals. The voids are visible because of a dynamical diffraction contrast. It is shown that voids occur only in dislocation-free parts of the crystal and do not show up in regions with homogeneous and moderate dislocation density. It is further suggested that the voids originate from clustering of vacancies during the growth process. A general method is proposed to verify the presence of voids for any crystalline material of high structural perfection.
    Schlagwort(e): 548 ; X-ray topography ; dynamical theory ; high-purity germanium ; vacancies ; voids ; dislocation density ; diffraction contrast
    Sprache: Englisch
    Materialart: map
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  • 15
    Publikationsdatum: 2021-10-07
    Beschreibung: To investigate transient dynamics of soil water redistribution during infiltration, we conducted horizontal borehole and surface ground penetrating radar measurements during a 4-day infiltration experiment at the rhizontron facility in Selhausen, Germany. Zero-offset ground penetrating radar profiling in horizontal boreholes was used to obtain soil water content information at specific depths (0.2, 0.4, 0.6, 0.8 and 1.2 m). However, horizontal borehole ground penetrating radar measurements do not provide accurate soil water content estimates of the top soil (0–0.1 m depth) because of interference between direct and critically refracted waves. Therefore, surface ground penetrating radar data were additionally acquired to estimate soil water content of the top soil. Due to the generation of electromagnetic waveguides in the top soil caused by infiltration, a strong dispersion in the ground penetrating radar data was observed in 500 MHz surface ground penetrating radar data. A dispersion inversion was thus performed with these surface ground penetrating radar data to obtain soil water content information for the top 0.1 m of the soil. By combining the complementary borehole and surface ground penetrating radar data, vertical soil water content profiles were obtained, which were used to investigate vertical soil water redistribution. Reasonable consistency was found between the ground penetrating radar results and independent soil water content data derived from time domain reflectometry measurements. Because of the improved spatial representativeness of the ground penetrating radar measurements, the soil water content profiles obtained by ground penetrating radar better matched the known water storage changes during the infiltration experiment. It was concluded that the combined use of borehole and surface ground penetrating radar data convincingly revealed spatiotemporal soil water content variation during infiltration. In addition, this setup allowed a better quantification of water storage, which is a prerequisite for future applications, where, for example, the soil hydraulic properties will be estimated from ground penetrating radar data.
    Schlagwort(e): 550.724 ; Ground-penetrating radar ; Hydrogeophysics ; Data processing
    Sprache: Englisch
    Materialart: map
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  • 16
    Publikationsdatum: 2021-10-07
    Beschreibung: High-quality single-crystal X-ray diffraction measurements are a prerequisite for obtaining precise and reliable structure data and electron densities. The single crystal should therefore fulfill several conditions, of which a regular defined shape is of particularly high importance for compounds consisting of heavy elements with high X-ray absorption coefficients. The absorption of X-rays passing through a 50 µm-thick LiNbO3 crystal can reduce the transmission of Mo Kα radiation by several tens of percent, which makes an absorption correction of the reflection intensities necessary. In order to reduce ambiguities concerning the shape of a crystal, used for the necessary absorption correction, a method for preparation of regularly shaped single crystals out of large samples is presented and evaluated. This method utilizes a focused ion beam to cut crystals with defined size and shape reproducibly and carefully without splintering. For evaluation, a single-crystal X-ray diffraction study using a laboratory diffractometer is presented, comparing differently prepared LiNbO3 crystals originating from the same macroscopic crystal plate. Results of the data reduction, structure refinement and electron density reconstruction indicate qualitatively similar values for all prepared crystals. Thus, the different preparation techniques have a smaller impact than expected. However, the atomic coordinates, electron densities and atomic charges are supposed to be more reliable since the focused-ion-beam-prepared crystal exhibits the smallest extinction influences. This preparation technique is especially recommended for susceptible samples, for cases where a minimal invasive preparation procedure is needed, and for the preparation of crystals from specific areas, complex material architectures and materials that cannot be prepared with common methods (breaking or grinding).
    Schlagwort(e): 548 ; X-ray diffraction ; sample preparation ; focused ion beams
    Sprache: Englisch
    Materialart: map
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  • 17
    Publikationsdatum: 2021-10-15
    Beschreibung: Entangled embedded periodic nets and crystal frameworks are defined, along with their dimension type, homogeneity type, adjacency depth and periodic isotopy type. Periodic isotopy classifications are obtained for various families of embedded nets with small quotient graphs. The 25 periodic isotopy classes of depth-1 embedded nets with a single-vertex quotient graph are enumerated. Additionally, a classification is given of embeddings of n-fold copies of pcu with all connected components in a parallel orientation and n vertices in a repeat unit, as well as demonstrations of their maximal symmetry periodic isotopes. The methodology of linear graph knots on the flat 3-torus [0,1)3 is introduced. These graph knots, with linear edges, are spatial embeddings of the labelled quotient graphs of an embedded net which are associated with its periodicity bases.
    Schlagwort(e): 548 ; periodic nets ; embedded nets ; coordination polymers ; isotopy types ; crystallographic frameworks
    Sprache: Englisch
    Materialart: map
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  • 18
    Publikationsdatum: 2021-10-12
    Beschreibung: Depending on their sizes, impact craters have either simple or complex geometries. Peak-ring craters such as the Chicxulub impact structure possess a single interior ring of peaks and hills and a flat interior floor. The exact mechanisms leading to the formation of a morphological peak-ring are still a matter of debate. In this study, analog modeling was used to study the flow field of a collapsing central uplift. A 3-D-printed cast was used to bring the analog material in the shape of an overheightened central uplift that was based on numerical modeling. The cast was then quickly removed and the central peak collapsed, forming a flattened broad mound that spread out onto the annular moat of the crater cavity. A subwoofer was used to fluidize the granular target material. The kinematics of the collapse were analyzed with the aid of particle image velocimetry, revealing a downward and outward collapse of the central uplift. This mode of collapse is partly in agreement with numerical models, in particular for the initial and middle phases. The overthrusting of the collapsing central peak onto the inward moving crater floor predicted by numerical modeling was observed, though to a lesser degree. A peak-ring, however, could not be reproduced since the collapse came to a halt before the central peak was completely leveled. Nevertheless, the method provides qualitative insights into the kinematics of collapse phenomena. This experimental study provides independent support of the theory of acoustic fluidization, in addition to numerical simulations.
    Schlagwort(e): 550.724 ; 551.397 ; impact craters ; morphological peak-rings ; analog modeling
    Sprache: Englisch
    Materialart: map
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  • 19
    Publikationsdatum: 2021-10-12
    Beschreibung: The vadose zone is subject to dynamic boundary conditions in the form of infiltration and evaporation. A better understanding of implications for flow and solute transport, arising from these dynamic boundary conditions in combination with heterogeneous structure, will help to improve the prediction of the fate of solutes. We present laboratory experiments and numerical simulations of heterogeneous porous media under unsaturated conditions where controlled, temporally varying precipitation and evaporation are applied to study the effect of dynamic boundary conditions on solute transport in the presence of material interfaces. Dye tracers Eosine Y and Brilliant Blue FCF are utilized to visualize solute transport and analyze redistribution processes in a flow cell. Water and solute fluxes in and out of the flow cell are quantified. While in dynamic experiments application of small infiltration rates (significantly below the saturated hydraulic conductivities of the materials) led to a reversal of transport paths between infiltration and succeeding evaporation, larger infiltration rates altered downward transport such that flow and transport paths differed from those observed during evaporation. Differences in transport paths ultimately led to a redistribution and trapping of solute in one material which manifested as pronounced tailing in breakthrough curves. Trapping was induced not by the formation of a stagnant zone as result of large parameter contrast but by an interplay of dynamic boundary conditions and material heterogeneity. This study thereby highlights the importance to consider dynamic boundary conditions in predictions of solute leaching.
    Schlagwort(e): 550.724 ; laboratory experiment ; unsaturated porous media ; conservative solute transport ; dynamic boundary conditions
    Sprache: Englisch
    Materialart: map
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  • 20
    Publikationsdatum: 2021-10-12
    Beschreibung: Volcanic lightning—a near ubiquitous feature of explosive volcanic eruptions—possesses great potential for the analysis of volcanic plume dynamics. To date, the lack of quantitative knowledge on the relationships between plume characteristics hinders efficient data analysis and application of the resulting parameterizations. We use a shock-tube apparatus for rapid decompression experiments to produce particle-laden jets. We have systematically and independently varied the water content (0–27 wt%) and the temperature (25–320 °C) of the particle-gas mixture. The addition of a few weight percent of water is sufficient to reduce the observed electrification by an order of magnitude. With increasing temperature, a larger number of smaller discharges are observed, with the overall amount of electrification staying similar. Changes in jet dynamics are proposed as the cause of the temperature-dependence, while multiple factors (including the higher conductivity of wet ash) can be seen responsible for the decreased electrification in wet experiments.
    Schlagwort(e): 550.724 ; volcanic lightning ; atmospheric electricity ; Faraday cage ; volcanic jets ; temperature ; water content
    Sprache: Englisch
    Materialart: map
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  • 21
    Publikationsdatum: 2021-10-12
    Beschreibung: Crystallographic textures, as they develop for example during cold forming, can have a significant influence on the mechanical properties of metals, such as plastic anisotropy. Textures are typically characterized by a non-uniform distribution of crystallographic orientations that can be measured by diffraction experiments like electron backscatter diffraction (EBSD). Such experimental data usually contain a large number of data points, which must be significantly reduced to be used for numerical modeling. However, the challenge in such data reduction is to preserve the important characteristics of the experimental data, while reducing the volume and preserving the computational efficiency of the numerical model. For example, in micromechanical modeling, representative volume elements (RVEs) of the real microstructure are generated and the mechanical properties of these RVEs are studied by the crystal plasticity finite element method. In this work, a new method is developed for extracting a reduced set of orientations from EBSD data containing a large number of orientations. This approach is based on the established integer approximation method and it minimizes its shortcomings. Furthermore, the L1 norm is applied as an error function; this is commonly used in texture analysis for quantitative assessment of the degree of approximation and can be used to control the convergence behavior. The method is tested on four experimental data sets to demonstrate its capabilities. This new method for the purposeful reduction of a set of orientations into equally weighted orientations is not only suitable for numerical simulation but also shows improvement in results in comparison with other available methods.
    Schlagwort(e): 548 ; texture reconstruction ; integer approximation ; crystal plasticity ; micromechanical modeling
    Sprache: Englisch
    Materialart: map
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  • 22
    Publikationsdatum: 2021-10-11
    Beschreibung: Abstract Evaporation—a key process for water exchange between soil and atmosphere—is controlled by internal water fluxes and surface vapor fluxes. Recent studies demonstrated that the dynamics of the water flow in corners determine the time behavior of the evaporation rate. The internal water flux of the porous media is often described by capillary flow assuming complete wetting. Particularly, the crucial influence of partial wetting, that is, the nonlinear contact angle dependency of the capillary flow has been neglected so far. The focus of the paper is to demonstrate that SiO2-surfaces can exhibit contact angles of about 40°. This reduces the internal capillary flow by 1 order of magnitude compared to complete wetting. First, we derived the contact angle by inverse modeling. We conducted a series of evaporation experiments in a 2-D square lattice microstructure connected by lognormal distributed throats. We used an explicit analytical power series solution of the single square capillary model. A contact angle of 38° ± 1° was derived. Second, we directly measured the contact angle of the Si-SiO2 wafer using the Drop Shape Analyzer Krüss 100 and obtained an averaged contact angle of 42° ± 2°. The results support the single square capillary model as an appropriate model for the description of the evaporation process in an ideal square capillary.
    Schlagwort(e): 550.724 ; 551.5 ; evaporation ; experiments
    Sprache: Englisch
    Materialart: map
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  • 23
    Publikationsdatum: 2021-10-13
    Beschreibung: The crystal structure of the mineral malayaite has been studied by single-crystal X-ray diffraction at a temperature of 20 K and by calculation of its phonon dispersion using density functional perturbation theory. The X-ray diffraction data show first-order satellite diffraction maxima at positions q = 0.2606 (8)b*, that are absent at room temperature. The computed phonon dispersion indicates unstable modes associated with dynamic displacements of the Ca atoms. The largest-frequency modulus of these phonon instabilities is located close to a wavevector of q = 0.3b*. These results indicate that the malayaite crystal structure is incommensurately modulated by static displacement of the Ca atoms at low temperatures, caused by the softening of an optic phonon with Bg symmetry.
    Schlagwort(e): 548 ; modulation ; optic phonon ; titanite ; satellite reflections ; DFPT
    Sprache: Englisch
    Materialart: map
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  • 24
    Publikationsdatum: 2021-10-13
    Beschreibung: A comprehensive understanding of the combined effects of surface roughness and wettability on the dynamics of the trapping process is lacking. This can be primarily attributed to the contradictory experimental and numerical results regarding the impact of wettability on the capillary trapping efficiency. The discrepancy is presumably caused by the surface roughness of the inner pore-solid interface. Herein, we present a comparative μ-CT study of the static fluid-fluid pattern in porous media with smooth (glass beads) and rough surfaces (natural sands). For the first time, a global optimization method was applied to map the characteristic geometrical and morphological properties of natural sands to 2-D micromodels that exhibit different degrees of surface roughness. A realistic wetting model that describes the apparent contact angle of the rough surface as a function surface morphology and the intrinsic contact angle was also proposed. The dynamics of the trapping processes were studied via visualization micromodel experiments. Our results revealed that sand and glass beads displayed opposite trends in terms of the contact angle dependence between 5° and 115°. Sand depicted a nonmonotonous functional contact angle dependency, that is, a transition from maximal trapping to no trapping, followed by an increase to medium trapping. In contrast, glass beads showed a sharp transition from no trapping to maximal trapping. Since both porous media exhibit similar morphological properties (similar Minkowski functions: porosity, surface density, mean curvature density, Euler number density), we deduce that this difference in behavior is caused by the difference in surface roughness that allows complete wetting and hence precursor thick-film flow for natural sands. Experimental results on micromodels verified this hypothesis.
    Schlagwort(e): 550.724 ; impact of wettability on trapping efficiency ; impact of surface roughness and pore space structure on trapping efficiency ; porous media with rough surface ; natural sand and glass ceramic micromodels ; wettability-controlled crossover from snap-off to bypass trapping ; spontaneous precursor thick-film flow (Wenzel's argument)
    Sprache: Englisch
    Materialart: map
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  • 25
    Publikationsdatum: 2021-10-13
    Beschreibung: Chromite ore processing residue (COPR) is a waste derived from the chromate extraction from roasted ores and is deposited in some countries in landfills. The objective of this study was to investigate the leaching characteristics of hexavalent Cr [Cr(VI)] from two COPR samples obtained from unlined landfills in the Kanpur area of northern India. Column experiments were conducted under water-saturated conditions to simulate Cr release from the wastes caused by tropical heavy-rain events. Leached Cr(VI) decreased from 1,800 to 300 mg L−1 (Rania site) and 1,200 to 163 mg L−1 (Chhiwali site) during exchange of 12 pore volumes, which approximately corresponds to 2 yr of monsoon precipitation. Flow interruptions for 10, 100, and 1,000 h had little effect on Cr(VI) concentrations in the leachate, suggesting that Cr(VI) leaching was not limited by slow release kinetics. Calcium aluminum chromium oxide hydrates (CAC), and highly soluble phases such as Na2CrO4 may play a role in controlling Cr(VI) concentration in the leachates. The amount of Cr(VI) leached from the columns accounted for 16% of the total Cr(VI) present in both COPR samples. A decrease in the solid-phase Cr(VI)/Crtotal ratio along the column was identified by X-ray absorption near edge structure (XANES) spectroscopy. Consistently, the smallest Cr(VI)/Crtotal ratios were found in the lower column section closest to the inflow. Our results suggest that Cr(VI) leaching from the unlined COPR landfills will continue for centuries, highlighting the urgent need to remediate these dumpsites.
    Schlagwort(e): 577.275 ; 550.724 ; Northern India ; chromite ore processing residue ; leaching ; experiments
    Sprache: Englisch
    Materialart: map
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  • 26
    Publikationsdatum: 2021-10-13
    Beschreibung: The generalized Darwin–Hamilton equations [Wuttke (2014). Acta Cryst. A70, 429–440] describe multiple Bragg reflection from a thick, ideally imperfect crystal. These equations are simplified by making full use of energy conservation, and it is demonstrated that the conventional two-ray Darwin–Hamilton equations are obtained as a first-order approximation. Then an efficient numeric solution method is presented, based on a transfer matrix for discretized directional distribution functions and on spectral collocation in the depth coordinate. Example solutions illustrate the orientational spread of multiply reflected rays and the distortion of rocking curves, especially if the detector only covers a finite solid angle.
    Schlagwort(e): 548 ; mosaic crystals ; multiple scattering ; Darwin–Hamilton equations ; spectral collocation
    Sprache: Englisch
    Materialart: map
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  • 27
    Publikationsdatum: 2021-10-13
    Beschreibung: The sulfidation and aging of silver nanoparticles (Ag-NPs) with natural organic matter (NOM) are major transformation processes along their pathway in wastewater treatment plants and surface waters. Although soils appear to be a sink for disposed Ag-NPs, the impact of variable saturation on the transport and retention behavior in porous media is still not fully understood. We studied the behavior of sulfidized silver nanoparticles (S-Ag-NPs, 1 mg L−1) in saturated and unsaturated sand columns regarding the effects of (i) the presence of NOM (5 mg L−1) in the aquatic phase on retention, transport, and remobilization of S-Ag-NPs and (ii) the distribution and quantity of air-water and solid-water interfaces for different flow velocities determined via X-ray microtomography (X-ray μCT). Unsaturated transport experiments were conducted under controlled conditions with unit gradients in water potential and constant water content along the flow direction for each applied flux. It was shown that (i) NOM in S-Ag-NP dispersion highly increased the NP-mobility; (ii) differences between saturated and unsaturated transport were increasing with decreasing flux and, consequently, decreasing water contents; (iii) both, solid-water and air-water interfaces were involved in retention of S-Ag-NPs aged by NOM. Using numerical model simulations and X-ray μCT of flow experiments, the breakthrough of Ag-NP could be explained by a disproportional increase in air-water interfaces and an increasing attachment efficiency with decreasing water content and flow velocity.
    Schlagwort(e): 577.275 ; 550.724 ; silver nanoparticles ; X-ray tomography ; phase distribution ; air-water interface ; natural organic matter ; transport
    Sprache: Englisch
    Materialart: map
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  • 28
    Publikationsdatum: 2021-10-13
    Beschreibung: Fluid invasion, displacement of one fluid by another in porous media, is important in a large number of industrial and natural processes. Of special interest is the trapping of gas and oil clusters. We study the impact of wettability on fluid pattern formation and capillary trapping in three-dimensional glass beads packs (dmean = 1 mm) during fluid invasion at capillary numbers of 10−7 using μ-CT. The invading fluid was water, and the defending fluid was air. The contact angle of the glass beads was altered between 5° and 115° using Piranha cleaning and silanization. We analyzed the front morphology of the invading fluid, the residual gas saturation, the fluid occupation frequency of pores, and the morphology and statistics of the trapped gas clusters. We found a sharp transition (crossover) at a critical contact angle θc = 96°. Below θc the morphology of the displacement front was flat and compact caused by the strong smoothing effect of cooperative filling. Above θc the morphology of the displacement front was fractal and ramified caused by single bursts (Haines jumps). Across this dynamical phase transition the trapping efficiency changes from no trapping to maximal trapping. For θ 〉 θc the experimental results show that invasion percolation governs the fluid displacement. Strong indicators are the universal scaling behavior of the size distribution of large clusters (relative data error εdata 〈 1%) and their linear surface-volume relationship (R2 = 0.99).
    Schlagwort(e): 550.724 ; percolation transition ; sharp transition (crossover) at a critical contact angle θc ; below θc, the displacement front was flat and compact ; above θc, the displacement front was fractal and ramified ; trapping efficiency changes from no trapping to maximal trapping ; trapped gas clusters show universal scaling law
    Sprache: Englisch
    Materialart: map
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  • 29
    Publikationsdatum: 2021-10-14
    Beschreibung: The quantification of greenhouse gas emissions from aquatic ecosystems requires knowledge about the spatial and temporal dynamics of free gas in sediments. Freezing the sediment in situ offers a promising method for obtaining gas-bearing sediment samples, unaffected by changes in hydrostatic pressure and sample temperature during core withdrawal and subsequent analysis. This article presents a novel freeze coring technique to preserve the in situ stratigraphy and gas bubble characteristics. Nondestructive X-ray computed tomography (CT) scans were used to identify and characterize coring disturbances of gravity and freeze cores associated with gassy sediment, as well as the effect of the freezing process on the gas bubble characteristics. Real-time X-ray CT scans were conducted to visualize the progression of the freezing process. Additional experiments were conducted to determine the freezing rate to assess the probability of sediment particle/bubble migration, and gas bubble nucleation at the phase transition of pore water to ice. The performance of the freeze coring technique was evaluated under field conditions in Olsberg and Urft Reservoir (Germany). The results demonstrate the capability of the freeze coring technique for the preservation of gas-bearing sediments and the analysis of gas bubble distribution pattern in both reservoirs. Nevertheless, the obtained cores showed that nearly all gravity and freeze cores show some degree of coring disturbances.
    Schlagwort(e): 550.724 ; gas-bearing sediments ; freeze coring technique
    Sprache: Englisch
    Materialart: map
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  • 30
    Publikationsdatum: 2021-10-14
    Beschreibung: We generated a large number 105,000 of aggregates composed of various monomer types and sizes using an aggregation model. Combined with hydrodynamic theory, we derived ice particle properties such as mass, projected area, and terminal velocity as a function of monomer number and size. This particle ensemble allows us to study the relation of particle properties with a high level of detail which is often not provided by in situ measurements. The ice particle properties change rather smoothly with monomer number. We find very little differences in all particle properties between monomers and aggregates at sizes below 1 mm which is in contrast to many microphysics schemes. The impact of the monomer type on the particle properties decreases with increasing monomer number. Whether, for example, the terminal velocity of an aggregate is larger or smaller than an equal-size monomer depends mostly on the monomer type. We fitted commonly used power laws as well as Atlas-type relations, which represent the saturation of the terminal velocity at large sizes (terminal velocity asymptotically approaching a limiting value) to the data set and tested the impact of incorporating different levels of complexity with idealized simulations using a 1D Lagrangian super particle model. These simulations indicate that it is sufficient to represent the monomer number dependency of ice particle properties with only two categories (monomers and aggregates). The incorporation of the saturation velocity at larger sizes is found to be important to avoid an overestimation of self-aggregation of larger snowflakes.
    Schlagwort(e): 551.5 ; 550.724 ; agreggation modeling ; cloud microphysics ; ice particle properties ; Lagrangian modeling ; terminal velocity
    Sprache: Englisch
    Materialart: map
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  • 31
    Publikationsdatum: 2021-10-14
    Beschreibung: With this comment we want to clarify a number of aspects of the paper recently published by Dioguardi, Mele, and Dellino “A New One-Equation Model of Fluid Drag for Irregularly Shaped Particles Valid Over a Wide Range of Reynolds Number” (hereafter referred to as DMD2018). In particular, we show that contrary to the conclusions of DMD2018, the model of Bagheri and Bonadonna (2016, https://doi.org/10.1016/j.powtec.2016.06.015), hereafter referred to as BB2016, is the best model in predicting the drag and terminal velocity of particles measured by DMD2018, as demonstrated here by comparison of estimation errors. The discrepancy is mainly due to a production error (misplaced parentheses) introduced in BB2016 during the publication process and partly due to the incorrect methodology used by DMD2018 to calculate particle terminal velocity. Here we present the correct sets of equations and methodology to show that typo-free model of BB2016 outperforms all existing drag models including the new model suggested by DMD2018.
    Schlagwort(e): 550.724 ; drag coefficient ; terminal velocity ; particle shape ; non-spherical ; irregular
    Sprache: Englisch
    Materialart: map
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  • 32
    Publikationsdatum: 2021-10-14
    Beschreibung: River processes are widely assumed to have impacted the integrity of lithic assemblages when artifacts are found in fluvial sediments, but the specifics of these influences remain largely unknown. We conducted a real-world experiment to determine how the initial stages of fluvial entrainment affected lithic artifact assemblages. We inserted replica artifacts with radio frequency identification tags into a gravel-bedded river in Wales (UK) for seven months and related their transport distances to their morphology and the recorded streamflow. In addition, nine artifacts were recovered at the end of the experiment and analyzed for microwear traces. In sum, our results show that in a gravel-bedded river with a mean discharge of 5.1 m3/s, artifact length and width were the main variables influencing artifact transport distances. The experiment also resulted in characteristic microwear traces developing on the artifacts over distances of 485 m or less. These results emphasize the multifaceted nature of alluvial site formation processes in a repeatable experiment and highlight new ways to identify the transport of replica Paleolithic material.
    Schlagwort(e): 550.724 ; 551.35 ; experimental archaeology ; fluvial dynamics ; Paleolithic ; RFID ; taphonomy ; use-wear
    Sprache: Englisch
    Materialart: map
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  • 33
    Publikationsdatum: 2021-09-24
    Beschreibung: During investigations of the formation of hydrated magnesium carbonates, a sample of the previously unknown magnesium carbonate hexahydrate (MgCO3·6H2O) was synthesized in an aqueous solution at 273.15 K. The crystal structure consists of edge-linked isolated pairs of Mg(CO3)(H2O)4 octahedra and noncoordinating water molecules, and exhibits similarities to NiCO3·5.5H2O (hellyerite). The recorded X-ray diffraction pattern and the Raman spectra confirmed the formation of a new phase and its transformation to magnesium carbonate trihydrate (MgCO3·3H2O) at room temperature.
    Schlagwort(e): 548 ; magnesium ; carbonate ; low-temperature hydrate ; Raman spectroscopy ; crystal structure
    Sprache: Englisch
    Materialart: map
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  • 34
    Publikationsdatum: 2021-10-06
    Beschreibung: Understanding the physical mechanisms governing fluid-induced fault slip is important for improved mitigation of seismic risks associated with large-scale fluid injection. We conducted fluid-induced fault slip experiments in the laboratory on critically stressed saw-cut sandstone samples with high permeability using different fluid pressurization rates. Our experimental results demonstrate that fault slip behavior is governed by fluid pressurization rate rather than injection pressure. Slow stick-slip episodes (peak slip velocity 〈 4 μm/s) are induced by fast fluid injection rate, whereas fault creep with slip velocity 〈 0.4 μm/s mainly occurs in response to slow fluid injection rate. Fluid-induced fault slip may remain mechanically stable for loading stiffness larger than fault stiffness. Independent of fault slip mode, we observed dynamic frictional weakening of the artificial fault at elevated pore pressure. Our observations highlight that varying fluid injection rates may assist in reducing potential seismic hazards of field-scale fluid injection projects.
    Schlagwort(e): 550.724 ; fault slip ; fluid injection ; induced seismicity ; fluid pressurization rate ; stick-slip ; fault creep
    Sprache: Englisch
    Materialart: map
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  • 35
    Publikationsdatum: 2021-10-06
    Beschreibung: Lateral movements of alluvial river channels control the extent and reworking rates of alluvial fans, floodplains, deltas, and alluvial sections of bedrock rivers. These lateral movements can occur by gradual channel migration or by sudden changes in channel position (avulsions). Whereas models exist for rates of river avulsion, we lack a detailed understanding of the rates of lateral channel migration on the scale of a channel belt. In a two-step process, we develop here an expression for the lateral migration rate of braided channel systems in coarse, non-cohesive sediment. On the basis of photographic and topographic data from laboratory experiments of braided channels performed under constant external boundary conditions, we first explore the impact of autogenic variations of the channel-system geometry (i.e. channel-bank heights, water depths, channel-system width, and channel slope) on channel-migration rates. In agreement with theoretical expectations, we find that, under such constant boundary conditions, the laterally reworked volume of sediment is constant and lateral channel-migration rates scale inversely with the channel-bank height. Furthermore, when channel-bank heights are accounted for, lateral migration rates are independent of the remaining channel geometry parameters. These constraints allow us, in a second step, to derive two alternative expressions for lateral channel-migration rates under different boundary conditions using dimensional analysis. Fits of a compilation of laboratory experiments to these expressions suggest that, for a given channel bank-height, migration rates are strongly sensitive to water discharges and more weakly sensitive to sediment discharges. In addition, external perturbations, such as changes in sediment and water discharges or base level fall, can indirectly affect lateral channel-migration rates by modulating channel-bank heights. © 2019 The Author. Earth Surface Processes and Landforms published by John Wiley & Sons, Ltd. © 2019 The Author. Earth Surface Processes and Landforms published by John Wiley & Sons, Ltd.
    Schlagwort(e): 550.724 ; 551.35 ; braided alluvial rivers ; physical experiments ; channel migration
    Sprache: Englisch
    Materialart: map
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  • 36
    Publikationsdatum: 2021-10-06
    Beschreibung: Recent advances in machine learning open new opportunities to gain deeper insight into hydrological systems, where some relevant system quantities remain difficult to measure. We use deep learning methods trained on numerical simulations of the physical processes to explore the possibilities of closing the information gap of missing system quantities. As an illustrative example we study the estimation of velocity fields in numerical and laboratory experiments of density-driven solute transport. Using high-resolution observations of the solute concentration distribution, we demonstrate the capability of the method to structurally incorporate the representation of the physical processes. Velocity field estimation for synthetic data for both variable and uniform concentration boundary conditions showed equal results. This capability is remarkable because only the latter was employed for training the network. Applying the method to measured concentration distributions of density-driven solute transport in a Hele-Shaw cell makes the velocity field assessable in the experiment. This assessability of the velocity field even holds for regions with negligible solute concentration between the density fingers, where the velocity field is otherwise inaccessible.
    Schlagwort(e): 550.724 ; Hele-Shaw cell experiment ; density-driven active solute transport ; convolutional neural network ; velocity field estimation
    Sprache: Englisch
    Materialart: map
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  • 37
    Publikationsdatum: 2021-12-03
    Beschreibung: In recent years, X-ray speckle-tracking techniques have emerged as viable tools for wavefront metrology and sample imaging applications. These methods are based on the measurement of near-field images. Thanks to their simple experimental setup, high angular sensitivity and compatibility with low-coherence sources, these methods have been actively developed for use with synchrotron and laboratory light sources. Not only do speckle-tracking techniques give the potential for high-resolution imaging, but they also provide rapid and robust characterization of aberrations of X-ray optical elements, focal spot profiles, and sample position and transmission properties. In order to realize these capabilities, software implementations are required that are equally rapid and robust. To address this need, a software suite has been developed for the ptychographic X-ray speckle-tracking technique, an X-ray speckle-based method suitable for highly divergent wavefields. The software suite is written in Python 3, with an OpenCL back end for GPU and multi-CPU core processing. It is accessible as a Python module, through the command line or through a graphical user interface, and is available as source code under Version 3 or later of the GNU General Public License.
    Schlagwort(e): 548 ; software ; wavefront metrology ; speckle tracking ; ptychography ; X-ray projection imaging
    Sprache: Englisch
    Materialart: map
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  • 38
    Publikationsdatum: 2021-12-03
    Beschreibung: Micro-macro models for dissolution processes are derived from detailed pore-scale models applying upscaling techniques. They consist of flow and transport equations at the scale of the porous medium (macroscale). Both include averaged time- and space-dependent coefficient functions (permeability, porosity, reactive surface, and effective diffusion). These are in turn explicitly computed from the time- and space-dependent geometry of unit cells and by means of auxiliary cell problems defined therein (microscale). The explicit geometric structure is characterized by a level set. For its evolution, information from the transport equations solutions is taken into account (micro-macro scales). A numerical scheme is introduced, which is capable of evaluating such complex settings. For the level-set equation a second-order scheme is applied, which enables us to accurately determine the dynamic reactive surface. Local mesh refinement methods are applied to evaluate Stokes type cell problems using P2/P1 elements and a Uzawa type linear solver. Applications of our permeability solver to scenarios involving static and evolving geometries are presented. Furthermore, macroscopic flow and transport equations are solved applying mixed finite elements. Finally, adaptive strategies to overcome the computational burden are discussed. We apply our approach to the dissolution of an array of dolomite grains in the micro-macro context and validate our numerical scheme.
    Schlagwort(e): 551.49 ; 550.724 ; porous media ; reactive flow ; dissolution processes ; modeling
    Sprache: Englisch
    Materialart: map
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  • 39
    Publikationsdatum: 2021-12-06
    Beschreibung: Abstract Although the majority of coastal sediments consist of sandy material, in some areas marine ingression caused the submergence of terrestrial carbon-rich peat soils. This affects the coastal carbon balance, as peat represents a potential carbon source. We performed a column experiment to better understand the coupled flow and biogeochemical processes governing carbon transformations in submerged peat under coastal fresh groundwater (GW) discharge and brackish water intrusion. The columns contained naturally layered sediments with and without peat (organic carbon content in peat 39 ± 14 wt%), alternately supplied with oxygen-rich brackish water from above and oxygen-poor, low-saline GW from below. The low-saline GW discharge through the peat significantly increased the release and ascent of dissolved organic carbon (DOC) from the peat (δ13CDOC − 26.9‰ to − 27.7‰), which was accompanied by the production of dissolved inorganic carbon (DIC) and emission of carbon dioxide (CO2), implying DOC mineralization. Oxygen respiration, sulfate (SO42−) reduction, and methane (CH4) formation were differently pronounced in the sediments and were accompanied with higher microbial abundances in peat compared to sand with SO42−-reducing bacteria clearly dominating methanogens. With decreasing salinity and SO42− concentrations, CH4 emission rates increased from 16.5 to 77.3 μmol m−2 d−1 during a 14-day, low-saline GW discharge phase. In contrast, oxygenated brackish water intrusion resulted in lower DOC and DIC pore water concentrations and significantly lower CH4 and CO2 emissions. Our study illustrates the strong dependence of carbon cycling in shallow coastal areas with submerged peat deposits on the flow and mixing dynamics within the subterranean estuary.
    Schlagwort(e): 550.724 ; coastal peatlands ; coastal peatlands ; biogeochemical processes ; carbon release ; column experiments
    Sprache: Englisch
    Materialart: map
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  • 40
    Publikationsdatum: 2021-12-03
    Beschreibung: The rising popularity and strong increase in the number of electric bicycles make it necessary to consider the built-in resources as well as possible treatments after the use phase. The time lag between the purchase and the occurrence of relevant defects suggests significant increases in defective components. Especially the great dynamics of the market due to regular innovations, product renewals, and the lack of spare parts availability for older models make the long-term use by customers much more difficult than for conventional bicycles. Therefore, it is necessary to analyze circular business models for the electric bicycle market. In this way, the required structures for a sustainable electric bicycle industry can be created so that valuable materials do not go into disposal but undergo a new use phase. Based on the results of "AddRE-Mo-Value Preservation Scenarios for Urban Electromobility of Persons and Loads through Additive Manufacturing and Remanufacturing," a research project funded by the German Federal Ministry of Education and Research, this paper addresses four circular business models, two sales models, and two service models. The guiding research interest of this paper is the combination of remanufacturing and additive manufacturing from a business model perspective, analyzing the extent to which additive remanufacturing can be considered a solution for electric bicycles' circularity. After describing the approach and methods used to develop these four circular business models the business models are described and analyzed using the Business Model Canvas. Based on this analysis, it is shown that the combination of remanufacturing and additive manufacturing can be applied to the electric bicycle market and be integrated into both sales and service models. The description of these business models will help managers design viable business models in the context of sustainable electric bicycles. It also shows that the individual partners within the value chain must collaborate more closely. In the electric bicycle industry, a single company will probably not be able to close the product cycle completely. Further research is needed to develop concepts of the business models and examine their practical feasibility in technical and organizational operations to achieve a circular economy.
    Schlagwort(e): ddc:330
    Repository-Name: Wuppertal Institut für Klima, Umwelt, Energie
    Sprache: Englisch
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  • 41
    Publikationsdatum: 2021-11-11
    Beschreibung: Reuse is still seen as a "niche phenomenon" and consumers seem to waste economic opportunities linked to buying and selling second-hand products. For this reason, this paper focuses on incentives and barriers to sell and buy second-hand products, as indicated in the literature, and applies a theoretical framework of transaction costs to explain the existing consumption patterns. For this paper, a representative online survey was conducted in which 1023 consumers in Germany participated, age 16 and older. The data were analyzed for statistically significant deviations between different groups of economic actors selling or buying second-hand products. Results show that valuable unused products exist in households, but barriers such as uncertainties about the reliability of the buyer or the quality of the product hinder the transition into sustainable consumption. Different forms of transaction costs are important explanatory variables to explain why consumers nevertheless predominantly buy new products, although they are aware that second-hand would save money and make an individual contribution to climate protection.
    Schlagwort(e): ddc:330
    Repository-Name: Wuppertal Institut für Klima, Umwelt, Energie
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 42
    Publikationsdatum: 2021-11-11
    Beschreibung: This paper argues that, although Japan's and Germany's energy transition paths differ in detail, a trend towards decentralisation is clearly evident in both countries. Based on comprehensive screening, own stocktaking and the results of a stakeholder dialogue, this paper highlights the motivation for different local actors to enter the energy market in both countries. Although there are challenges to success in a market dominated by large energy companies, this paper argues that the benefits to local communities outweigh the efforts. Overall, it is shown that democratisation and the decentralisation of the energy system are suitable to facilitate a successful transformation process in both countries.
    Schlagwort(e): ddc:330
    Repository-Name: Wuppertal Institut für Klima, Umwelt, Energie
    Sprache: Englisch
    Materialart: article , doc-type:article
    Format: application/pdf
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  • 43
    Publikationsdatum: 2021-11-26
    Beschreibung: More and more companies are announcing their intention to become climate-neutral and numerous companies already offer climate-neutral products or services: From climate-neutral parcel delivery to air travel. But what exactly do the companies' net-zero targets mean? Is the target set ambitious? And what role does offsetting play, i.e., purchasing carbon credits that are accounted against the company's own climate target? The approaches behind the proclaimed targets are often difficult to understand. Against this background, this Zukunftsimpuls provides ten recommendations for the definition and implementation of neutrality targets. Among other things, the authors advocate the use of a robust database as the basis for net-zero targets, emphasize the importance of transparent communication, and highlight the role that offsetting should play. Purchased carbon credits should make as limited a contribution as possible for meeting climate targets and should only be used to offset emissions that cannot be reduced or avoided. More generally, net-zero targets should not be made the sole criterion for ambitious climate strategies. Rather, they are a building block of a much more comprehensive strategy of corporate climate action.
    Schlagwort(e): ddc:330
    Repository-Name: Wuppertal Institut für Klima, Umwelt, Energie
    Sprache: Englisch
    Materialart: workingpaper , doc-type:workingPaper
    Format: application/pdf
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