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Optimised use of data fusion and memory‐based learning with an Austrian soil library for predictions with infrared data (2023)

Ludwig, Bernard ; Greenberg, Isabel ; Vohland, Michael ; [weitere]

Blackwell Publishing Ltd | Oxford, UK

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Publikationsdatum: 2023-12-12

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Infrared spectroscopy in the visible to near‐infrared (vis–NIR) and mid‐infrared (MIR) regions is a well‐established approach for the prediction of soil properties. Different data fusion and training approaches exist, and the optimal procedures are yet undefined and may depend on the heterogeneity present in the set and on the considered scale. The objectives were to test the usefulness of partial least squares regressions (PLSRs) for soil organic carbon (SOC), total carbon (C〈sub〉t〈/sub〉), total nitrogen (N〈sub〉t〈/sub〉) and pH using vis–NIR and MIR spectroscopy for an independent validation after standard calibration (use of a general PLSR model) or using memory‐based learning (MBL) with and without spiking for a national spectral database. Data fusion approaches were simple concatenation of spectra, outer product analysis (OPA) and model averaging. In total, 481 soils from an Austrian forest soil archive were measured in the vis–NIR and MIR regions, and regressions were calculated. Fivefold calibration‐validation approaches were carried out with a region‐related split of spectra to implement independent validations with n ranging from 47 to 99 soils in different folds. MIR predictions were generally superior over vis–NIR predictions. For all properties, optimal predictions were obtained with data fusion, with OPA and spectra concatenation outperforming model averaging. The greatest robustness of performance was found for OPA and MBL with spiking with 〈italic toggle="no"〉R〈/italic〉〈sup〉2〈/sup〉 ≥ 0.77 (N), 0.85 (SOC), 0.86 (pH) and 0.88 (C〈sub〉t〈/sub〉) in the validations of all folds. Overall, the results indicate that the combination of OPA for vis–NIR and MIR spectra with MBL and spiking has a high potential to accurately estimate properties when using large‐scale soil spectral libraries as reference data. However, the reduction of cost‐effectiveness using two spectrometers needs to be weighed against the potential increase in accuracy compared to a single MIR spectroscopy approach.〈/p〉

Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Schlagwort(e): ddc:631.4 ; data fusion ; independent validation ; infrared spectroscopy ; MBL ; nitrogen ; outer product analysis ; pH ; soil organic carbon ; spiking ; total carbon

Sprache: Englisch

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Importance of catchment hydrological processes and calibration of hydrological‐hydrodynamic rainfall‐runoff models in small rural catchments (2023)

David, Amrei ; Rodriguez, Ernesto Ruiz ; Schmalz, Britta ; [weitere]

Blackwell Publishing Ltd | Oxford, UK

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Publikationsdatum: 2024-01-19

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉In recent years, many two‐dimensional (2D) hydrodynamic models have been extended to include the direct rainfall method (DRM). This allows their application as a hydrological‐hydrodynamic model for the determination of floodplains in one model system. In previous studies on DRM, the role of catchment hydrological processes (CaHyPro) and its interaction with the calibration process was not investigated in detail. In the present, case‐oriented study, the influence of the spatiotemporal distribution of the processes precipitation and runoff formation in combination with the 2D model HEC‐RAS is investigated. In a further step, a conceptual approach for event‐based interflow is integrated. The study is performed on the basis of a single storm event in a small rural catchment (low mountain range, 38 km〈sup〉2〈/sup〉) in Hesse (Germany). The model results are evaluated against six quality criteria and compared to a simplified baseline model. Finally, the calibrated improved model is contrasted with a calibrated baseline model. The results show the enhancement of the model results due to the integration of the CaHyPro and highlight its interplay with the calibrated model parameters.〈/p〉

Schlagwort(e): ddc:551.48 ; 2D hydrodynamic modeling ; calibration ; direct rainfall modeling ; hydrological processes ; radar data ; runoff formation

Sprache: Englisch

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Redoxtrons – An experimental system to study redox processes within the capillary fringe (2023)

Dorau, Kristof ; Uteau, Daniel ; Maisch, Markus ; [weitere]

Blackwell Publishing Ltd | Oxford, UK

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Publikationsdatum: 2023-11-18

Beschreibung: Spatiotemporal characterisation of the soil redox status within the capillary fringe (CF) is a challenging task. Air‐filled porosities (ε), oxygen concentration (O〈sub〉2〈/sub〉) and soil redox potential (EH) are interrelated soil variables within active biogeochemical domains such as the CF. We investigated the impact of water table (WT) rise and drainage in an undisturbed topsoil and subsoil sample taken from a Calcaric Gleysol for a period of 46 days. We merged 1D (EH and matric potential) and 2D (O〈sub〉2〈/sub〉) systems to monitor at high spatiotemporal resolution redox dynamics within self‐constructed redoxtron housings and complemented the data set by a 3D pore network characterization using X‐ray microtomography (X‐ray μCT). Depletion of O〈sub〉2〈/sub〉 was faster in the organic matter‐ and clay‐rich aggregated topsoil and the CF extended 〉10 cm above the artificial WT. The homogeneous and less‐aggregated subsoil extended only 4 cm above the WT as indicated by ε–O〈sub〉2〈/sub〉–EH data during saturation. After drainage, 2D O〈sub〉2〈/sub〉 imaging revealed a fast aeration towards the lower depths of the topsoil, which agrees with the connected ε derived by X‐ray μCT (ε〈sub〉CT_conn〈/sub〉) of 14.9% of the total porosity. However, small‐scaled anoxic domains with O〈sub〉2〈/sub〉 saturation 〈5% were apparent even after lowering the WT (down to 0.25 cm〈sup〉2〈/sup〉 in size) for 23 days. These domains remained a nucleus for reducing soil conditions (E〈sub〉H〈/sub〉 〈 −100 mV), which made it challenging to characterise the soil redox status in the CF. In contrast, the subsoil aeration reached O〈sub〉2〈/sub〉 saturation after 8 days for the complete soil volume. Values of ε〈sub〉CT_conn〈/sub〉 around zero in the subsoil highlighted that soil aeration was independent of this parameter suggesting that other variables such as microbial activity must be considered when predicting the soil redox status from ε alone. The use of redoxtrons in combination with localised redox‐measurements and image based pore space analysis resulted in a better 2D/3D characterisation of the pore system and related O〈sub〉2〈/sub〉 transport properties. This allowed us to analyse the distribution and activity of microbiological niches highly associated with the spatiotemporal variable redox dynamics in soil environments. Highlights: The time needed to turn from reducing to oxidising (period where all platinum electrodes feature E〈sub〉H〈/sub〉 〉 300 mV) condition differ for two samples with contrasting soil structure. The subsoil with presumably low O〈sub〉2〈/sub〉 consumption rates aerated considerably faster than the topsoil and exclusively by O〈sub〉2〈/sub〉 diffusion through medium‐ and fine‐sized pores. To derive the soil redox status based upon the triplet ε–O〈sub〉2〈/sub〉–E〈sub〉H〈/sub〉 is challenging at present in heterogeneous soil domains and larger soil volumes than 250 cm〈sup〉3〈/sup〉. Undisturbed soil sampling along with 2D/3D redox measurement systems (e.g., redoxtrons) improve our understanding of redox dynamics within the capillary fringe.

Schlagwort(e): ddc:631.4 ; environmental monitoring ; incubation experiments ; redox processes ; soil reducing conditions ; undisturbed soil ; X‐ray microtomography

Sprache: Englisch

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The dilemma of analytical method changes for soil organic carbon in long‐term experiments (2023)

Grahmann, Kathrin ; Zwink, Mariam ; Barkusky, Dietmar ; [weitere]

Blackwell Publishing Ltd | Oxford, UK

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Publikationsdatum: 2023-11-17

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈sec xmlns:mml="http://www.w3.org/1998/Math/MathML" id="ejss13362-sec-1003" xml:lang="en"〉 〈p xml:lang="en"〉Long‐term experiments (LTEs) have provided data to modellers and agronomists to investigate changes and dynamics of soil organic carbon (SOC) under different cropping systems. As treatment changes have occurred due to agricultural advancements, so too have analytical soil methods. This may lead to method bias over time, which could affect the robust interpretation of data and conclusions drawn. This study aims to quantify differences in SOC due to changes in dry combustion methods over time, using soil samples of a LTE established in 1963 that focuses on mineral and organic fertilizer management in the temperate zone of Northeast Germany. For this purpose, 1059 soil samples, collected between 1976 and 2008, have been analysed twice, once with their historical laboratory method right after sampling, and a second time in 2016 when all samples were analysed using the same elementary analyser. In 9 of 11 soil sampling campaigns, a paired 〈italic toggle="no"〉t〈/italic〉‐test provided evidence for significant differences in the historical SOC values when compared with the re‐analysed concentrations of the same LTE sample. In the sampling years 1988 and 2004, the historical analysis obtained about 0.9 g kg〈sup〉−1〈/sup〉 lower SOC compared with the re‐analysed one. For 1990 and 1998, this difference was about 0.4 g kg〈sup〉−1〈/sup〉. Correction factors, an approach often used to correct for different analytical techniques, could only be applied for 5 of 11 sampling campaigns to account for constant and proportional systematic method error. For this particular LTE, the interpretation of SOC changes due to agronomic management (here fertilization) deviates depending on the analytical method used, which may weaken the explanatory power of the historical data. We demonstrate that analytical method changes over time present one of many challenges in the interpretation of time series data of SOC dynamics. Therefore, LTE site managers need to ensure providing all necessary protocols and data in order to retrace method changes and if necessary recalculate SOC.〈/p〉 〈/sec〉〈sec xmlns:mml="http://www.w3.org/1998/Math/MathML" id="ejss13362-sec-0003" xml:lang="en"〉 〈title〉Highlights〈/title〉 〈p xml:lang="en"〉〈list list-type="bullet" id="ejss13362-list-0001"〉 〈list-item id="ejss13362-li-0001"〉〈p〉A total of 1059 LTE soil samples taken between 1976 and 2008 were re‐analysed for SOC in 2016〈/p〉〈/list-item〉 〈list-item id="ejss13362-li-0002"〉〈p〉Several methodological changes for SOC determination led to significant different SOC concentration in the same sample〈/p〉〈/list-item〉 〈list-item id="ejss13362-li-0003"〉〈p〉Interpretation and time series of LTE soil data suffer from consideration of analytical method changes and poor documentation of the same〈/p〉〈/list-item〉 〈list-item id="ejss13362-li-0004"〉〈p〉Soil archive establishment, thorough method protocols and diligent proficiency testing after soil method changes ameliorate the dilemma〈/p〉〈/list-item〉 〈/list〉〈/p〉 〈/sec〉

Beschreibung: Brandenburger Staatsministerium für Wissenschaft, Forschung und Kultur http://dx.doi.org/10.13039/501100004581

Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100004937

Beschreibung: https://doi.org/10.4228/zalf-acge-b683

Schlagwort(e): ddc:631.4 ; Bland–Altman ; carbon stocks ; data trueness ; Deming regression ; method bias ; soil archive ; soil survey

Sprache: Englisch

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Toward an adequate level of detail in flood risk assessments (2023)

Sieg, Tobias ; Kienzler, Sarah ; Rözer, Viktor ; [weitere]

Blackwell Publishing Ltd | Oxford, UK

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Publikationsdatum: 2024-01-24

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Flood risk assessments require different disciplines to understand and model the underlying components hazard, exposure, and vulnerability. Many methods and data sets have been refined considerably to cover more details of spatial, temporal, or process information. We compile case studies indicating that refined methods and data have a considerable effect on the overall assessment of flood risk. But are these improvements worth the effort? The adequate level of detail is typically unknown and prioritization of improvements in a specific component is hampered by the lack of an overarching view on flood risk. Consequently, creating the dilemma of potentially being too greedy or too wasteful with the resources available for a risk assessment. A “sweet spot” between those two would use methods and data sets that cover all relevant known processes without using resources inefficiently. We provide three key questions as a qualitative guidance toward this “sweet spot.” For quantitative decision support, more overarching case studies in various contexts are needed to reveal the sensitivity of the overall flood risk to individual components. This could also support the anticipation of unforeseen events like the flood event in Germany and Belgium in 2021 and increase the reliability of flood risk assessments.〈/p〉

Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Beschreibung: BMBF http://dx.doi.org/10.13039/501100002347

Beschreibung: Federal Environment Agency http://dx.doi.org/10.13039/501100010809

Beschreibung: http://howas21.gfz-potsdam.de/howas21/

Beschreibung: https://www.umwelt.niedersachsen.de/startseite/themen/wasser/hochwasser_amp_kustenschutz/hochwasserrisikomanagement_richtlinie/hochwassergefahren_und_hochwasserrisikokarten/hochwasserkarten-121920.html

Beschreibung: https://download.geofabrik.de/europe/germany.html

Beschreibung: https://emergency.copernicus.eu/mapping/list-of-components/EMSN024

Beschreibung: https://data.jrc.ec.europa.eu/collection/id-0054

Beschreibung: https://oasishub.co/dataset/surface-water-flooding-footprinthurricane-harvey-august-2017-jba

Beschreibung: https://www.wasser.sachsen.de/hochwassergefahrenkarte-11915.html

Schlagwort(e): ddc:551.48 ; decision support ; extreme events ; integrated flood risk management ; risk assessment

Sprache: Englisch

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BODIUM—A systemic approach to model the dynamics of soil functions (2023)

König, Sara ; Weller, Ulrich ; Betancur‐Corredor, Bibiana ; [weitere]

Blackwell Publishing Ltd | Oxford, UK

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Publikationsdatum: 2024-01-26

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The increasing demand for biomass for food, animal feed, fibre and bioenergy requires optimization of soil productivity, while at the same time, protecting other soil functions such as nutrient cycling and buffering, carbon storage, habitat for biological activity and water filter and storage. Therefore, one of the main challenges for sustainable agriculture is to produce high yields while maintaining all the other soil functions. Mechanistic simulation models are an essential tool to fully understand and predict the complex interactions between physical, biological and chemical processes of soils that generate those functions. We developed a soil model to simulate the impact of various agricultural management options and climate change on soil functions by integrating the relevant processes mechanistically and in a systemic way. As a special feature, we include the dynamics of soil structure induced by tillage and biological activity, which is especially relevant in arable soils. The model operates on a 1D soil profile consisting of a number of discrete layers with dynamic thickness. We demonstrate the model performance by simulating crop growth, root growth, nutrient and water uptake, nitrogen cycling, soil organic matter turnover, microbial activity, water distribution and soil structure dynamics in a long‐term field experiment including different crops and different types and levels of fertilization. The model is able to capture essential features that are measured regularly including crop yield, soil organic carbon, and soil nitrogen. In this way, the plausibility of the implemented processes and their interactions is confirmed. Furthermore, we present the results of explorative simulations comparing scenarios with and without tillage events to analyse the effect of soil structure on soil functions. Since the model is process‐based, we are confident that the model can also be used to predict quantities that have not been measured or to estimate the effect of management measures and climate states not yet been observed. The model thus has the potential to predict the site‐specific impact of management decisions on soil functions, which is of great importance for the development of a sustainable agriculture that is currently also on the agenda of the ‘Green Deal’ at the European level.〈/p〉

Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347

Beschreibung: https://git.ufz.de/bodium/bodium_v1.0

Schlagwort(e): ddc:631.4 ; agriculture ; computational model ; simulation ; soil microbiology ; soil structure ; sustainable soil

Sprache: Englisch

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Temperature and soil moisture change microbial allocation of pesticide‐derived carbon (2023)

Wirsching, Johannes ; Rodriguez, Luciana Chavez ; Ditterich, Franziska ; [weitere]

Blackwell Publishing Ltd | Oxford, UK

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Publikationsdatum: 2024-03-18

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Temperature and soil moisture are known to control pesticide mineralization. Half‐life times (DT〈sub〉50〈/sub〉) derived from pesticide mineralization curves generally indicate longer residence times at low soil temperature and moisture but do not consider potential changes in the microbial allocation of pesticide‐derived carbon (C). We aimed to determine carbon use efficiency (CUE, formation of new biomass relative to total C uptake) to better understand microbial utilization of pesticide‐derived C under different environmental conditions and to support the conventional description of degradation dynamics based on mineralization. We performed a microcosm experiment at two MCPA (2‐methyl‐4‐chlorophenoxyacetic acid) concentrations (1 and 20 mg kg〈sup〉−1〈/sup〉) and defined 20°C/pF 1.8 as optimal and 10°C/pF 3.5 as limiting environmental conditions. After 4 weeks, 70% of the initially applied MCPA was mineralized under optimal conditions but MCPA mineralization reached less than 25% under limiting conditions. However, under limiting conditions, an increase in CUE was observed, indicating a shift towards anabolic utilization of MCPA‐derived C. In this case, increased C assimilation implied C storage or the formation of precursor compounds to support resistance mechanisms, rather than actual growth since we did not find an increase in the 〈italic toggle="no"〉tfdA〈/italic〉 gene relevant to MCPA degradation. We were able to confirm the assumption that under limiting conditions, C assimilation increases relative to mineralization and that C redistribution, may serve as an explanation for the difference between mineralization and MCPA dissipation‐derived degradation dynamics. In addition, by introducing CUE to the temperature‐ and moisture‐dependent degradation of pesticides, we can capture the underlying microbial constraints and adaptive mechanisms to changing environmental conditions.〈/p〉

Beschreibung: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Changing environmental conditions alter the MCPA degradation dynamics and the allocation of pesticide‐derived carbon to anabolic or catabolic metabolism.〈boxed-text position="anchor" content-type="graphic" id="ejss13417-blkfxd-0001" xml:lang="en"〉 〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:13510754:media:ejss13417:ejss13417-toc-0001"〉 〈/graphic〉 〈/boxed-text〉〈/p〉

Beschreibung: Collaborative Research Center 1253 CAMPOS (DFG)

Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Beschreibung: DFG Priority Program 2322 “Soil System”

Beschreibung: Ellrichshausen Foundation

Beschreibung: Research Training Group “Integrated Hydrosystem modeling”

Beschreibung: https://doi.org/10.5281/zenodo.5081655

Schlagwort(e): ddc:631.4 ; anabolism ; carbon use efficiency ; catabolism ; effect of soil moisture and temperature ; gene‐centric process model ; MCPA biodegradation

Sprache: Englisch

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Small lateral air pressure gradients generated by a large chamber system have a strong effect on CO2 transport in soil (2023)

Osterholt, Laurin ; Maier, Martin ; Schindler, Dirk ; [weitere]

Blackwell Publishing Ltd | Oxford, UK

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Publikationsdatum: 2024-02-09

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Gas transport in soils is usually assumed to be purely diffusive, although several studies have shown that non‐diffusive processes can significantly enhance soil gas transport. These processes include barometric air pressure changes, wind‐induced pressure pumping and static air pressure fields generated by wind interacting with obstacles. The associated pressure gradients in the soil can cause advective gas fluxes that are much larger than diffusive fluxes. However, the contributions of the respective transport processes are difficult to separate. We developed a large chamber system to simulate pressure fields and investigate their influence on soil gas transport. The chamber consists of four subspaces in which pressure is regulated by fans that blow air in or out of the chamber. With this setup, we conducted experiments with oscillating and static pressure fields. CO〈sub〉2〈/sub〉 concentrations were measured along two soil profiles beneath the chamber. We found a significant relationship between static lateral pressure gradients and the change in the CO〈sub〉2〈/sub〉 profiles (R〈sup〉2〈/sup〉 = 0.53; 〈italic toggle="no"〉p〈/italic〉‐value 〈2e‐16). Even small pressure gradients between −1 and 1 Pa relative to ambient pressure resulted in an increase or decrease in CO〈sub〉2〈/sub〉 concentrations of 8% on average in the upper soil, indicating advective flow of air in the pore space. Positive pressure gradients resulted in decreasing, negative pressure gradients in increasing CO〈sub〉2〈/sub〉 concentrations. The concentration changes were probably caused by an advective flow field in the soil beneath the chamber generated by the pressure gradients. No effect of oscillating pressure fields was observed in this study. The results indicate that static lateral pressure gradients have a substantial impact on soil gas transport and therefore are an important driver of gas exchange between soil and atmosphere. Lateral pressure gradients in a comparable range can be induced under windy conditions when wind interacts with terrain features. They can also be caused by chambers used for flux measurements at high wind speed or by fans used for head‐space mixing within the chambers, which yields biased flux estimates.〈/p〉

Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Schlagwort(e): ddc:631.4 ; advective flux ; chamber flux measurements ; static air pressure fields ; wind‐induced pressure pumping

Sprache: Englisch

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Fifty years after deep‐ploughing: Effects on yield, roots, nutrient stocks and soil structure (2023)

Burger, Dymphie J. ; Schneider, Florian ; Bauke, Sara L. ; [weitere]

Blackwell Publishing Ltd | Oxford, UK

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Publikationsdatum: 2024-05-30

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Deep‐ploughing far beyond the common depth of 30 cm was used more than 50 years ago in Northern Germany with the aim to break root‐restricting layers and thereby improve access to subsoil water and nutrient resources. We hypothesized that effects of this earlier intervention on soil properties and yields prevailed after 50 years. Hence, we sampled two sandy soils and one silty soil (Cambisols and a Luvisol) of which half of the field had been deep‐ploughed 50 years ago (soils then re‐classified as Treposols). The adjacent other half was not deep‐ploughed and thus served as the control. At all the three sites, both deep‐ploughed and control parts were then conventionally managed over the last 50 years. We assessed yields during the dry year 2019 and additionally in 2020, and rooting intensity at the year of sampling (2019), as well as changes in soil structure, carbon and nutrient stocks in that year. We found that deep‐ploughing improved yields in the dry spell of 2019 at the sandy sites, which was supported by a more general pattern of higher NDVI indices in deep‐ploughed parts for the period from 2016 to 2021 across varying weather conditions. Subsoil stocks of soil organic carbon and total plant‐available phosphorus were enhanced by 21%–199% in the different sites. Root biomass in the subsoil was reduced due to deep‐ploughing at the silty site and was increased or unaffected at the sandy sites. Overall, the effects of deep‐ploughing were site‐specific, with reduced bulk density in the buried topsoil stripes in the subsoil of the sandy sites, but with elevated subsoil density in the silty site. Hence, even 50 years after deep‐ploughing, changes in soil properties are still detectable, although effect size differed among sites.〈/p〉

Beschreibung: BonaRes http://dx.doi.org/10.13039/501100022576

Schlagwort(e): ddc:631.4 ; aggregates ; carbon sequestration ; deep‐ploughing ; macronutrients ; subsoil ; Treposol

Sprache: Englisch

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Vertical SOC distribution and aromatic carbon in centuries old charcoal‐rich Technosols (2022)

Bonhage, Alexander ; Raab, Thomas ; Schneider, Anna ; [weitere]

Blackwell Publishing Ltd | Oxford, UK

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Publikationsdatum: 2023-01-21

Beschreibung: Charcoal‐rich Technosols on century‐old relict charcoal hearths (RCHs) are the subject of ongoing research regarding potential legacy effects that result from historic charcoal production and subsequent charcoal amendments on forest soil properties and forest ecosystems today. RCHs consist mostly of Auh horizons that are substantially enriched in soil organic carbon (SOC), of which the largest part seems to be of pyrogenic origin (PyC). However, the reported range of SOC and PyC contents in RCH soil also suggests that they are enriched in nonpyrogenic SOC. RCH soils are discussed as potential benchmarks for the long‐term influence of biochar amendment and the post‐wildfire influences on soil properties. In this study, we utilised a large soil sample dataset (n = 1245) from 52 RCH sites in north‐western Connecticut, USA, to quantify SOC contents by total element analysis. The contents of condensed highly aromatic carbon as a proxy for black carbon (BC) were predicted by using a modified benzene polycarboxylated acid (BPCA) marker method in combination with diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy‐based partial least square regression (r2 = 0.89). A high vertical spatial sampling resolution allowed the identification of soil organic matter (SOM) enrichment and translocation processes. The results show an average 75% and 1862% increase in TOC and BPCA‐derived carbon, respectively, for technogenic Auh horizons compared to reference soils. In addition to an increase in aromatic properties, increased carboxylic properties of the RCH SOC suggest self‐humification effects of degrading charcoal and thereby the continuing formation of leachable aromatic carbon compounds, which could have effects on pedogenic processes in buried soils. Indeed, we show BPCA‐derived carbon concentrations in intermediate technogenic Cu horizons and buried top/subsoils that suggest vertical translocation of highly aromatic carbon originating in RCH Auh horizons. Topmost Auh horizons showed a gradual decrease in total organic carbon (TOC) contents with increasing depth, suggesting accumulation of recent, non‐pyrogenic SOM. Lower aliphatic absorptions in RCH soil spectra suggest different SOM turnover dynamics compared to reference soils. Furthermore, studied RCH soils featured additional TOC enrichment, which cannot be fully explained now. Highlights BC to TOC ratio and high resolution vertical SOC distribution in 52 RCH sites were studied. RCH soils non‐BC pool was potentially different to reference soils. RCH soils feature TOC accumulation in the topmost horizon. There is BC translocation into buried soils on RCH sites.

Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Schlagwort(e): ddc:631.4 ; benzene polycarboxylated acid marker (BPCA) ; black carbon ; charcoal degradation ; charcoal kiln ; pyrogenic carbon ; relict charcoal hearth ; biochar

Sprache: Englisch

Materialart: doc-type:article

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Potential erodibility of semi‐arid steppe soils derived from aggregate stability tests (2022)

Koza, Moritz ; Pöhlitz, Julia ; Prays, Aleksey ; [weitere]

Blackwell Publishing Ltd | Oxford, UK

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Publikationsdatum: 2023-01-26

Beschreibung: Erosion is a severe threat to the sustainable use of agricultural soils. However, the structural resistance of soil against the disruptive forces steppe soils experience under field conditions has not been investigated. Therefore, 132 topsoils under grass‐ and cropland covering a large range of physico‐chemical soil properties (sand: 2–76%, silt: 18–80%, clay: 6–30%, organic carbon: 7.3–64.2 g kg−1, inorganic carbon: 0.0–8.5 g kg−1, pH: 4.8–9.5, electrical conductivity: 32–946 μS cm−1) from northern Kazakhstan were assessed for their potential erodibility using several tests. An adjusted drop‐shatter method (low energy input of 60 Joule on a 250‐cm3 soil block) was used to estimate the stability of dry soil against weak mechanical forces, such as saltating particles striking the surface causing wind erosion. Three wetting treatments with various conditions and energies (fast wetting, slow wetting, and wet shaking) were applied to simulate different disruptive effects of water. Results indicate that aggregate stability was higher for grassland than cropland soils and declined with decreasing soil organic carbon content. The results of the drop‐shatter test suggested that 29% of the soils under cropland were at risk of wind erosion, but only 6% were at high risk (i.e. erodible fraction 〉60%). In contrast, the fast wetting treatment revealed that 54% of the samples were prone to become “very unstable” and 44% “unstable” during heavy rain or snowmelt events. Even under conditions comparable to light rain events or raindrop impact, 53–59% of the samples were “unstable.” Overall, cropland soils under semi‐arid conditions seem much more susceptible to water than wind erosion. Considering future projections of increasing precipitation in Kazakhstan, we conclude that the risk of water erosion is potentially underestimated and needs to be taken into account when developing sustainable land use strategies. Highlights Organic matter is the important binding agent enhancing aggregation in steppe topsoils. Tillage always declines aggregate stability even without soil organic carbon changes. All croplands soil are prone to wind or water erosion independent of their soil properties. Despite the semi‐arid conditions, erosion risk by water seems higher than by wind.

Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347

Schlagwort(e): ddc:631.4 ; climate change ; land use ; soil organic carbon ; soil texture ; water erosion ; wind erosion

Sprache: Englisch

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Non‐exchangeable stable hydrogen isotope ratios in clay minerals and soil clay fractions: A method test (2022)

Merseburger, Stefan ; Kessler, Arnim ; Oelmann, Yvonne ; [weitere]

Blackwell Publishing Ltd | Oxford, UK

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Publikationsdatum: 2023-01-20

Beschreibung: Stable hydrogen isotope ratios (δ2H values) in structural hydroxyl groups of pedogenic clay minerals are inherited from the surrounding water at the time of their formation. Only non‐exchangeable H preserves the environmental forensic and paleoclimate information (δ2Hn value). To measure δ2Hn values in structural H of clay minerals and soil clay fractions, we adapted a steam equilibration method by accounting for high hygroscopicity. Our δ2Hn values for USGS57 biotite (−95.3 ± SD 0.9‰) and USGS58 muscovite (30.7 ± 1.4‰) differed slightly but significantly from the reported δ2H values (−91.5 ± 2.4‰ and −28.4 ± 1.6‰), because the minerals contained 1.1%–4.4% of exchangeable H. The low SD of replicate measurements (n = 3) confirmed a high precision. The clay separation method including destruction of Fe oxides, carbonates and soil organic matter, and dispersion did not significantly change the δ2Hn values of five different clay minerals. However, we were unable to remove all organic matter from the soil clay fractions resulting in an estimated bias of 1‰ in two samples and 15‰ in the carbon‐richest sample. Our results demonstrate that δ2Hn values of structural H of clay minerals and soil clay fractions can be reliably measured without interference from atmospheric water and the method used to separate the soil clay fraction. Highlights We tested steam equilibration to determine stable isotope ratios of structural H in clay. Gas‐tight capsule sealing in Ar atmosphere was necessary to avoid remoistening. Our steam equilibration method showed a high accuracy and precision. The clay separation method did not change stable isotope ratios of structural H in clay.

Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Schlagwort(e): ddc:549 ; controlled isotope exchange technique ; deuterium ; montmorillonite ; soil clay separation ; soil organic matter removal ; steam equilibration ; structural H ; USGS57 biotite ; vermiculite ; δ2H

Sprache: Englisch

Materialart: doc-type:article

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Reducing tillage intensity benefits the soil micro‐ and mesofauna in a global meta‐analysis (2022)

Betancur‐Corredor, Bibiana ; Lang, Birgit ; Russell, David J. ; [weitere]

Blackwell Publishing Ltd | Oxford, UK

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Publikationsdatum: 2024-03-22

Beschreibung: Soil fauna drives crucial processes of energy and nutrient cycling in agricultural systems, and influences the quality of crops and pest incidence. Soil tillage is the most influential agricultural manipulation of soil structure, and has a profound influence on soil biology and its provision of ecosystem services. The objective of this study was to quantify through meta‐analyses the effects of reducing tillage intensity on density and diversity of soil micro‐ and mesofaunal communities, and how these effects vary among different pedoclimatic conditions and interact with concurrent management practices. We present the results of a global meta‐analysis of available literature data on the effects of different tillage intensities on taxonomic and functional groups of soil micro‐ and mesofauna. We collected paired observations (conventional vs. reduced forms of tillage/no‐tillage) from 133 studies across 33 countries. Our results show that reduced tillage intensity or no‐tillage increases the total density of springtails (+35%), mites (+23%), and enchytraeids (+37%) compared to more intense tillage methods. The meta‐analyses for different nematode feeding groups, life‐forms of springtails, and taxonomic mite groups showed higher densities under reduced forms of tillage compared to conventional tillage on omnivorous nematodes (+53%), epedaphic (+81%) and hemiedaphic (+84%) springtails, oribatid (+43%) and mesostigmatid (+57%) mites. Furthermore, the effects of reduced forms of tillage on soil micro‐ and mesofauna varied with depth, climate and soil texture, as well as with tillage method, tillage frequency, concurrent fertilisation, and herbicide application. Our findings suggest that reducing tillage intensity can have positive effects on the density of micro‐ and mesofaunal communities in areas subjected to long‐term intensive cultivation practices. Our results will be useful to support decision making on the management of soil faunal communities and will facilitate modelling efforts of soil biology in global agroecosystems. HIGHLIGHTS Global meta‐analysis to estimate the effect of reducing tillage intensity on micro‐ and mesofauna Reduced tillage or no‐tillage has positive effects on springtail, mite and enchytraeid density Effects vary among nematode feeding groups, springtail life forms and mite suborders Effects vary with texture, climate and depth and depend on the tillage method and frequency

Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347

Beschreibung: https://doi.org/10.20387/bonares-eh0f-hj28

Schlagwort(e): ddc:631.4 ; agricultural land use ; conservation agriculture ; conventional agriculture ; soil biodiversity ; soil cultivation

Sprache: Englisch

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Defining Hydrogeological Site Similarity with Hierarchical Agglomerative Clustering (2022)

Kawa, Nura ; Cucchi, Karina ; Rubin, Yoram ; [weitere]

Blackwell Publishing Ltd | Malden, US

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Publikationsdatum: 2024-02-28

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Hydrogeological information about an aquifer is difficult and costly to obtain, yet essential for the efficient management of groundwater resources. Transferring information from sampled sites to a specific site of interest can provide information when site‐specific data is lacking. Central to this approach is the notion of site similarity, which is necessary for determining relevant sites to include in the data transfer process. In this paper, we present a data‐driven method for defining site similarity. We apply this method to selecting groups of similar sites from which to derive prior distributions for the Bayesian estimation of hydraulic conductivity measurements at sites of interest. We conclude that there is now a unique opportunity to combine hydrogeological expertise with data‐driven methods to improve the predictive ability of stochastic hydrogeological models.〈/p〉

Beschreibung: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉〈italic〉Article impact statement〈/italic〉: This article introduces hierarchical clustering as a method for defining a notion of site similarity; the aim of this method is to improve the derivation of prior distributions in Bayesian methods in hydrogeology.〈/p〉

Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Beschreibung: https://github.com/GeoStat-Bayesian/geostatDB

Beschreibung: https://github.com/GeoStat-Bayesian/exPrior

Beschreibung: https://github.com/GeoStat-Bayesian/siteSimilarity

Schlagwort(e): ddc:551.49 ; hydrogeological sites ; hydrogeological modeling

Sprache: Englisch

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Fermionic systems for quantum information people (2021)

Szalay, Szilárd ; Zimborás, Zoltán ; Máté, Mihály ; [weitere]

Institute of Physics

In: Journal of Physics A: Mathematical and Theoretical. 2021; 54(39): 393001. Published 2021 Oct 01. doi: 10.1088/1751-8121/ac0646.

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Publikationsdatum: 2021-10-01

Beschreibung: The operator algebra of fermionic modes is isomorphic to that of qubits, the difference between them is twofold: the embedding of subalgebras corresponding to mode subsets and multiqubit subsystems on the one hand, and the parity superselection in the fermionic case on the other. We discuss these two fundamental differences extensively, and illustrate these through the Jordan–Wigner representation in a coherent, self-contained, pedagogical way, from the point of view of quantum information theory. Our perspective leads us to develop useful new tools for the treatment of fermionic systems, such as the fermionic (quasi-)tensor product, fermionic canonical embedding, fermionic partial trace, fermionic products of maps and fermionic embeddings of maps. We formulate these by direct, easily applicable formulas, without mode permutations, for arbitrary partitionings of the modes. It is also shown that fermionic reduced states can be calculated by the fermionic partial trace, containing the proper phase factors. We also consider variants of the notions of fermionic mode correlation and entanglement, which can be endowed with the usual, local operation based motivation, if the parity superselection rule is imposed. We also elucidate some other fundamental points, related to joint map extensions, which make the parity superselection inevitable in the description of fermionic systems.

Print ISSN: 1751-8113

Digitale ISSN: 1751-8121

Thema: Mathematik , Physik

Publiziert von Institute of Physics

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Forced convection heat transfer from a plate stack embedded in a homogeneous porous medium (2021)

Lehre, Khadija Tul Kubra ; McKibbin, R. ; Lehre, Sana Ullah Ullah ; [weitere]

Institute of Physics

In: Physica Scripta. 2021; Published 2021 Oct 29. doi: 10.1088/1402-4896/ac34b4. [early online release]

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Publikationsdatum: 2021-10-29

Print ISSN: 0031-8949

Digitale ISSN: 1402-4896

Thema: Physik

Publiziert von Institute of Physics

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Towards reducing inter-city economic inequality embedded in China's Environmental Protection Tax Law (2021)

Wang, Jingxu ; Lin, Jintai ; Feng, Kuishuang ; [weitere]

Institute of Physics

In: Environmental Research Letters. 2021; Published 2021 Oct 29. doi: 10.1088/1748-9326/ac34bd. [early online release]

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Publikationsdatum: 2021-10-29

Beschreibung: Cities are at the front line of combating environmental pollution and climate change, thus support from cities is crucial for successful enforcement of environmental policy. To mitigate environmental problems, China introduced at provincial level the Environmental Protection Tax Law in 2018. Yet the resulting economic burden on households in different cities with significantly different affluence levels remains unknown. The extent of the economic impacts is likely to affect cities’ support and public acceptability. This study quantifies the economic burden of urban households from taxation of fine particle pollution (PM2.5) for 200 cities nationwide from a “consumer” perspective, accounting for PM2.5 and precursor emissions along the national supply chain. Calculations are based on a Multi-Regional Input-Output (MRIO) analysis, the official tax calculation method and urban household consumption data from China’s statistical yearbooks. We find that the current taxation method intensifies economic inequality between cities nationally and within each province, with some of the richest cities having lower tax intensities than some of the poorest. This is due to the fact that taxes are collected based on tax rates of producing regions rather than consuming regions, that cities with very different affluence levels within a province bear the same tax rate, and that emission intensities in several less affluent cities are relatively high. If the tax could be levied based on tax rates of each city where the consumer lives, with tax rates determined based on cities’ affluence levels and with tax revenues used to support emission control, inter-city economic inequality could be reduced. Our work provides quantitative evidence to improve the environmental tax and can serve as the knowledge base for coordinated inter-city policy.

Print ISSN: 1748-9318

Digitale ISSN: 1748-9326

Thema: Energietechnik

Publiziert von Institute of Physics

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Fabrication and Characterization of Annular-Shaped Piezoelectric Micromachined Ultrasonic Transducer Mounted with Pb(Zr,Ti)O3-Based Monocrystalline Thin Film (2021)

Liu, Ziyi ; Yoshida, Shinya ; Tanaka, Shuji

Institute of Physics

In: Journal of Micromechanics and Microengineering. 2021; Published 2021 Oct 29. doi: 10.1088/1361-6439/ac349f. [early online release]

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Publikationsdatum: 2021-10-29

Beschreibung: In this study, we propose an annular-shaped piezoelectric micromachined ultrasonic transducer (pMUT) based on a Pb(Zr,Ti)O3-based monocrystalline thin film. This pMUT is expected to increase the resonance frequency while maintaining displacement sensitivity, making it superior to an island-shaped pMUT, which is a conventional design. To demonstrate the validity of this assumption, annular- and island-shaped pMUTs with a 60-μm-diameter diaphragm were prototyped and characterized. As a result, the annular-shaped pMUT exhibited a resonance frequency of 11.9 MHz, a static displacement sensitivity of 2.35 nm/V and a transmitting figure-of-merit (FOM) of 28 nm∙MHz/V. On the other hand, the island-shaped pMUT exhibited a resonance frequency of 9.6 MHz and a static displacement of 2.5 nm/V and an FOM of 24 nm∙MHz/V. Therefore, the annular-shaped pMUT was experimentally demonstrated to provide a higher FOM compared to the island-shaped pMUT. In addition, the annular-shaped pMUT with the optimal dimensions is found to be able to keep a relatively large fabrication margin. This is an advantageous point for the practical device fabrication. We believe this design has a potential to become a standard design for high-performance pMUT devices.

Print ISSN: 0960-1317

Digitale ISSN: 1361-6439

Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Maschinenbau

Publiziert von Institute of Physics

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A simple discrete-element model for numerical studying the dynamic thermal response of granular materials (2021)

Wu, Ze-Xiang ; Yang, Lei ; Wang, Zhe ; [weitere]

Institute of Physics

In: Materials Research Express. 2021; Published 2021 Oct 29. doi: 10.1088/2053-1591/ac34b8. [early online release]

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Publikationsdatum: 2021-10-29

Beschreibung: This paper aims to investigate the influence of periodicity temperature change on the properties of dry granular materials in macroscopic and microscopic. A series of cyclic thermal consolidation tests have been carried out based on the discrete element method (DEM) that incorporate particles’ volumetric thermal expansion coefficient. The simulation of the direct shear test was carried out on the samples after thermal cycling. Results showed that thermally-induced volumetric strain accumulation of the specimen can be calculated by the DEM model, based on the PFC2D software. The lateral pressure degraded concomitantly thanks to decreases in particles’ horizontal contact during periodic thermal cycling. In addition, the shear dilatancy level decreases during the shearing process with the number of thermal cycles. Both the size and anisotropy of the normal contact force and contact number and the force chain are affected by the temperature cycle. Finally, the results of this paper have a certain reference for the engineering practice, such as thermal piles or others, when granular materials are subjected to thermal cycling.

Digitale ISSN: 2053-1591

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Publiziert von Institute of Physics

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Smart actuation of liquid crystal elastomer elements: cross-link density-controlled response (2021)

Brighenti, Roberto ; Cosma, Mattia Pancrazio

Institute of Physics

In: Smart Materials and Structures. 2021; Published 2021 Oct 29. doi: 10.1088/1361-665x/ac34bf. [early online release]

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Publikationsdatum: 2021-10-29

Beschreibung: Liquid crystalline elastomers (LCEs) exhibit some remarkable physical properties, such as the reversible large mechanical deformation induced by proper environmental stimuli of different nature, such as the thermal stimulus, allowing their use as soft actuators. The unique features displayed by LCE are originated from their anisotropic microstructure characterized by the preferential orientation of the mesogen molecules embedded in the polymer network. An open issue in the design of LCEs is how to control their actuation effectiveness: the amount of mesogens molecules, how they are linked to the network, the order degree, the cross-link density are some controllable parameters whose spatial distribution, however, in general cannot be tuned except the last one. In this paper, we develop a theoretical micromechanical-based framework to model and explore the effect of the network cross-link density on the mechanical actuation of elements made of liquid crystalline elastomer. In this context, the light-induced polymerization (photopolymerization) for obtaining the elastomers’ cross-linked network is of particular interest, being suitable for precisely tuning the cross-link density distribution within the material; this technology enables to obtain a molecular-scale architected LCEs, allowing the optimal design of the obtainable actuation. The possibility to properly set the cross-link density arrangement within the smart structural element (LCE microstructure design and optimization), represents an intriguing way to create molecular-scale engineered LCE elements having material microstructure encoded desired actuation capabilities.

Print ISSN: 0964-1726

Digitale ISSN: 1361-665X

Thema: Maschinenbau

Publiziert von Institute of Physics

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Quantitative signal subspace imaging (2021)

Gonzalez-Rodriguez, Pedro ; Kim, Arnold D ; Tsogka, Chrysoula

Institute of Physics

In: Inverse Problems. 2021; Published 2021 Oct 29. doi: 10.1088/1361-6420/ac349b. [early online release]

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Publikationsdatum: 2021-10-29

Beschreibung: We develop and analyze a quantitative signal subspace imaging method for single-frequency array imaging. This method is an extension to MUSIC (multiple signal classification) which uses (i) the noise subspace to determine the location and support of targets, and (ii) the signal subspace to recover quantitative information about the targets. For point targets, we are able to recover the complex reflectivity and for an extended target under the Born approximation, we are able to recover a scalar quantity that is related to the product of the volume and relative dielectric permittivity of the target. Our resolution analysis for a point target demonstrates this method is capable of achieving exact recovery of the complex reflectivity at subwavelength resolution. Additionally, this resolution analysis shows that noise in the data effectively acts as a regularization to the imaging functional resulting in a method that is surprisingly more robust and effective with noise than without noise.

Print ISSN: 0266-5611

Digitale ISSN: 1361-6420

Thema: Mathematik , Physik

Publiziert von Institute of Physics

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Modeling and parameter identification of thin, tightly rolled dielectric elastomer actuators (2021)

Prechtl, Johannes ; Kunze, Julian ; Moretti, Giacomo ; [weitere]

Institute of Physics

In: Smart Materials and Structures. 2021; Published 2021 Oct 29. doi: 10.1088/1361-665x/ac34be. [early online release]

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Publikationsdatum: 2021-10-29

Beschreibung: Due to their large deformation, high energy density, and high compliance, dielectric elastomer actuators (DEAs) have found a number of applications in several areas of mechatronics and robotics. Among the many types of DEAs proposed in the literature, rolled DEAs (RDEAs) represent one of the most popular configurations. RDEAs can be effectively used as compact muscle-like actuators for soft robots, since they allow eliminating the need for external motors or compressors while providing at the same time a flexible and lightweight structure with self-sensing capabilities. To effectively design and control complex RDEA-driven systems and robots, accurate and numerically efficient mathematical models need to be developed. In this work, we propose a novel lumped-parameter model for silicone-based, thin and tightly rolled DEAs. The model is grounded on a free-energy approach, and permits to describe the electro-mechanically coupled response of the transducer with a set of nonlinear ordinary differential equations. After deriving the constitutive relationships, the model is validated by means of an extensive experimental campaign, conducted on three RDEA specimens having different geometries. It is shown how the developed model permits to accurately predict the effects of several parameters (external load, applied voltage, actuator geometry) on the RDEA electro-mechanical response, while maintaining an overall simple mathematical structure.

Print ISSN: 0964-1726

Digitale ISSN: 1361-665X

Thema: Maschinenbau

Publiziert von Institute of Physics

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Low pedestal sub-17 fs pulse generation through cascaded self-similar compression in photonic crystal ﬁbers (2021)

A, Esther Lidiya ; R, Vasantha Jayakantha Raja ; K. Varshney, shailendra

Institute of Physics

In: Journal of Optics. 2021; Published 2021 Oct 29. doi: 10.1088/2040-8986/ac34e8. [early online release]

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Publikationsdatum: 2021-10-29

Beschreibung: We propound a realistic numerical model based on cascaded self-similar pulse compression to generate low pedestal ultrashort pulses at 2.5 µm. Self-similarity has been attained by modeling exponential dispersion decreasing and exponentially nonlinearity increasing chalcogenide photonic crystal ﬁbers (PCFs). Initially, fundamental soliton compression in As2S3tapered PCF is investigated for the pedestal-free reduction of the pulse width. Subsequently, the compression factor is further enhanced in the As2Se3 PCF-based nonlinear optical loop mirror. Numerical outcomes reveal a compression of 1 ps pulse down to a pulse width of 16.6 fs with a peak power of 116 W in a total ﬁber length of L=61 cm.

Print ISSN: 2040-8978

Digitale ISSN: 2040-8986

Thema: Physik

Publiziert von Institute of Physics

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Design of Floating Photovoltaic Power Plant and its Environmental Effects in Different Stages: A Review (2021)

Ma, Chao ; Wu, Runze ; Su, Hui

American Institute of Physics

In: Journal of Renewable and Sustainable Energy. 2021; Published 2021 Oct 29. doi: 10.1063/5.0065845. [early online release]

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Publikationsdatum: 2021-10-29

Digitale ISSN: 1941-7012

Thema: Energietechnik

Publiziert von American Institute of Physics

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Comment on ‘Unintentional unfairness when applying new greenhouse gas emissions metrics at country level’ (2021)

Cain, Michelle ; Shine, Keith ; Frame, David ; [weitere]

Institute of Physics

In: Environmental Research Letters. 2021; 16(6): 068001. Published 2021 Jun 01. doi: 10.1088/1748-9326/ac02eb.

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Publikationsdatum: 2021-06-01

Print ISSN: 1748-9318

Digitale ISSN: 1748-9326

Thema: Energietechnik

Publiziert von Institute of Physics

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Development of MEMS Composite Sensor with Temperature Compensation for Tire Pressure Monitoring System (2021)

Zhang, Jiahong ; Wang, Chao ; Xie, Xiaolu ; [weitere]

Institute of Physics

In: Journal of Micromechanics and Microengineering. 2021; Published 2021 Oct 29. doi: 10.1088/1361-6439/ac349d. [early online release]

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Publikationsdatum: 2021-10-29

Beschreibung: The pressure and temperature inside the tire is mainly monitored by the tire pressure monitoring system (TPMS). In order to improve the integration of the TPMS system, moreover enhance the sensitivity and temperature-insensitivity of pressure measurement, this paper proposes a microelectromechanical (MEMS) chip-level sensor based on stress-sensitive aluminum-silicon hybrid structures with amplified piezoresistive effect and temperature-dependent aluminum-silicon hybrid structures for hardware and software temperature compensations. Two types of aluminum-silicon hybrid structures are located inside and outside the strained menbrane to simultaneously realize the measurement of pressure and temperature. The model of this composite sensor chip is firstly designed and verified for its effectiveness by using finite element numerical simulation, and then it is fabricated based on the standard MEMS process. The experiments indicate that the pressure sensitivity of the sensor is between 0.126 mV/(V·kPa) and 0.151 mV/(V·kPa) during the ambient temperature ranges from -20 ℃ to 100 ℃, while the measurement error, sensitivity and temperature coefficient of temperature-dependent hybrid structures are individually ± 0.91℃, -1.225 mV/(V·℃) and -0.150%/℃. The thermal coefficient of offset (TCO) of pressure measurement can be reduced from -3.553%FS/℃ to -0.375%FS/℃ based on the differential output of the proposed sensor. In order to obtain the better performance of temperature compensation, Elman neural network based on ant colony algorithm is applied in the data fusion of differential output to further eliminate the temperature drift error. Based on which, the overall measured error is within 3.45 kPa, which is less than ±1.15%FS. The thermal coefficient of offset (TCO) is -0.017%FS/℃, and the thermal coefficient of span (TCS) is -0.020%/FS℃. The research results may provide a useful reference for the development of the high-performance MEMS composite sensor for the TPMS system.

Print ISSN: 0960-1317

Digitale ISSN: 1361-6439

Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Maschinenbau

Publiziert von Institute of Physics

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Evaluation of Surface Integrity in Electrochemical Micromachining of A286 Super alloy (2021)

E, Rajkeerthi ; P, Hariharan

Institute of Physics

In: Surface Topography: Metrology and Properties. 2021; Published 2021 Oct 29. doi: 10.1088/2051-672x/ac34c1. [early online release]

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Beschreibung: Surface integrity of micro components is a major concern particularly in manufacturing industries as most geometry of the products must meet out necessary surface quality requirements. Advanced machining process like electrochemical micro machining possess the capabilities to machine micro parts with best surface properties exempting them from secondary operations. In this research work, different electrolytes have been employed for producing micro holes in A286 super alloy material to achieve the best surface quality and the measurement of surface roughness and surface integrity to evaluate the machined surface is carried out. The machined micro hole provides detailed information on the geometrical features. A study of parametric analysis meant for controlling surface roughness and improvement of surface integrity has been made to find out the suitable parameters for machining. The suitability of various electrolytes with their dissolution mechanism and the influence of various electrolytes have been thoroughly studied. Among the utilized electrolytes, EG + NaNO3 electrolyte provided the best results in terms of overcut and average surface roughness.

Digitale ISSN: 2051-672X

Thema: Physik

Publiziert von Institute of Physics

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Post-measurement quantumness (2021)

Sun, Yuan ; Luo, Shunlong

Institute of Physics

In: Physica Scripta. 2021; Published 2021 Oct 29. doi: 10.1088/1402-4896/ac34b5. [early online release]

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Print ISSN: 0031-8949

Digitale ISSN: 1402-4896

Thema: Physik

Publiziert von Institute of Physics

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Hot tensile deformation behavior and microstructure evolution of Mg-1Al-6Y alloy (2021)

Yuan, Shuai ; Wang, Jinhui ; Jin, Peipeng ; [weitere]

Institute of Physics

In: Materials Research Express. 2021; Published 2021 Oct 29. doi: 10.1088/2053-1591/ac34b6. [early online release]

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Beschreibung: In this study, the hot tensile test was carried out using the extruded and annealed Mg-1Al-6Y alloy. The effect of temperature and strain rate on the hot tensile deformation behavior of the alloy was systematically studied at different temperatures (200 ℃ ~ 350 ℃) and different strain rates (8×10-5 s-1 ~ 1.6×10-3 s-1). In addition, the effect of temperature on the evolution of microstructure when the strain rate is 1.6×10-3 s-1 was investigated. The results showed that as the temperature increased or the strain rate decreased, the peak stress decreased and the elongation increased. Hot tensile at different temperatures all increased the texture intensity, and the microstructure after deformation showed obvious characteristics of basal fiber texture ([0001]⊥ED). Correspondingly, the weaker [-15-40]//ED texture before deformation transformed into a stronger [01-10]//ED fiber texture. After deformation, the average Schmid factor (SF) of each non-basal slip was significantly increased compared with the average SF before deformation, indicating that abundant non-basal slip was activated during the deformation. When the deformation temperature was 300 °C, dynamic recrystallization (DRX) occurred significantly, and the DRXed grains accounted for 15.9%. DRX was a combination of continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX). Furthermore, the calculated activation energy of the alloy was about 98.8 kJ/mol. Comprehensive research showed that the hot tensile deformation mechanism mainly included intragranular slip, grain boundary slip (GBS) and DRX.

Digitale ISSN: 2053-1591

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Publiziert von Institute of Physics

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Two-dimensional collisions of rough disks or spheres (2021)

Cross, Rod

Institute of Physics

In: European Journal of Physics. 2021; Published 2021 Oct 29. doi: 10.1088/1361-6404/ac3494. [early online release]

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Print ISSN: 0143-0807

Digitale ISSN: 1361-6404

Thema: Physik

Publiziert von Institute of Physics

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On the relation between visual quality and landscape characteristics: a case study application to the waterfront linear parks in Shenyang, China (2021)

Sun, Dong ; Li, Qingyu ; Gao, Weijun ; [weitere]

Institute of Physics

In: Environmental Research Communications. 2021; Published 2021 Oct 29. doi: 10.1088/2515-7620/ac34c7. [early online release]

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Beschreibung: In recent years, Chinese cities have begun to pay attention to their rivers, and a large number of waterfront linear parks have been built in the riverside areas, so that the public can easily enjoy their landscape and entertainment functions. In this study, the visual quality of the waterfront trails and the greenbelt trails in the Waterfront linear Park around the Hunhe river in Shenyang was evaluated the basis of the Scenic Beauty Estimation Method and Semantic Differential Method, and the principal components of the landscape characteristics were extracted and a regression model of the visual quality and the landscape characteristics was established. Results show that the natural feature and the formal feature have a positive influence on the visual quality in waterfront linear parks, and the man-made feature has a negative impact on the visual quality. The six landscape characteristics are Sense of seclusion, ecology, intactness, uniqueness, unity and vitality, which are the main factors which affect the visual quality. This study puts forward improvement measures for the waterfront trails and the greenbelt trails, and the results can be applied to the planning, construction, and management of waterfront linear parks.

Digitale ISSN: 2515-7620

Thema: Energietechnik

Publiziert von Institute of Physics

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Eﬀective modulation of spin accumulation using a ferromagnetic/nonmagnetic bilayer spin channel (2021)

Ariki, Taisei ; Nomura, Tatsuya ; Ohnishi, Kohei ; [weitere]

Institute of Physics

In: Journal of Physics D: Applied Physics. 2021; Published 2021 Oct 29. doi: 10.1088/1361-6463/ac34aa. [early online release]

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Beschreibung: A lateral spin valve consisting of highly spin-polarized CoFeAl electrodes with a CoFeAl/Cu bilayer spin channel has been developed. Despite a large spin absorption into the CoFeAl capping channel layer, an eﬃcient spin injection and detection using the CoFeAl electrodes enable us to observe a clear spin valve signal. We demonstrate that the nonlocal spin accumulation signal is signiﬁcantly modulated depending on the relative angle of the magnetizations between the spin injector and absorber. The observed modulation phenomena is explained by the longitudinal and transverse spin absorption eﬀects into the CoFeAl channel layer with the spin resistance model.

Print ISSN: 0022-3727

Digitale ISSN: 1361-6463

Thema: Physik

Publiziert von Institute of Physics

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A systematic review of life cycle assessment of hydrogen for road transport use (2021)

Rinawati, Dyah Ika ; Keeley, Alexander Ryota ; Takeda, Shutaro ; [weitere]

Institute of Physics

In: Progress in Energy. 2021; Published 2021 Oct 29. doi: 10.1088/2516-1083/ac34e9. [early online release]

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Beschreibung: This study conducted a systematic literature review of the technical aspects and methodological choices in life cycle assessment (LCA) studies of using hydrogen for road transport. More than 70 scientific papers published during 2000–2021 were reviewed, in which more than 350 case studies of use of hydrogen in the automotive sector were found. Only some studies used hybrid LCA and energetic input-output LCA, whereas most studies addressed attributional process-based LCA. A categorization based on the life cycle scope distinguished case studies that addressed the well-to-tank (WTT), well-to-wheel (WTW), and complete life cycle approaches. Furthermore, based on the hydrogen production process, these case studies were classified into four categories: thermochemical, electrochemical, thermal-electrochemical, and biochemical. Moreover, based on the hydrogen production site, the case studies were classified as centralized, on-site, and on-board. The fuel cell vehicle passenger car was the most commonly used vehicle. The functional unit for the WTT studies was mostly mass or energy, and vehicle distance for the WTW and complete life cycle studies. Global warming potential (GWP) and energy consumption were the most influential categories. Apart from the GREET (Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation) model and the Intergovernmental Panel on Climate Change for assessing the GWP, the Centrum voor Milieukunde Leiden method was most widely used in other impact categories. Most of the articles under review were comparative LCA studies on different hydrogen pathways and powertrains. The findings provide baseline data not only for large-scale applications, but also for improving the efficiency of hydrogen use in road transport.

Digitale ISSN: 2516-1083

Thema: Energietechnik , Physik , Technik allgemein

Publiziert von Institute of Physics

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Stability for the Calderón’s problem for a class of anisotropic conductivities via an ad-hoc misﬁt functional (2021)

Foschiatti, Sonia ; Gaburro, Romina ; Sincich, Eva

Institute of Physics

In: Inverse Problems. 2021; Published 2021 Oct 29. doi: 10.1088/1361-6420/ac349c. [early online release]

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Beschreibung: We address the stability issue in Calderón’s problem for a special class of anisotropic conductivities of the form σ=γA in a Lipschitz domain Ω⊆R, n≧3, when A is a known Lipschitz continuous matrix-valued function and γ is the unknown piecewise affine scalar function on a given partition of Ω. We define an ad-hoc misfit functional encoding our data and establish estimates for this class of anisotropic conductivities in terms of both the misfit functional and the more commonly used local Dirichlet-to-Neumann map.

Print ISSN: 0266-5611

Digitale ISSN: 1361-6420

Thema: Mathematik , Physik

Publiziert von Institute of Physics

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Technology computer aided design based deep level transient spectra: Simulation of high-purity germanium crystals (2021)

Lauwaert, Johan

Institute of Physics

In: Journal of Physics D: Applied Physics. 2021; Published 2021 Oct 29. doi: 10.1088/1361-6463/ac34ad. [early online release]

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Beschreibung: Very often Deep Level Transient Spectroscopy (DLTS) specimens deviate from ideal textbook examples making the interpretation of spectra a huge challenge. This challenge introduces inaccurate estimates of the emission signatures and the lack of appropriate estimates for the concentrations of the observed trap levels. In this work it is shown with the example of high-purity germanium that Technology computer aided design including symbolic differentiation provides the necessary numerical stability over a wide temperature range to model DLTS spectra. Moreover this high-purity germanium is a quasi intrinsic semiconductor for which it is well-known that the original small signal theory can introduce strong errors. It is furthermore shown that the parasitic impact of fractional filling and high resistivity material can be modelled and that these modelled spectra can in the future assist the interpretation of experimental results.

Print ISSN: 0022-3727

Digitale ISSN: 1361-6463

Thema: Physik

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A theoretical model of flexible capacitive pressure sensor with microstructured electrode for highly sensitive electronic skin (2021)

Yang, Weidong ; Ding, Wenxuan ; Liu, Menglong ; [weitere]

Institute of Physics

In: Journal of Physics D: Applied Physics. 2021; Published 2021 Oct 29. doi: 10.1088/1361-6463/ac34a9. [early online release]

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Publikationsdatum: 2021-10-29

Beschreibung: Electronic skin (E-skin) has attracted much attention in smart wearables, prosthetics, and robotics. The capacitive-type pressure sensor is generally regarded as one good option to design tactile sensing devices owing to its superior sensitivity in low-pressure region, fast response time and convenient manufacturing. Introducing microstructures on electrode surface is an effective approach to achieve highly sensitive capacitive pressure sensors. In this work, an electromechanical model is proposed to build the relationship between capacitance change and compressive force. The present model can predict the sensitivity of capacitive pressure sensor with microstructured electrodes, where each cellular microstructure is modeled using the contact mechanics theory. It is the first time in the literature that based on Hertz theory framework, one rigorous electromechanical theory framework is established to model flexible capacitive pressure sensor, and the model can be extended to other microstructures, such as micro-pyramid, micro-pillar, and micro-dome array. The validation indicates that the analytical results well agree with the experimental data from our previous work and other literatures. Moreover, the present model can well capture the sensitivity of pressure sensor on the beginning range of small pressure. The sensitivity on this range is the most significant for the E-skin due to its robust linearity for one pressure sensor. Besides, we analyzed the compressive force-displacement relationship, the compressive force-contact radius relationship and the influences of the geometrical and material parameters on the electromechanical coupling effect. The results show that the height and the Young’s modulus of the soft dielectric layer are regarded as the dominant influencing factors in the sensitivity of capacitive pressure sensors.

Print ISSN: 0022-3727

Digitale ISSN: 1361-6463

Thema: Physik

Publiziert von Institute of Physics

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The influence of thermo-mechanical treatment on phase transformation and shape memory effect of CuAl9Fe4Ni2 alloy (2021)

Khanh, Pham Mai ; Tuan, Vu Anh ; Nhung, Le Thi ; [weitere]

Institute of Physics

In: Materials Research Express. 2021; 8(10): 106527. Published 2021 Oct 01. doi: 10.1088/2053-1591/ac3167.

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Publikationsdatum: 2021-10-01

Beschreibung: Shape memory alloys can return to their original shape by reversible martensitic transformation. The shape memory effect of these alloys has been considered to relate to phase transformation, especially martensite transformation. In the copper-aluminum alloys containing Fe and Ni additives, the relationship between the martensitic transformation and shape memory effect occurs by applying a thermo-mechanical deformation and heat treatment process. This paper presents the phase transformation of the CuAl9Fe4Ni2 alloy that suffered from the deformation and heat treatment process. The samples were heated above 1173°K for homogenization. Then, they were rolled with an appropriate degree of strain to prepare the good conditions for the next steps. They were heated again to 1173°K, then quenched in water to 373°K, and then cooling down in cold water to form martensites with fine grain sizes. Next, the samples underwent cold deformation to create a fine grain in the structure and a favorable distribution for the shape memory process. Finally, the samples were shaped and heated at 843°K to decompose the martensite phase and return to their original shape. The phase transformation and the structure of martensite were determined by modern analytical techniques. The results show that the shape memory level was up to 80%.

Digitale ISSN: 2053-1591

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Publiziert von Institute of Physics

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An improved method for PV output prediction using artificial neural network with overlap training range (2021)

Wang, Siyi ; Zhang, Yunpeng ; Hao, Peng ; [weitere]

American Institute of Physics

In: Journal of Renewable and Sustainable Energy. 2021; Published 2021 Oct 29. doi: 10.1063/5.0061408. [early online release]

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Digitale ISSN: 1941-7012

Thema: Energietechnik

Publiziert von American Institute of Physics

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A model study on superfluidity of a unitary Fermi gas of atoms interacting with a finite-ranged potential (2021)

Mal, Subhanka ; Deb, Bimalendu

Institute of Physics

In: Journal of Physics B: Atomic, Molecular and Optical Physics. 2021; Published 2021 Oct 29. doi: 10.1088/1361-6455/ac34df. [early online release]

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Beschreibung: We calculate Bardeen-Cooper-Schrieffer (BCS) state of a unitary Fermi gas of atoms interacting with the finite-ranged Jost-Kohn potential which has been recently shown to account for the resonant interactions [2019 { m J. Phys. B: At. Mol. Opt. Phys.} { f 52}, 165004]. Using exact scattering solution of the potential, we derive two-body ${mathbf T}$-matrix element which is employed to construct the BCS Hamiltonian in momentum space. We present results on the energy- and range-dependence of the pairing gap and superfluid density and the range-dependence of the chemical potential for a wide variation of the scattering length including the extcolor{red}{unitary} regime. In the zero range limit our calculated gap at the Fermi energy is found to be nearly equal to that calculated extcolor{red}{in mean-field theory with contact potential}. The mean gap averaged over the full width at half maximum of the gap function in the zero range and unitary limits is found to be $0.42 E_F$ which is quite close to the recent result of the quantum Monte Carlo simulation [2018 { m Phys. Rev.A} { f 97}, 013601]. The chemical potential in the zero range limit also agrees well with that for the contact potential.

Print ISSN: 0953-4075

Digitale ISSN: 1361-6455

Thema: Physik

Publiziert von Institute of Physics

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Using deep learning to predict the East Asian summer monsoon (2021)

Tang, Yuheng ; Duan, Anmin

Institute of Physics

In: Environmental Research Letters. 2021; Published 2021 Oct 29. doi: 10.1088/1748-9326/ac34bc. [early online release]

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Beschreibung: Accurate prediction of the East Asian summer monsoon (EASM) is beneficial to billions of people’s production and lives. Here convolutional neural networks (CNN) and transfer learning are used for predicting the EASM. The results of the constructed CNN regression model show that the prediction of the CNN regression model is highly consistent with the reanalysis dataset, with correlation coefficient of 0.78, which is higher than that of each of the current state-of-the-art dynamic models. The heat map method indicates that the robust precursor signals in the CNN regression model agree well with previous theoretical studies, and can provide the quantitative contribution of different signals for EASM prediction. The CNN regression model can predict the EASM one year ahead with a confidence level above 95%. The above method can not only improve the prediction of the EASM but also help to identify the involved physical predictors.

Print ISSN: 1748-9318

Digitale ISSN: 1748-9326

Thema: Energietechnik

Publiziert von Institute of Physics

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Investigations on the properties of filament generated in gas mixtures pumped by femtosecond laser pulses (2021)

Jing, Chenrui ; Wang, Zhaohui ; Qi, Xiexing

Institute of Physics

In: Journal of Optics. 2021; Published 2021 Oct 29. doi: 10.1088/2040-8986/ac34e3. [early online release]

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Beschreibung: In this paper, we compare the properties of filament generated in Ne-N2 mixture, pure N2, Kr-N2 mixture and Xe-N2 mixture pumped by femtosecond laser pulses systematically. Due to different nonlinear refractive indices and ioniation potentials of these noble gases, the clamped intensity and plasma density can be tuned in a certain range when a small amount of different noble gases is injected into pure N2. In addition, we also demonstrate that the higher proportional of noble gas and shorter incident pulse duration can benefit to manipulate the plasma density in a relative larger scale.

Print ISSN: 2040-8978

Digitale ISSN: 2040-8986

Thema: Physik

Publiziert von Institute of Physics

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Integrated approach in treatment of solid olive residue and olive wastewater (2021)

Altalhi, Tariq ; El-moemen, A. Abd ; Ibrahim, Mohamed M. ; [weitere]

Institute of Physics

In: Materials Research Express. 2021; Published 2021 Oct 29. doi: 10.1088/2053-1591/ac34b9. [early online release]

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Beschreibung: Olive oil production processes breed two kinds of environmentally detriment waste by-products; the solid olive residue (SOR) and olive waste water (OWW) by-products. The current work aims to treat simultaneously both wastes in the same location. The solid olive residue was converted to activated carbon with pyrolysis at 600°C, followed by steam activation at 600, 700 and 800°C. The produced activated carbons were investigated by FTIR, SEM, BET surface areas analyzer and iodine number. The surface area increases with increasing stream activation temperature up to 800°C (1020 m2/g BET). However, steam activation at 700°C is most environmental and economically feasible, because increasing the activation temperature from 700 to 800°C increases the surface area only from 979 to 1020 m2/g. Activated carbon steam cured at 700°C shows high removal capacity of both polyphenolic compounds and COD of OWW. 95.5% of COD and 84.2% of polyphenolic compounds was removed after equilibrium with activated carbon for 2 hours at room temperature.

Digitale ISSN: 2053-1591

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Publiziert von Institute of Physics

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Numerical Simulations of 22% Efficient All-Perovskite Tandem Solar Cell Utilizing Lead-Free and Low Lead Content Halide Perovskites (2021)

Pandey, Rahul ; Sharma, Sakshi ; Madan, Jaya ; [weitere]

Institute of Physics

In: Journal of Micromechanics and Microengineering. 2021; Published 2021 Oct 29. doi: 10.1088/1361-6439/ac34a0. [early online release]

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Beschreibung: Lead-free or low lead content perovskite materials are explored in photovoltaic devices to mitigate the challenges of toxic lead-based halides. However, the conversion efficiency from such materials is far below compared to its counterparts. Therefore, to make a humble contribution in the development of lead-free or low lead content perovskite solar cells (PSCs) for future thin-film photovoltaic (PV) technology, a simulation study of tin (Sn) and Pb mixed halide (MAPb0.5Sn0.5I3, 1.22 eV) PSC is carried out in this manuscript. The device is further optimized in terms of transport layer and thickness variation to get 15.1% conversion efficiency. Moreover, the optimized narrow bandgap halide (NBH) based device is further deployed in the monolithic tandem configuration with lead-free wide bandgap (1.82 eV) halide, i.e., Cs2AgBi0.75Sb0.25Br6, 1.82eV (WBH) PSC, to mitigate the thermalization as well as transparent Eg losses. Filtered spectrum, current matching, and construction of tandem J-V curve at the current matching point are utilized to design the tandem solar cell under consideration. Tandem device delivered short current density, JSC (15.21 mA.cm-2), open-circuit voltage, VOC (1.95 V), fill factor, FF (74.09 %) and power conversion efficiency, PCE (21.97%). The performance of the devices considered in this work is found to be in good approximation with experimental work.

Print ISSN: 0960-1317

Digitale ISSN: 1361-6439

Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Maschinenbau

Publiziert von Institute of Physics

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X-type vortex and its eﬀect on beam shaping (2021)

Pang, Xiaoyan ; Xiao, Weiwei ; Zhang, Han ; [weitere]

Institute of Physics

In: Journal of Optics. 2021; Published 2021 Oct 29. doi: 10.1088/2040-8986/ac34e7. [early online release]

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Publikationsdatum: 2021-10-29

Beschreibung: In this article we propose a new type of optical vortex, the X-type vortex. This vortex inherits and develops the conventional noncanonical vortex, i.e., it no longer has a constant phase gradient around the center, while the intensity keeps invariant azimuthally. The strongly focusing properties of the Xtype vortex and its eﬀect on the beam shaping in three-dimensional (3D) ﬁelds are analyzed. The interesting phenomena, which cannot be seen in canonical vortices, are observed, for instance the `switch eﬀect' which shows that the intensity pattern can switch from one transverse axis to another in the focal plane by controlling the phase gradient parameter. It is shown that by adjusting the phase gradient of this vortex, the focal ﬁeld can have marvelous patterns, from the doughnut shape to the shapes with diﬀerent lobes, and the beam along propagation direction will form a twisting shape in 3D space with controllable rotation direction and location. The physical mechanisms underlying the rule of the beam shaping are also discussed, which generally say that the phase gradient of the X-type vortex, the orbital angular momentum, the polarization and the `nongeneric' characteristic contribute diﬀerently in shaping ﬁelds. This new type of vortex may supply a new freedom for tailoring 3D optical ﬁelds, and our work will pave a way for exploration of new vortices and their applications.

Print ISSN: 2040-8978

Digitale ISSN: 2040-8986

Thema: Physik

Publiziert von Institute of Physics

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FFT based approaches in micromechanics: fundamentals, methods and applications (2021)

Lucarini, Sergio ; Upadhyay, Manas Vijay ; Segurado, Javier

Institute of Physics

In: Modelling and Simulation in Materials Science and Engineering. 2021; Published 2021 Oct 29. doi: 10.1088/1361-651x/ac34e1. [early online release]

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Publikationsdatum: 2021-10-29

Beschreibung: FFT methods have become a fundamental tool in computational micromechanics since they were first proposed in 1994 by H. Moulinec and P. Suquet for the homogenization of composites. From that moment on many dierent approaches have been proposed for a more accurate and efficient resolution of the non- linear homogenization problem. Furthermore, the method has been pushed beyond its original purpose and has been adapted to many other problems including continuum and discrete dislocation dynamics, multi-scale modeling or homogenization of coupled problems as fracture or multiphysical problems. In this paper, a comprehensive review of FFT approaches for micromechanical simulations will be made, covering the basic mathematical aspects and a complete description of a selection of approaches which includes the original basic scheme, polarization based methods, Krylov approaches, Fourier-Galerkin and displacement-based methods. The paper will present then the most relevant applications of the method in homogenization of composites, polycrystals or porous materials including the simulation of damage and fracture. It will also include an insight into synergies with experiments or its extension towards dislocation dynamics, multi-physics and multi-scale problems. Finally, the paper will analyze the current limitations of the method and try to analyze the future of the application of FFT approaches in micromechanics.

Print ISSN: 0965-0393

Digitale ISSN: 1361-651X

Thema: Maschinenbau

Publiziert von Institute of Physics

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Plasma wakeﬁeld acceleration beyond the dephasing limit with 400 GeV proton driver (2021)

Lotov, Konstantin V ; Tuev, Petr

Institute of Physics

In: Plasma Physics and Controlled Fusion. 2021; Published 2021 Oct 29. doi: 10.1088/1361-6587/ac349a. [early online release]

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Publikationsdatum: 2021-10-29

Beschreibung: A new regime of proton-driven plasma wakeﬁeld acceleration is discovered, in which the plasma nonlinearity increases the phase velocity of the excited wave compared to that of the protons. If the beam charge is much larger than minimally necessary to excite a nonlinear wave, there is suﬃcient freedom in choosing the longitudinal plasma density proﬁle to make the wave speed close to the speed of light. This allows electrons or positrons to be accelerated to about 200 GeV with a 400 GeV proton driver.

Print ISSN: 0741-3335

Digitale ISSN: 1361-6587

Thema: Physik

Publiziert von Institute of Physics

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Exploring oscillations with a nonlinear restoring force (2021)

Kontomaris, Stylianos - Vasileios ; Malamou, Anna

Institute of Physics

In: European Journal of Physics. 2021; Published 2021 Oct 29. doi: 10.1088/1361-6404/ac3495. [early online release]

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Publikationsdatum: 2021-10-29

Print ISSN: 0143-0807

Digitale ISSN: 1361-6404

Thema: Physik

Publiziert von Institute of Physics

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Experimental observation of transverse spin of plasmon polaritons in a single crystalline silver nanowire (2021)

Taneja, Chetna ; Paul, Diptabrata ; Pavan Kumar, G. V.

American Institute of Physics

In: Applied Physics Letters. 2021; 119(16): 161108. Published 2021 Oct 18. doi: 10.1063/5.0055788.

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Publikationsdatum: 2021-10-18

Print ISSN: 0003-6951

Digitale ISSN: 1077-3118

Thema: Physik

Publiziert von American Institute of Physics

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Reply to Comment on ‘Unintentional unfairness when applying new greenhouse gas emissions metrics at country level’ (2021)

Rogelj, Joeri ; Schleussner, Carl-Friedrich

Institute of Physics

In: Environmental Research Letters. 2021; 16(6): 068002. Published 2021 Jun 01. doi: 10.1088/1748-9326/ac02ec.

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Publikationsdatum: 2021-06-01

Print ISSN: 1748-9318

Digitale ISSN: 1748-9326

Thema: Energietechnik

Publiziert von Institute of Physics

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Development of an integrated core-edge scenario using the Super H-mode (2021)

Wilks, Theresa M ; Knölker, M ; Snyder, Philip B ; [weitere]

Institute of Physics

In: Nuclear Fusion. 2021; Published 2021 Oct 29. doi: 10.1088/1741-4326/ac34d6. [early online release]

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Publikationsdatum: 2021-10-29

Print ISSN: 0029-5515

Digitale ISSN: 1741-4326

Thema: Physik

Publiziert von Institute of Physics

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A feasibility study on the development and use of a deep learning model to automate real-time monitoring of tumor position and assessment of interfraction fiducial marker migration in prostate radiotherapy patients (2021)

Motley, Ryan ; Fielding, Andrew L ; Ramachandran, Prabhakar

Institute of Physics

In: Biomedical Physics & Engineering Express. 2021; Published 2021 Oct 29. doi: 10.1088/2057-1976/ac34da. [early online release]

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Publikationsdatum: 2021-10-29

Beschreibung: Purpose The aim of this study was to assess the feasibility of the development and training of a deep learning object detection model for automating the assessment of fiducial marker migration and tracking of the prostate in radiotherapy patients. Methods and Materials A fiducial marker detection model was trained on the YOLO v2 detection framework using approximately 20,000 pelvis kV projection images with fiducial markers labelled. The ability of the trained model to detect marker positions was validated by tracking the motion of markers in a respiratory phantom and comparing detection data with the expected displacement from a reference position. Marker migration was then assessed in 14 prostate radiotherapy patients using the detector for comparison with previously conducted studies. This was done by determining variations in intermarker distance between the first and subsequent fractions in each patient. Results On completion of training, a detection model was developed that operated at a 96% detection efficacy and with a root mean square error of 0.3 pixels. By determining the displacement from a reference position in a respiratory phantom, experimentally and with the detector it was found that the detector was able to compute displacements with a mean accuracy of 97.8% when compared to the actual values. Interfraction marker migration was measured in 14 patients and the average and maximum ± standard deviation marker migration were found to be 2.0±0.9 mm and 2.3±0.9 mm, respectively. Conclusion This study demonstrates the benefits of pairing deep learning object detection, and image-guided radiotherapy and how a workflow to automate the assessment of organ motion and seed migration during prostate radiotherapy can be developed. The high detection efficacy and low error make the advantages of using a pre-trained model to automate the assessment of the target volume positional variation and the migration of fiducial markers between fractions.

Digitale ISSN: 2057-1976

Thema: Biologie , Medizin , Physik , Technik allgemein

Publiziert von Institute of Physics

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Ferromagnetic resonances in single-crystal yttrium iron garnet nanofilms fabricated by metal-organic decomposition (2021)

Wang, Szu-Fan (Paul) ; Chorazewicz, Kayetan ; Lamichhane, Suvechhya ; [weitere]

American Institute of Physics

In: Applied Physics Letters. 2021; 119(17): 172405. Published 2021 Oct 25. doi: 10.1063/5.0067122.

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Publikationsdatum: 2021-10-25

Print ISSN: 0003-6951

Digitale ISSN: 1077-3118

Thema: Physik

Publiziert von American Institute of Physics

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Current status of eye-lens dosimetry in Canada (2021)

Dubeau, Jacques ; Sun, Jiansheng ; Djeffal, Salah ; [weitere]

Institute of Physics

In: Journal of Radiological Protection. 2021; Published 2021 Oct 29. doi: 10.1088/1361-6498/ac34a1. [early online release]

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Publikationsdatum: 2021-10-29

Print ISSN: 0952-4746

Digitale ISSN: 1361-6498

Thema: Energietechnik

Publiziert von Institute of Physics

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Defect concentration and Δn change in light- and elevated temperature- induced degradation (2021)

Kim, Moonyong ; Wright, Matthew ; Chen, Daniel ; [weitere]

Institute of Physics

In: Journal of Physics D: Applied Physics. 2021; Published 2021 Oct 29. doi: 10.1088/1361-6463/ac34a8. [early online release]

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Publikationsdatum: 2021-10-29

Beschreibung: The wide variety of silicon materials used by various groups to investigate LeTID make it difficult to directly compare the defect concentrations (Nt) using the typical normalised defect density (NDD) metric. Here, we propose a new formulation for a relative defect concentration (β) as a correction for NDD that allows flexibility to perform lifetime analysis at arbitrary injection levels (Δn), away from the required ratio between Δn and the background doping density (Ndop) for NDD of Δn/N dop = 0.1. As such, β allows for a meaningful comparison of the maximum degradation extent between different samples in different studies and also gives a more accurate representative value to estimate the defect concentration. It also allows an extraction at the cross-over point in the undesirable presence of iron, or flexibility to reduce the impact of modulation in surface passivation. Although the accurate determination of β at a given Δn requires knowledge of the capture cross-section ratio (k), the injection-independent property of the β formulation allows a self-consistent determination of k. Experimental verification is also demonstrated for boron-oxygen related defects and LeTID defects, yielding k-values of 10.6 ± 3.2 and 30.7 ± 4.0, respectively, which are within the ranges reported in the literature. With this, when extracting the defect density at different Δn ranging between 1014 /cm3 to 1015 /cm3 with Ndop = 9.1 ×1015 /cm3, the error is less than 12% using β, allowing for a greatly improved understanding of the defect concentration in a material.

Print ISSN: 0022-3727

Digitale ISSN: 1361-6463

Thema: Physik

Publiziert von Institute of Physics

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Active and passive transductions – definitions and implications for learning (2021)

Svensson, Kim ; Lundqvist, Jennie ; Campos, Esmeralda ; [weitere]

Institute of Physics

In: European Journal of Physics. 2021; Published 2021 Oct 29. doi: 10.1088/1361-6404/ac3493. [early online release]

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Publikationsdatum: 2021-10-29

Print ISSN: 0143-0807

Digitale ISSN: 1361-6404

Thema: Physik

Publiziert von Institute of Physics

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Simulation of pellet ELM triggering in low-collisionality, ITER-like discharges (2021)

Wingen, Andreas ; Lyons, Brendan C. ; Wilcox, Robert S ; [weitere]

Institute of Physics

In: Nuclear Fusion. 2021; Published 2021 Oct 29. doi: 10.1088/1741-4326/ac34d7. [early online release]

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Publikationsdatum: 2021-10-29

Print ISSN: 0029-5515

Digitale ISSN: 1741-4326

Thema: Physik

Publiziert von Institute of Physics

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A Molecular Structure-Informed Viscoelastic Constitutive Model for Natural Rubber Materials (2021)

Jung, Jiwon ; Park, Chanwook ; RYU, myungshin ; [weitere]

Institute of Physics

In: Functional Composites and Structures. 2021; Published 2021 Oct 31. doi: 10.1088/2631-6331/ac34fc. [early online release]

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Publikationsdatum: 2021-10-31

Beschreibung: This paper presents a molecular structure-informed viscoelastic constitutive equation that adopts the Doi-Edward’s tube model with coarse-grained molecular dynamics (MD) simulation and primitive path analysis. Since this model contains polymer physics-related parameters directly obtained from molecular simulations, it can reflect molecular information in predictions of the viscoelastic behavior of elastomers, unlike other empirical models. The proposed incremental formulations and constitutive stiffness matrix were implemented into implicit finite element analysis (FEA) codes as a user-supplied material model and viscoelastic properties (storage, loss modulus, and tan⁡δ) were calculated from the constitutive equation. While obtaining polymer dynamics parameter of the molecular system, a relationship between self-diffusivity coefficient (D_c) and the polymerization degree of the polymer was confirmed. Furthermore, a series of parametric studies showed that increase of the primitive path length (L) and decrease of D_c have led to the strengthening of moduli and decrease of tan⁡δ peak. Moreover, under the same condition, the shift of tan⁡δ peak to low-frequency domain was observed, which implies a decline in free volume in the molecular system and an increase in the glass transition temperature.

Digitale ISSN: 2631-6331

Thema: Maschinenbau , Technik allgemein

Publiziert von Institute of Physics

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Flexoelectric effect on thickness-shear vibration of a rectangular piezoelectric crystal plate (2021)

Zheng, Yang ; Huang, Bin ; Wang, Ji

Institute of Physics

In: Materials Research Express. 2021; Published 2021 Oct 29. doi: 10.1088/2053-1591/ac34b7. [early online release]

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Publikationsdatum: 2021-10-29

Beschreibung: Thickness-shear (TSh) vibration of a rectangular piezoelectric crystal plate is studied with the consideration of flexoelectric effect in this paper. The developed theoretical model is based on the assumed displacement function which includes the anti-symmetric mode through thickness and symmetric mode in length. The constitutive equation with flexoelectricity, governing equations and boundary conditions are derived from the Gibbs energy density function and variational principle. For the effect of flexoelectricity, we only consider the shear strain gradient in the thickness direction so as to simply the mathematical model. Thus, two flexoelectric coefficients are used in the present model. The electric potential functions are also obtained for different electric boundary conditions. The present results clearly show that the flexoelectric effect has significant effect on vibration frequencies of thickness-shear modes of thin piezoelectric crystal plate. It is also found that the flexoelectric coefficients and length to thickness ratio have influence on the thickness-shear modes. The results tell that flexoelectricity cannot be neglected for design of small size piezoelectric resonators.

Digitale ISSN: 2053-1591

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Publiziert von Institute of Physics

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Spatial priorities for biodiversity and ecosystem services considering theoretical decision-makers' attitudes to risk (2021)

Wang, Lijuan ; Zheng, Hua ; Polasky, Stephen ; [weitere]

Institute of Physics

In: Environmental Research Communications. 2021; Published 2021 Oct 29. doi: 10.1088/2515-7620/ac34c6. [early online release]

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Publikationsdatum: 2021-10-29

Beschreibung: Choosing appropriate spatial priorities for protected areas (PAs) to conserve ecosystem services (ESs) and biodiversity is a challenge for decision-makers under limited land resources, especially when facing uncertain protection consequences or conflicting protection objectives. Attitudes toward risk will influence actions, which will, in turn, impact consequences. To understand how theoretical decision-maker attitudes towards risk impact protection effectiveness for biodiversity and ESs (e.g., water retention, soil retention, flood mitigation, water purification and carbon sequestration) and how this information can be integrated into effective PAs management, we examined Hainan Island as a case study. We used the ordered weighted averaging algorithm to assess the impact of attitude towards risk in PA management. Decision-makers’ attitude towards risk scenarios (from risk-averse and risk-taking) showed higher mean protection effectiveness (2.41–2.85) than existing PAs (2.37), indicating that there is still room for improvement in biodiversity and ESs conservation in existing PAs. In addition, among the seven examined risk scenarios, the higher risk aversion scenario showed the best outcome. In comparison to existing PAs, this scenario improved mean protection effectiveness (20.13%) as well as the protection effectiveness of water retention (24.84%), water purification (11.46%), flood mitigation (8.84%), soil retention (16.63%), carbon sequestration (5.31%), and biodiversity (12.84%). Thus, our research shows that the influence of theoretical decision-makers’ attitudes towards risk could be considered by OWA method which could provide a normative model of what the right choice given theoretical risk attitudes is while selecting priority area for biodiversity and ESs.

Digitale ISSN: 2515-7620

Thema: Energietechnik

Publiziert von Institute of Physics

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Wavefronts, light rays and caustic associated with the refraction of a plane wavefront by a conospherical lens (2021)

Galindo-Rodríguez, José Israel ; Silva-Ortigoza, Gilberto

Institute of Physics

In: Journal of Optics. 2021; Published 2021 Oct 29. doi: 10.1088/2040-8986/ac34e4. [early online release]

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Publikationsdatum: 2021-10-29

Beschreibung: The aim of the present work is to introduce a lens whose faces are a conical surface and a spherical surface. We illuminate this lens by a plane wavefront and its associated refracted wavefronts, light rays and caustic are computed. We find that the caustic region has two branches and can be virtual, real or one part virtual and the other real, depending on the values of the parameters characterizing the lens. Furthermore, we present a particular example where one of the branches of the caustic region is constituted by two segments of a line, one part is real and the other one virtual. The second branch is a two-dimensional surface with a singularity of the cusp ridge type such that its Gaussian curvature is different from zero. It is important to remark that for this example, the two branches of the caustic are disconnected. Because of this property and the result obtained by Berry and Balazs on the relationship between the acceleration of an Airy beam and the curvature of its corresponding caustic, we believe that using this optical element one could generate a scalar optical accelerating beam in the region where the caustic is a two-dimensional surface of revolution, and at the same time a scalar optical beam with similar properties to the Bessel beam of zero order in the region were the real caustic is a segment of a line along the optical axis.

Print ISSN: 2040-8978

Digitale ISSN: 2040-8986

Thema: Physik

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A particle image velocimetry measurement of flow over a highly confined circular cylinder at 60% blockage ratio (2021)

Nguyen, Quang Duy ; Lei, Chengwang

American Institute of Physics

In: Physics of Fluids. 2021; 33(10): 104111. Published 2021 Oct 01. doi: 10.1063/5.0066606.

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Publikationsdatum: 2021-10-01

Print ISSN: 1070-6631

Digitale ISSN: 1089-7666

Thema: Physik

Publiziert von American Institute of Physics

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Growth kinetics of (CuxNi1-x)6Sn5 intermetallic compound at the interface of mixed Sn63Pb37/SAC305 BGA solder joints during thermal aging test (2021)

Cong, Sen ; Zhang, Weiwei ; Zhang, He ; [weitere]

Institute of Physics

In: Materials Research Express. 2021; 8(10): 106301. Published 2021 Oct 01. doi: 10.1088/2053-1591/ac3168.

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Publikationsdatum: 2021-10-01

Beschreibung: Sn63Pb37/SAC305 mixed solder joint is inevitably in the electronic device requiring high reliability, such as health care, aerospace etc. However, the usage history of mixed solder joint is relatively short and as such their interfacial behaviour and reliability in service has not been completely figure out. Herein, the evolution of microstructures in fully mixed Sn63Pb37/SAC305 BGA solder joints during high-temperature storage were systematically studied. After reflow soldering process, the Pb-rich phases uniformly distributed in the fully mixed joint. During the thermal aging test, the size of Pb-rich phases gradually coarsened. The intermetallic compound (IMC) layers thickness at the two-side interface (upper interface: between the pad on substrate and solder; lower interface: between the pad on PCB and solder) were also increased. Moreover, the growth kinetics models of two-side IMC layer were successfully established according to the Arrhenius equation. IMC layer grows faster at higher temperature, because of higher diffusion coefficient. With the increasing of aging time, the fracture position partially moved from the interface between Ni layer and IMC layer into IMC internal. These results may provide support for the reliable applications of mixed Sn63Pb37/SAC305 solder joints.

Digitale ISSN: 2053-1591

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Publiziert von Institute of Physics

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Adhesion of water-based paint on plasma-treated high-density polyethylene sheets (2021)

De Leon, Mark Jeffry D ; Vasquez, Magdaleno R

Institute of Physics

In: Materials Research Express. 2021; 8(10): 105306. Published 2021 Oct 01. doi: 10.1088/2053-1591/ac3164.

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Publikationsdatum: 2021-10-01

Beschreibung: In this study, high-density polyethylene (HDPE) surfaces were treated with plasma to enhance the adhesion of a water-based paint. A custom-built cold atmospheric pressure plasma jet (CAPPJ) device using a neon transformer as its power source was developed and used in the surface treatment. The jet nozzle of the device was made from polytetrafluoroethylene with two bare stainless-steel electrodes positioned laterally through the nozzle and opposite each other with a 1 mm gap. Gas was allowed to pass through the nozzle, exiting through a 1 mm diameter hole where a plasma jet is ejected through the arc from the electrodes. The effect of plasma treatment on HDPE surfaces was determined. Air and nitrogen were used as the process gases and exposure times were also varied. Hydrophilicity of the surface increased with longer plasma exposure with a corresponding 50% increase in surface free energy compared to the untreated surface. From Fourier transform infrared and x-ray photoelectron spectroscopy analysis, it was seen that plasma treatment introduced oxygen containing functionalities onto the surface. Increase in adhesion of a water-based paint was observed for plasma-treated HDPE sheets.

Digitale ISSN: 2053-1591

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Publiziert von Institute of Physics

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Theory of spin–charge-coupled transport in proximitized graphene: an SO(5) algebraic approach (2021)

Ferreira, Aires

Institute of Physics

In: JPhys Materials. 2021; 4(4): 045006. Published 2021 Oct 01. doi: 10.1088/2515-7639/ac31b5.

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Publikationsdatum: 2021-10-01

Digitale ISSN: 2515-7639

Thema: Maschinenbau

Publiziert von Institute of Physics

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Analytical and experimental study of the dynamics of a micro-electromechanical resonator based digital-to-analog converter (2021)

Zhao, Wen ; Ahmed, Sally ; Fariborzi, Hossein ; [weitere]

Institute of Physics

In: Journal of Micromechanics and Microengineering. 2021; 31(12): 125010. Published 2021 Nov 03. doi: 10.1088/1361-6439/ac3219.

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Publikationsdatum: 2021-11-03

Beschreibung: In this paper, an analytical model of a micro-electromechanical (MEM) resonator used as a 4-bit digital-to-analog converter (DAC) is presented. First, we derive the dynamic equation of the 4-bit DAC device, and the nonlinear governing equation is solved by the Galerkin method combined with a shooting technique to simulate the static response, linear eigenvalue problem, and forced vibration response of the device for various electrostatic actuation cases. Also, we optimize the air gaps in the linear domain to ensure enhanced performance of the DAC. Further, to analyze the operation of the DAC in the nonlinear regime, two experimental samples powered by −2 dBm and −12 dBm AC inputs are examined. Forward and backward frequency sweeps are conducted experimentally and analytically. The proposed analytical results are validated by comparison with experimental data. The results indicate that the presented modeling, simulations, and optimization are effective tools for the design of MEM resonator-based circuits.

Print ISSN: 0960-1317

Digitale ISSN: 1361-6439

Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Maschinenbau

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Sputter deposition of Mo-alumina cermet solar selective coatings: Interrelation between residual oxygen incorporation, structure and optical properties (2021)

Becerril-Gonzalez, J J ; Castro-Chong, A M ; Oskam, G ; [weitere]

Institute of Physics

In: Materials Research Express. 2021; 8(10): 105506. Published 2021 Oct 01. doi: 10.1088/2053-1591/ac3042.

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Beschreibung: Mo/alumina cermet-based selective coatings are of great interest for concentrated solar-thermal power systems, in particular, parabolic trough collectors. We report on the sputter deposition of high-performance multilayer Mo/alumina cermet coatings on stainless steel with a solar absorptance of 94% and a thermal emittance of 8% (at 400 °C), and excellent thermal stability. The selective coatings were deposited in a 0.95 m3 sputtering chamber in order to correlate the deposition parameters, such as presence of residual gases, deposition power, and sputtering method (DC or RF), with the coating composition and the resulting optical properties. X-ray photoelectron spectroscopy, x-ray diffraction, and Raman spectroscopy have been applied to quantitatively describe the effect of residual oxygen on the distribution of oxidation states of Mo in the metallic infrared reflector layer, the high and low metallic volume fraction cermet layers, as well as the composition of the alumina top layer. The results provide strategies to obtain optimal selective coatings under conditions where residual oxygen cannot be avoided, which are essential for a successful transition from a laboratory to pre-industrial scale of vacuum deposition systems.

Digitale ISSN: 2053-1591

Thema: Chemie und Pharmazie , Maschinenbau , Physik

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Experimental investigation of shape memory polymer hybrid nanocomposites modified by carbon fiber reinforced multi-walled carbon nanotube (MWCNT) (2021)

Markad, Kanif ; Lal, Achchhe

Institute of Physics

In: Materials Research Express. 2021; 8(10): 105015. Published 2021 Oct 01. doi: 10.1088/2053-1591/ac2fcc.

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Beschreibung: This paper presents the effect of the variations of multi-walled carbon nanotube (MWCNT) modification in shape memory polymer hybrid composites concerning their mechanical, thermomechanical, and shape memory characterizations. The process of fabrication includes preparation of the MWCNT/epoxy hybrid nanocomposites by shear mixing, ultrasonication, magnetic stirring, and subsequent molding by hand layup method. The appropriate post-processing was performed for the curing and cutting to prepare the samples for the mechanical and thermomechanical characterizations as per the ASTM standards. An enhancement in the thermomechanical properties was noticed due to the incorporation of the MWCNT. These observations were also validated with improvement in the interfacial bonding between the carbon fiber and the modified matrix, as shown in the morphological fractography. The tensile strengths were improved by 18%, 39%, and 26% with the incorporation of 0.4%, 0.6%, and 0.8% modified MWCNT nanocomposites as compared to pure unmodified SMPC. However, the shape recovery of all the configurations of the shape memory polymer hybrid composites was not compromised on polymer-modified remaining almost unchanged at 94%.

Digitale ISSN: 2053-1591

Thema: Chemie und Pharmazie , Maschinenbau , Physik

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Green synthesis of Nd substituted Co-Ni nanospinel ferrites: a structural, magnetic, and antibacterial/anticancer investigation (2021)

Almessiere, Munirah A ; Slimani, Yassine ; Rehman, Suriya ; [weitere]

Institute of Physics

In: Journal of Physics D: Applied Physics. 2021; 55(5): 055002. Published 2021 Oct 29. doi: 10.1088/1361-6463/ac2fd8.

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Beschreibung: Co0.5Ni0.5Nd0.02Fe1.98O4 (CoNiNdFO) nanospinel ferrites (NSFs) with and without plant extracts (cardamom seeds, date fruits, flaxseed, tragacanth gum, lavender seeds, and moringa) were prepared using a sol-gel approach. The impact of utilizing different plant extracts on the structural, morphological, and magnetic features of the final products is discussed. Room temperature (300 K) magnetization findings illustrate superparamagnetic (SPM) characteristics for the products synthesized using the cardamom and moringa plant extracts mediated sol-gel approach, whereas the remaining products display ferromagnetic characteristics. On the other hand, lower temperature (10 K) magnetization curves indicate that all the prepared samples exhibit ferromagnetic (FM) behavior. It was found that the magnetic parameters vary greatly with the synthesis approach, plant extract solution, distribution of cations, morphology, and size of NSFs, spin canting, etc. The obtained results indicate that the different synthesis approaches employed in the present investigation are simple, inexpensive, and eco-friendly, and could lead to obtaining interesting magnetic properties. The biological applications of these NSFs were examined. The impact of NSFs with and without cardamom and moringa extracts on human colorectal carcinoma cells (HCT-116) and cervical cancer cells (HeLa) was assessed by checking cell viability using 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and 4′,6-diamidino-2-phenylindole (DAPI) staining methods. The treatments of NSFs with and without cardamom and moringa extracts decreased cancer cell viability. We calculated the inhibitory concentration (IC50) values for NSFs with and without cardamom and moringa extracts. The treatment of NSFs with and without cardamom and moringa extracts on HCT-116 cells and HeLa cells induced a significant decrease in cancer viability, as revealed by MTT assay. The treatment of NSFs with and without cardamom and moringa extracts caused a noteworthy decrease in colon cancer cells as the number of DAPI stained cells was found to be less in the treated cells. The evaluation of the anti-staphylococcal activity of NSFs with and without cardamom and moringa extracts via the colony-forming unit (CFU) method showed growth inhibition of S. aureus. It was observed that the nanoparticles synthesized via green synthesis had a marked cell count reduction, proving the microbial toxicity of nanoparticles to S. aureus.

Print ISSN: 0022-3727

Digitale ISSN: 1361-6463

Thema: Physik

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Intersystem crossing and internal conversion dynamics with GAIMS-TeraChem: Excited state relaxation in 2-cyclopentenone (2021)

Mukherjee, Saikat ; Varganov, Sergey A.

American Institute of Physics

In: Journal of Chemical Physics. 2021; 155(17): 174107. Published 2021 Nov 07. doi: 10.1063/5.0068040.

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Print ISSN: 0021-9606

Digitale ISSN: 1089-7690

Thema: Chemie und Pharmazie , Physik

Publiziert von American Institute of Physics

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Welding of 304 stainless steel and glass using high-repetition-frequency femtosecond laser (2021)

Wang, Yipeng ; Li, Yang ; Ao, Sansan ; [weitere]

Institute of Physics

In: Materials Research Express. 2021; 8(10): 106523. Published 2021 Oct 01. doi: 10.1088/2053-1591/ac30b1.

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Beschreibung: In this study, a femtosecond laser with a repetition frequency of 0–400 kHz was used to join soda lime glass and 304 stainless steel. The effects of single-pulse power, repetition frequency, welding speed, and defocusing on the weld quality were investigated. The joining mechanism and fracture surface morphologies were studied using scanning electron microscopy and x-ray diffraction analysis. The results show that no new phases were formed between the glass and stainless steel, and that the joining mechanism consisted mainly of mechanical mixing between the two materials. Using a suitable combination of process parameters, a good weld with a strength of 8.79 MPa was obtained. The weld strength was influenced mainly by the amount of glass that adhered to the stainless steel, the bonding strength between the glass base material and the remelted glass, and the wetting of the stainless steel by the molten glass.

Digitale ISSN: 2053-1591

Thema: Chemie und Pharmazie , Maschinenbau , Physik

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β-Decay properties of neutron-rich yttrium isotopes (2021)

Farooq, Fakeha ; Nabi, Jameel-Un ; Shehzadi, Ramoona

Institute of Physics

In: Physica Scripta. 2021; 96(12): 125312. Published 2021 Oct 29. doi: 10.1088/1402-4896/ac30a9.

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Print ISSN: 0031-8949

Digitale ISSN: 1402-4896

Thema: Physik

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All-nitrogen spiropentadiene—N5+ (2021)

Tian, Xiao ; Bo, Xiao-xu ; Ding, Yi-hong

American Institute of Physics

In: Journal of Chemical Physics. 2021; 155(17): 174304. Published 2021 Nov 07. doi: 10.1063/5.0070369.

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Thema: Chemie und Pharmazie , Physik

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Multi-state formulation of the frozen-density embedding quasi-diabatization approach (2021)

Eschenbach, Patrick ; Artiukhin, Denis G. ; Neugebauer, Johannes

American Institute of Physics

In: Journal of Chemical Physics. 2021; 155(17): 174104. Published 2021 Nov 07. doi: 10.1063/5.0070486.

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Thema: Chemie und Pharmazie , Physik

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Time evolution for quantum systems with a dynamical Hilbert space (2021)

Chou, Hsiang Shun

Institute of Physics

In: European Journal of Physics. 2021; 43(1): 015402. Published 2021 Oct 29. doi: 10.1088/1361-6404/ac2ecc.

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Print ISSN: 0143-0807

Digitale ISSN: 1361-6404

Thema: Physik

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Quantum Fisher information and skew information correlations in dipolar spin system (2021)

Muthuganesan, R ; Chandrasekar, V K

Institute of Physics

In: Physica Scripta. 2021; 96(12): 125113. Published 2021 Oct 29. doi: 10.1088/1402-4896/ac2eca.

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Print ISSN: 0031-8949

Digitale ISSN: 1402-4896

Thema: Physik

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Phase-field crystal study on the influence of nanoscale intergranular structures on grain boundary segregation (2021)

Su, Shasha ; Tang, Sai ; Liang, Chaoping ; [weitere]

Institute of Physics

In: Modelling and Simulation in Materials Science and Engineering. 2021; 29(8): 085009. Published 2021 Oct 27. doi: 10.1088/1361-651x/ac2ec5.

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Beschreibung: Grain boundary (GB) segregation can substantially affect the performance of materials by greatly changing the chemical compositions of GB. It is well known that GB segregation is essentially attributed to the structural differences between the bulk of grain and GB. Nevertheless, we still lack a clear understanding about the correlation between nanoscale intergranular structures and solute segregation. In this work, by using the phase-field crystal model, we performed atomic scale simulations to investigate the segregation of Li atoms to symmetric ⟨110⟩ tilt GBs in binary Al–Li alloys. It was found that the amount of segregated solute increases proportionally to GB misorientation angle in the case of low-angle tilt GBs, and converges at high-angle tilt GBs, except some special GBs with coincidence-site lattice. This is analogous to the dependences of GB energy and density on the misorientation angle. The correlations among GB structure, misfit strain around GBs and solute segregation are quantified at atomic scale. In low-angle tilt GBs, Li atoms are segregated to the compress zone around the core of intergranular dislocations to release the misfit strain energy. In the general high-angle tilt GBs, since the GB structure and misfit strain energy is uniform, the segregated atoms distribute homogeneously along GB. Particularly, the regular arrangement of structural units in some low Σ GBs lead to very low misfit strain energy, and accordingly to a periodically distributed and very low amount of solute segregation.

Print ISSN: 0965-0393

Digitale ISSN: 1361-651X

Thema: Maschinenbau

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Explicit derivation of the Fraunhofer diffraction formula for oblique incidence (2021)

Biswas, Shyamal ; Bhattacharyya, Rhitabrata ; Bhattacharyya, Saugata

Institute of Physics

In: European Journal of Physics. 2021; 43(1): 015301. Published 2021 Oct 29. doi: 10.1088/1361-6404/ac2ece.

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High resolution measurement of near-field radiative heat transfer enabled by nanomechanical resonators (2021)

Giroux, Mathieu ; Zhang, Chang ; Snell, Nikaya ; [weitere]

American Institute of Physics

In: Applied Physics Letters. 2021; 119(17): 173104. Published 2021 Oct 25. doi: 10.1063/5.0068700.

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Publikationsdatum: 2021-10-25

Print ISSN: 0003-6951

Digitale ISSN: 1077-3118

Thema: Physik

Publiziert von American Institute of Physics

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Engineering antiferromagnetic topological insulator by strain in two-dimensional rare-earth pnictide EuCd2Sb2 (2021)

Li, Runhan ; Wang, Hao ; Mao, Ning ; [weitere]

American Institute of Physics

In: Applied Physics Letters. 2021; 119(17): 173105. Published 2021 Oct 25. doi: 10.1063/5.0063353.

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Print ISSN: 0003-6951

Digitale ISSN: 1077-3118

Thema: Physik

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Improved field-effect mobility in transfer-free graphene films synthesized via the metal agglomeration technique using high-crystallinity Ni catalyst films (2021)

Kubo, Toshiharu ; Takahashi, Akira ; Miyoshi, Makoto ; [weitere]

Institute of Physics

In: Applied Physics Express. 2021; 14(11): 116503. Published 2021 Oct 29. doi: 10.35848/1882-0786/ac30ed.

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Print ISSN: 1882-0778

Digitale ISSN: 1882-0786

Thema: Physik

Publiziert von Institute of Physics

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Fabrication of magnetic cobalt-nickel ferrite nanoparticles for the adsorption of methyl blue in aqueous solutions (2021)

Ouyang, Hezhong ; Liu, Shuyan ; Liu, Dandan ; [weitere]

Institute of Physics

In: Materials Research Express. 2021; 8(10): 105013. Published 2021 Oct 01. doi: 10.1088/2053-1591/ac3106.

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Beschreibung: An innovative method of combustion–calcination of a nitrate–ethanol solution to produce magnetic Co0.5Ni0.5Fe2O4 nanoparticles was developed. The calcination temperature and the volume of ethanol were two pivotal elements that determine the properties of the Co0.5Ni0.5Fe2O4 nanoparticles in this study. When the volume of ethanol used was increased from 20 ml to 40 ml, the crystallinity of the Co0.5Ni0.5Fe2O4 nanoparticles increased; further increase of the volume of ethanol decreased the crystallinity. The smallest nanoparticle was obtained using 20 ml ethanol. As the calcination temperature increased from 400 °C to 700 °C, the saturation magnetization of the Co0.5Ni0.5Fe2O4 nanoparticles increased from 12.8 emu g−1 to 30.8 emu g−1. Co0.5Ni0.5Fe2O4 nanoparticles fabricated using 20 ml ethanol at 400 °C were used to study the removal of methyl blue (MB) by adsorption. Experimental data revealed that the adsorption was best described by pseudo-second kinetics. The adsorption isotherm applied the Temkin model, which indicated the presence of a single and multilayer associative mechanism in the adsorption of MB on the Co0.5Ni0.5Fe2O4 nanoparticles. The effect of pH and recycling on the adsorption was measured. At pH values ≥5, the adsorption was high. After eight cycles of use and recycling, the relative removal rate of MB by the Co0.5Ni0.5Fe2O4 nanoparticles was 75% of the initial adsorption value.

Digitale ISSN: 2053-1591

Thema: Chemie und Pharmazie , Maschinenbau , Physik

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Ultrafast stimulated resonance Raman signatures of lithium polysulfides for shuttling effect characterization: An ab initio study (2021)

Ren, Hao ; Wang, Zhengjie ; Guo, Sibei ; [weitere]

American Institute of Physics

In: Journal of Chemical Physics. 2021; 155(17): 174301. Published 2021 Nov 07. doi: 10.1063/5.0070577.

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Print ISSN: 0021-9606

Digitale ISSN: 1089-7690

Thema: Chemie und Pharmazie , Physik

Publiziert von American Institute of Physics

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Critical study of partial discharge inception in voids: statistical behavior to stochastic nature (2021)

Zhang, Rui ; Zhang, Qiaogen ; Zhou, Junjie ; [weitere]

Institute of Physics

In: Journal of Physics D: Applied Physics. 2021; 55(6): 065501. Published 2021 Oct 29. doi: 10.1088/1361-6463/ac30ba.

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Beschreibung: Although many studies have been done and advanced progress has been made in understanding partial discharge (PD) behavior in the void, this is not the case firinception of PD, especially its stochastic nature. The statistical behaviors of PD inception voltage (PDIV) and inception time delay (PDTD) inside the void were investigated in this study through repeated tests to observe the stochastic nature of PD inception. The results show that the PDIV and PDTD of the void are highly dispersed and obey Weibull and exponential distributions, respectively. The significant dispersion of PDIV can be attributed to the statistical time delay of PD inception. The lengthy inception delay is attributable to a lack of free electrons. The exponential distribution of PDTD indicates that free-electron generation is completely random; further, the stochastic nature of void PD inception is determined by the supply of free electrons. The test method (voltage rise rate, test time, and test time interval), void parameters (size, material, and surface condition), and background radiation determine PD inception by affecting the volume ionization or surface-emission process providing free electrons. Enhanced background ionization or significant increase in test voltage and test time allow for the effective detection of void defects during PD tests. This work contributes to an empirical understanding of the physical process of PD inception in voids and improving existing PD testing technologies.

Print ISSN: 0022-3727

Digitale ISSN: 1361-6463

Thema: Physik

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The validity of triple contact line theory from hydrophilic to superhydrophobic surfaces (2021)

Taher, Md Abu ; Rajput, Vinod K ; Krishnan P K, Navanith ; [weitere]

Institute of Physics

In: Journal of Physics D: Applied Physics. 2021; 55(5): 055305. Published 2021 Oct 29. doi: 10.1088/1361-6463/ac30b8.

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Beschreibung: The anisotropic droplet formulation is generalized from hydrophilic to superhydrophobic surfaces. An experimental method to calibrate the ellipsoidal droplet volume on both hydrophilic and hydrophobic surfaces is presented. A broad range of contact angles (CAs) is produced on the copper and stainless-steel surfaces using femtosecond laser patterning. The effects of line spacing between the laser scanning on the formation of anisotropic CAs are discussed. The comparative study of the evolution of anisotropic CAs and droplet’s spreading dynamics are studied on both surfaces. According to the triple contact line (TCL) theory, CAs are determined by the TCL between droplet and surface rather than the contact area. We presented the mathematical formalism and the experimental validity of the TCL theory on ellipsoidal droplets over a broad range of CAs, from as low as 37°–172°. This work experimentally validated the TCL theory over a broad range of CAs with good confidence.

Print ISSN: 0022-3727

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Thema: Physik

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Liquid nucleation around charged particles in the vapor phase (2021)

Kroll, Roni ; Tsori, Yoav

American Institute of Physics

In: Journal of Chemical Physics. 2021; 155(17): 174101. Published 2021 Nov 07. doi: 10.1063/5.0067249.

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Print ISSN: 0021-9606

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Thema: Chemie und Pharmazie , Physik

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Solution of quantum eigenvalue problems by means of algebraic consistency conditions (2021)

de la Peña, L ; Cetto, A M ; Valdés-Hernández, A

Institute of Physics

In: European Journal of Physics. 2021; 43(1): 015401. Published 2021 Oct 29. doi: 10.1088/1361-6404/ac2ecd.

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Print ISSN: 0143-0807

Digitale ISSN: 1361-6404

Thema: Physik

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First results from beam emission spectroscopy in SPIDER negative ion source (2021)

Barbisan, M ; Zaniol, B ; Pasqualotto, R ; [weitere]

Institute of Physics

In: Plasma Physics and Controlled Fusion. 2021; 63(12): 125009. Published 2021 Oct 27. doi: 10.1088/1361-6587/ac2eb2.

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Beschreibung: The SPIDER experiment, part of the neutral beam test facility at Consorzio RFX (Padua, Italy), is the prototype of the negative ion source for the ITER neutral beam injectors; the source is coupled to a 100 kV three-grid acceleration system. A beam emission spectroscopy (BES) diagnostic was installed in SPIDER to study and optimize the energy distribution, aim, uniformity and divergence of the H−/D− beam extracted from the source. The diagnostic is based on analysis of the Doppler shifted Hα /Dα light emitted in the interaction between the beam particles and the H 2/D 2 molecules of the background. In 2019 the BES diagnostic in SPIDER was installed and calibrated, allowing us to characterize the first hydrogen beams extracted from the SPIDER source, in cesium-free conditions. The number of active beamlets of which the beam was composed was reduced from 1280 to 80, affecting the BES diagnostic capabilities. This paper presents the BES diagnostic setup and discusses the first collected results. Under limited extracted current density (∼10 A m−2) and ion energy (⩽35 keV), no significant vertical beam deflection caused by the magnetic filter field in the source was detected. In some cases the beamlets were observed to be elongated in the horizontal direction; beamlet divergence values down to 20 mrad and 30 mrad e-folding were measured in the vertical and horizontal directions, respectively; the intensity of the Doppler shifted radiation was found to be strongly correlated to the beam current and to the beam divergence. The progressive compensation of beamlet deflections (caused by electron suppression filter fields), with increasing voltage in the extraction gap, was studied.

Print ISSN: 0741-3335

Digitale ISSN: 1361-6587

Thema: Physik

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Analysis of thermo-plasmonic lab-on-fiber probes in liquid environments (2021)

Giaquinto, M ; Principe, S ; Micco, A ; [weitere]

Institute of Physics

In: Smart Materials and Structures. 2021; 30(12): 125007. Published 2021 Oct 27. doi: 10.1088/1361-665x/ac2ef6.

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Publikationsdatum: 2021-10-27

Beschreibung: Lab-on-fiber (LOF) optrodes are recently emerging not only as valid platforms for biosensing, but also as promising light-controlled actuators in drug-delivery, optical trapping and thermo-ablation systems. In this regard, the thermo-plasmonic effect has been recognized as an intriguing tool for conferring to the optical fiber the capability of interacting with the external environment through the fine control of local overheating actuated by light in the range of few mW. However, the evaluation of the thermo-plasmonic overheating on small areas such as that of a standard single mode fiber tip is not trivial, especially in liquid solutions, where these probes typically operate. Here we demonstrate that by functionalizing the metallic nanostructure of LOF devices with a thermoresponsive smart materials, it is possible to measure the light-induced overheating on the fiber tip. Specifically, we monitored the plasmonic resonance wavelength shift induced by the temperature-dependent swelling dynamics of different microgel films deposited on the nanostructure. We find a local overheating of about 8 °C mW−1, i.e. also in line with our theoretical predictions based on numerical simulations. Our results demonstrate that the proposed approach is a valid methodology for the direct and continuous monitoring of the temperature changes in LOF devices induced by the input optical power in liquid environment. Our findings lay the basis for the analysis of thermo-plasmonic optical fiber probes exploitable in many applications, especially for the life science sector.

Print ISSN: 0964-1726

Digitale ISSN: 1361-665X

Thema: Maschinenbau

Publiziert von Institute of Physics

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Thermosolutal convection of nano–encapsulated phase change materials within a porous circular cylinder containing crescent with periodic side-wall temperature and concentration: ISPH simulation (2021)

Aly, Abdelraheem M. ; Raizah, Zehba

Institute of Physics

In: Physica Scripta. 2021; 96(12): 125243. Published 2021 Oct 29. doi: 10.1088/1402-4896/ac3118.

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Publikationsdatum: 2021-10-29

Print ISSN: 0031-8949

Digitale ISSN: 1402-4896

Thema: Physik

Publiziert von Institute of Physics

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Characterization of the seismic field at Virgo and improved estimates of Newtonian-noise suppression by recesses (2021)

Singha, Ayatri ; Hild, Stefan ; Harms, Jan ; [weitere]

Institute of Physics

In: Classical and Quantum Gravity. 2021; Published 2021 Oct 29. doi: 10.1088/1361-6382/ac348a. [early online release]

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Publikationsdatum: 2021-10-29

Beschreibung: Fluctuations of gravitational forces cause so-called Newtonian noise (NN) in gravitational-wave (GW) detectors which is expected to limit their low-frequency sensitivity in upcoming observing runs. Seismic NN is produced by seismic waves passing near a detector's suspended test masses. It is predicted to be the strongest contribution to NN. Modeling this contribution accurately is a major challenge. Arrays of seismometers were deployed at the Virgo site to characterize the seismic field near the four test masses. In this paper, we present results of a spectral analysis of the array data from one of Virgo's end buildings to identify dominant modes of the seismic field. Some of the modes can be associated with known seismic sources. Analyzing the modes over a range of frequencies, we provide a dispersion curve of Rayleigh waves. We find that the Rayleigh speed in the NN frequency band 10,Hz--20,Hz is very low ($lesssim$100,m/s), which has important consequences for Virgo's seismic NN. Using the new speed estimate, we find that the recess formed under the suspended test masses by a basement level at the end buildings leads to a 10 fold reduction of seismic NN.

Print ISSN: 0264-9381

Digitale ISSN: 1361-6382

Thema: Physik

Publiziert von Institute of Physics

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Energy absorption within elastic range for AZ31 magnesium alloy (2021)

Yang, Yongbiao ; Zhang, TingYan ; Guo, Jinxuan ; [weitere]

Institute of Physics

In: Materials Research Express. 2021; 8(10): 106522. Published 2021 Oct 01. doi: 10.1088/2053-1591/ac3104.

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Publikationsdatum: 2021-10-01

Beschreibung: Energy absorption for AZ31 magnesium Alloy was investigated with Split Hopkinson Pressure Bar using single stress wave so as to avoid multiple stress wave loading. The stress wave amplitude, which was in elastic stress range and propagated along the AZ31 magnesium bar, was reduced with increasing propagating distance, and with increasing stress wave amplitude, the stress wave amplitude reduction along the magnesium bar was increased losing more energy as compared with that of the stress wave with lower amplitude. The drastically decreased stress wave amplitude could be explained based on dislocations movements, which was similar to the established theory of damping for the explanation of the energy loss during cyclic loading. However, it was not the case for LY12 aluminum alloy: the stress wave amplitude changed slightly without drastic energy loss regardless of the variation of stress wave amplitude.

Digitale ISSN: 2053-1591

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Publiziert von Institute of Physics

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Direct ink write printing of resistive-type humidity sensors (2021)

Yan, Feng-Jie ; Huang, Wan-Qing ; Sang, Xu-Hui ; [weitere]

Institute of Physics

In: Flexible and Printed Electronics. 2021; 6(4): 045007. Published 2021 Nov 01. doi: 10.1088/2058-8585/ac310b.

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Publikationsdatum: 2021-11-01

Digitale ISSN: 2058-8585

Thema: Elektrotechnik, Elektronik, Nachrichtentechnik

Publiziert von Institute of Physics

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First principles study of the 2D Mo(S1-XTeX)2 TMD alloy adsorbed on an Al-terminated sapphire (0001)-substrate (2021)

Burton, B P

Institute of Physics

In: Materials Research Express. 2021; 8(10): 105016. Published 2021 Oct 01. doi: 10.1088/2053-1591/ac303e.

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Publikationsdatum: 2021-10-01

Beschreibung: A first principles study, was performed for a 2D, three atom thick monolayer of the Transition Metal Dichalcogenide (TMD) alloy Mo(S1-XTeX)2 adsorbed on an Al-terminated (0001)-sapphire surface. Bulk composition dependent binding energies and band-gaps, and a partial phase diagram, were calculated, using the cluster expansion method. Although the 3D Mo(S1-XTeX)2 alloy system has a phase diagram that is dominated by S-rich/Te-rich phase separation, the 2D system adsorbed on sapphire is dominated by S:Te-ordering. Five ground-state phases are predicted; all have P1 symmetry, and all disorder via contiuous (2’nd order) transitions. These results indicate that synthesis on the sapphire substrate is favorable for band-gap engineering, in which a continuous single phase solid solution allows continuous band-gap tuning, as a function of bulk composition. Whereas, bulk TMD-synthesis followed by exfoliation favors the formation of two-phase mixtures.

Digitale ISSN: 2053-1591

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Publiziert von Institute of Physics

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Effects of oxidizer structure on thermal and combustion behavior of Fe2O3/Zr thermite (2021)

Li, Chunhong ; Kang, Xiaoli

Institute of Physics

In: Materials Research Express. 2021; 8(10): 105014. Published 2021 Oct 01. doi: 10.1088/2053-1591/ac3040.

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Publikationsdatum: 2021-10-01

Beschreibung: Performance of MOF-derived micrometer porous Fe2O3 as the oxidizer in Zr-fuelled thermite is compared with commercial nano-sized Fe2O3 by characterizing thermal and combustion behavior of Fe2O3/Zr mixture via differential scanning calorimetry, optical emission measurement as well as composition and morphology analysis on condensed combustion products. Results show that thermal behaviors of Fe2O3/Zr with a slow heating rate have little difference regardless of the kind of Fe2O3. However, MOF-derived micrometer porous Fe2O3 show an obvious superiority in enhancing combustion of Fe2O3/Zr heated by a high rate. Combustion reactions of Fe2O3/Zr under high heating rates are probably rate-controlled by condensed reaction. The better performance of MOF-derived Fe2O3 is attributed to its larger contact area with Zr particle in that micrometer porous Fe2O3 particles are easily broken into primitive nano-sized particles, which effectively avoid the agglomeration of oxidizer. The MOF-derived Fe2O3 particles obtained at calcination temperature of 550 °C enable the best combustion performance of Fe2O3/Zr thermite. This should be because the crystallinity and porous structure of 550 °C-Fe2O3 are more favorable for the mass transfer process during high-rate combustion.

Digitale ISSN: 2053-1591

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Publiziert von Institute of Physics

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Unveiling the formation and control of unique swirling discharge pattern in helium plasma candle device (2021)

Abdelaziz, Ayman A ; Teramoto, Yoshiyuki ; Kim, Hyun-Ha

Institute of Physics

In: Journal of Physics D: Applied Physics. 2021; 55(6): 065201. Published 2021 Oct 29. doi: 10.1088/1361-6463/ac3036.

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Publikationsdatum: 2021-10-29

Beschreibung: The generation of a large cold plasma jet while maintaining the reproducibility and homogeneity of the discharge is one of the major challenges encountered by the plasma community to efficiently apply this technology in the industry. Here, we report on the discharge in a recently developed device called the plasma candle (PC), wherein a stable plasma jet with a diameter of 20 mm can be generated at atmospheric pressure and temperature. Unlike the discharge morphology previously reported for conventional plasma jet devices, the unique configuration of PC device resulted in distinctive discharge patterns. Homogenous discharge was generated in the electrode gap and followed by a swirling discharge toward the tube nozzle. Fast photography and electrical measurements revealed that filament propagation and its morphology form the visually observable swirl discharge. Detailed analysis indicated that residual helium metastable species (Hem) and their penning ionization play an essential role in the discharge mode and its transition, which was verified by changing the feeding gas and the frequency of the applied voltage. For instance, it is found that only filamentary discharge was observed along the entire tube at frequencies less than 3 kHz, at which the time between consecutive discharges was long enough for Hem decay. Consequently, the homogenous discharge pattern was recovered by increasing the pre-ionization levels by adding a trace of impurities (N2, O2 or H2O) to the feeding gas. However, the level of these impurities must be carefully adjusted to achieve a homogenous discharge without negatively affecting the jet properties. A trivial change in the gas impurity, in the range of adsorption and desorption of water from the gas tubing, is sufficient to cause a noticeable change and instability in the discharge mode. This finding is critical to predicting the production of reactive species and plasma-surface interaction for different applications.

Print ISSN: 0022-3727

Digitale ISSN: 1361-6463

Thema: Physik

Publiziert von Institute of Physics

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Theory of frequency-selective homonuclear dipolar recoupling in solid-state NMR (2021)

Xiao, Hang ; Zhang, Zhengfeng ; Yang, Jun

American Institute of Physics

In: Journal of Chemical Physics. 2021; 155(17): 174105. Published 2021 Nov 07. doi: 10.1063/5.0065396.

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Publikationsdatum: 2021-11-07

Print ISSN: 0021-9606

Digitale ISSN: 1089-7690

Thema: Chemie und Pharmazie , Physik

Publiziert von American Institute of Physics

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Nonadiabatic quantum state engineering by time-dependent decoherence-free subspaces in open quantum systems (2021)

Wu, Qi-Cheng ; Zhou, Yan-Hui ; Ye, Biao-Liang ; [weitere]

Institute of Physics

In: New Journal of Physics. 2021; 23(11): 113005. Published 2021 Nov 01. doi: 10.1088/1367-2630/ac309d.

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Publikationsdatum: 2021-11-01

Digitale ISSN: 1367-2630

Thema: Physik

Publiziert von Institute of Physics

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Faraday waves in strongly interacting superfluids (2021)

Hernández-Rajkov, Diego ; Padilla-Castillo, José Eduardo ; Río-Lima, Alejandra del ; [weitere]

Institute of Physics

In: New Journal of Physics. 2021; 23(10): 103038. Published 2021 Oct 01. doi: 10.1088/1367-2630/ac2d70.

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Publikationsdatum: 2021-10-01

Digitale ISSN: 1367-2630

Thema: Physik

Publiziert von Institute of Physics

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Investigating the absorption performance of a monolayer-coated absorber at oblique incidence (2021)

Zhang, Junming ; Liu, Chang ; Wang, Tao ; [weitere]

Institute of Physics

In: Journal of Physics D: Applied Physics. 2021; 55(6): 065001. Published 2021 Oct 29. doi: 10.1088/1361-6463/ac2f14.

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Publikationsdatum: 2021-10-29

Beschreibung: There is a widely observed phenomenon in the microwave absorption field that an absorber always exhibits good oblique incidence absorption capacity if it has high performance at normal incidence. However, if a certain angle is exceeded, this kind of effective absorptive capacity will no longer be maintained. Besides, an absorber performs differently for incident transverse electric (TE) and transverse magnetic (TM) waves: for the TE case, the absorber can no longer obtain effective absorption; for the TM case, another efficient absorption region was observed at higher frequencies even when the incident angle exceeded 80°. These phenomena are widely found in the literature, which demonstrates that they are caused by physical laws rather than material properties. To demonstrate the underlying reason, in this study, the common spherical carbonyl iron-polyurethane composite absorbers were fabricated as a typical example. Their absorbing performance was investigated via both simulation and experiment. All the phenomena mentioned above were observed, studied in detail by employing the multiple reflection model, and explained quantitatively. Further, along with establishing the underlying mechanism of electromagnetic wave transmission in the absorber, two formulas were deduced to predict: (a) the maximum incident angle for efficient absorption of the TE polarized wave; and (b) the required absorber thickness for obtaining efficient absorption for a large incident angle of the TM polarized wave.

Print ISSN: 0022-3727

Digitale ISSN: 1361-6463

Thema: Physik

Publiziert von Institute of Physics

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Low-speed flutter of artificial stalk-leaf and its application in wind energy harvesting (2021)

Wang, Kun ; Xia, Wei ; Lin, Tianlong ; [weitere]

Institute of Physics

In: Smart Materials and Structures. 2021; 30(12): 125002. Published 2021 Oct 25. doi: 10.1088/1361-665x/ac2de3.

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Publikationsdatum: 2021-10-25

Beschreibung: Developing wind energy harvester (WEH) by mimicking the leaf flutter may provide an innovative way for increasing the power efficiency and decreasing the cut-in speed. The low-speed flutter mechanism of the stalk-leaf system is investigated through introducing a frictionless hinge into the stalk-leaf finite element model. The aeroelastic system is established by the usage of doublet-lattice aerodynamics and the spline interpolation between structural motion and flow downwash. The critical flutter speed and frequency are analyzed via V-g method. The evolution of damping and frequency with wind speed which various from static air to Beaufort level 5 are simulated. The influence of inclined angle of the stalk on the flutter characteristics is studied. The stainless-steel artificial stalk-leaf systems with inclined angles of 0°, 15°, 30°, 45°, 60°, 75°, and 90° are fabricated and tested in wind tunnel. The wind energy harvesting performance is also measured by attaching macro-fiber composite patches on root of the stalk. It is found that the 30° stalk-leaf WEH has the lowest critical flutter speed, while the energy harvesting output (voltage and power) increases slowly with the increase of the wind speed. On the contrary, although the 90° stalk-leaf (vertical stalk) WEH has the steepest velocity-voltage and velocity-power curve, it also has the highest cut-in speed. In the preliminary tests, the 30° stalk-leaf WEH outputs steady power density of 47.46 μW cm−3 with stable oscillating frequency of 6.6 Hz at 11 m s−1 wind, while the 90° stalk-leaf WEH outputs power density of 92.88 μW cm−3 with oscillating frequency of 7.2 Hz at the same wind speed. The stalk-leaf design presents a possible way to balance the performance between the high efficiency and the low cut-in speed for the WEHs.

Print ISSN: 0964-1726

Digitale ISSN: 1361-665X

Thema: Maschinenbau

Publiziert von Institute of Physics

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