Fakultät Naturwissenschaften

Permanent URI for this communityhttps://hohpublica.uni-hohenheim.de/handle/123456789/1

Biologie, Ernährungs-wissenschaften und Lebensmittelwissenschaften sind die Schwerpunkte der Fakultät. Die Forschung befasst sich mit Schlüsselthemen der Life Sciences.

Homepage: https://natur.uni-hohenheim.de/

Browse

Browsing Fakultät Naturwissenschaften by Classification "620"

Type the first few letters and click on the Browse button
Now showing 1 - 4 of 4
  • Thumbnail Image
    Publication
    Estimating the technical wind energy potential of Kansas that incorporates the effect of regional wind resource depletion by wind turbines
    (2024) Minz, Jonathan; Kleidon, Axel; Mbungu, Nsilulu T.
    Energy scenarios require realistic estimates of technical wind energy potentials – estimates for how much electricity can be generated by wind turbines given a certain level of deployed capacity within a region. These are typically obtained using observed wind speeds, neglecting the depletion of the wind energy resource with increasing deployment at the regional scale. Here, we use the kinetic energy budget of the atmosphere (KEBA) approach to evaluate the importance of this resource depletion effect for the technical potential of Kansas, USA. To do so, we first apply the KEBA approach to a previously conducted set of numerical simulations with the Weather Research Forecasting (WRF) model. This set simulated the resource depletion effect for a range of different levels of wind turbine deployments within Kansas, which we use to test the KEBA approach. We specifically test the approach for nighttime and daytime conditions to capture the different mixing regimes of the atmospheric boundary layer. We find that KEBA can adequately capture the effect for both settings. We then extend our analysis by using ERA-5 forcing to the climatological scale. We find that this resource depletion effect increases almost linearly with the level of wind turbine deployment. Compared to previously published estimates for the technical potential for Kansas, the resource depletion effect lowers capacity factors by a third to a half. Since this resource depletion effect increases with installed capacity within a region, it is policy relevant even at relatively low deployment levels.
  • Thumbnail Image
    Publication
    Ingenious wheat starch/Lepidium perfoliatum seed mucilage hybrid composite films: Synthesis, incorporating nanostructured Dy₂Ce₂O₇ synthesized via an ultrasound-assisted approach and characterization
    (2025) Zinatloo-Ajabshir,Sahar; Yousefi, Alireza; Jekle, Mario; Sharifianjazi, Fariborz
    In this study, Dy₂Ce₂O₇ nanostructures were fabricated using an environmentally friendly, ultrasound-assisted method. These nanostructures were then incorporated into a blend of wheat starch (WS) and Lepidium perfoliatum seed mucilage (LPSM), along with sodium montmorillonite (Na-MMT) nanoparticles. The composite films were produced through a casting method, combining these components to enhance the films' structural and functional properties. FTIR results confirmed the chemical interactions between the NPs and the biopolymeric matrix of the nanocomposites. SEM surface morphology and XRD crystallography results indicated that up to a 1 % weight ratio, the dispersion of Dy₂Ce₂O₇ in the nanocomposite matrix was uniform, while at higher percentages, due to nanoparticle aggregation, crystallinity increased. Interestingly, the elongation of nanocomposites containing Dy₂Ce₂O₇ increased, while their tensile strength and elastic modulus decreased. More than 92 % of UV radiation in the 240–360 nm range was absorbed with the inclusion of 1 % wt. Dy₂Ce₂O₇, and the water vapor permeability (WVP) significantly decreased. Among the Dy₂Ce₂O₇-based nanocomposites, TGA results showed that the WS/LPSM/MMT/Dy1 % sample had the highest thermal stability. Overall, based on the results of this study, the WS/LPSM/MMT/Dy1 % sample was introduced as a composite film with suitable physicochemical and mechanical properties for food and pharmaceutical packaging.
  • Thumbnail Image
    Publication
    Macroscopic rheology of non-Brownian suspensions at high shear rates: the influence of solid volume fraction and non-Newtonian behaviour of the liquid phase
    (2021) Wilms, Patrick; Hinrichs, Jörg; Kohlus, Reinhard
    Modelling the macroscopic rheology of non-Brownian suspensions is complicated by the non-linear behaviour that originates from the interaction between solid particles and the liquid phase. In this contribution, a model is presented that describes suspension rheology as a function of solid volume fraction and shear rate dependency of both the liquid phase, as well as the suspension as a whole. It is experimentally validated using rotational rheometry ( ≤ 0.40) and capillary rheometry (0.55 ≤  ≤ 0.60) at shear rates > 50 s−1. A modified Krieger-Dougherty relation was used to describe the influence of solid volume fraction on the consistency coefficient, , and was fitted to suspensions with a shear thinning liquid phase, i.e. having a flow index, , of 0.50. With the calculated fit parameters, it was possible to predict the consistency coefficients of suspensions with a large variation in the shear rate dependency of the liquid phase ( = 0.20–1.00). With increasing solid volume fraction, the flow indices of the suspensions were found to decrease for Newtonian and mildly shear thinning liquid phases ( ≥0.50), whereas they were found to increase for strongly shear thinning liquid phases ( ≤0.27). It is hypothesized that this is related to interparticle friction and the relative contribution of friction forces to the viscosity of the suspension. The proposed model is a step towards the prediction of the flow curves of concentrated suspensions with non-Newtonian liquid phases at high shear rates.
  • Thumbnail Image
    Publication
    Statistical analysis of simulated spaceborne thermodynamics lidar measurements in the planetary boundary layer
    (2022) Whiteman, David N.; Di Girolamo, Paolo; Behrendt, Andreas; Wulfmeyer, Volker; Franco, Noemi
    The performance of a spaceborne Raman lidar offering measurements of water vapor, temperature, aerosol backscatter and extinction is assessed statistically by use of a lidar simulator and a global model to provide inputs for simulation. The candidate thermodynamics lidar system is envisioned to make use of a sun-synchronous, dawn/dusk orbit. Cloud-free atmospheric profiles simulated by the NASA/GSFC GEOS model for the orbit of the CALIPSO satellite on 15 July 2009 were used as input to a previously validated lidar simulator where GEOS profiles that satisfy the solar zenith angle restrictions of the dawn/dusk orbit, and are located within the Planetary Boundary Layer as defined by the GEOS model, were selected for the statistical analysis. To assess the performance of the simulated thermodynamics lidar system, measurement goals were established by considering the WMO Observing Systems Capability Analysis and Review (OSCAR) requirements for Numerical Weather Prediction. The efforts of Di Girolamo et al., 2018 established the theoretical basis for the current work and discussed many of the technological considerations for a spaceborne thermodynamics lidar. The work presented here was performed during 2017–2018 under the auspices of the NASA/GSFC Planetary Boundary Layer Science Task Group and expanded on previous efforts by considerably increasing the statistical robustness of the performance simulations and extending the statistics to include those of aerosol backscatter and extinction measurements. Further work that is currently being conducted includes Observing Systems Simulation Experiments to assess the impact of a thermodynamics lidar on global forecast improvement.