Advanced thermal response tests: A review Wilke, Sascha; Menberg, Kathrin; Steger, Hagen ...
Renewable & sustainable energy reviews,
March 2020, 2020-03-00, Letnik:
119
Journal Article
Recenzirano
In this study, the historical and technical development and the current status of distributed (DTRT) and enhanced (ETRT) thermal response tests (TRT) are reviewed. The different test setups of these ...advanced TRT are critically assessed and future research questions are outlined. Advanced TRT use specific temperature measurement techniques for the depth-resolved determination of site-specific ground parameters that are required for an optimal design of borehole heat exchanger (BHE) fields. The depth-resolved determination of these thermal properties, such as effective thermal conductivities and thermal borehole resistances, is the key advantage in comparison to conventional TRT, promising economic benefits during the installation and operating phase of ground source heat pump (GSHP) systems. Various test setups exist which differ regarding the heating procedure, i.e. circulating heating fluid and heating wire, the temperature measurement technique, i.e. optical fiber and wireless probe, as well as in their suitability for parameter estimation. These advanced techniques can furthermore provide information about geological layers, fractured zones and groundwater influenced sections in the subsurface as well as inadequate backfilled zones along the borehole heat exchanger. Despite this, advanced TRT are reported in international literature only for a few locations and some test setups are purely theoretical without any practical demonstration. Uncertainties exist regarding the comparability of the test setups, the sensitivity of the measurement devices under test conditions, as well as the best evaluation procedure. Also, scarce information is available about the use beyond academic field and economic aspects in comparison to conventional TRT. Encouraging further research and a more extensive transfer of these promising techniques from academia to practice is therefore also the aim of this review.
•Advanced TRT enable the depth-resolved determination of ground thermal parameters.•The temperature measurement is conducted either by optical fibers or wireless probes.•Different test setups exist for advanced TRT, with individual (dis)advantages.•Open questions exist regarding the best test setup and the utilization in practice.
Unmanned aerial vehicles (UAVs) open new opportunities in precision agriculture and phenotyping because of their flexibility and low cost. In this study, the potential of UAV imagery was evaluated to ...quantify lodging percentage and lodging severity of barley using structure from motion (SfM) techniques. Traditionally, lodging quantification is based on time-consuming manual field observations. Our UAV-based approach makes use of a quantitative threshold to determine lodging percentage in a first step. The derived lodging estimates showed a very high correlation to reference data (R2 = 0.96, root mean square error (RMSE) = 7.66%) when applied to breeding trials, which could also be confirmed under realistic farming conditions. As a second step, an approach was developed that allows the assessment of lodging severity, information that is important to estimate yield impairment, which also takes the intensity of lodging events into account. Both parameters were tested on three ground sample distances. The lowest spatial resolution acquired from the highest flight altitude (100 m) still led to high accuracy, which increases the practicability of the method for large areas. Our new lodging assessment procedure can be used for insurance applications, precision farming, and selecting for genetic lines with greater lodging resistance in breeding research.
The controlled synthesis of superparamagnetic iron oxide nanoparticles is crucial for a variety of biomedical applications. Among different synthesis routes, thermal precursor decomposition methods ...are the most versatile, yielding monodisperse nanoparticles on the multigram scale. Recent in situ kinetic studies of the nucleation and growth processes during thermal decomposition routes revealed nonclassical nucleation and growth paths involving amorphous precursor phases and aggregative growth steps. With the knowledge of this kinetic mechanism, we systematically examined a range of different iron oxide heat-up synthesis routes to understand and conclude which methods allow good and reproducible size control over a range of relevant nanoparticle diameters. Using transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) for the characterization of the nanoparticle size distribution, we find that a set of solvents (1-octadecene, trioctylamine, docosane) provides access to a temperature range between 300 and 370 °C, allowing us to synthesize monodisperse nanoparticles in a size range of 6–24 nm on a large scale. We confirm that a thermal pretreatment of the iron oxide precursor is essential to achieve reproducible size control. We find that each solvent provides access to a certain temperature range, within which the variation of temperature, heating rate, or precursor concentration allows us to reproducibly control the nanoparticle size.
Land surface temperature (LST) is a fundamental parameter within the system of the Earth’s surface and atmosphere, which can be used to describe the inherent physical processes of energy and water ...exchange. The need for LST has been increasingly recognised in agriculture, as it affects the growth phases of crops and crop yields. However, challenges in overcoming the large discrepancies between the retrieved LST and ground truth data still exist. Precise LST measurement depends mainly on accurately deriving the surface emissivity, which is very dynamic due to changing states of land cover and plant development. In this study, we present an LST retrieval algorithm for the combined use of multispectral optical and thermal UAV images, which has been optimised for operational applications in agriculture to map the heterogeneous and diverse agricultural crop systems of a research campus in Germany (April 2018). We constrain the emissivity using certain NDVI thresholds to distinguish different land surface types. The algorithm includes atmospheric corrections and environmental thermal emissions to minimise the uncertainties. In the analysis, we emphasise that the omission of crucial meteorological parameters and inaccurately determined emissivities can lead to a considerably underestimated LST; however, if the emissivity is underestimated, the LST can be overestimated. The retrieved LST is validated by reference temperatures from nearby ponds and weather stations. The validation of the thermal measurements indicates a mean absolute error of about 0.5 K. The novelty of the dual sensor system is that it simultaneously captures highly spatially resolved optical and thermal images, in order to construct the precise LST ortho-mosaics required to monitor plant diseases and drought stress and validate airborne and satellite data.
Background: Foam rolling is a type of self-massage using tools such as foam or roller sticks. However, to date, there is no consensus on contraindications and cautions of foam rolling. A ...methodological approach to narrow that research gap is to obtain reliable opinions of expert groups. The aim of the study was to develop experts’ consensus on contraindications and cautions of foam rolling by means of a Delphi process. Methods: An international three-round Delphi study was conducted. Academic experts, defined as having (co-) authored at least one PubMed-listed paper on foam rolling, were invited to participate. Rounds 1 and 2 involved generation and rating of a list of possible contraindications and cautions of foam rolling. In round 3, participants indicated their agreement on contraindications and cautions for a final set of conditions. Consensus was evaluated using a priori defined criteria. Consensus on contraindications and cautions was considered as reached if more than 70% of participating experts labeled the respective item as contraindication and contraindication or caution, respectively, in round 3. Results: In the final Delphi process round, responses were received from 37 participants. Panel participants were predominantly sports scientists (n = 21), physiotherapists (n = 6), and medical professionals (n = 5). Consensus on contraindications was reached for open wounds (73% agreement) and bone fractures (84%). Consensus on cautions was achieved for local tissue inflammation (97%), deep vein thrombosis (97%), osteomyelitis (94%), and myositis ossificans (92%). The highest impact/severity of an adverse event caused by contraindication/cautions was estimated for bone fractures, deep vein thrombosis, and osteomyelitis. Discussion: The mechanical forces applied through foam rolling can be considered as potential threats leading to adverse events in the context of the identified contraindications and cautions. Further evaluations by medical professionals as well as the collection of clinical data are needed to assess the risks of foam rolling and to generate guidance for different applications and professional backgrounds.
Determining the temporal or spatial origin of an invasive population is a challenging task as first detections are often made only after the respective species is established. In this study we ...propose an indirect method for dating introduction events. It is based on the characteristic competition dynamics of two invasive freshwater taxa in Western Europe: the established invader
Dreissena polymorpha
(zebra mussel) and the recent invader
Dreissena rostriformis bugensis
(quagga mussel). The underlying assumption is that in sympatric populations, the quagga mussel outcompetes the zebra mussel over time. Thus, relative abundance of the quagga mussel might correlate with time since introduction. On a European scale, we tested this assumption with a combination of data from field samplings and the literature. The correlation analysis confirmed the assumption of a time depended displacement of the zebra mussel by the quagga mussel. In a second step, we calculated the specific rates of displacement based on a regular monitoring of four selected sites in the western part of Europe. These time-series studies revealed an increase of relative abundance of the quagga mussel of 36% per year. We then tested our novel tool by using three case studies, showing that our estimations of quagga mussel introduction events are in concordance with data from independent studies. We propose that our method provides a useful tool to estimate the age of a given quagga mussel population within few years after introduction.
Summary form only given. Ultrafast transmission electron microscopy (UTEM) is a powerful tool to study the dynamics of nanoscale systems, combining the versatile imaging, diffraction and spectroscopy ...capabilities of state-of-the-art TEM with femtosecond temporal resolution of a laser pump/electron probe scheme 1,2. In particular, inelastic scattering between a free electron pulse and strong optical near fields 3,4 (Fig.1a) allows for a coherent manipulation of the electron quantum state. In this mechanism, the optical field imprints a sinusoidal phase modulation on the electron wave function 4, which manifests in a comb of photon sidebands in the kinetic energy distribution (Fig.1b) and - by energy-filtering - enables photon-induced near-field electron microscopy (PINEM) 3. Here, we discuss a range of applications enabled by quantum-coherent electron-light interactions in ultrafast transmission electron microscopy. Specifically, we employ electron spectroscopy to map intense optical near fields by phase -resolved P1NEM, and utilize the interaction to manipulate the longitudinal and transverse free electron wave function. The Gottingen UTEM instrument features optical sample excitation and the generation of highly coherent electron pulses with a pulse duration down to 200 fs (full-width-at-half-maximum), a spectral width of 0.6 eV, and a sub-1 nm electron focal spot size 2. Hereby, in a scanning variant of photon-induced near-field electron microscopy (S-P1NEM), we quantitatively map local plasmonic modes and their optical properties with nanometer spatial resolution. Specifically, tailoring the polarization state of the illuminating light gives access to the li near or chiral optical response of a nanostructure 2,5. In a further application, we employ two subsequent near field interactions (Figid) to demonstrate the temporal structuring of free -electron beams on the attosecond timescale 6. By dispersive propagation after the first interaction, the phase modulation of the initial electron wave function results in an electron density modulation. After the second interaction at varied propagation distances we record spectrograms with accurately controllable phase delay (Fig.le), which allows us to reconstruct the temporal shape of the electron density and to show the compression of electron pulses into trains of attosecond bursts. In conclusion, we demonstrated the quantitative nanoscale mapping of the local optical response in tailored nanostructures. Furthermore, the generation of attosecond electron pulse trains paves the way towards a new kind of optically phase -resolved electron microscopy.
PDF
