TY  - CHAP
A1  - Caminos, Ricardo Alexander Chico
A1  - Schmitz, Pascal
A1  - Atti, Vikrama
A1  - Mahdi, Zahra
A1  - Teixeira Boura, Cristiano José
A1  - Sattler, Johannes Christoph
A1  - Herrmann, Ulf
A1  - Hilger, Patrick
A1  - Dieckmann, Simon
T1  - Development of a micro heliostat and optical qualification assessment with a 3D laser scanning method
T2  - SOLARPACES 2020
N2  - The Solar-Institut Jülich (SIJ) and the companies Hilger GmbH and Heliokon GmbH from Germany have developed a small-scale cost-effective heliostat, called “micro heliostat”. Micro heliostats can be deployed in small-scale concentrated solar power (CSP) plants to concentrate the sun's radiation for electricity generation, space or domestic water heating or industrial process heat. In contrast to conventional heliostats, the special feature of a micro heliostat is that it consists of dozens of parallel-moving, interconnected, rotatable mirror facets. The mirror facets array is fixed inside a box-shaped module and is protected from weathering and wind forces by a transparent glass cover. The choice of the building materials for the box, tracking mechanism and mirrors is largely dependent on the selected production process and the intended application of the micro heliostat. Special attention was paid to the material of the tracking mechanism as this has a direct influence on the accuracy of the micro heliostat. The choice of materials for the mirror support structure and the tracking mechanism is made in favor of plastic molded parts. A qualification assessment method has been developed by the SIJ in which a 3D laser scanner is used in combination with a coordinate measuring machine (CMM). For the validation of this assessment method, a single mirror facet was scanned and the slope deviation was computed.
KW  - Concentrated solar power
KW  - Electricity generation
KW  - Measuring instruments
KW  - Heliostats
KW  - Global change
Y1  - 2022
SN  - 978-0-7354-4195-8
U6  - http://dx.doi.org/10.1063/5.0086262
SN  - 1551-7616 (online)
SN  - 0094-243X (print)
N1  - 26th International Conference on Concentrating Solar Power and Chemical Energy Systems
28 September–2 October 2020
Freiburg, Germany
IS  - 2445 / 1
PB  - AIP conference proceedings / American Institute of Physics
CY  - Melville, NY
ER  - 
TY  - CHAP
A1  - Niederwestberg, Stefan
A1  - Schneider, Falko
A1  - Teixeira Boura, Cristiano José
A1  - Herrmann, Ulf
T1  - Introduction to a direct irradiated transparent tube particle receiver
T2  - SOLARPACES 2020
N2  - New materials often lead to innovations and advantages in technical applications. This also applies to the particle receiver proposed in this work that deploys high-temperature and scratch resistant transparent ceramics. With this receiver design, particles are heated through direct-contact concentrated solar irradiance while flowing downwards through tubular transparent ceramics from top to bottom. In this paper, the developed particle receiver as well as advantages and disadvantages are described. Investigations on the particle heat-up characteristics from solar irradiance were carried out with DEM simulations which indicate that particle temperatures can reach up to 1200 K. Additionally, a simulation model was set up for investigating the dynamic behavior. A test receiver at laboratory scale has been designed and is currently being built. In upcoming tests, the receiver test rig will be used to validate the simulation results. The design and the measurement equipment is described in this work.
KW  - Solar irradiance
KW  - Ceramics
Y1  - 2022
SN  - 978-0-7354-4195-8
U6  - http://dx.doi.org/10.1063/5.0086735
SN  - 1551-7616 (online)
SN  - 0094-243X (print)
N1  - 26th International Conference on Concentrating Solar Power and Chemical Energy Systems
28 September–2 October 2020
Freiburg, Germany
IS  - 2445 / 1
PB  - AIP conference proceedings / American Institute of Physics
CY  - Melville, NY
ER  - 
TY  - CHAP
A1  - Sattler, Johannes Christoph
A1  - Schneider, Iesse Peer
A1  - Angele, Florian
A1  - Atti, Vikrama
A1  - Teixeira Boura, Cristiano José
A1  - Herrmann, Ulf
T1  - Development of heliostat field calibration methods: Theory and experimental test results
T2  - SolarPACES conference proceedings
N2  - In this work, three patent pending calibration methods for heliostat fields of central receiver systems (CRS) developed by the Solar-Institut Jülich (SIJ) of the FH Aachen University of Applied Sciences are presented. The calibration methods can either operate in a combined mode or in stand-alone mode. The first calibration method, method A, foresees that a camera matrix is placed into the receiver plane where it is subjected to concentrated solar irradiance during a measurement process. The second calibration method, method B, uses an unmanned aerial vehicle (UAV) such as a quadrocopter to automatically fly into the reflected solar irradiance cross-section of one or more heliostats (two variants of method B were tested). The third calibration method, method C, foresees a stereo central camera or multiple stereo cameras installed e.g. on the solar tower whereby the orientations of the heliostats are calculated from the location detection of spherical red markers attached to the heliostats. The most accurate method is method A which has a mean accuracy of 0.17 mrad. The mean accuracy of method B variant 1 is 1.36 mrad and of variant 2 is 1.73 mrad. Method C has a mean accuracy of 15.07 mrad. For method B there is great potential regarding improving the measurement accuracy. For method C the collected data was not sufficient for determining whether or not there is potential for improving the accuracy.
KW  - Heliostat Field Calibration
KW  - Unmanned aerial vehicle
KW  - UAV
KW  - Quadrocopter
KW  - Camera system
Y1  - 2024
U6  - http://dx.doi.org/10.52825/solarpaces.v1i.678
SN  - 2751-9899 (online)
N1  - 28th International Conference on Concentrating Solar Power and Chemical Energy Systems, 27-30 September, Albuquerque, NM, USA
IS  - Vol. 1
PB  - TIB Open Publishing
CY  - Hannover
ER  - 
TY  - CHAP
A1  - Sattler, Johannes Christoph
A1  - Atti, Vikrama
A1  - Alexopoulos, Spiros
A1  - Teixeira Boura, Cristiano José
A1  - Herrmann, Ulf
A1  - Dutta, Siddharth
A1  - Kioutsioukis, Ioannis
T1  - DNI forecast tool for the smart operation of a parabolic trough collector system with concrete thermal energy storage: Theory, results and outlook
T2  - SolarPACES conference proceedings
N2  - This work presents a basic forecast tool for predicting direct normal irradiance (DNI) in hourly resolution, which the Solar-Institut Jülich (SIJ) is developing within a research project. The DNI forecast data shall be used for a parabolic trough collector (PTC) system with a concrete thermal energy storage (C-TES) located at the company KEAN Soft Drinks Ltd in Limassol, Cyprus. On a daily basis, 24-hour DNI prediction data in hourly resolution shall be automatically produced using free or very low-cost weather forecast data as input. The purpose of the DNI forecast tool is to automatically transfer the DNI forecast data on a daily basis to a main control unit (MCU). The MCU automatically makes a smart decision on the operation mode of the PTC system such as steam production mode and/or C-TES charging mode. The DNI forecast tool was evaluated using historical data of measured DNI from an on-site weather station, which was compared to the DNI forecast data. The DNI forecast tool was tested using data from 56 days between January and March 2022, which included days with a strong variation in DNI due to cloud passages. For the evaluation of the DNI forecast reliability, three categories were created and the forecast data was sorted accordingly. The result was that the DNI forecast tool has a reliability of 71.4 % based on the tested days. The result fulfils SIJ’s aim to achieve a reliability of around 70 %, but SIJ aims to still improve the DNI forecast quality.
KW  - Direct normal irradiance forecast
KW  - DNI forecast
KW  - Parabolic trough collector
KW  - PTC
KW  - Thermal Energy Storage
Y1  - 2024
U6  - http://dx.doi.org/10.52825/solarpaces.v1i.731
SN  - 2751-9899 (online)
N1  - 28th International Conference on Concentrating Solar Power and Chemical Energy Systems, 27-30 September, Albuquerque, NM, USA
IS  - VOL. 1
PB  - TIB Open Publishing
CY  - Hannover
ER  - 
TY  - CHAP
A1  - Schwager, Christian
A1  - Angele, Florian
A1  - Nouri, Bijan
A1  - Schwarzbözl, Peter
A1  - Teixeira Boura, Cristiano José
A1  - Herrmann, Ulf
T1  - Impact of DNI forecast quality on performance prediction for a commercial scale solar tower: Application of nowcasting DNI maps to dynamic solar tower simulation
T2  - SolarPACES conference proceedings
N2  - Concerning current efforts to improve operational efficiency and to lower overall costs of concentrating solar power (CSP) plants with prediction-based algorithms, this study investigates the quality and uncertainty of nowcasting data regarding the implications for process predictions. DNI (direct normal irradiation) maps from an all-sky imager-based nowcasting system are applied to a dynamic prediction model coupled with ray tracing. The results underline the need for high-resolution DNI maps in order to predict net yield and receiver outlet temperature realistically. Furthermore, based on a statistical uncertainty analysis, a correlation is developed, which allows for predicting the uncertainty of the net power prediction based on the corresponding DNI forecast uncertainty. However, the study reveals significant prediction errors and the demand for further improvement in the accuracy at which local shadings are forecasted.
KW  - Process prediction
KW  - DNI forecasting
KW  - Nowcasting
KW  - Uncertainty analysis
KW  - Molten salt receiver system,
Y1  - 2024
U6  - http://dx.doi.org/10.52825/solarpaces.v1i.675
SN  - 2751-9899 (online)
N1  - 28th International Conference on Concentrating Solar Power and Chemical Energy Systems, 27-30 September, Albuquerque, NM, USA
IS  - Vol. 1
PB  - TIB Open Publishing
CY  - Hannover
ER  - 
TY  - CHAP
A1  - Schulte, Jonas
A1  - Schwager, Christian
A1  - Frantz, Cathy
A1  - Schloms, Felix
A1  - Teixeira Boura, Cristiano José
A1  - Herrmann, Ulf
T1  - Control concept for a molten salt receiver in star design: Development, optimization and testing with cloud passage scenarios
T2  - SolarPACES conference proceedings
N2  - A promising approach to reduce the system costs of molten salt solar receivers is to enable the irradiation of the absorber tubes on both sides. The star design is an innovative receiver design, pursuing this approach. The unconventional design leads to new challenges in controlling the system. This paper presents a control concept for a molten salt receiver system in star design. The control parameters are optimized in a defined test cycle by minimizing a cost function. The control concept is tested in realistic cloud passage scenarios based on real weather data. During these tests, the control system showed no sign of unstable behavior, but to perform sufficiently in every scenario further research and development like integrating Model Predictive Controls (MPCs) need to be done. The presented concept is a starting point to do so.
KW  - Molten salt receiver
KW  - Star design
KW  - Control optimization
KW  - Cloud passages
Y1  - 2023
U6  - http://dx.doi.org/10.52825/solarpaces.v1i.693
SN  - 2751-9899 (online)
N1  - 28th International Conference on Concentrating Solar Power and Chemical Energy Systems, 27-30 September, Albuquerque, NM, USA
IS  - Vol. 1
PB  - TIB Open Publishing
CY  - Hannover
ER  - 
TY  - CHAP
A1  - Bergmann, Ole
A1  - Götten, Falk
A1  - Braun, Carsten
A1  - Janser, Frank
T1  - Comparison and evaluation of blade element methods against RANS simulations and test data
T2  - CEAS Aeronautical Journal
N2  - This paper compares several blade element theory (BET) method-based propeller simulation tools, including an evaluation against static propeller ground tests and high-fidelity Reynolds-Average Navier Stokes (RANS) simulations. Two proprietary propeller geometries for paraglider applications are analysed in static and flight conditions. The RANS simulations are validated with the static test data and used as a reference for comparing the BET in flight conditions. The comparison includes the analysis of varying 2D aerodynamic airfoil parameters and different induced velocity calculation methods. The evaluation of the BET propeller simulation tools shows the strength of the BET tools compared to RANS simulations. The RANS simulations underpredict static experimental data within 10% relative error, while appropriate BET tools overpredict the RANS results by 15–20% relative error. A variation in 2D aerodynamic data depicts the need for highly accurate 2D data for accurate BET results. The nonlinear BET coupled with XFOIL for the 2D aerodynamic data matches best with RANS in static operation and flight conditions. The novel BET tool PropCODE combines both approaches and offers further correction models for highly accurate static and flight condition results.
KW  - BET
KW  - CFD propeller simulation
KW  - Propeller aerodynamics
KW  - Actuator disk modelling
KW  - Propeller performance
Y1  - 2022
U6  - http://dx.doi.org/10.1007/s13272-022-00579-1
SN  - 1869-5590 (Online)
SN  - 1869-5582 (Print)
N1  - Corresponding author: Ole Bergmann
VL  - 13
SP  - 535
EP  - 557
PB  - Springer
CY  - Wien
ER  - 
TY  - JOUR
A1  - Topçu, Murat
A1  - Madabhushi, Gopal S.P.
A1  - Staat, Manfred
T1  - A generalized shear-lag theory for elastic stress transfer between matrix and fibres having a variable radius
JF  - International Journal of Solids and Structures
N2  - A generalized shear-lag theory for fibres with variable radius is developed to analyse elastic fibre/matrix stress transfer. The theory accounts for the reinforcement of biological composites, such as soft tissue and bone tissue, as well as for the reinforcement of technical composite materials, such as fibre-reinforced polymers (FRP). The original shear-lag theory proposed by Cox in 1952 is generalized for fibres with variable radius and with symmetric and asymmetric ends. Analytical solutions are derived for the distribution of axial and interfacial shear stress in cylindrical and elliptical fibres, as well as conical and paraboloidal fibres with asymmetric ends. Additionally, the distribution of axial and interfacial shear stress for conical and paraboloidal fibres with symmetric ends are numerically predicted. The results are compared with solutions from axisymmetric finite element models. A parameter study is performed, to investigate the suitability of alternative fibre geometries for use in FRP.
KW  - Natural fibres
KW  - Polymer-matrix composites
KW  - Biocomposites
KW  - Stress concentrations
KW  - Finite element analysis
Y1  - 2022
U6  - http://dx.doi.org/10.1016/j.ijsolstr.2022.111464
SN  - 0020-7683
VL  - 239–240
IS  - Art. No. 111464
PB  - Elsevier
CY  - New York, NY
ER  - 
TY  - JOUR
A1  - Mandekar, Swati
A1  - Holland, Abigail
A1  - Thielen, Moritz
A1  - Behbahani, Mehdi
A1  - Melnykowycz, Mark
T1  - Advancing towards Ubiquitous EEG, Correlation of In-Ear EEG with Forehead EEG
JF  - Sensors
N2  - Wearable EEG has gained popularity in recent years driven by promising uses outside of clinics and research. The ubiquitous application of continuous EEG requires unobtrusive form-factors that are easily acceptable by the end-users. In this progression, wearable EEG systems have been moving from full scalp to forehead and recently to the ear. The aim of this study is to demonstrate that emerging ear-EEG provides similar impedance and signal properties as established forehead EEG. EEG data using eyes-open and closed alpha paradigm were acquired from ten healthy subjects using generic earpieces fitted with three custom-made electrodes and a forehead electrode (at Fpx) after impedance analysis. Inter-subject variability in in-ear electrode impedance ranged from 20 kΩ to 25 kΩ at 10 Hz. Signal quality was comparable with an SNR of 6 for in-ear and 8 for forehead electrodes. Alpha attenuation was significant during the eyes-open condition in all in-ear electrodes, and it followed the structure of power spectral density plots of forehead electrodes, with the Pearson correlation coefficient of 0.92 between in-ear locations ELE (Left Ear Superior) and ERE (Right Ear Superior) and forehead locations, Fp1 and Fp2, respectively. The results indicate that in-ear EEG is an unobtrusive alternative in terms of impedance, signal properties and information content to established forehead EEG.
KW  - in-ear EEG
KW  - correlation
KW  - forehead EEG
KW  - impedance spectroscopy
KW  - biopotential electrodes
Y1  - 2022
U6  - http://dx.doi.org/10.3390/s22041568
SN  - 1424-8220
VL  - 22
IS  - 4
SP  - 1
EP  - 19
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Defosse, Jerome
A1  - Kleinschmidt, Joris
A1  - Schmutz, Axel
A1  - Loop, Torsten
A1  - Staat, Manfred
A1  - Gatzweiler, Karl-Heinz
A1  - Wappler, Frank
A1  - Schieren, Mark
T1  - Dental strain on maxillary incisors during tracheal intubation with double-lumen tubes and different laryngoscopy techniques - a blinded manikin study
JF  - Journal of Cardiothoracic and Vascular Anesthesia
KW  - anaesthetic complications
KW  - dental trauma
KW  - difficult airway
KW  - double-lumen tube intubation
KW  - videolaryngoscopy
Y1  - 2022
U6  - http://dx.doi.org/10.1053/j.jvca.2022.02.017
SN  - 1053-0770
VL  - 36
IS  - 8, Part B
SP  - 3021
EP  - 3027
PB  - Elsevier
CY  - New York, NY
ER  -