Corrigendum: Data-Driven Digital Twins in Surgery utilizing Augmented Reality and Machine Learning

Das Dokument ist ein Corrigendum zu dem veröffentlichten Paper ”Data-Driven Digital Twins in Surgery utilizing Augmented Reality and Machine Learning”. Es enthält Korrekturen zu den fehlerhaften Abschnitten des Originalpapers.This document is a corrigendum for the published paper 'Data-Driven Digital Twins in Surgery utilizing Augmented Reality and Machine Learning'. It contains corrections for faulty sections of the original paper

Combining the lumped capacitance method and the simplified distributed activation energy model to describe the pyrolysis of thermally small biomass particles

The pyrolysis process of thermally small biomass particles was modeled combining the Lumped Capacitance Method (LCM) to describe the transient heat transfer and the Distributed Activation Energy Model (DAEM) to account for the chemical kinetics. The inverse exponential temperature increase predicted by the LCM was considered in the mathematical derivation of the DAEM, resulting in an Arrhenius equation valid to describe the evolution of the pyrolysis process under inverse exponential temperature profiles. The Arrhenius equation on which the simple LCM-DAEM model proposed is based was derived for a wide range of pyrolysis reactor temperatures, considering the chemical kinetics data of four lignocellulosic biomass species: pine wood, olive kernel, thistle flower, and corncob. The LCM-DAEM model proposed was validated by comparison to the experimental results of the pyrolysis conversion evolution of biomass samples subjected to various inverse exponential temperature increases in a TGA. To extend the validation, additional biomass samples of Chlorella Vulgaris and sewage sludge were selected due to the different composition of microalgae and sludge compared to lignocellulosic biomass. The deviations obtained between the experimental measurements in TGA and the LCM-DAEM predictions for the evolution of the pyrolysis conversion, regarding the root mean square error of temperature, are below 5 degrees C in all cases. Therefore, the simple LCM-DAEM model proposed can describe-accurately the pyrolysis-process of a thermally small biomass particle, accounting for both the transient heat transfer and the chemical kinetics by solving a simple Arrhenius equation.The authors express their gratitude to the BIOLAB experimental facility and to the “Programa de movilidad de investigadores en centros de investigación extranjeros (Modalidad A)” from the Carlos III University of Madrid (Spain) for the financial support conceded to Antonio Soria-Verdugo for a research stay at the German Aerospace Center DLR (Stuttgart, Germany) during the summer of 2018. Funding by Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR), the German Aerospace Center, is also gratefully acknowledged

On the characteristic heating and pyrolysis time of thermally small biomass particles in a bubbling fluidized bed reactor

Pyrolysis of crushed olive stone particles in a lab scale Bubbling Fluidized Bed (BFB) reactor wasinvestigated. The time evolution of the pyrolysis conversion degree of the olive stone particles, while moving freely in the BFB, was determined from the evolution of the mass of olive stones remaining in thebed, measured by a precision scale holding the whole reactor installation. The experimental measurements of the pyrolysis conversion degree were employed to validate a simple model combining heattransfer and chemical kinetics, which is valid for thermally small particles. The model combines the Lumped Capacitance Method (LCM) and the simplified Distributed Activation Energy Model (DAEM) toaccount for heat transfer and pyrolysis chemical kinetics, respectively. The estimations of the combined LCM-DAEM model for the pyrolysis conversion degree were found to be in good agreement with the experimental measurements for the pyrolysis of olive kernels in a BFB operated at various bed temperatures,fluidizing gas velocities, and biomass particle size ranges. From the combined LCM-DAEM model, the characteristic heating time and the pyrolysis time of the olive stone particles were derived, obtaining a direct relation between these two parameters for constant values of the bed temperature.The authors express their gratitude to the BIOLAB experimentalfacility and to the program "Research Stays for University Academics and Scientists" from the German Academic Exchange Service (DAAD) for the financial support conceded to Antonio Soria-Verdugo for a research stay at the German Aerospace Center(DLR) (Stuttgart, Germany) during the summer of 2019. Funding by Deutsches Zentrum für Luft-und Raumfahrt e. V. (DLR), the German Aerospace Center, and the Helmholtz Association in the research fields energy, fuels and gasification, especially in the Program "Energy Efficiency, Materials and Resources" Topic 4 "Efficient Use of Fuel Resources" is also gratefully acknowledged

Analyzing the pyrolysis kinetics of several microalgae species by various differential and integral isoconversional kinetic methods and the Distributed Activation Energy Model

The pyrolysis kinetics of the microalgae Chlorella vulgaris (CV), Isochrysis galbana (IG), Nannochloropsis gaditana (NG), Nannochloropsis limnetica (NL), Phaeodactylum tricornutum (PT), and Spirulina platensis (SP) were studied by non-isothermal thermogravimetric analysis conducted at nine different constant heating rates. The kinetic parameters of each microalgae species were calculated using several kinetic methods, such as those of Kissinger, Friedman, Ozawa-Flynn-Wall (OFW), Kissinger-Akahira-Sunose (KAS), Vyazovkin, and the simplified Distributed Activation Energy Model (DAEM). The results show that the kinetic parameters calculated from the integral isoconversional methods OFW, KAS and Vyazovkin are similar to those determined by applying the simplified DAEM. In contrast, application of the differential isoconversional method of Friedman led to moderate deviations in the activation energies and pre-exponential factors computed, whereas the unique values of the kinetic parameters determined by the Kissinger method resulted in the highest deviations.The authors express their gratitude to the BIOLAB experimental facility. Funding by Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR), the German Aerospace Center, is gratefully acknowledged as well as funding by the DLR international collaboration project “Accurate Kinetic Data of Biomass Pyrolysis”.Publicad

Low temperature oxidation of cyclohexane: uncertainty of important thermo-chemical properties

The study of the standard formation enthalpy, entropy, and heat capacity for key species relevant to the low-temperature combustion of cyclohexane has been performed by applying the group additivity method of Benson. The properties of 18 Benson groups (8 of them for the first time), and 10 ring correction factors for cyclic species were estimated through different empirical and semi-empirical methods. The method validation proceeded through comparison of predicted values for certain number of newly estimated groups and available literature data derived from quantum chemistry estimations. Further validations of the estimated properties of groups have been provided by comparing estimated properties of test species with data in literature and kinetic databases. Also the standard deviation between prediction and reported values has been evaluated for each validation case. A similar approach has been applied for validation of the estimated ring correction groups. For selected well-studied cyclic molecules the predicted values and the literature data have been compared with each other, and the standard deviations have been also reported. The evaluated properties of the cyclohexane relevant species were also compared with similar ones available in other kinetic models and in databases. At the end the estimated properties have been presented in a tabulated form of NASA polynomial coefficients with extrapolation up to 3500 K

Thermochemical reduction of iron oxide powders with hydrogen: Review of selected thermal analysis studies

The reduction of iron oxide with hydrogen is a much-studied research topic, whose interest is growing even more with the emergence of new applications, for example the hydrogen-based direct reduction or for the production of a carbon-free chemical energy carrier. But the numerous works on this topic reveal the great disparity in the authors’ findings, especially regarding the reduction of powders. And while many authors point out this issue, no attempt has been made to converge towards a common understanding of this heterogeneous thermochemical conversion. The endeavor of the present review is to identify the points of consensus, and where discrepancies exist, to explain them. The first part starts with a revision of the latest recommendations on the thermodynamics of iron and its oxides, easing the further comprehension of the reduction process. Then, twelve publications meeting specific criteria on the sample type and reducing agents are systematically confronted. The types of experiments and major experimental conditions have been listed, leading to the identification of typical profiles. Furthermore, chemical pathways are proposed based on these observations and supported by various analytical measurements. Finally, the multiple mathematical approaches to derive kinetic models are compared and discussed. This present review points out the need for appropriate experimental conditions to derive the intrinsic chemistry of the reduction, such as the limitation of water vapor, and also emphasizes the need for more detailed chemical mechanisms

Pyrolysis of biofuels of the future: Sewage sludge and microalgae-Thermogravimetric analysis and modelling of the pyrolysis under different temperature conditions

The pyrolysis process of both microalgae and sewage sludge was investigated separately, by means of non-isothermal thermogravimetric analysis. The Distributed Activation Energy Model (DAEM) was employed to obtain the pyrolysis kinetic parameters of the samples, i.e. the activation energy Ea and the pre-exponential factor k0. Nine different pyrolysis tests at different constant heating rates were conducted for each sample in a thermogravimetric analyzer (TGA) to obtain accurate values of the pyrolysis kinetic parameters when applying DAEM. The accurate values of the activation energy and the pre-exponential factor that characterize the pyrolysis reaction of Chlorella vulgaris and sewage sludge were reported, together with their associated uncertainties. The activation energy and pre-exponential factor for the C. vulgaris vary between 150–250 kJ/mol and 1010–1015 s−1 respectively, whereas values ranging from 200 to 400 kJ/mol were obtained for the sewage sludge activation energy, and from 1015 to 1025 s−1 for its pre-exponential factor. These values of Ea and k0 were employed to estimate the evolution of the reacted fraction with temperature during the pyrolysis of the samples under exponential and parabolic temperature increases, more typical for the pyrolysis reaction of fuel particles in industrial reactors. The estimations of the relation between the reacted fraction and the temperature for exponential and parabolic temperature increases were found to be in good agreement with the experimental values measured in the TGA for both the microalgae and the sludge samples. Therefore, the values reported in this work for the activation energy and the pre-exponential factor of the C. vulgaris can be employed as reference values in numerical studies of the pyrolysis process of this biofuel since its chemical composition is quite homogeneous. In the case of sewage sludge, due to the heterogeneity of its composition, the results reported for the kinetic parameters of the pyrolysis process can be employed to describe the pyrolysis of sludge with similar composition.The authors express their gratitude to the BIOLAB experimental facility and to the “Programa de movilidad de investigadores en centros de investigación extranjeros (Modalidad A)” from the Carlos III University of Madrid (Spain) for the financial support conceded to Antonio Soria for a research stay at the German Aerospace Center DLR (Stuttgart, Germany) during the summer of 2016. The authors also gratefully acknowledge the financial support provided by Fundación Iberdrola under the “VI Programa de Ayudas a la Investigación en Energía y Medioambiente”. Funding by the energy, combustion, and gas turbine technology program (EVG) of Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR), the German Aerospace Center, is gratefully acknowledged as well as funding by the DLR international collaboration project “Accurate Kinetic Data of Biomass Pyrolysis”Publicad