75 research outputs found
Reliabilität - die Genauigkeit einer Messung (Version 1.1)
Die Reliabilität beschreibt die Genauigkeit einer Messung. In diesem Beitrag wird das Konzept Reliabilität definiert und es wird erläutert, warum die Reliabilität einer Messung relevant ist. Danach wird diskutiert, welche Modellannahmen getroffen werden müssen, um die Reliabilität einer Messung zu schätzen und es werden fünf Methoden zum Schätzen der Reliabilität vorgestellt: die Re-Test Korrelation, die Parallel-Test Korrelation, die Split-Half Korrelation, die interne Konsistenz und das Schätzen der Reliabilität mit Strukturgleichungsmodellen. Abschließend wird in knapper Form auf Gemeinsamkeiten und Unterschiede der klassischen Testtheorie und der Item-Response Theorie und deren Bedeutung für die Schätzung der Reliabilität eingegangen
Influence of the substitutional solute on the mechanical properties of Ti-Nb binary alloys for biomedical use
Clustering of risk factors for cardiometabolic diseases in low-income, female adolescents
A prepartum diet supplemented with oilseeds high in oleic or linoleic acid reduced GnRH-induced LH release in dairy cows during second week postpartum
A contribuição do farmacêutico para a promoção do acesso e uso racional de medicamentos essenciais no SUS
Efeito da sazonalidade climática na ocorrência de sintomas respiratórios em uma cidade de clima tropical
Percepção sobre qualidade de vida de mulheres participantes de oficinas educativas para dor na coluna
Comparative wood anatomy of species of Psychotria L. (Rubiaceae) in Atlantic Rainforest remnants of Rio de Janeiro State, Brazil
Autothermal reforming of palm empty fruit bunch bio-oil: thermodynamic modelling
This work focuses on thermodynamic analysis of the autothermal reforming of palm empty fruit bunch (PEFB) bio-oil for the production of hydrogen and syngas. PEFB bio-oil composition was simulated using bio-oil surrogates generated from a mixture of acetic acid, phenol, levoglucosan, palmitic acid and furfural. A sensitivity analysis revealed that the hydrogen and syngas yields were not sensitive to actual bio-oil composition, but were determined by a good match of molar elemental composition between real bio-oil and surrogate mixture. The maximum hydrogen yield obtained under constant reaction enthalpy and pressure was about 12 wt% at S/C = 1 and increased to about 18 wt% at S/C = 4; both yields occurring at equivalence ratio Φ of 0.31. The possibility of generating syngas with varying H2 and CO content using autothermal reforming was analysed and application of this process to fuel cells and Fischer-Tropsch synthesis is discussed. Using a novel simple modelling methodology, reaction mechanisms were proposed which were able to account for equilibrium product distribution. It was evident that different combinations of reactions could be used to obtain the same equilibrium product concentrations. One proposed reaction mechanism, referred to as the ‘partial oxidation based mechanism’ involved the partial oxidation reaction of the bio-oil to produce hydrogen, with the extent of steam reforming and water gas shift reactions varying depending on the amount of oxygen used. Another proposed mechanism, referred to as the ‘complete oxidation based mechanism’ was represented by thermal decomposition of about 30% of bio-oil and hydrogen production obtained by decomposition, steam reforming, water gas shift and carbon gasification reactions. The importance of these mechanisms in assisting in the eventual choice of catalyst to be used in a real ATR of PEFB bio-oil process was discussed
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