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António M. G. Lopes,Gilberto C. Vaz,Aldina Santiago 국제구조공학회 2005 Steel and Composite Structures, An International J Vol.5 No.6
The present work reports on a numerical simulation of a compartment fire. The fire was modeled using a simplified approach, where combustion is simulated as a volumetric heat release. Computations were performed with the commercial code CFX 5.6. Radiation was modeled with a differential approximation (P1 model), while turbulence effects upon the mean gas flow were dealt with a SST turbulence model. Simulations were carried out using a transient approach, starting at the onset of ignition. Results are provided for the temperature field time evolution, thus allowing a direct comparison with the analytical and experimental data. The high spatial resolution available for the results proved to be of great utility for a more detailed analysis of the thermal impact on the steel structure.
Liping Chen,Xiaomin Li,Xiang Li,Min Zhu,Ranchao Wu,António M. Lopes 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.11
This work investigates the guaranteed cost leader-following consensus of a class of uncertain fractionalorder (FO) multi-agent systems (FOMASs) affected by state time delay. The leader and following group are exposed to norm-bounded time-varying parametric uncertainty and time-delay. A delay- and order-dependent consensus protocol is developed which guarantees robust stability of the controlled system and ensures that the effect of uncertainty on the system performance is below some prescribed index. The FO Razumikhin theorem and the linear matrix inequality approach are adopted to derive the method that can be applied to FOMASs with deterministic parameters. The analysis can be extended to distinct consensus problems for different types of FOMASs. Three numerical examples illustrate the effectiveness and feasibility of the approach.
Rubieli Carla Frezza Zeferino,Vinicius Aleixo Angonese Piaia,Vinícius Tres Orso,Vítor Machado Pinheiro,Micheli Zanetti,Gustavo Lopes Colpani,Natan Padoin,Cíntia Soares,Márcio Antônio Fiori,Humberto Gr 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.105 No.-
This work aims to synthesize neryl acetate from the nerol esterification reaction with acetic anhydridethrough heterogeneous catalysis using the ion exchange resin Lewatit GF 101. The reaction was monitoredby gas chromatography and the neryl acetate chemical structure was confirmed by mass spectrometryand nuclear magnetic resonance spectroscopy. The variables effect on the neryl acetate synthesiswas evaluated from an experimental design analysis. The reaction showed the highest combined valuesfor nerol conversion (98.11%) and neryl acetate selectivity (86.10%) at 30 min within optimal experimentalconditions of temperature at 40 C, catalyst content at 7% wt, molar ratio at 1:4 (nerol: acetic anhydride),agitation speed at 250 rpm and nerol content at 3 mmol. The complete nerol conversion wasachieved at 40 min with 82.34% selectivity. The reaction rate was controlled only by the nerol decay,an expected behavior due to the excess of acetic anhydride used. In addition, the value obtained forthe main reaction kinetic constant found by a pseudo-homogeneous model was 6 times greater than thatof the parallel reaction. The catalyst reuse was investigated and after 3 cycles a high conversion (96.68%)and selectivity (83.78%) were observed indicating a low loss of the catalytic activity.