Effect of liquid-phase surface tension on hydrodynamics of a three-phase airlift reactor with an enlarged degassing zone

The effect of the addition of ethanol (10 g/l) to the liquid-phase on gas and solids holdup, circulation and mixing times and interstitial liquid velocity in a threephase airlift reactor was investigated. The airlift reactor (60 l) is of the concentric draught-tube type with an enlarged degassing zone. Ca-alginate beads were used as solid-phase and airflow rate (from 1.9 to 90.2 l/min) and solids loading (0-30% (v/v)) were manipulated. Riser and downcomer gas holdup were found to increase with the addition of ethanol, leading to a decrease on the relative solids holdup. The presence of ethanol seems to have no influence on the circulation time. On the other hand, mixing time variation depends on the solids loading and airflow rate. Riser and downcomer interstitial liquid velocity are lower for ethanol solution than for water.Junta Nacional de Investigação Científica e Tecnológica (JNICT) - PRAXIS/2/2.1/ BIO/1061/95 , grant GGP XXI/BD/2937/96

Hydrodynamic studies in an airlift reactor with an enlarged degassing zone

The hydrodynamic behaviour of a 60 l threephase airlift bioreactor, of the concentric draught tube type, with an enlarged degassing zone has been studied. Ca-alginate beads were used as the solid phase. Airflow rate (from 1.9 to 90.2 l/min), solids loading (0% to 40% (v/v)) and solids density (1016 and 1038 kg/m³) were manipulated and their influence on solids and gas holdup, circulation and mixing times and in the interstitial liquid velocity was determined. Riser and downcomer solids holdup was found to decrease with the increase of airflow rate and to increase with solids loading and density. On the contrary, gas holdup in the riser and in the downcomer increased with airflow rate and decreased with solids loading and density. By increasing airflow rate, a decrease in circulation time was observed while the effects of solids loading and density were negligible. Mixing time decreased with airflow rate, increased with solids density, in the studied range, and presented a maximum for solids loading of approximately 20% (v/v).Junta Nacional de Investigação Científica e Tecnológica (JNICT) Instituto de Biotecnologia e Química Fina (IBQF) - GGP XXI/BD/2937/9

Oxygen mass transfer in a high solids loading three-phase internal-loop airlift reactor

Determinations of volumetric mass transfer coefficient were conducted in a three-phase internal-loop airlift reactor with an enlarged degassing zone. The effect of parameters such as the airflow rate (riser superficial gas velocities between 0.01 and 0.5 m/s), solids loading (up to 30%, v/v), solids density (1023 and 1048 kg/m3) and the liquid-phase properties on kLa was studied. It was observed that the increase of the airflow rate and the introduction of ethanol enhanced the volumetric mass transfer coefficient in the system. On the contrary, the progressive introduction of solids and a small increase on solids density were responsible for the diminishing of the mass transfer rate. Correlations for the volumetric mass transfer coefficient with the riser superficial gas velocity and solids loading were determined for the two solids density and the two liquid-phases. A good agreement between experimental data and the calculated values was obtained.Instituto de Biotecnologia e Química Fina. Fundação para a Ciência e a Tecnologia -PRAXIS/2/2.1/BIO/1061/95, GGPXXI/BD/2937/96. EC - INCO-COPERNICUS - no. ERB IC15-CT98-0904

Air Budjet: a VTOL virtual operator company in Portugal

Creation of sustainable transportation service for a new and virtual airline company that uses VTOL aircraft in order to increase mobility and flexibility in Portugal. This study started with the VTOL concepts, peripherally and accessibility, and business models and plans reviews. The air service characterization was then carried out using localization and trajectory optimization algorithms, thus allowing to elaborate two applications (software): one for clients to book their flights and another that compiles flight's data booked by clients and optimizes flights routes/trajectories. With this study, it is possible to depict the viability of the economic-financial results of the new virtual company and the application development results with the optimized trajectories. The development of this air service will increase accessibility and mobility in all regions of Portugal and companies that cannot afford the costs of executive aviation, too. In order to facilitate the booking of the flights, an application was created for the client in order to optimize the company costs related to this air service, and thus to make the cost of a trip more appealing; a second application was elaborated that optimizes the trajectories of the aircraft.info:eu-repo/semantics/publishedVersio

Hydrodynamic model for three-phase internal- and external-loop airlift reactors

A mathematical model predicting the hydrodynamic behaviour of three-phase airlift reactors, working with low-density solids and with high solids loading, was developed. The model allows for the prediction of local gas holdup and liquid velocity in airlift bioreactors. Model was validated for an external-loop airlift reactor and an internal-loop airlift reactor with an enlarged degassing zone, being a good agreement obtained between calculated and experimental data.Fundação para a Ciência e a Tecnologia (FCT) Junta Nacional de Investigação Científica e Tecnológica (JNICT) - PRAXIS 2/2.1/BIO/1061/95 Instituto de Biotecnologia e Química Fina (IBQF) - GGP XXI/BD/2937/9

Application of Fractional Calculus in the Dynamical Analysis and Control of Mechanical Manipulators

Mathematics Subject Classification: 26A33, 93C83, 93C85, 68T40Fractional Calculus (FC) goes back to the beginning of the theory of differential calculus. Nevertheless, the application of FC just emerged in the last two decades. In the field of dynamical systems theory some work has been carried out but the proposed models and algorithms are still in a preliminary stage of establishment. This article illustrates several applications of fractional calculus in robot manipulator path planning and control

A systematic review protocol: Examining the evidence of whole body vibration produced by mining equipment

Whole body vibration (WBV) is an emerging issue for the mining industry, occuring from the exposure due to many mining operations. This systematic review protocol intends to give answer to the question "what mining equipment contributes the most to occupational whole body vibration and under what conditions?". For that, the main engineering and health databases were selected (i.e Scopus, Science Direct and PubMed) and a set of keywords was defined to latter combination. The selection process of the papers was also described in an attempt to contribute to the general research on this field. All of the data treatment is detailed, including the risk of bias and attempts to deal with it.*x0D; The protocol for the systematic review is registered in PROSPERO under the code CRD42018087629.*x0D;  </jats:p

Catálogo das Plantas Vasculares da Ilha de São Jorge

XV Expedição Científica do Departamento de Biologia - São Jorge 2011.Foi construído um catálogo das plantas vasculares citadas para a ilha de São Jorge com base nas obras de síntese de Trelease (1897), Palhinha (1966), Franco (1971, 1984), Franco & Afonso (1994, 1998, 2003), Hansen & Sunding (1993), Silva et al. (2010), Schäfer (2003a,b, 2005) e no Portal da Biodiversidade dos Açores [http://www.azoresbioportal.angra.uac.pt/]. Nesta compilação a grafia dos nomes científicos segue a base de dados International Plant Names Index (IPNI, 2005). O presente catálogo assinala para a ilha de São Jorge 519 taxa vasculares, correspondendo a 513 espécies, distribuídas por 101 famílias. O número de taxa nativos representa apenas 29,5% do total de taxa presentes na ilha

Fractional-order harmonics in the trajectory control of redundant manipulators

Redundant manipulators are superior to classical arms because they allow the trajectory optimization, the obstacle avoidance, and the resolution of singularities. For this type of manipulators, the kinematic control algorithms adopt generalized inverse matrices that may lead to unpredictable responses. Motivated by these problems this paper studies the complexity revealed by the trajectory planning scheme when controlling redundant manipulators. The result reveals a chaotic phenomenon and the existence of fractional order sub-harmonics in the robot signals.N/