1,720,956 research outputs found
MODEL-BASED APPROACHES TO SUPPORT THE OPTIMISATION OF MICROALGAE GROWTH IN PHOTOBIOREACTORS
Full text linkMicroalgae are a wide class of photosynthetic organisms that, through photosynthesis, use solar
energy to fix CO2, release O2 as a by-product and produce a biomass rich in carbohydrates, proteins,
lipids and bioactive compounds. Their high photosynthetic yield and ability of growing fast and in
harsh environments make them a promising candidate for sustainable bio-based technologies in
critical sectors such as pharmaceutics, cosmetics, human and animal nutrition, aquaculture, chemicals
and fuels, and pollution prevention. Currently, a great obstacle to the actual industrialisation of
microalgae technology is represented by a limited comprehension of microalgae growth processes
and reliable tools for representing their response in an industrial environment. For this reason, the
development of reliable mathematical models that are capable of quantitative predictions of biomass
growth as a response to different cultivation conditions is of paramount importance.
The aim of this Thesis is to enhance the comprehension and representation of the phenomena that
affect microalgae growth in photobioreactors by employing a combination of experimental
photobioreactor development and formulation and application of mathematical models. First of all,
the influence of light on microalgae on the microalgae photosynthetic response has been investigated,
considering different aspects. Firstly, the effect of continuous light on ultra-thin photobioreactors has
been examined. Parameters of a Haldane-like models were estimated from experimental data at
different optical paths. It was found that, due to the inability to account explicitly for mixing-induced
light-dark cycles, Haldane-like models have limited capability in capturing experimental results at
ultra-thin light paths and thus can be unsuitable to scale up experimental results from ultra-thin scales
to higher scales. Then, microalgae growth under pulsed light regimes has been addressed, with both
low and high light frequencies. To describe the dynamic effect of low frequencies on microalgae
growth, a dynamic reformulation of the Camacho Rubio model was proposed, based on the theoretical
knowledge of photosynthetic characteristic times, and its parameters were precisely estimated from
High Throughput Screening data. For high frequency pulsed light cultivation, a different
mathematical model accounting for photons absorption, usage and dissipation was examined. The
model was modified, and its parameters were retrieved from experimental data. The modified model
was able to provide meaningful physical explanations of the observed data and was further employed
to guide respirometry experiments. The understanding of nutrient dynamics is also crucial to ensure
the sustainability of microalgal production. Although different modelling approaches are available, their calibration is often a complex and time-consuming task. The second main contribution of the
Thesis is thus concerned with the use of model-based design of experiments techniques for the precise
estimation of the Droop model in continuous photobioreactors to capture the dynamic effect of
nitrogen uptake on microalgae growth. Results demonstrate that the proposed methodology can help
reducing the experimental effort needed to estimate the model parameters. It is also shown that the
newly calibrated model can represent nitrogen uptake dynamics effectively
Thermal modeling of industrial-scale vanadium redox flow batteries in high-current operations
Full text linkA cell-resolved model that simulates the dynamic thermal behavior of a Vanadium Redox Flow Battery during charge and discharge is presented. It takes into account, at a cell level, the reversible entropic heat of the electrochemical reactions, irreversible heat due to overpotentials, self-discharge reactions due to ion crossover, and shunt current losses. The model accounts for the heat transfer between cells and toward the environment, the pump hydraulic losses and the heat transfer of piping and tanks. It provides the electrolyte temperature in each cell, at the stack inlet and outlet, along the piping and in the tanks. Validation has been carried out against the charge/discharge measurements from a 9kW/27kWh VRFB test facility. The model has been applied to study a VRFB with the same stack but a much larger capacity, operating at 400 A for 8 h, in order to identify critical thermal conditions which may occur in next-generation industrial VRFB stacks capable to operating at high current density. The most critical condition has been found at the end a long discharge, when temperatures above 50°C appeared, possibly resulting in 〖VO〗_2^+ precipitation and battery faults. These results call for heat exchangers tailored to assist high-power VRFB systems
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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