Jean-Sébastien Deschênes

Marennine, Promising Blue Pigments from a Widespread Haslea Diatom Species Complex

In diatoms, the main photosynthetic pigments are chlorophylls a and c, fucoxanthin, diadinoxanthin and diatoxanthin. The marine pennate diatom Haslea ostrearia has long been known for producing, in addition to these generic pigments, a water-soluble blue pigment, marennine. This pigment, responsible for the greening of oysters in western France, presents different biological activities: allelopathic, antioxidant, antibacterial, antiviral, and growth-inhibiting. A method to extract and purify marennine has been developed, but its chemical structure could hitherto not be resolved. For decades, H. ostrearia was the only organism known to produce marennine, and can be found worldwide. Our knowledge about H. ostrearia-like diatom biodiversity has recently been extended with the discovery of several new species of blue diatoms, the recently described H. karadagensis, H. silbo sp. inedit. and H. provincialis sp. inedit. These blue diatoms produce different marennine-like pigments, which belong to the same chemical family and present similar biological activities. Aside from being a potential source of natural blue pigments, H. ostrearia-like diatoms thus present a commercial potential for aquaculture, cosmetics, food and health industries.

FT-IR/ATR univariate and multivariate calibration models for in situ monitoring of sugars in complex microalgal culture media

The objective of this work is to develop a quick and simple method for the in situ monitoring of sugars in biological cultures. A new technology based on Attenuated Total Reflectance-Fourier Transform Infrared (FT-IR/ATR) spectroscopy in combination with an external light guiding fiber probe was tested, first to build predictive models from solutions of pure sugars, and secondly to use those models to monitor the sugars in the complex culture medium of mixotrophic microalgae. Quantification results from the univariate model were correlated with the total dissolved solids content (R(2)=0.74). A vector normalized multivariate model was used to proportionally quantify the different sugars present in the complex culture medium and showed a predictive accuracy of >90% for sugars representing >20% of the total. This method offers an alternative to conventional sugar monitoring assays and could be used at-line or on-line in commercial scale production systems.

Numerical modeling wind-diesel hybrid system: Overview of the requirements, models and software tools

Various aspects must be taken into account when working with wind-diesel hybrid systems for the generation of electricity especially in remote areas. Reliability and cost are two of these aspects. On the other hand, various mathematical models of the elements that make up these systems can be used, as well as various design and simulation models. This paper will review the simulation and design models of the hybrid systems that have been used up to this moment in time, indicating which tools have been developed for this purpose.

Achievable performances for basic perturbation-based extremum seeking control in Wiener-Hammerstein plants

This paper presents a case study for determining achievable performances in the basic form of extremum seeking control. Despite recent developments on more powerful versions of the algorithm, no detailed study that investigates this aspect thoroughly and provides clear guidelines for the tuning of this simpler, readily-implementable version is yet available. Interest remains for this basic version, for a variety of reasons. A review of extremum seeking fundamentals, with the support of a few simulations, allows to determine better means of selecting the elementary loop components, maximizing the gradient capture information. The choice of the excitation (dither) fundamental frequency is also better addressed under this optimal condition to effectively discuss achievable loop performance aspects. Most results apply to Wiener-Hammerstein classes of systems (strictly proper and stable system dynamics) and still allow other loop improvement modifications to be applied. Extensions to square wave dither signals and a few comparisons with other recently developed loop improvement techniques are also provided.

Process Control Through a Case Study: A Mixing Process. I. SISO Case

Using a simulator developed for process control education, this paper details the case study of a mixing process, in an educational context. Depending on process design, the control problem can either be seen as single input single output (SISO) or multiple input multiple output (MIMO). The SISO case which is presented in this paper covers: process mathematical modeling, actuator sizing, instrumentation, PI tuning, process linearization, and constraints handling.

Demodulation considerations in extremum seeking control loops

This paper addresses a few demodulation aspects in extremum seeking (ES) control loops and their possible use in the tuning of the algorithm. After a quick review of the basics, different situations are discussed, and loop tuning methods are derived for each case. Main contributions are on high-pass filter and demodulation signal selection, under consideration of the excitation (dither) signal frequency and the systems dynamics. Robustness issues are addressed, along with the following loop performance indicators: convergence speed and steady-state accuracy. Results are validated in computer simulations on an ideal case study, characterized by constant open-loop dynamics and an exact parabolic nonlinearity over its entire domain of operation. These two conditions allow for constant closed-loop characteristics of the ES algorithm and are necessary to obtain to establish its ideal behavior.

No-storage wind-diesel system: Mechanical modeling based on power flow models

In remote areas and small islands, diesel generators are often the main source of electric power. A hybrid system of wind power and genset can benefit islands or other isolated communities and increase fuel savings. In order to understand the effect of wind power regarding to reducing the rate of power supplied by the diesel generator especially when the wind turbine and genset operate simultaneously, we studied a no-storage wind-diesel system by using a power flow model tested on different operation modes of the hybrid system.

Development and treatment procedure of arsenic-contaminated water using a new and green chitosan sorbent: kinetic, isotherm, thermodynamic and dynamic studies

Abstract Arsenic is classified as one of the most toxic elements for humans by the World Health Organization (WHO). With the tightening drinking water regulation to 10 μg L−1 by the WHO, it is necessary to find efficient sorbent materials for arsenic. In this work, the removal of arsenic(V) from water is achieved with an insoluble chitosan sorbent in the protonated form obtained by a simple heating process. Kinetic studies show a very fast sorption (less than 10 min). The Langmuir isotherm model is best describing experimental data with a capacity of 42 mg g−1 at pH 8. The sorption process is based on anion exchange (chemisorption) determined from the Dubinin-Radushkevich model. The sorption efficiency of the chitosan sorbent is 97% at low concentrations (e.g. 100 μg L−1). Thermodynamic analysis reveals that the sorption process is exothermic and is controlled by enthalpic factors. Breakthrough curves (BTC) were acquired in real-time by instrumental chromatography and was better described by the Thomas model. BTC from column sorption and desorption with a salt solution suggest that this sorbent is relevant for large scale applications. With this new renewable product, it will be possible to treat arsenic contaminated water at low cost and with little waste (concentration factor of 1500).

Extremum Seeking Control of Batch Cultures of Microalgae Nannochloropsis Oculata in Pre-Industrial Scale Photobioreactors

Abstract Extremum seeking control is applied to batch cultures of microalgae Nannochloropsis Oculata with the objective of maximizing the growth rate through manipulation of the pH. A commercial biomass monitor (BugEye from BugLab) using on-line optical density (OD) measurements at 725 nm is used to provide signals relative to both biomass density and growth. Parameters for the optimization algorithm are derived from system identification data and simulation results on a phenomenological simulator built specifically to represent the system. A summary of the simulator development and validation on available data from the physical system, a pre-industrial scale photobioreactor, are also presented.

Lab@home for analog electronic circuit laboratory

Laboratory activities of analog electronic circuit undergraduate course at École de technologie supérieure (ETS) require the physical presence of students in groups of 2 in the laboratory to complete predefined or project based laboratories. This classical or traditional approach continuously requires big investments on laboratory equipment and significant space requirements. Moreover, it obliges students to be physically present in the laboratory to complete their experiments. The lab instructor is also present to help them with their needs or to answer their specific questions related to the experiments. With the evolution of Information and Communications Technology (ICT) and electronic circuit board technologies, further possibilities even include to bring the laboratory at home (Lab@home). This philosophy can be achieved with the advantages of miniaturized and low cost equipment and facilities, complemented with the students already available personal computers. Available miniature kits include basic electronics for the generation and processing of various types of signals. The personal computer coupled with the kit, acts as a set of signal injecting and measuring devices. Pedagogical strategies to encourage team collaborative work, ensuring simultaneous information exchanges between the students themselves and with the laboratory instructor can be elaborated specifically for this innovative setup. This recent approach can be used to help enforce the knowledge and competence of the students, allowing them to develop their autonomy, their creativity and thus develop their ability to innovate. This paper presents and further details the Lab@home approach, with its impacts on the students, the Professor, the lab instructor and on the academic institution more globally. The necessary resources, common challenges and difficulties, advantages and drawbacks of the approach, and recommendations for its implementation are also included. A Lab@home implementation case study is also presented at the end of this paper.