A model-free control strategy for an experimental greenhouse with an application to fault accommodation

Writing down mathematical models of agricultural greenhouses and regulating them via advanced controllers are challenging tasks since strong perturbations, like meteorological variations, have to be taken into account. This is why we are developing here a new model-free control approach and the corresponding intelligent controllers, where the need of a good model disappears. This setting, which has been introduced quite recently and is easy to implement, is already successful in many engineering domains. Tests on a concrete greenhouse and comparisons with Boolean controllers are reported. They not only demonstrate an excellent climate control, where the reference may be modified in a straightforward way, but also an efficient fault accommodation with respect to the actuators

2D Electrical Resistivity Tomography surveys optimisation of solutes transports in porous media

International audienceThe purpose of this study is to quantify experimentally the evolution of dissolved species in porous media from 2D resistivity models. Transport experiments are carried out at the laboratory scale by performing flow in a model porous medium obtained by filling a transparent container with mono disperse glass beads. A tracer made by mixing a dissolved of blue dye and a known NaCl concentration is injected with a constant flow rate through the porous medium already saturated by a transparent fluid. ERT measurements are acquired during the fluid flow. The measurement conditions and the inversion parameters are estimated so that the relation between spatial and temporal resolutions is optimised. A video follow-up is also carried out during the upward tracer propagation. The comparison of the temporal evolution of the NaCl concentration distribution estimated from ERT models with Video analysis shows remarkable agreement

Miasto bez schematu. Plany komunikacji miejskiej i rozwój Warszawy

W Warszawie brakuje jednej generalnej mapy środków transportu publicznego o łatwo rozpoznawalnej formie graficznej. Prezentujący podejście kulturoznawcze i historyczno-kulturowe artykuł służy przyjrzeniu się współczesnym substytutom takiego schematu, jak również zawiera analizę dwóch dwudziestowiecznych przypadków publicznego wykorzystania planów miasta jako map sieci komunikacji zbiorczej. Ponieważ, jak dowodzi autor, są to praktyki chwalenia się sukcesami w modernizacji stolicy, a zarazem ukrywające mankamenty i kompleksy (zwłaszcza brak kilku linii metra), ich analiza tworzy pretekst do refleksji nad przestrzennym i infrastrukturalnym rozwojem miasta, m.in. w kontekście dziedzictwa modernizmu i zapoznanej krytyki transportu spalinowego w Karcie Ateńskiej

On the model-free control of an experimental greenhouse

International audienceIn spite of a large technical literature, an efficient climate control of a greenhouse remains a very difficult task. Indeed, this process is a complex nonlinear system with strong meteorological disturbances. The newly introduced ''model-free control'' setting is employed here. It is easy to implement, and has already shown excellent performances in many other concrete domains. Successful experimental tests are presented and discussed. They are compared to a Boolean approach, which is often utilized in practice

Keeping an Eye Open for Scents and Stenches. Reflections on Combining Smelling with Visual Data in Perspective of Anthropology of Waste

The text deals with an issue of reading images as a way of perceiving the osmosphere. The author observes that eyesight might enhance other sensory modalities, provided that the eye no longer is isolated from natural interaction with the environment which has olfactory properties, but also audio and haptic. The analysis is related to two possibilities of reasoning about smells based on visual data. In the first case, the photograph appeals to the olfactory memory and serve as a tool to elicit a narration on scents from a person. In the second case, the use of the olfactory imagination seems to be necessary as a sort of subconscious for the hegemonic eye. The image an individual can see evokes internal representations, which should be taken into account when analysing and interpreting the urban space

Model-free control and fault accommodation for an experimental greenhouse

International audienceThe greenhouse climate control is important in modern agriculture. It is also rather difficult to design: as a matter of fact writing down a "good" mathematical model, which takes into account strong meteorological disturbances, might be an impossible task. The control is here synthesized via a new "model-free" setting, which yields an "intelligent" proportional feedback controller, the tuning of which is straightforward, and even simpler than the intelligent proportional-integral controller, which was already utilized in a previous publication. Our control strategy is successfully tested via an experimental greenhouse. The comparison with the classic Boolean approach, which is popular among manufacturers, demonstrates the superiority of our viewpoint, which permits moreover an efficient actuator fault accommodation. It might be the first model-free fault-tolerant control, which works satisfactorily in practice

Reply to the comment by A. Revil on ''Review of Self-potential methods in Hydrogeophysics'' by L. Jouniaux et al. [C. R. Geoscience 341 (2009) 928-936]

International audienceWe did not discuss subjects that are still not well understood and still being debated since the title of our paper includes "review". We did not review and discuss all aspects of the theoretical background based on microscaled thermodynamics because we focused on field applications in hydrogeophysics. Moreover we submitted our manuscript in 2008 and thus did not acknowledge any paper published in 2009. However this comment is of interest because it gives us the opportunity to provide more precision by answering some points

Review of Self-potential methods in Hydrogeophysics

International audienceThe self-potential (SP) method is a passive geophysical method based on the natural occurrence of electrical fields on the Earth's surface. Combined with other geophysical methods, SP surveys are especially useful for localizing and quantifying groundwater flows and pollutant plume spreading, and estimating pertinent hydraulic properties of aquifers (water table, hydraulic conductivity). Laboratory experiments have shown that the involved coupling coefficients mainly depend on the fluid chemistry, conductivity and pH, and on the soil or rock properties. The interpretation of SP observations can be done qualitatively, for instance by correlation of SP gradients with water fluxes (through electrokinetics) or salt fluxes (through electro-diffusion). In recent years, the interpretation has been improved with the help of modelling or/and inversion of the Poisson equation and endeavours to estimate hydraulic parameters by means of the intensity of electric current sources caused by underground flows

2D Electrical Resistivity Tomography survey optimisation of solute transport in porous media

The purpose of this study is to quantify experimentally the evolution of dissolved species in porous media from 2D resistivity models. Transport experiments are done at the lab level by performing flow in a model porous medium obtained by filling a transparent container with mono disperse glass beads. A tracer made by mixing a dissolved blue dye and a known NaCl concentration is injected with a constant flow rate through the porous medium already saturated by a transparent fluid. ERT measurem..

Early Biometric Lag in the Prediction of Small for Gestational Age Neonates and Preeclampsia

OBJECTIVE: An early fetal growth lag may be a marker of future complications. We sought to determine the utility of early biometric variables in predicting adverse pregnancy outcomes. METHODS: In this retrospective cohort study, the crown-rump length at 11 to 14 weeks and the head circumference, biparietal diameter, abdominal circumference, femur length, humerus length, transverse cerebellar diameter, and estimated fetal weight at 18 to 24 weeks were converted to an estimated gestational age using published regression formulas. Sonographic fetal growth (difference between each biometric gestational age and the crown-rump length gestational age) minus expected fetal growth (number of days elapsed between the two scans) yielded the biometric growth lag. These lags were tested as predictors of small for gestational age (SGA) neonates (≤10th percentile) and preeclampsia. RESULTS: A total of 245 patients were included. Thirty-two (13.1%) delivered an SGA neonate, and 43 (17.6%) had the composite outcome. The head circumference, biparietal diameter, abdominal circumference, and estimated fetal weight lags were identified as significant predictors of SGA neonates after adjusted analyses (P \u3c .05). The addition of either the estimated fetal weight or abdominal circumference lag to maternal characteristics alone significantly improved the performance of the predictive model, achieving areas under the curve of 0.72 and 0.74, respectively. No significant association was found between the biometric lag variables and the development of preeclampsia. CONCLUSIONS: Routinely available biometric data can be used to improve the prediction of adverse outcomes such as SGA. These biometric lags should be considered in efforts to develop screening algorithms for adverse outcomes