Search results for "Simulation"
showing 10 items of 5095 documents
AlomySys: Modelling black-grass (Alopecurus myosuroides Huds.) germination and emergence, in interaction with seed characteristics, tillage and soil …
2006
International audience; Weed emergence models are increasingly necessary to evaluate and design cropping systems. The model AlomySys was developed for a frequent and harmful weed, i.e. Alopecurus myosuroides Huds. [Colbach, N., Dürr, C., Roger-Estrade, J., Caneill, J., 2005a. How to model the effects of farming practices on weed emergence. Weed Res. 45, 2–17; Colbach, N., Dürr, C., Roger-Estrade, J., Chauvel, B., Caneill, J., 2005b. AlomySys: modelling blackgrass (Alopecurus myosuroides Huds.) germination and emergence, in interaction with seed characteristics, tillage and soil climate. I. Construction. Eur. J. Agronomy] and is based on sub-models predicting (a) soil environment (climate, s…
Plankton Tracker: A novel integrated system to investigate the dynamic sinking behavior in phytoplankton
2020
Abstract Phytoplankton sinking is an important property that can determine community composition, affecting nutrient and light absorption in the photic zone, and influencing biogeochemical cycling via material loss to the deep ocean. To date, the difficulty in exploring the sinking processes is partly due to methodological limitations in measuring phytoplankton sinking rate. However, in the last decade, works have illustrated various methods based on some non-invasive and low perturbing approaches (laser scanner, video-microscopy, fluorescence spectroscopy). In this study, we review the methods for sinking rate estimation and describe the Plankton Tracker, a novel integrated system to inves…
Coexistence and resource competition.
2000
How large numbers of species coexist on a seemingly limited number of different resources is a classic problem in ecology1, and attempts have been made to solve it experimentally. But we are not convinced that Huisman and Weissing's2 proposal to add non-stationary dynamics in species abundance to the list of possible explanations offers any new insight into this biodiversity enigma.
Combined effects of fishing and oil spills on marine fish: Role of stock demographic structure for offspring overlap with oil
2018
It has been proposed that the multiple pressures of fishing and petroleum activities impact fish stocks in synergy, as fishing-induced demographic changes in a stock may lead to increased sensitivity to detrimental effects of acute oil spills. High fishing pressure may erode the demographic structure of fish stocks, lead to less diverse spawning strategies, and more concentrated distributions of offspring in space and time. Hence an oil spill may potentially hit a larger fraction of a year-class of offspring. Such a link between demographic structure and egg distribution was recently demonstrated for the Northeast Arctic stock of Atlantic cod for years 1959–1993. We here estimate that this …
Biotrickling filter modeling for styrene abatement. Part 1: Model development, calibration and validation on an industrial scale
2017
Abstract A three-phase dynamic mathematical model based on mass balances describing the main processes in biotrickling filtration: convection, mass transfer, diffusion, and biodegradation was calibrated and validated for the simulation of an industrial styrene-degrading biotrickling filter. The model considered the key features of the industrial operation of biotrickling filters: variable conditions of loading and intermittent irrigation. These features were included in the model switching from the mathematical description of periods with and without irrigation. Model equations were based on the mass balances describing the main processes in biotrickling filtration: convection, mass transfe…
Modeling of Dead Wood Potential Based on Tree Stand Data
2020
Here we present a framework for identifying areas with high dead wood potential (DWP) for conservation planning needs. The amount and quality of dead wood and dying trees are some of the most important factors for biodiversity in forests. As they are easy to recognize on site, it is widely used as a surrogate marker for ecological quality of forests. However, wall-to-wall information on dead wood is rarely available on a large scale as field data collection is expensive and local dead wood conditions change rapidly. Our method is based on the forest growth models in the Motti forest simulator, taking into account 168 combinations of tree species, site types, and vegetation zones as well as …
Hydrodynamic characterization of a new small-scale reactor mixed by a magnetic bar
2015
International audience; The purpose of this study was to evaluate the mixing characteristics of a new milliliter-scale (mL-scale) reactor developed for studying enzymatic activity or physiological cell response. The mL-scale reactor was designed to enable the integration of several sensors to carry out dynamic measurements in a controlled environment. Rapid homogeneity of the entire system is essential to ensure reproducible and reliable results, consequently the reactor was stirred to optimize both mass and heat transfers. A comparative study using three different techniques was undertaken to study mixing performances in the system. Firstly, mixing time (4,) was estimated in the reactor us…
Parameter identification and state estimation of a microalgae dynamical model in sulphur deprived conditions: Global sensitivity analysis, optimizati…
2014
International audience; In this article, a dynamic model describing the growth of the green microalgae Chlamydomonas reinhardtii , under light attenuation and sulphur‐deprived conditions leading to hydrogen production in a photobioreactor is presented. The strong interactions between biological and physical phenomena require complex mathematical expressions with an important number of parameters. This article presents a global identification procedure in three steps using data from batch experiments. First, it includes the application of a sensitivity function analysis, which allows one to determine the parameters having the greatest influence on model outputs. Secondly, the most influentia…
Simple learning rules to cope with changing environments
2008
10 pages; International audience; We consider an agent that must choose repeatedly among several actions. Each action has a certain probability of giving the agent an energy reward, and costs may be associated with switching between actions. The agent does not know which action has the highest reward probability, and the probabilities change randomly over time. We study two learning rules that have been widely used to model decision-making processes in animals-one deterministic and the other stochastic. In particular, we examine the influence of the rules' 'learning rate' on the agent's energy gain. We compare the performance of each rule with the best performance attainable when the agent …
Value of information in multiple criteria decision making: an application to forest conservation
2019
Abstract Developing environmental conservation plans involves assessing trade-offs between the benefits and costs of conservation. The benefits of conservation can be established with ecological inventories or estimated based on previously collected information. Conducting ecological inventories can be costly, and the additional information may not justify these costs. To clarify the value of these inventories, we investigate the multiple criteria value of information associated with the acquisition of improved ecological data. This information can be useful when informing the decision maker to acquire better information. We extend the concept of the value of information to a multiple crite…