| Records |
| Author |
Mansouri, M.; Dumont, B.; Destain, M.-F. |
| Title |
Modeling and prediction of nonlinear environmental system using Bayesian methods |
Type |
Journal Article |
| Year |
2013 |
Publication |
Computers and Electronics in Agriculture |
Abbreviated Journal |
Computers and Electronics in Agriculture |
| Volume |
92 |
Issue |
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Pages |
16-31 |
| Keywords |
state and parameter estimation; variational filter; particle filter; extended kalman filter; nonlinear environmental system; leaf area index and soil moisture model; extended kalman filter; state-space models; parameter-estimation; particle filters; navigation; tutorial; tracking |
| Abstract |
An environmental dynamic system is usually modeled as a nonlinear system described by a set of nonlinear ODEs. A central challenge in computational modeling of environmental systems is the determination of the model parameters. In these cases, estimating these variables or parameters from other easily obtained measurements can be extremely useful. This work addresses the problem of monitoring and modeling a leaf area index and soil moisture model (LSM) using state estimation. The performances of various conventional and state-of-the-art state estimation techniques are compared when they are utilized to achieve this objective. These techniques include the extended Kalman filter (EKF), particle filter (PF), and the more recently developed technique variational filter (VF). Specifically, two comparative studies are performed. In the first comparative study, the state variables (the leaf-area index LAI, the volumetric water content of the soil layer 1, HUR1 and the volumetric water content of the soil layer 2, HUR2) are estimated from noisy measurements of these variables, and the various estimation techniques are compared by computing the estimation root mean square error (RMSE) with respect to the noise-free data. In the second comparative study, the state variables as well as the model parameters are simultaneously estimated. In this case, in addition to comparing the performances of the various state estimation techniques, the effect of number of estimated model parameters on the accuracy and convergence of these techniques are also assessed. The results of both comparative studies show that the PF provides a higher accuracy than the EKF, which is due to the limited ability of the EKF to handle highly nonlinear processes. The results also show that the VF provides a significant improvement over the PF because, unlike the PF which depends on the choice of sampling distribution used to estimate the posterior distribution, the VF yields an optimum choice of the sampling distribution, which also accounts for the observed data. The results of the second comparative study show that, for all techniques, estimating more model parameters affects the estimation accuracy as well as the convergence of the estimated states and parameters. However, the VF can still provide both convergence as well as accuracy related advantages over other estimation methods. (C) 2013 Elsevier B.V. All rights reserved. |
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English |
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0168-1699 |
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Article |
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CropM |
Approved |
no |
| Call Number |
MA @ admin @ |
Serial |
4495 |
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| Author |
Conradt, T.; Wechsung, F.; Bronstert, A. |
| Title |
Three perceptions of the evapotranspiration landscape: comparing spatial patterns from a distributed hydrological model, remotely sensed surface temperatures, and sub-basin water balances |
Type |
Journal Article |
| Year |
2013 |
Publication |
Hydrology and Earth System Sciences |
Abbreviated Journal |
Hydrol. Earth System Sci. |
| Volume |
17 |
Issue |
7 |
Pages |
2947-2966 |
| Keywords |
senegal river-basin; data assimilation; sensing data; regional evapotranspiration; intercomparison project; environmental-models; oklahoma experiments; solar-radiation; satellite data; scale |
| Abstract |
A problem encountered by many distributed hydrological modelling studies is high simulation errors at interior gauges when the model is only globally calibrated at the outlet. We simulated river runoff in the Elbe River basin in central Europe (148 268 km(2)) with the semi-distributed eco-hydrological model SWIM (Soil and Water Integrated Model). While global parameter optimisation led to Nash-Sutcliffe efficiencies of 0.9 at the main outlet gauge, comparisons with measured runoff series at interior points revealed large deviations. Therefore, we compared three different strategies for deriving sub-basin evapotranspiration: (1) modelled by SWIM without any spatial calibration, (2) derived from remotely sensed surface temperatures, and (3) calculated from long-term precipitation and discharge data. The results show certain consistencies between the modelled and the remote sensing based evapotranspiration rates, but there seems to be no correlation between remote sensing and water balance based estimations. Subsequent analyses for single sub-basins identify amongst others input weather data and systematic error amplification in inter-gauge discharge calculations as sources of uncertainty. The results encourage careful utilisation of different data sources for enhancements in distributed hydrological modelling. |
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English |
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1607-7938 |
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Article |
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CropM |
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no |
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MA @ admin @ |
Serial |
4485 |
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| Author |
Legarrea, S.; Betancourt, M.; Plaza, M.; Fraile, A.; García-Arenal, F.; Fereres, A. |
| Title |
Dynamics of nonpersistent aphid-borne viruses in lettuce crops covered with UV-absorbing nets |
Type |
Journal Article |
| Year |
2012 |
Publication |
Virus Research |
Abbreviated Journal |
Virus Res. |
| Volume |
165 |
Issue |
1 |
Pages |
1-8 |
| Keywords |
Absorption; Animals; Aphids/growth & development/radiation effects/*virology; Insect Control/instrumentation/*methods; Insect Vectors/growth & development/radiation effects/*virology; Lettuce/parasitology/*virology; Plant Diseases/prevention & control/*virology; Plant Viruses/*physiology; Protective Devices/virology; Ultraviolet Rays |
| Abstract |
Aphid-transmitted viruses frequently cause severe epidemics in lettuce grown under Mediterranean climates. Spatio-temporal dynamics of aphid-transmitted viruses and its vector were studied on lettuce (Lactuca sativa L.) grown under tunnels covered by two types of nets: a commercial UV-absorbing net (Bionet) and a Standard net. A group of plants infected by Cucumber mosaic virus (CMV, family Bromoviridae, genus Cucumovirus) and Lettuce mosaic virus (LMV, family Potyviridae, genus Potyvirus) was transplanted in each plot. The same virus-infected source plants were artificially infested by the aphid Macrosiphum euphorbiae (Thomas). Secondary spread of insects was weekly monitored and plants were sampled for the detection of viruses every two weeks. In 2008, the infection rate of both CMV and LMV were lower under the Bionet than under the Standard cover, probably due to the lower population density and lower dispersal rate achieved by M. euphorbiae. However, during spring of 2009, significant differences in the rate of infection between the two covers were only found for LMV six weeks after transplant. The spatial distribution of the viruses analysed by SADIE methodology was “at random”, and it was not associated to the spatial pattern of the vector. The results obtained are discussed analyzing the wide range of interactions that occurred among UV-radiation, host plant, viruses, insect vector and environmental conditions. Our results show that UV-absorbing nets can be recommended as a component of an integrated disease management program to reduce secondary spread of lettuce viruses, although not as a control measure on its own. |
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English |
Summary Language |
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Abbreviated Series Title |
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Edition |
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| ISSN |
0168-1702 |
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Article |
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CropM |
Approved |
no |
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MA @ admin @ |
Serial |
4475 |
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| Author |
Milford, A.B.; Kildal, C. |
| Title |
Meat Reduction by Force: The Case of “Meatless Monday” in the Norwegian Armed Forces |
Type |
Journal Article |
| Year |
2019 |
Publication |
Sustainability |
Abbreviated Journal |
Sustainability |
| Volume |
11 |
Issue |
10 |
Pages |
2741 |
| Keywords |
sustainable diets; meat reduction; Meatless Monday; policy implementation; attitudes to vegetarian food; multivariate regression analysis; Climate-Change; Food Choices; Consumption; Attitudes; Consumers; Health; Diet; Willingness; Information; Barriers |
| Abstract |
Despite the scientific evidence that more plants and less animal-based food is more sustainable, policy interventions to reduce meat consumption are scarce. However, campaigns for meat free days in school and office canteens have spread globally over the last years. In this paper, we look at the Norwegian Armed Forces’ attempt to introduce the Meatless Monday campaign in their camps, and we evaluate the implementation process as well as the effect of the campaign on soldiers. Qualitative interviews with military staff indicate that lack of conviction about benefits of meat reduction, and the fact that kitchen staff did not feel ownership to the project, partly explain why vegetarian measures were not fully implemented in all the camps. A multivariate regression analysis with survey data from soldiers indicate that those who have experienced meat free days in the military kitchen are more prone to claim that joining the military has given them a more positive view on vegetarian food. Furthermore, the survey gives evidence that stated willingness to eat more vegetarian food is higher among soldiers who believe in the environmental and health benefits of meat reduction. |
| Address |
2019-06-27 |
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English |
Summary Language |
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Series Title |
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Series Issue |
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Edition |
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| ISSN |
2071-1050 |
ISBN |
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Article |
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| Notes |
TradeM, ft_macsur |
Approved |
no |
| Call Number |
MA @ admin @ |
Serial |
5221 |
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| Author |
Saetnan, E.R.; Kipling, R.P. |
| Title |
Evaluating a European knowledge hub on climate change in agriculture: Are we building a better connected community |
Type |
Journal Article |
| Year |
2016 |
Publication |
Scientometrics |
Abbreviated Journal |
Scientometrics |
| Volume |
109 |
Issue |
2 |
Pages |
1057-1074 |
| Keywords |
Agriculture; Climate change; Interdisciplinary collaboration; Co-authorship; networks; EU research policy; Collaborative funding initiatives; Knowledge hub |
| Abstract |
In order to maintain food security and sustainability of production under climate change, interdisciplinary and international collaboration in research is essential. In the EU, knowledge hubs are important funding instruments for the development of an interconnected European Research Area. Here, network analysis was used to assess whether the pilot knowledge hub MACSUR has affected interdisciplinary collaboration, using co-authorship of peer reviewed articles as a measure of collaboration. The broad community of all authors identified as active in the field of agriculture and climate change was increasingly well connected over the period studied. Between knowledge hub members, changes in network parameters suggest an increase in collaborative interaction beyond that expected due to network growth, and greater than that found in the broader community. Given that interdisciplinary networks often take several years to have an impact on research outputs, these changes within the relatively new MACSUR community provide evidence that the knowledge hub structure has been effective in stimulating collaboration. However, analysis showed that knowledge hub partners were initially well-connected, suggesting that the initiative may have gathered together researchers with particular resources or inclinations towards collaborative working. Long term, consistent funding and ongoing reflection to improve networking structures may be necessary to sustain the early positive signs from MACSUR, to extend its success to a wider community of researchers, or to repeat it in less connected fields of science. Tackling complex challenges such as climate change will require research structures that can effectively support and utilise the diversity of talents beyond the already well-connected core of scientists at major research institutes. But network research shows that this core, well-connected group are vital brokers in achieving wider integration. |
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0138-9130 1588-2861 |
ISBN |
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LiveM |
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| Notes |
LiveM; wos; ft=macsur; macsur-text; wsnotyet |
Approved |
no |
| Call Number |
MA @ admin @ |
Serial |
4760 |
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