Approximate Bayesian algorithms for multiple target tracking with binary sensors

In this paper, we propose an approximate Bayesian computation approach to perform a multiple target tracking within a binary sensor network. The nature of the binary sensors (getting closer - moving away information) do not allow the use of the classical tools (e.g. Kalman Filter, Particle Filer), because the exact likelihood is intractable. To overcome this, we use the particular feature of the likelihood-free algorithms to produce an efficient multiple target tracking methodology.Comment: 19 pages, 6 figure

Direct and indirect effects of climate change on the livestock sector from an economic and social perspective

Livestock production systems provide multiple services to population and within territories. Based on studies carried on in different countries in Mediterranean and tropical environments, we show that climate change and/or climate variability have clear impacts on social organization and economic activities of livestock producers. This is due in part to direct impact of climate factor on production systems but also to indirect impact of global economic factors that are sensible to climate change or variability. Livestock producers hence identify and develop specific strategies to mitigate climate impact on the sustainability of their production systems

Fodder function of trees and shrubs for domestic ruminants in arid areas: Characterization with multi-dimensional functional traits

Farmers in arid regions traditionally know trees and shrub species with fodder and medicinal interest. This knowledge has been capitalized by naturalists. Then ecologists, agro?forestry and livestock scientists have applied their analytical specialized methods. Droughts have prompted investigations to characterize, quantitatively and qualitatively, forage provision by trees and preferences of animals. Exotic species were also tested. Many descriptive and analytical data have been collected but had little effect on the management of forestry and tree species in agro pastoral rangelands. New research stimulated by climatic and demographic changes must integrate socio?economic processes of management of forest stands and the multi?functionality of trees. Within this overall framework, the functional traits related to forage function must express: ? productivity of foliage and reproductive organs ? availability of forage for livestock following simultaneity between phenological cycles and major nutritive needs of animals ? palatibility of species ? nutritional value expressed by concentration of digestible nutrients (nitrogen, minerals, fiber) ? capability of re?sprouting after grazing or pruning. Traits are related to demography, phenology, morphology, anatomy, chemical composition, animal browsing behavior and intake. Many data exist. It must be organized so that they are accessible, located in their agro?climatic and socio?economical environments and taking into account the multi?functionality of species. These criteria are not absolute and depend on biodiversity of forest stands. The use of such data for engineering in land management based on needs and constraints of the users must take into account this diversity between species and intra?species according conditions. Examples of situation and species present this diversity and explore ways for useful integration of information in databases. (Texte intégral

Modelling Hospital length of stay using convolutive mixtures distributions

Length of hospital stay (LOS) is an important indicator of the hospital activity and management of health care. The skewness in the distribution of LOS poses problems in statistical modelling because it fails to adequately follow the usual traditional distribution such as the log-normal distribution. The aim of this work is to model the variable LOS using the convolution of two distributions; a technique well known in the signal processing community. The specificity of that model is that the variable of interest is considered to be the resulting sum of two random variables with different distributions. One of the variables will feature the patient-related factors in terms their need to recover from their admission condition, while the other models the hospital management process such as the discharging process. Two estimation procedures are proposed. One is the classical maximum likelihood, while the other relates to the expectation maximisation algorithm. We will present some results obtained by applying this model to a set of real data from a group of hospitals in Victoria (Australia).Comment: 26 pages, 3 figure

Estimation of an Origin/Destination matrix: Application to a ferry transport data

The estimation of the number of passengers with the identical journey is a common problem for public transport authorities. This problem is also known as the Origin- Destination estimation (OD) problem and it has been widely studied for the past thirty years. However, the theory is missing when the observations are not limited to the passenger counts but also includes station surveys. Our aim is to provide a solid framework for the estimation of an OD matrix when only a portion of the journey counts are observable. Our method consists of a statistical estimation technique for OD matrix when we have the sum-of-row counts and survey-based observations. Our technique differs from the previous studies in that it does not need a prior OD matrix which can be hard to obtain. Instead, we model the passengers behavior through the survey data, and use the diagonalization of the partial OD matrix to reduce the space parameter and derive a consistent global OD matrix estimator. We demonstrate the robustness of our estimator and apply it to several examples showcasing the proposed models and approach. We highlight how other sources of data can be incorporated in the model such as explanatory variables, e.g. rainfall, indicator variables for major events, etc, and inference made in a principled, non-heuristic way.Comment: 21 pages, 12 figures. Submitted to Transportation Research Part B: Methodolog

On the Effect of Data Contamination on Track Purity

This paper is concerned with performance analysis for data association, in a target tracking environment. Effects of misassociation are considered in a simple (linear) multiscan framework so as to provide closed-form expressions of the probability of correct association. In this paper, we focus on the development of explicit approximations of this probability. Via rigorous calculations the effect of dimensioning parameters (number of scans, false measurement positions or densities) is analyzed, for various modelings of the false measurements. Remarkably, it is possible to derive very simple expressions of the probability of correct association which are independent of the scenario kinematic parameters.Comment: 15 pages, dc, 11 figures. To appear in IEEE Transactions on Aerospace and Electronic System

Livestock farming systems and local development: A review of the multiple dimensions of "Territory" in livestock science

A review of the international literature was carried out, in order to describe how researchers study links between livestock farming and local development (i.e. 'territory'). We highlight three different sets of approaches: the first focused on relations between livestock farming systems and natural resources through landscape / spatial analyses. Secondly, livestock farming systems are analysed through the diversity of the farming systems existing within a territory. The third set of approaches considers livestock farming systems as technical systems structured around human groups. Finally, some publications combine two or three sets of approaches. The combination of these three approaches is useful in a landscape and territorial perspective. (Résumé d'auteur

A mixture model approach to infer land-use influence on point referenced water quality

The assessment of water quality across space and time is of considerable interest for both agricultural and public health reasons. The standard method to assess the water quality of a catchment, or a group of catchments, usually involves collecting point measurements of water quality and other additional information such as the date and time of measurements, rainfall amounts, the land-use and soil-type of the catchment and the elevation. Some of this auxiliary information will be point data, measured at the exact location, whereas other such as land-use will be areal data often in a compositional format. Two problems arise if analysts try to incorporate this information into a statistical model in order to predict (for example) the influence of land-use on water quality. First is the spatial change of support problem that arises when using areal data to predict outcomes at point locations. Secondly, the physical process driving water quality is not compositional, rather it is the observation process that provides compositional data. In this paper we present an approach that accounts for these two issues by using a latent variable to identify the land-use that most likely influences water quality. This latent variable is used in a spatial mixture model to help estimate the influence of land-use on water quality. We demonstrate the potential of this approach with data from a water quality research study in the Mount Lofty range, in South Australia.Comment: 20 pages, 2 figure

Multifunctions and contributions of grassland-based livestock systems in North-West Vietnam

In Northwest mountains of Vietnam, the smallholder livestock farms depend largely on natural pastures for animal feed. However, the management or improvement of grazing areas has not yet been recognized or regulated by local authorities. There is a need to provide reasonable evidence of the grassland-based livestock systems contribution for sustainable development. An ontology proposed by the AN2-GASL group was used to evaluate the contribution of grazing livestock systems in four dimensions: production, ecosystems, social and local development in the case of the Quài Nưa commune, a northwest mountain commune of Vietnam. Livestock contributed multifunction to all types of family farms. Cattle and buffaloes make an high contribution through meat for domestic consumption, sacrifices and donations, traction force, manure production and stock value as bank saving. This study provides quantified evidence of the multi-functionality of extensive cattle production at farm and communal levels. The contribution of grazing areas for meat production, but also for the creation of employment and the revenue and profit along the beef value chain was calculated at commune level. It appears that a balance between different types of farms with different roles could be a basis for local sustainable development

Natural resources utilization the sylvopastoral region of Senegal : The answers of the pastoral populations facing tecll innovations

To promote a sustainable pastoral production, some ecological regions of Senegal particularly the one in the sylvopastoral Zone (ZSP) have been devoted to livestock raising. At the same time as the installation of water supply equipments was done, natural resource management techniques such as the delimitation of protected areas, application of a stocking rate in rangelands and recently, the adoption of a holistic approach of resource management, were implemented with the participation of divers stakeholders with the aim of enhancing production in the region. However, heavy climatic constraints have revealed the limits of these technologies and sometimes of their non adaptation. This situation has also shown the efficiency of pastoral practices that have allowed pastoralists to save their livestock when regressive tendency was observed on the rangelands. This paper describe the evolution in the utilization of natural resources in the sylvopastoral realize and the reactions of pastoral people face to proposed natural resource management techniques. (Résumé d'auteur