Assessing impacts of alternative agricultural land use scenarios on nitrogen leaching with the INCA-N model

The Integrated Nutrients Model for Catchments - Nitrogen (INCA-N) model was applied in Savijoki, a small (15,4 km2) agricultural catchment, in order to analyse possibilities to achieve the targeted 50 % reduction in agricultural nitrogen loading. The model was applied for the years 1995-1999, representing the first period of the Finnish Agri-Environmental Programme, a widely adapted policy measure for controlling environmental impacts of agriculture in Finland

Testing the INCA model in a small agricultural catchment in southern Finland

International audienceNutrient leaching from agricultural production is still recognised as a major environmental problem in Finland. To estimate agricultural nitrogen loading under changing land-use and climate conditions, the Integrated Nitrogen Model for Catchments (INCA) was applied in Savijoki, a small (15.4 km2) agricultural catchment, which represents the intensively cultivated areas in south-western Finland. Hydrological calibration and testing of the INCA model was first carried out in Savijoki during 1981?2000. In spite of heterogeneous soil and land-use conditions, INCA was able to reproduce the overall hydrological regime in the stream. The model was calibrated further in respect of nitrogen processes during 1995?2000. The model was able, reasonably well, to simulate the overall annual dynamics of the inorganic N concentrations in the stream water and the annual N export from the catchment. The average simulated NO3-N export was 550 kg N km?2 yr?1 and the observed one (constituting more than half of the annual total N export) was 592 kg N km?2 yr?1. For NH4-N, the simulated export was somewhat higher than that measured but NH4-N was only 4% of the total N export. In spite of some underestimation of flow and N concentration during extreme hydrological conditions, the INCA model proved to be a useful tool for analysing flow pattern and inorganic nitrogen leaching in a small agricultural catchment, characterised by a rapid response to rainfall. Keywords: nitrogen, integrated modelling, hydrology, catchment, agricultur

Theoretical analysis of perching and hovering maneuvers

Unsteady aerodynamic phenomena are encountered in a large number of modern aerospace and non-aerospace applications. Leading edge vortices (LEVs) are of particular interest because of their large impact on the forces and performance. In rotorcraft applications, they cause large vibrations and torsional loads (dynamic stall), affecting the performance adversely. In insect flight however, they contribute positively by enabling high-lift flight. Identifying the conditions that result in LEV formation and modeling their effects on the flow is an important ongoing challenge. Perching (airfoil decelerates to rest) and hovering (zero freestream velocity) maneuvers are of special interest. In earlier work by the authors, a Leading Edge Suction Parameter (LESP) was developed to predict LEV formation for airfoils undergoing arbitrary variation in pitch and plunge at a constant freestream velocity. In this research, the LESP criterion is extended to situations where the freestream velocity is varying or zero. A point-vortex model based on this criterion is developed and results from the model are compared against those from a computational fluid dynamics (CFD) method. Abstractions of perching and hovering maneuvers are used to validate the low-order model's performance in highly unsteady vortex-dominated flows, where the time-varying freestream/translational velocity is small in magnitude compared to the other contributions to the velocity experienced by the leading edge region of the airfoil. Time instants of LEV formation, flow topologies and force coefficient histories for the various motion kinematics from the low-order model and CFD are obtained and compared. The LESP criterion is seen to be successful in predicting the start of LEV formation and the point-vortex method is effective in modeling the flow development and forces on the airfoil. Typical run-times for the low-order method are between 30-40 seconds, making it a potentially convenient tool for control/design applications

Examining the rights of children with intellectual disability in South Africa : children’s perspectives

BACKGROUND. Human rights provide fundamental conditions for people to maintain dignity and selfdetermination and protect a nation’s most vulnerable citizens. In South Africa, children with intellectual disability who experience socioeconomic disadvantage may be particularly vulnerable due to their cognitive impairments and inability to garner needed resources. METHOD. The perceptions of children with intellectual disability regarding their access to basic amenities in their home environments were examined to determine whether their positive human rights were met. Risk factors were examined in relation to these perceptions. RESULTS. The results suggested that participants generally reported high degrees of access to basic resources. Logistic regressions suggested socioeconomic risk factors (e.g., income, education, household size, relationship status) were negatively related to children’s reports of access to food and their own beds and positively related to having someone available to explain confusing concepts to them. CONCLUSIONS. The positive human rights of children living in high risk environments should be monitored to ensure all South Africans have their rights met.http://www.tandfonline.com/loi/cjid20hb201

A modelling framework for the assessment of the impacts of alternative policy and management options on the sustainability of Finnish agrifood systems

Recently, a new project focussing on integrated assessment modelling of agrifood systems (IAM-Tools) has been launched at MTT Agrifood Research Finland to gather, evaluate, refine and develop these component models and to link tem in an IAM framework for Finnish conditions

Model Reduction in Discrete Vortex Methods for 2D Unsteady Aerodynamic Flows

In this paper, we propose a method for model reduction in discrete-vortex methods. Discrete vortex methods have been successfully employed to model separated and unsteady airfoil flows. Earlier research revealed that a parameter called the Leading Edge Suction Parameter (LESP) can be used to model leading-edge vortex (LEV) shedding in unsteady flows. The LESP is a measure of suction developed at the leading edge, and whenever the LESP exceeds a critical value, a discrete vortex is released from the leading edge so as to keep the LESP at the critical value. Though the method was successful in predicting the forces on and the flow field around an airfoil in unsteady vortex-dominated flows,it was necessary to track a large number of discrete vortices in order to obtain the solution. The current study focuses on obtaining a model with a reduced number of leading-edge vortices, thus improving the computation time. Vortex shedding from the leading edge is modelled by a shear layer that comprises of a few discrete vortices, and a single concentrated vortex whose strength varies with time. The single vortex at the end of the shear layer accounts for the concentrated vortical structure that comprises several discrete vortex elements in conventional vortex methods. A merging algorithm is initiated when the edge of the shear layer starts rolling up. Suitable discrete vortices are identified using a kinematic criterion, and are merged to the growing vortex at every time step. The reduced order method is seen to bring down the number of discrete vortices shed from the leading edge significantly

Aerodynamics of Pitching Wings: Theory and Experiments

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140444/1/6.2014-2881.pd