WorldWideScience

Sample records for farm scale modeling

  1. Wind Farm Wake Models From Full Scale Data

    DEFF Research Database (Denmark)

    Knudsen, Torben; Bak, Thomas

    2012-01-01

    on real full scale data. The modelling is based on so called effective wind speed. It is shown that there is a wake for a wind direction range of up to 20 degrees. Further, when accounting for the wind direction it is shown that the two model structures considered can both fit the experimental data......This investigation is part of the EU FP7 project “Distributed Control of Large-Scale Offshore Wind Farms”. The overall goal in this project is to develop wind farm controllers giving power set points to individual turbines in the farm in order to minimise mechanical loads and optimise power. One...... control configuration examined is distributed control where turbines only communicate with their nearest upwind neighbors. Design of such controllers needs wake models and these models should ideally be distributed. This paper compares two simple multiple wake models for this purpose. The study is based...

  2. Optimization Model for Mitigating Global Warming at the Farm Scale: An Application to Japanese Rice Farms

    Directory of Open Access Journals (Sweden)

    Kiyotaka Masuda

    2016-06-01

    Full Text Available In Japan, greenhouse gas emissions from rice production, especially CH4 emissions in rice paddy fields, are the primary contributors to global warming from agriculture. When prolonged midseason drainage for mitigating CH4 emissions from rice paddy fields is practiced with environmentally friendly rice production based on reduced use of synthetic pesticides and chemical fertilizers, Japanese rice farmers can receive an agri-environmental direct payment. This paper examines the economic and environmental effects of the agri-environmental direct payment on the adoption of a measure to mitigate global warming in Japanese rice farms using a combined application of linear programming and life cycle assessment at the farm scale. Eco-efficiency, which is defined as net farm income divided by global warming potential, is used as an integrated indicator for assessing the economic and environmental feasibilities. The results show that under the current direct payment level, the prolonged midseason drainage technique does not improve the eco-efficiency of Japanese rice farms because the practice of this technique in environmentally friendly rice production causes large economic disadvantages in exchange for small environmental advantages. The direct payment rates for agri-environmental measures should be determined based on the condition that environmentally friendly agricultural practices improve eco-efficiency compared with conventional agriculture.

  3. Field Scale Spatial Modelling of Surface Soil Quality Attributes in Controlled Traffic Farming

    Science.gov (United States)

    Guenette, Kris; Hernandez-Ramirez, Guillermo

    2017-04-01

    The employment of controlled traffic farming (CTF) can yield improvements to soil quality attributes through the confinement of equipment traffic to tramlines with the field. There is a need to quantify and explain the spatial heterogeneity of soil quality attributes affected by CTF to further improve our understanding and modelling ability of field scale soil dynamics. Soil properties such as available nitrogen (AN), pH, soil total nitrogen (STN), soil organic carbon (SOC), bulk density, macroporosity, soil quality S-Index, plant available water capacity (PAWC) and unsaturated hydraulic conductivity (Km) were analysed and compared among trafficked and un-trafficked areas. We contrasted standard geostatistical methods such as ordinary kriging (OK) and covariate kriging (COK) as well as the hybrid method of regression kriging (ROK) to predict the spatial distribution of soil properties across two annual cropland sites actively employing CTF in Alberta, Canada. Field scale variability was quantified more accurately through the inclusion of covariates; however, the use of ROK was shown to improve model accuracy despite the regression model composition limiting the robustness of the ROK method. The exclusion of traffic from the un-trafficked areas displayed significant improvements to bulk density, macroporosity and Km while subsequently enhancing AN, STN and SOC. The ability of the regression models and the ROK method to account for spatial trends led to the highest goodness-of-fit and lowest error achieved for the soil physical properties, as the rigid traffic regime of CTF altered their spatial distribution at the field scale. Conversely, the COK method produced the most optimal predictions for the soil nutrient properties and Km. The use of terrain covariates derived from light ranging and detection (LiDAR), such as of elevation and topographic position index (TPI), yielded the best models in the COK method at the field scale.

  4. Let's put this in perspective: using dynamic simulation modelling to assess the impacts of farm-scale land management change on catchment-scale water quality

    Science.gov (United States)

    Rivers, Mark; Clarendon, Simon; Coles, Neil

    2013-04-01

    Natural Resource Management and Agri-industry development groups in Australia have invested considerable resources into the investigation of the economic, social and, particularly, environmental impacts of varying farming activities in a "catchment context". This research has resulted in the development of a much-improved understanding of the likely impacts of changed management practices at the farm-scale as well as the development of a number of conceptual models which place farming within this broader catchment context. The project discussed in this paper transformed a conceptual model of dairy farm phosphorus (P) management and transport processes into a more temporally and spatially dynamic model. This was then loaded with catchment-specific data and used as a "policy support tool" to allow the Australian dairy industry to examine the potential farm and catchment-scale impacts of varying dairy farm management practices within some key dairy farming regions. Models were developed, validated and calibrated using "STELLA©" dynamic modelling software for three catchments in which dairy is perceived as a significant land use. The models describe P movement and cycling within and through dairy farms in great detail and also estimate P transport through major source, sink and flow sectors of the catchments. A series of scenarios were executed for all three catchments which examined three main "groups" of tests: changes to farm P input rates; implementation of perceived environmental "Best Management Practices" (BMPs), and; changes to land use mosaics. Modifications to actual P input rates into dairy farms (not surprisingly) had a major effect on nutrient transport within and from the farms with a significant rise in nutrient loss rates at all scales with increasing fertiliser use. More surprisingly, however, even extensive environmental BMP implementation did not have marked effects on off-farm nutrient loss rates. On and off-farm riparian management implemented

  5. Linking on-farm change to catchment response using dynamic simulation modelling: assessing the impacts of farm-scale land management change on catchment-scale phosphorus transport processes and water-quality.

    Science.gov (United States)

    Rivers, M.; Clarendon, S.

    2012-04-01

    Australian Natural Resource Management and Agri-industry Development agencies have recently invested considerable resources into a number of research and development projects that have investigated the actual and potential economic, social and, particularly, environmental impacts of varying farming activities (with a strong focus on dairies) in a "catchment context". These activities have resulted in the development of a much-improved understanding of the likely impacts of changed farm management practices within the farms and regions in which they were investigated, as well as the development of a number of conceptual models which place dairy farming within this broader catchment context. The project discussed in this paper was charged with the objective of transforming these conceptual models of dairy farm nutrient management and transport processes into a more temporally and spatially dynamic model. This could then be loaded with catchment-specific data and used as a "policy support tool" to allow the Australian dairy industry to examine the potential farm and catchment-scale impacts of varying dairy farm management practices within some key dairy farming regions. This paper describes the series of dynamic models and farm management - land use scenarios which were executed to examine these issues. Models were developed, validated and calibrated for the Peel-Harvey catchment in Western Australia and the Gippsland and Latrobe (a sub-catchment of Gippsland) catchments in Victoria. Scenarios which range from simple, on-farm riparian management, through changes in fertiliser application rates, to gross changes in the land use mosaic were examined and described in terms which included changes to phosphorus (P) loss rates at the farm scale, the relative contributions to catchment P loads from dairying and, ultimately, changes to downstream water quality. A comprehensive suite of scenarios and policy options was examined but, in summary, the results indicate that whilst

  6. Modeling a farm population to estimate on-farm compliance costs and environmental effects of a grassland extensification scheme at the regional scale

    DEFF Research Database (Denmark)

    Uthes, Sandra; Sattler, Claudia; Piorr, Annette

    2010-01-01

    production orientations and grassland types was modeled under the presence and absence of the grassland extensification scheme using the bio-economic model MODAM. Farms were based on available accountancy data and surveyed production data, while information on farm location within the district was derived...... from a spatial allocation procedure. The reduction in total gross margin per unit area was used to measure on-farm compliance costs. A dimensionless environmental index was used to assess the suitability of the scheme to reduce the risk of nitrate-leaching. Calculated on-farm compliance costs...

  7. Benchmarking of wind farm scale wake models in the EERA - DTOC project

    DEFF Research Database (Denmark)

    Réthoré, Pierre-Elouan; Hansen, Kurt Schaldemose; Barthelmie, R.J.

    2013-01-01

    Designing offshore wind farms next to existing or planned wind farm clusters has recently become a common practice in the North Sea. These types of projects face unprecedented challenges in term of wind energy siting. The currently ongoing European project FP7 EERA - DTOC (Design Tool for Offshor...

  8. Improving Wind Farm Dispatchability Using Model Predictive Control for Optimal Operation of Grid-Scale Energy Storage

    Directory of Open Access Journals (Sweden)

    Douglas Halamay

    2014-09-01

    Full Text Available This paper demonstrates the use of model-based predictive control for energy storage systems to improve the dispatchability of wind power plants. Large-scale wind penetration increases the variability of power flow on the grid, thus increasing reserve requirements. Large energy storage systems collocated with wind farms can improve dispatchability of the wind plant by storing energy during generation over-the-schedule and sourcing energy during generation under-the-schedule, essentially providing on-site reserves. Model predictive control (MPC provides a natural framework for this application. By utilizing an accurate energy storage system model, control actions can be planned in the context of system power and state-of-charge limitations. MPC also enables the inclusion of predicted wind farm performance over a near-term horizon that allows control actions to be planned in anticipation of fast changes, such as wind ramps. This paper demonstrates that model-based predictive control can improve system performance compared with a standard non-predictive, non-model-based control approach. It is also demonstrated that secondary objectives, such as reducing the rate of change of the wind plant output (i.e., ramps, can be considered and successfully implemented within the MPC framework. Specifically, it is shown that scheduling error can be reduced by 81%, reserve requirements can be improved by up to 37%, and the number of ramp events can be reduced by 74%.

  9. Modelling Farm Animal Welfare

    Science.gov (United States)

    Collins, Lisa M.; Part, Chérie E.

    2013-01-01

    Simple Summary In this review paper we discuss the different modeling techniques that have been used in animal welfare research to date. We look at what questions they have been used to answer, the advantages and pitfalls of the methods, and how future research can best use these approaches to answer some of the most important upcoming questions in farm animal welfare. Abstract The use of models in the life sciences has greatly expanded in scope and advanced in technique in recent decades. However, the range, type and complexity of models used in farm animal welfare is comparatively poor, despite the great scope for use of modeling in this field of research. In this paper, we review the different modeling approaches used in farm animal welfare science to date, discussing the types of questions they have been used to answer, the merits and problems associated with the method, and possible future applications of each technique. We find that the most frequently published types of model used in farm animal welfare are conceptual and assessment models; two types of model that are frequently (though not exclusively) based on expert opinion. Simulation, optimization, scenario, and systems modeling approaches are rarer in animal welfare, despite being commonly used in other related fields. Finally, common issues such as a lack of quantitative data to parameterize models, and model selection and validation are discussed throughout the review, with possible solutions and alternative approaches suggested. PMID:26487411

  10. Determining the Appropriate Crop Rotation Plan in a Farm Scale Using Fuzzy Goal Programming Model

    Directory of Open Access Journals (Sweden)

    A. Alizadeh Zoeram

    2016-03-01

    Full Text Available Introduction One of the important subject in the field of agricultural programming is reaching to a pattern or appropriate crop rotation to plant. Existing constraints, including the amount of available resources, and different goals, makes the decision to optimize the use of resources and production factors a complicated task. Therefore, applying mathematical models can be a grate help in this field. The goal of this study is to determine the appropriate patterns of crop cultivation in a farm in the North Khorasan province. Materials and Methods Implem enting fuzzy goal programming (FGP model based on different scenarios was employed to achieve our goals. According to results ,represented process , constraints and problem goals, four plant patterns are offered based on eight proposed scenarios for crop products in this farm or this study. These proposed cultivation pattern can help to make better decision for determination the appropriate rotation of crops in different conditions and different goals by decision makers. Results Discussion Finally, proposed cultivation patterns were prioritized according to maximum amount of reaching the desired level of total goals. Based on maximum level of reaching goals, different scenarios consisted of income, cost, production resources, income-cost, income-production resources, cost-production resources, income-cost-production resources with equal weights, and income-cost-production resources with different weights have been prioritized and four cropping pattern have been detected. In first pattern, three scenario consisted of scenario 1 (income, scenario 4 (income-cost and scenario 5 (income-production resources have combined. The second pattern have made scenario 2 (cost. In third pattern, scenario 3 (production resources, scenario 6 (cost-production resources and scenario 7 (income-cost-production resources with equal weights have combined. The scenario 8 (income-cost-production resources with different

  11. Evaluating the impact of farm scale innovation at catchment scale

    Science.gov (United States)

    van Breda, Phelia; De Clercq, Willem; Vlok, Pieter; Querner, Erik

    2014-05-01

    Hydrological modelling lends itself to other disciplines very well, normally as a process based system that acts as a catalogue of events taking place. These hydrological models are spatial-temporal in their design and are generally well suited for what-if situations in other disciplines. Scaling should therefore be a function of the purpose of the modelling. Process is always linked with scale or support but the temporal resolution can affect the results if the spatial scale is not suitable. The use of hydrological response units tends to lump area around physical features but disregards farm boundaries. Farm boundaries are often the more crucial uppermost resolution needed to gain more value from hydrological modelling. In the Letaba Catchment of South Africa, we find a generous portion of landuses, different models of ownership, different farming systems ranging from large commercial farms to small subsistence farming. All of these have the same basic right to water but water distribution in the catchment is somewhat of a problem. Since water quantity is also a problem, the water supply systems need to take into account that valuable production areas not be left without water. Clearly hydrological modelling should therefore be sensitive to specific landuse. As a measure of productivity, a system of small farmer production evaluation was designed. This activity presents a dynamic system outside hydrological modelling that is generally not being considered inside hydrological modelling but depends on hydrological modelling. For sustainable development, a number of important concepts needed to be aligned with activities in this region, and the regulatory actions also need to be adhered to. This study aimed at aligning the activities in a region to the vision and objectives of the regulatory authorities. South Africa's system of socio-economic development planning is complex and mostly ineffective. There are many regulatory authorities involved, often with unclear

  12. Improving environmental management on small-scale farms: perspectives of extension educators and horse farm operators.

    Science.gov (United States)

    Rebecca, Perry-Hill; Linda, Prokopy

    2015-01-01

    Although the number of small-scale farms is increasing in North America and Europe, few studies have been conducted to better understand environmental management in this sector. We investigate this issue by examining environmental management on horse farms from both the perspective of the "expert" extension educator and horse farm operator. We conducted a Delphi survey and follow-up interviews with extension educators in Indiana and Kentucky. We also conducted interviews and farm assessments with 15 horse farm operators in the two states. Our results suggest a disconnection between the perceptions of extension educators and horse farm operators. Extension educators believed that operators of small horse farms are unfamiliar with conservation practices and their environmental benefits and they found it difficult to target outreach to this audience. In the interviews with horse farm operators, we found that the majority were somewhat familiar with conservation practices like rotational grazing, soil testing, heavy use area protection, and manure composting. It was not common, however, for practices to be implemented to generally recognized standards. The horse farm respondents perceived these practices as interrelated parts of a system of farm management that has developed over time to best deal with the physical features of the property, needs of the horses, and available resources. Because conservation practices must be incorporated into a complex farm management system, traditional models of extension (i.e., diffusion of innovations) may be inappropriate for promoting better environmental management on horse farms.

  13. Mussel farming as a large-scale bioengineering tool: a numerical modelling case study in Rødsand lagoon, Denmark

    DEFF Research Database (Denmark)

    Forsberg, Pernille Louise; Ernstsen, Verner Brandbyge; Lumborg, Ulrik

    spill of sediment, which could increase the longshore sediment influx to Rødsand lagoon. Mussels can reduce the SSC in marine environments (Schröder et al., 2014), why the implementation of a mussel farm has been considered as a management option. In the present study we developed a module to include....... and Krost P. (2014). The impact of a mussel farm on water transparency in the Kiel Fjord. Ocean & Coastal Management, 101:42-52....... mussels as a bioengineering measure in a numerical sediment transport model and investigated how the implementation of an exterior mussel farm affect the sediment dynamics within Rødsand lagoon. On the basis of 2D modelling (MIKE21 by DHI) and field measurements, the flow and sediment dynamics to and from...

  14. Modularised process-based modelling of phosphorus loss at farm and catchment scale

    Directory of Open Access Journals (Sweden)

    M. G. Hutchins

    2002-01-01

    Full Text Available In recent years, a co-ordinated programme of data collection has resulted in the collation of sub-hourly time-series of hydrological, sediment and phosphorus loss data, together with soil analysis, cropping and management information for two small ( Keywords: phosphorus, erosion, process-based modelling, agriculture

  15. Report on farm scale eco-efficiency of mitigation and adaption options. D10.3

    DEFF Research Database (Denmark)

    Kristensen, Ib Sillebak; Olesen, Jørgen Eivind; Hutchings, Nicholas John

    2015-01-01

    This deliverable collates the information on simulated effects of mitigation and adaptation options at the farm scale in Europe, primarily using the FarmAC model for the mitigation options, and applying semi quantitative modelling for the adaptation options....

  16. Modeling greenhouse gas emissions from dairy farms.

    Science.gov (United States)

    Rotz, C Alan

    2017-11-15

    Dairy farms have been identified as an important source of greenhouse gas emissions. Within the farm, important emissions include enteric CH 4 from the animals, CH 4 and N 2 O from manure in housing facilities during long-term storage and during field application, and N 2 O from nitrification and denitrification processes in the soil used to produce feed crops and pasture. Models using a wide range in level of detail have been developed to represent or predict these emissions. They include constant emission factors, variable process-related emission factors, empirical or statistical models, mechanistic process simulations, and life cycle assessment. To fully represent farm emissions, models representing the various emission sources must be integrated to capture the combined effects and interactions of all important components. Farm models have been developed using relationships across the full scale of detail, from constant emission factors to detailed mechanistic simulations. Simpler models, based upon emission factors and empirical relationships, tend to provide better tools for decision support, whereas more complex farm simulations provide better tools for research and education. To look beyond the farm boundaries, life cycle assessment provides an environmental accounting tool for quantifying and evaluating emissions over the full cycle, from producing the resources used on the farm through processing, distribution, consumption, and waste handling of the milk and dairy products produced. Models are useful for improving our understanding of farm processes and their interacting effects on greenhouse gas emissions. Through better understanding, they assist in the development and evaluation of mitigation strategies for reducing emissions and improving overall sustainability of dairy farms. The Authors. Published by the Federation of Animal Science Societies and Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article

  17. Wind Farms: Modeling and Control

    DEFF Research Database (Denmark)

    Soleimanzadeh, Maryam

    2012-01-01

    is minimized. The controller is practically feasible. Yet, the results on load reduction in this approach are not very significant. In the second strategy, the wind farm control problem has been divided into below rated and above rated wind speed conditions. In the above rated wind speed pitch angle and power....... Distributed controller design commences with formulating the problem, where a structured matrix approach has been put in to practice. Afterwards, an H2 control problem is implemented to obtain the controller dynamics for a wind farm such that the structural loads on wind turbines are minimized.......The primary purpose of this work is to develop control algorithms for wind farms to optimize the power production and augment the lifetime of wind turbines in wind farms. In this regard, a dynamical model for wind farms was required to be the basis of the controller design. In the first stage...

  18. Review of whole-farm economic modelling for irrigation farming ...

    African Journals Online (AJOL)

    The main objective of this paper is to review the progress that has been made in South Africa with respect to whole-farm economic modelling over the past 2 decades. Farming systems are complex and careful consideration to the stochastic dynamic nature of irrigation farming processes and their linkages with the larger ...

  19. Forecasting Transplanted Rice Yield at the Farm Scale Using Moderate-Resolution Satellite Imagery and the AquaCrop Model: A Case Study of a Rice Seed Production Community in Thailand

    OpenAIRE

    Kulapramote Prathumchai; Masahiko Nagai; Nitin K. Tripathi; Nophea Sasaki

    2018-01-01

    Thailand has recently introduced agricultural policies to promote large-scale rice farming through supporting and integrating small-scale farmers. However, achieving these policies requires agricultural tools that can assist farmers in rice farming planning and management. Crop models, along with remote sensing technologies, can be useful for farmers and field managers in this regard. In this study, we used the AquaCrop model along with moderate-resolution satellite images (30 m) to simulate ...

  20. An aggregate model of grid-connected, large-scale, offshore wind farm for power stability investigations-importance of windmill mechanical system

    DEFF Research Database (Denmark)

    Akhmatov, Vladislav; Knudsen, H.

    2002-01-01

    . Because the shaft system gives a soft coupling between the rotating wind turbine and the induction generator, the large-scale wind farm cannot always be reduced to one-machine equivalent and use of multi-machine equivalents will be necessary for reaching accuracy of the investigation results....... This will be in cases with irregular wind distribution over the wind farm area. The torsion mode of the shaft systems of large wind turbines is commonly in the range of 1-2 Hz and close to typical values of the electric power grid eigenfrequencies why there is a risk of oscillation between the wind turbines...... and the entire network. All these phenomena are different compared to previous experiences with modelling of conventional power plants with synchronous generators and stiff shaft systems....

  1. Simulation analysis of a wind farm with different aggregated models

    DEFF Research Database (Denmark)

    Li, H.; Wang, H.; Zhao, B.

    2011-01-01

    Based on a wind farm including wind turbines with squirrel cage induction generators (SCIGs), different aggregated models of a wind farm, such as a single weighted average model, a reduced-order re-scaled model, a parameter transformed model and a single weighted arithmetic model were presented, ...

  2. Experimental Study on the Wake Meandering Within a Scale Model Wind Farm Subject to a Wind-Tunnel Flow Simulating an Atmospheric Boundary Layer

    Science.gov (United States)

    Coudou, Nicolas; Buckingham, Sophia; Bricteux, Laurent; van Beeck, Jeroen

    2018-04-01

    The phenomenon of meandering of the wind-turbine wake comprises the motion of the wake as a whole in both horizontal and vertical directions as it is advected downstream. The oscillatory motion of the wake is a crucial factor in wind farms, because it increases the fatigue loads, and, in particular, the yaw loads on downstream turbines. To address this phenomenon, experimental investigations are carried out in a wind-tunnel flow simulating an atmospheric boundary layer with the Coriolis effect neglected. A 3 × 3 scaled wind farm composed of three-bladed rotating wind-turbine models is subject to a neutral boundary layer over a slightly-rough surface, i.e. corresponding to offshore conditions. Particle-image-velocimetry measurements are performed in a horizontal plane at hub height in the wakes of the three wind turbines occupying the wind-farm centreline. These measurements allow determination of the wake centrelines, with spectral analysis indicating the characteristic wavelength of the wake-meandering phenomenon. In addition, measurements with hot-wire anemometry are performed along a vertical line in the wakes of the same wind turbines, with both techniques revealing the presence of wake meandering behind all three turbines. The spectral analysis performed with the spatial and temporal signals obtained from these two measurement techniques indicates a Strouhal number of ≈ 0.20 - 0.22 based on the characteristic wake-meandering frequency, the rotor diameter and the flow speed at hub height.

  3. Farm scale biogas concepts in Europe

    Energy Technology Data Exchange (ETDEWEB)

    Wellinger, A. [Nova Energie, Ettenhausen (Switzerland)

    1997-08-01

    The near future of farm scale biogas production looks bright as long as the high electricity prices are maintained by political will and subsidies remain higher than approx. 20%. If in all the number of biogas plants is growing as it is in Germany (Within the last two years about 200 new plants have been built) then biogas will add its share to a nuclear power free electricity production, as does wind energy in Germany, Holland or Denmark. The standard for manure digesters is set. There is still some way to go for solid waste digesters. However, first inputs have been given. (EG) 10 refs.

  4. Reliability Evaluation considering Structures of a Large Scale Wind Farm

    DEFF Research Database (Denmark)

    Shin, Je-Seok; Cha, Seung-Tae; Wu, Qiuwei

    2012-01-01

    evaluation on wind farm is necessarily required. Also, because large scale offshore wind farm has a long repair time and a high repair cost as well as a high investment cost, it is essential to take into account the economic aspect. One of methods to efficiently build and to operate wind farm is to construct......Wind energy is one of the most widely used renewable energy resources. Wind power has been connected to the grid as large scale wind farm which is made up of dozens of wind turbines, and the scale of wind farm is more increased recently. Due to intermittent and variable wind source, reliability...... wind farm which is able to enhance a capability of delivering a power instead of controlling an uncontrollable output of wind power. Therefore, this paper introduces a method to evaluate the reliability depending upon structures of wind farm and to reflect the result to the planning stage of wind farm....

  5. Modelling the economics of farm-based anaerobic digestion in a UK whole-farm context

    International Nuclear Information System (INIS)

    Jones, Philip; Salter, Andrew

    2013-01-01

    Anaerobic digestion (AD) technologies convert organic wastes and crops into methane-rich biogas for heating, electricity generation and vehicle fuel. Farm-based AD has proliferated in some EU countries, driven by favourable policies promoting sustainable energy generation and GHG mitigation. Despite increased state support there are still few AD plants on UK farms leading to a lack of normative data on viability of AD in the whole-farm context. Farmers and lenders are therefore reluctant to fund AD projects and policy makers are hampered in their attempts to design policies that adequately support the industry. Existing AD studies and modelling tools do not adequately capture the farm context within which AD interacts. This paper demonstrates a whole-farm, optimisation modelling approach to assess the viability of AD in a more holistic way, accounting for such issues as: AD scale, synergies and conflicts with other farm enterprises, choice of feedstocks, digestate use and impact on farm Net Margin. This modelling approach demonstrates, for example, that: AD is complementary to dairy enterprises, but competes with arable enterprises for farm resources. Reduced nutrient purchases significantly improve Net Margin on arable farms, but AD scale is constrained by the capacity of farmland to absorb nutrients in AD digestate. -- Highlights: •Lack of empirical data on UK farm AD is barrier to investment and policy formulation. •A modelling approach used to assess economic viability of AD in whole-farm context. •AD increases dairy and arable farm net margin including by savings in nutrient costs. •AD margins better for a few crops than other uses, especially wheat and beet crops. •AD co-exists with dairy, but to obtain best margin displaces conventional cropping

  6. Wake characteristics of wind turbines in utility-scale wind farms

    Science.gov (United States)

    Yang, Xiaolei; Foti, Daniel; Sotiropoulos, Fotis

    2017-11-01

    The dynamics of turbine wakes is affected by turbine operating conditions, ambient atmospheric turbulent flows, and wakes from upwind turbines. Investigations of the wake from a single turbine have been extensively carried out in the literature. Studies on the wake dynamics in utility-scale wind farms are relatively limited. In this work, we employ large-eddy simulation with an actuator surface or actuator line model for turbine blades to investigate the wake dynamics in utility-scale wind farms. Simulations of three wind farms, i.e., the Horns Rev wind farm in Denmark, Pleasant Valley wind farm in Minnesota, and the Vantage wind farm in Washington are carried out. The computed power shows a good agreement with measurements. Analysis of the wake dynamics in the three wind farms is underway and will be presented in the conference. This work was support by Xcel Energy (RD4-13). The computational resources were provided by National Renewable Energy Laboratory.

  7. A canopy-type similarity model for wind farm optimization

    Science.gov (United States)

    Markfort, Corey D.; Zhang, Wei; Porté-Agel, Fernando

    2013-04-01

    The atmospheric boundary layer (ABL) flow through and over wind farms has been found to be similar to canopy-type flows, with characteristic flow development and shear penetration length scales (Markfort et al., 2012). Wind farms capture momentum from the ABL both at the leading edge and from above. We examine this further with an analytical canopy-type model. Within the flow development region, momentum is advected into the wind farm and wake turbulence draws excess momentum in from between turbines. This spatial heterogeneity of momentum within the wind farm is characterized by large dispersive momentum fluxes. Once the flow within the farm is developed, the area-averaged velocity profile exhibits a characteristic inflection point near the top of the wind farm, similar to that of canopy-type flows. The inflected velocity profile is associated with the presence of a dominant characteristic turbulence scale, which may be responsible for a significant portion of the vertical momentum flux. Prediction of this scale is useful for determining the amount of available power for harvesting. The new model is tested with results from wind tunnel experiments, which were conducted to characterize the turbulent flow in and above model wind farms in aligned and staggered configurations. The model is useful for representing wind farms in regional scale models, for the optimization of wind farms considering wind turbine spacing and layout configuration, and for assessing the impacts of upwind wind farms on nearby wind resources. Markfort CD, W Zhang and F Porté-Agel. 2012. Turbulent flow and scalar transport through and over aligned and staggered wind farms. Journal of Turbulence. 13(1) N33: 1-36. doi:10.1080/14685248.2012.709635.

  8. Simulation analysis of a wind farm with different aggregated models

    DEFF Research Database (Denmark)

    Li, H.; Wang, H.; Zhao, B.

    2011-01-01

    Based on a wind farm including wind turbines with squirrel cage induction generators (SCIGs), different aggregated models of a wind farm, such as a single weighted average model, a reduced-order re-scaled model, a parameter transformed model and a single weighted arithmetic model were presented, ...... by using Matlab/Simulink, based on the conditions of the wind speed disturbance and three-phase short-circuit fault at the point of connected grid. The results have shown that the presented wind farm models are correct and valid.......Based on a wind farm including wind turbines with squirrel cage induction generators (SCIGs), different aggregated models of a wind farm, such as a single weighted average model, a reduced-order re-scaled model, a parameter transformed model and a single weighted arithmetic model were presented......, as well as the detailed SCIG wind turbine model. Regarding for the two cases of a wind farm including SCIGs with identical parameters and different parameters, the dynamic characteristics and transient performances of the presented wind farm using different aggregated models were studied and compared...

  9. Mesoscale to microscale wind farm flow modeling and evaluation: Mesoscale to Microscale Wind Farm Models

    Energy Technology Data Exchange (ETDEWEB)

    Sanz Rodrigo, Javier [National Renewable Energy Centre (CENER), Sarriguren Spain; Chávez Arroyo, Roberto Aurelio [National Renewable Energy Centre (CENER), Sarriguren Spain; Moriarty, Patrick [National Renewable Energy Laboratory (NREL), Golden CO USA; Churchfield, Matthew [National Renewable Energy Laboratory (NREL), Golden CO USA; Kosović, Branko [National Center for Atmospheric Research (NCAR), Boulder CO USA; Réthoré, Pierre-Elouan [Technical University of Denmark (DTU), Roskilde Denmark; Hansen, Kurt Schaldemose [Technical University of Denmark (DTU), Lyngby Denmark; Hahmann, Andrea [Technical University of Denmark (DTU), Roskilde Denmark; Mirocha, Jeffrey D. [Lawrence Livermore National Laboratory, Livermore CA USA; Rife, Daran [DNV GL, San Diego CA USA

    2016-08-31

    The increasing size of wind turbines, with rotors already spanning more than 150 m diameter and hub heights above 100 m, requires proper modeling of the atmospheric boundary layer (ABL) from the surface to the free atmosphere. Furthermore, large wind farm arrays create their own boundary layer structure with unique physics. This poses significant challenges to traditional wind engineering models that rely on surface-layer theories and engineering wind farm models to simulate the flow in and around wind farms. However, adopting an ABL approach offers the opportunity to better integrate wind farm design tools and meteorological models. The challenge is how to build the bridge between atmospheric and wind engineering model communities and how to establish a comprehensive evaluation process that identifies relevant physical phenomena for wind energy applications with modeling and experimental requirements. A framework for model verification, validation, and uncertainty quantification is established to guide this process by a systematic evaluation of the modeling system at increasing levels of complexity. In terms of atmospheric physics, 'building the bridge' means developing models for the so-called 'terra incognita,' a term used to designate the turbulent scales that transition from mesoscale to microscale. This range of scales within atmospheric research deals with the transition from parameterized to resolved turbulence and the improvement of surface boundary-layer parameterizations. The coupling of meteorological and wind engineering flow models and the definition of a formal model evaluation methodology, is a strong area of research for the next generation of wind conditions assessment and wind farm and wind turbine design tools. Some fundamental challenges are identified in order to guide future research in this area.

  10. Comparing satellite SAR and wind farm wake models

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Vincent, P.; Husson, R.

    2015-01-01

    . These extend several tens of kilometres downwind e.g. 70 km. Other SAR wind maps show near-field fine scale details of wake behind rows of turbines. The satellite SAR wind farm wake cases are modelled by different wind farm wake models including the PARK microscale model, the Weather Research and Forecasting...... (WRF) model in high resolution and WRF with coupled microscale parametrization....

  11. FARM WORK, OFF-FARM WORK, AND HIRED FARM LABOR: ESTIMATING A DISCRETE-CHOICE MODEL OF FRENCH FARM COUPLES' LABOR DECISIONS

    OpenAIRE

    Benjamin, Catherine; Kimhi, Ayal

    2003-01-01

    We estimate jointly three types of discrete-choice labor decisions of farm couples: farm work, off-farm work, and hired farm labor. Using a 16-choice multinomial logit model, we find that operators' and spouses' farm labor are substitutes. Hired farm labor increases with farmers' qualifications, perhaps substituting for the couples' labor inputs. Other adults in the households substitute for the farm labor input of the farm couple and hired workers.

  12. The Quiet Rise of Medium-Scale Farms in Malawi

    Directory of Open Access Journals (Sweden)

    Ward Anseeuw

    2016-06-01

    Full Text Available Medium-scale farms have become a major force in Malawi’s agricultural sector. Malawi’s most recent official agricultural survey indicates that these account for over a quarter of all land under cultivation in Malawi. This study explores the causes and multifaceted consequences of the rising importance of medium-scale farms in Malawi. We identify the characteristics and pathways of entry into farming based on surveys of 300 medium-scale farmers undertaken in 2014 in the districts of Mchinji, Kasungu and Lilongwe. The area of land acquired by medium-scale farmers in these three districts is found to have almost doubled between 2000 and 2015. Just over half of the medium-scale farmers represent cases of successful expansion out of small-scale farming status; the other significant proportion of medium-scale farmers are found to be urban-based professionals, entrepreneurs and/or civil servants who acquired land, some very recently, and started farming in mid-life. We also find that a significant portion of the land acquired by medium-scale farmers was utilized by others prior to acquisition, that most of the acquired land was under customary tenure, and that the current owners were often successful in transferring the ownership structure of the acquired land to a long-term leaseholding with a title deed. The study finds that, instead of just strong endogenous growth of small-scale famers as a route for the emergence of medium-scale farms, significant farm consolidation is occurring through land acquisitions, often by urban-based people. The effects of farmland acquisitions by domestic investors on the country’s primary development goals, such as food security, poverty reduction and employment, are not yet clear, though some trends appear to be emerging. We consider future research questions that may more fully shed light on the implications of policies that would continue to promote land acquisitions by medium-scale farms.

  13. Small-Scale Irrigation, Farm Income and Access to Essential ...

    African Journals Online (AJOL)

    2017-05-01

    , Farm Income,. Regression, Small-Scale .... food production and income and reduced youth out-migration from their communities. Banson et al. (2014) ...... Oromia National Regional State Ethiopia. International Journal of ...

  14. Empirical Analysis of Farm Credit Risk under the Structure Model

    Science.gov (United States)

    Yan, Yan

    2009-01-01

    The study measures farm credit risk by using farm records collected by Farm Business Farm Management (FBFM) during the period 1995-2004. The study addresses the following questions: (1) whether farm's financial position is fully described by the structure model, (2) what are the determinants of farm capital structure under the structure model, (3)…

  15. Wind-Farm Parametrisations in Mesoscale Models

    DEFF Research Database (Denmark)

    Volker, Patrick; Badger, Jake; Hahmann, Andrea N.

    2013-01-01

    In this paper we compare three wind-farm parametrisations for mesoscale models against measurement data from the Horns Rev I offshore wind-farm. The parametrisations vary from a simple rotor drag method, to more sophisticated models. Additional to (4) we investigated the horizontal resolution...

  16. Prototyping and farm system modelling - Partners on the road towards more sustainable farm systems?

    NARCIS (Netherlands)

    Sterk, B.; Ittersum, van M.K.; Leeuwis, C.; Wijnands, F.G.

    2007-01-01

    Farm system modelling and prototyping are two research methods proposed to enhance the process of developing sustainable farm systems. Farm system models provide means to formalize, expand and refine expert knowledge and to integrate this with scientific agro-ecological knowledge at the farm level.

  17. Modelling the impact of land-use change and farm dam construction on hillslope sediment delivery to rivers at the regional scale

    Science.gov (United States)

    Verstraeten, Gert; Prosser, Ian P.

    2008-06-01

    Landscapes in southeastern Australia have changed dramatically since the spread of European colonisation in the 19th century. Due to widespread forest clearance for cultivation and grazing, erosion and sediment yields have increased by a factor of more than 150. In the 20th century, erosion and sediment yield were reduced again due to an increasing vegetative cover. Furthermore, during the last decades, thousands of small farm dams were constructed to provide drinking water for cattle. These dams trap a lot of sediment, thereby further reducing sediment delivery from hillslopes to river channels. Changes in sediment delivery since European colonisation are documented in sediment archives. Within this study, these changing rates in hillslope erosion and sediment delivery were modelled using a spatially distributed erosion and sediment delivery model (WATEM/SEDEM) that was calibrated for Australian ecosystems using sediment yield data derived from sedimentation rates in 26 small farm dams. The model was applied to the Murrumbidgee river basin (30,000 km 2) under different land-use scenarios. First, the erosion and sediment yield under pre-European land-use was modelled. Secondly, recent land-use patterns were used in the model. Finally, recent land-use including the impact of farm dams and large reservoirs was simulated. The results show that the WATEM/SEDEM model is capable of predicting the intensity of the geomorphic response to changes in land-use through time. Changes in hillslope erosion and hillslope sediment delivery rates are not equal, illustrating the non-linear response of the catchment. Current hillslope sediment supply to the river channel network is predicted to be 370% higher compared to the pre-European settlement period, yet farm dams have reduced this back to 2.5 times the pre-19th century values. The role of larger reservoirs is even more important as they have reduced the current sediment supply downstream to their pre-European values, thus

  18. Harmonic Propagation and Interaction Evaluation between Small-Scale Wind Farms and Nonlinear Loads

    Directory of Open Access Journals (Sweden)

    Cheng-Xiong Mao

    2013-07-01

    Full Text Available Distributed generation is a flexible and effective way to utilize renewable energy. The dispersed generators are quite close to the load, and pose some power quality problems such as harmonic current emissions. This paper focuses on the harmonic propagation and interaction between a small-scale wind farm and nonlinear loads in the distribution grid. Firstly, by setting the wind turbines as P – Q(V nodes, the paper discusses the expanding Newton-Raphson power flow method for the wind farm. Then the generalized gamma mixture models are proposed to study the non-characteristic harmonic propagation of the wind farm, which are based on Gaussian mixture models, improved phasor clustering and generalized Gamma models. After the integration of the small-scale wind farm, harmonic emissions of nonlinear loads will become random and fluctuating due to the non-stationary wind power. Furthermore, in this paper the harmonic coupled admittance matrix model of nonlinear loads combined with a wind farm is deduced by rigorous formulas. Then the harmonic propagation and interaction between a real wind farm and nonlinear loads are analyzed by the harmonic coupled admittance matrix and generalized gamma mixture models. Finally, the proposed models and methods are verified through the corresponding simulation models in MATLAB/SIMULINK and PSCAD/EMTDC.

  19. Climate Response to Large-Scale Wind Farms

    Science.gov (United States)

    Malyshev, S. L.; Pacala, S. W.; Keith, D. W.; Denkenberger, D. C.; Roy, S. B.; Shevliakova, E.

    2003-12-01

    Enhanced reliance on wind energy is one of the possible ways to solve the greenhouse gas problem. However, because wind farms modify the interaction between atmosphere and surface, there is a possibility that wind energy might also change the global climate if developed on a scale large enough to make material reductions in greenhouse emissions. To investigate possible effect of large wind farm arrays on climate, we used a version of GFDL AGCM with prescribed climatological SST and ice extent. A series of 20-year integration included a range of spatial coverage and several different parameterizations for wind farms, as well as controls. Presented here are the results of the experiments with the largest wind farm arrays considered, where significant parts of Europe,North America, andChinaare covered. The total wind farm area in this case is about 10% of land surface; the resulting dissipation of kinetic energy on wind farms ranges from 12 to 19 TW (compared to current global primary energy consumption of 12 TW). The results of the simulations show similar effects on climate despite differences in parameterization for the wind farms. The global-average climate reaction is negligible, but regional effects are not. The effect of wind farms on annual mean surface air temperature reaches a regional maximum of the order of 1 degree, which is smaller than the 2XCO2 signal. The temperature response is strongest inEurasia, where it is characterized by cooling in northern mid-latitudes of entire continent and warming in the South in all seasons except JJA, when the pattern is much weaker. The response of precipitation does not show an obvious large-scale pattern and is likely to be statistically not significant.

  20. Distributed Model Predictive Control for Active Power Control of Wind Farm

    DEFF Research Database (Denmark)

    Zhao, Haoran; Wu, Qiuwei; Rasmussen, Claus Nygaard

    2014-01-01

    This paper presents the active power control of a wind farm using the Distributed Model Predictive Controller (D- MPC) via dual decomposition. Different from the conventional centralized wind farm control, multiple objectives such as power reference tracking performance and wind turbine load can......-scale wind farm control....

  1. Small Signal Modeling of Wind Farms

    DEFF Research Database (Denmark)

    Ebrahimzadeh, Esmaeil; Blaabjerg, Frede; Wang, Xiongfei

    2017-01-01

    In large power electronic systems like a wind farm, the mutual interactions between the control systems of the power converters can lead to various stability and power quality problems. In order to predict the system dynamic behavior, this paper presents an approach to model a wind farm as a Multi......-Input Multi-Output (MIMO) dynamic system, where the current control loops with Phase-Locked Loops (PLLs) are linearized around an operating point. Each sub-module of the wind farm is modeled as a 2×2 admittance matrix in dq-domain and all are combined together by using a dq nodal admittance matrix....... The frequency and damping of the oscillatory modes are calculated by finding the poles of the introduced MIMO matrix. Time-domain simulation results obtained from a 400-MW wind farm are used to verify the effectiveness of the presented model....

  2. Wind Farm parametrization in the mesoscale model WRF

    DEFF Research Database (Denmark)

    Volker, Patrick; Badger, Jake; Hahmann, Andrea N.

    2012-01-01

    , but are parametrized as another sub-grid scale process. In order to appropriately capture the wind farm wake recovery and its direction, two properties are important, among others, the total energy extracted by the wind farm and its velocity deficit distribution. In the considered parametrization the individual...... the extracted force is proportional to the turbine area interfacing a grid cell. The sub-grid scale wake expansion is achieved by adding turbulence kinetic energy (proportional to the extracted power) to the flow. The validity of both wind farm parametrizations has been verified against observational data. We...... turbines produce a thrust dependent on the background velocity. For the sub-grid scale velocity deficit, the entrainment from the free atmospheric flow into the wake region, which is responsible for the expansion, is taken into account. Furthermore, since the model horizontal distance is several times...

  3. The Interactive Effect of Diversification and Farming Scale on Productivity of Family Farm:Taking Rice Cultivation as An Example

    Science.gov (United States)

    Wei, Zhou

    2017-05-01

    Based on the diversification and cultivation scale, the rice cropping data of rural fixed observation points in 2011 were selected and the effect of diversification degree on rice productivity was analyzed by the Tobit model. The empirical results of the model show that diversification of sample farm will lead to loss of rice production efficiency. With the increase of rice planting scale, the loss of rice production efficiency will need to be further increased by diversification. Thus, we should stick to the family farm of specialized production operation. The transfer of land, the price and quantity of leasing, respecting the law of the market; the raising of funds can be considered non-subsidized capital market financing to help, while maintaining a certain degree of diversification, to avoid idle assets, low resource efficiency loss.

  4. The Relevance of Indigenous Knowledge for Small-Scale Farming ...

    African Journals Online (AJOL)

    This article is based on a study that sought to explore small-scale farmers' perceptions and understanding of indigenous farming with an ultimate goal of promoting the use of IK for agricultural development in Tanzania. This study was mainly qualitative, where semistructured interviews were used to collect data from 181 ...

  5. Small - Scale Livestock Farming in Developing Areas of Swaziland ...

    African Journals Online (AJOL)

    ... shortage of feed, poor breading practice, lack of production skills, poor infrastructure, livestock theft, inadequate veterinary services, poor marketing services, and poor extension services. Keywords: Small scale farmer, livestock farming, agricultural development, socio-economic development, developing areas, Swaziland ...

  6. Farm-scale biogas development in Southern Germany

    Energy Technology Data Exchange (ETDEWEB)

    Koeberle, E. [Biogaskontor, Obermarchtal (Germany)

    1997-08-01

    This work provides a description of the development of farm-scale plants in Bayern and Baden-Wuerttemberg. The historical development is explained as well as the technical. Main topics are digester concepts, stirring system and co-generation with dual-fuel and gas-engines. (au)

  7. A model of ammonia volatilization from a grazing livestock farm

    Science.gov (United States)

    Hutchings, N. J.; Sommer, S. G.; Jarvis, S. C.

    A dynamic model was developed to predict the ammonia volatilization from grazing livestock farms and to allow potential control measures to be evaluated. The relationships within the model were based on the underlying physical and chemical processes but empirically based factors were used to reduce the demand for input data and where the understanding of the underlying processes was inadequate. On a daily basis, the model simulates the partitioning of dietary nitrogen into dung and urine and its subsequent fate within the pasture or the slurry handling system. The fate of dry matter and water added in dung, urine and from other sources is also predicted. The model illustrates the indirect interactions between ammonia sources, highlights the influence of slurry management on ammonia losses, stresses the need for integrated, whole farm measurements and demonstrates that assessments of the impact of control measures may be misleading unless considered at the scale of the whole farm.

  8. Pore-Water Extraction Scale-Up Study for the SX Tank Farm

    Energy Technology Data Exchange (ETDEWEB)

    Truex, Michael J.; Oostrom, Martinus; Wietsma, Thomas W.; Last, George V.; Lanigan, David C.

    2013-01-15

    The phenomena related to pore-water extraction from unsaturated sediments have been previously examined with limited laboratory experiments and numerical modeling. However, key scale-up issues have not yet been addressed. Laboratory experiments and numerical modeling were conducted to specifically examine pore-water extraction for sediment conditions relevant to the vadose zone beneath the SX Tank Farm at Hanford Site in southeastern Washington State. Available SX Tank Farm data were evaluated to generate a conceptual model of the subsurface for a targeted pore-water extraction application in areas with elevated moisture and Tc-99 concentration. The hydraulic properties of the types of porous media representative of the SX Tank Farm target application were determined using sediment mixtures prepared in the laboratory based on available borehole sediment particle size data. Numerical modeling was used as an evaluation tool for scale-up of pore-water extraction for targeted field applications.

  9. Design Performance Standards for Large Scale Wind Farms

    DEFF Research Database (Denmark)

    Gordon, Mark

    2009-01-01

    This document presents, discusses and provides a general guide on electrical performance standard requirements for connection of large scale onshore wind farms into HV transmission networks. Experiences presented here refer mainly to technical requirements and issues encountered during the process...... of connection into the Eastern Australian power system under the Rules and guidelines set out by AEMC and NEMMCO (AEMO). Where applicable some international practices are also mentioned. Standards are designed to serve as a technical envelope under which wind farm proponents design the plant and maintain...... ongoing technical compliance of the plant during its operational lifetime. This report is designed to provide general technical information for the wind farm connection engineer to be aware of during the process of connection, registration and operation of wind power plants interconnected into the HV TSO...

  10. Experimental study of the impact of large-scale wind farms on land–atmosphere exchanges

    International Nuclear Information System (INIS)

    Zhang Wei; Markfort, Corey D; Porté-Agel, Fernando

    2013-01-01

    Large-scale wind farms, covering a significant portion of the land and ocean surface, may affect the transport of momentum, heat, mass and moisture between the atmosphere and the land locally and globally. To understand the wind-farm–atmosphere interaction, we conducted wind-tunnel experiments to study the surface scalar (heat) flux using model wind farms, consisting of more than ten rows of wind turbines—having typical streamwise and spanwise spacings of five and four rotor diameters—in a neutral boundary layer with a heated surface. The spatial distribution of the surface heat flux was mapped with an array of surface heat flux sensors within the quasi-developed regime of the wind-farm flow. Although the overall surface heat flux change produced by the wind farms was found to be small, with a net reduction of 4% for a staggered wind farm and nearly zero change for an aligned wind farm, the highly heterogeneous spatial distribution of the surface heat flux, dependent on the wind-farm layout, was significant. The difference between the minimum and maximum surface heat fluxes could be up to 12% and 7% in aligned and staggered wind farms, respectively. This finding is important for planning intensive agriculture practice and optimizing farm land use strategy regarding wind energy project development. The well-controlled wind-tunnel experiments presented in this study also provide a first comprehensive dataset on turbulent flow and scalar transport in wind farms, which can be further used to develop and validate new parameterizations of surface scalar fluxes in numerical models. (letter)

  11. Wind farm models and control strategies

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, Poul; Hansen, Anca D.; Iov, F.; Blaabjerg, F.; Donovan, M.H.

    2005-08-01

    This report describes models and control strategies for 3 different concepts of wind farms. Initially, the potential in improvement of grid integration, structural loads and energy production is investigated in a survey of opportunities. Then simulation models are described, including wind turbine models for a fixed speed wind turbine with active stall control and a variable speed wind turbine with doubly-fed induction generator. After that, the 3 wind farm concepts and control strategies are described. The 3 concepts are AC connected doubly fed turbines, AC connected active stall turbines and DC connected active stall turbines. Finally, some simulation examples and conclusions are presented. (au)

  12. A whole farm model for quantifying total greenhouse gas emissions ...

    African Journals Online (AJOL)

    This paper presents a model to quantify total greenhouse gas (GHG) emissions from dairy farms. The model, which is based on a whole farm management approach, accounts for the variability that occurs in GHG emissions among farm production and management practices. The variation is accommodated in six dairy farm ...

  13. Magnitude, spatial scale and optimization of ecosystem services from a nutrient extraction mussel farm in the eutrophic Skive Fjord, Denmark

    DEFF Research Database (Denmark)

    Nielsen, Pernille; Cranford, P. J.; Maar, M.

    2016-01-01

    mussel farm in a highly eu - trophic Danish fjord. Spatial variations in mussel biomass were examined throughout the year and no significant differences were detected within the farm. Food depletion by mussels was examined at spatial scales ranging from individuals to the entire farm and surrounding area....... Phytoplankton depletion on the scale of individual mussel loops, determined using the siphon mimic approach, indicated between 27 and 44% depletion of chlorophyll a (chl a). Farm-scale depletion was detected and visualized based on intensive 3D spatial surveys of the distribution of chl a and total suspended...... phytoplankton. The model employed mussel clearance rate estimates derived from the observed magnitude of food depletion within the farm. Model results indicate that the mussel population filtration rate could be increased by 80 to 120% without any negative feedback on mussel growth. This could be accomplished...

  14. Including spatial data in nutrient balance modelling on dairy farms

    Science.gov (United States)

    van Leeuwen, Maricke; van Middelaar, Corina; Stoof, Cathelijne; Oenema, Jouke; Stoorvogel, Jetse; de Boer, Imke

    2017-04-01

    The Annual Nutrient Cycle Assessment (ANCA) calculates the nitrogen (N) and phosphorus (P) balance at a dairy farm, while taking into account the subsequent nutrient cycles of the herd, manure, soil and crop components. Since January 2016, Dutch dairy farmers are required to use ANCA in order to increase understanding of nutrient flows and to minimize nutrient losses to the environment. A nutrient balance calculates the difference between nutrient inputs and outputs. Nutrients enter the farm via purchased feed, fertilizers, deposition and fixation by legumes (nitrogen), and leave the farm via milk, livestock, manure, and roughages. A positive balance indicates to which extent N and/or P are lost to the environment via gaseous emissions (N), leaching, run-off and accumulation in soil. A negative balance indicates that N and/or P are depleted from soil. ANCA was designed to calculate average nutrient flows on farm level (for the herd, manure, soil and crop components). ANCA was not designed to perform calculations of nutrient flows at the field level, as it uses averaged nutrient inputs and outputs across all fields, and it does not include field specific soil characteristics. Land management decisions, however, such as the level of N and P application, are typically taken at the field level given the specific crop and soil characteristics. Therefore the information that ANCA provides is likely not sufficient to support farmers' decisions on land management to minimize nutrient losses to the environment. This is particularly a problem when land management and soils vary between fields. For an accurate estimate of nutrient flows in a given farming system that can be used to optimize land management, the spatial scale of nutrient inputs and outputs (and thus the effect of land management and soil variation) could be essential. Our aim was to determine the effect of the spatial scale of nutrient inputs and outputs on modelled nutrient flows and nutrient use efficiencies

  15. Farm scale biogas production; Gaardsbaserad biogasproduktion. System, ekonomi och klimatpaaverkan

    Energy Technology Data Exchange (ETDEWEB)

    Edstroem, Mats; Jansson, Lars-Erik; Lantz, Mikael; Johansson, Lars-Gunnar; Nordberg, Ulf; Nordberg, Aake

    2008-06-15

    The purpose of this study was to investigate economic conditions for farm-scale biogas production in Sweden and to calculate the nutrient and greenhouse gas benefits of such systems. To give a more general description of the agricultural sector's possibilities to produce biogas, a comparison is carried out for 3 different scales of production as follows: Alternative 1: Digestion of a small amount of liquid manure from cattle. Evolved biogas is used for heat production which is used to provide space heating and hot water for one or two cottages on the farm. Alternative 2: Digestion of a larger amount of liquid manure from pig production. The biogas is used for co-generation of heat and electricity. The heat produced is used to provide space heating and hot water on 3-4 cottages at the farm. Alternative 3: Production of approx. 6 GWh biogas/year for direct sale on the external gas market. The plant co-digests energy crops, manure and vegetable waste. In this case the following energy crops are compared: a) ensiled ley crop, ensiled maize and c) grain. In the economic analysis, most of the data used comes from German sources. Based on the current market prices for energy in Sweden, only plant alternatives where the biogas is upgraded for use as vehicle fuel are profitable for the farmer. However, one significant barrier is that there is currently no significant market for vehicle fuel-grade biogas in Sweden, makes it difficult for farmers building up new local market. The purchase price of electricity from biogas is lower in Sweden than the most countries in Europe. The current prevailing market price for electricity is on the other hand quite volatile and future price increases are likely. The debate about how to reduce GHG emissions from the agricultural has recently attracted increased interest in wider circles. It is also likely that the Swedish government will start an investment program for farm scale biogas production from year 2009. Taken together, this

  16. Automatic Installation and Configuration for Large Scale Farms

    CERN Document Server

    Novák, J

    2005-01-01

    Since the early appearance of commodity hardware, the utilization of computers rose rapidly, and they became essential in all areas of life. Soon it was realized that nodes are able to work cooperatively, in order to solve new, more complex tasks. This conception got materialized in coherent aggregations of computers called farms and clusters. Collective application of nodes, being efficient and economical, was adopted in education, research and industry before long. But maintainance, especially in large scale, appeared as a problem to be resolved. New challenges needed new methods and tools. Development work has been started to build farm management applications and frameworks. In the first part of the thesis, these systems are introduced. After a general description of the matter, a comparative analysis of different approaches and tools illustrates the practical aspects of the theoretical discussion. CERN, the European Organization of Nuclear Research is the largest Particle Physics laboratory in the world....

  17. Medium fidelity modelling of loads in wind farms under non-neutral ABL stability conditions – a full-scale validation study

    DEFF Research Database (Denmark)

    Larsen, Gunner Chr.; Larsen, Torben J.; Chougule, A.

    2017-01-01

    The aim of the present paper is to demonstrate the capability of medium fidelity modelling of wind turbine component fatigue loading, when the wind turbines are subjected to wake affected non-stationary flow fields under non-neutral atmospheric stability conditions. To accomplish this we combine...... the classical Dynamic Wake Meandering model with a fundamental conjecture stating: Atmospheric boundary layer stability affects primary wake meandering dynamics driven by large turbulent scales, whereas wake expansion in the meandering frame of reference is hardly affected. Inclusion of stability (i.e. buoyancy......) in description of both large- and small scale atmospheric boundary layer turbulence is facilitated by a generalization of the classical Mann spectral tensor, which consistently includes buoyancy effects. With non-stationary wind turbine inflow fields modelled as described above, fatigue loads are obtained using...

  18. Wind speed dynamical model in a wind farm

    DEFF Research Database (Denmark)

    Soleimanzadeh, Maryam; Wisniewski, Rafal

    2010-01-01

    , the dynamic model for wind flow will be established. The state space variables are determined based on a fine mesh defined for the farm. The end goal of this method is to assist the development of a dynamical model of a wind farm that can be engaged for better wind farm control strategies.......This paper presents a model for wind speed in a wind farm. The basic purpose of the paper is to calculate approximately the wind speed in the vicinity of each wind turbine in a farm. In this regard the governing equations of flow will be solved for the whole wind farm. In ideal circumstances...

  19. Marine Model Trout Farms: developments in marine RAS

    DEFF Research Database (Denmark)

    Pedersen, Per Bovbjerg

    2011-01-01

    . This development and demonstration unit in commercial scale will during the next four years hopefully provide scientific and practical basis and support for further development in coming generations of Marine Model Trout Farms for large salmonids. The unit consist in the recirculation loop of one large fish tank......, nitrogen is removed in a full-scale experimental set-up where sludge from the drum filter is hydrolysed and the VFAs generated used as energy-source for the denitrification process in separate tanks/filters. Final polishing follows in a constructed wetland. For the first 2 years of operation production...... will be focussed on rainbow trout production, mimicking the typical Danish net cage farming cycle, where the cages are stocked with fish of 750 – 1,000 g in April/May and all harvested before Christmas weighing some 4 kg/pcs. During these two years important production parameters such as growth-rate, feed...

  20. Effects of farm heterogeneity and methods for upscaling on modelled nitrogen losses in agricultural landscapes

    Energy Technology Data Exchange (ETDEWEB)

    Dalgaard, T., E-mail: tommy.dalgaard@agrsci.dk [Aarhus University, Department of Agroecology, Blichers Alle 20, P.O. Box 50, DK-8830 Tjele (Denmark); Hutchings, N. [Aarhus University, Department of Agroecology, Blichers Alle 20, P.O. Box 50, DK-8830 Tjele (Denmark); Dragosits, U. [CEH Edinburgh, Bush Estate, Penicuik, Midlothian EH26 0QB, Scotland (United Kingdom); Olesen, J.E.; Kjeldsen, C. [Aarhus University, Department of Agroecology, Blichers Alle 20, P.O. Box 50, DK-8830 Tjele (Denmark); Drouet, J.L.; Cellier, P. [INRA, UMR Environnement et Grandes Cultures, BP 01, 78850 Thiverval-Grignon (France)

    2011-11-15

    The aim of this study is to illustrate the importance of farm scale heterogeneity on nitrogen (N) losses in agricultural landscapes. Results are exemplified with a chain of N models calculating farm-N balances and distributing the N-surplus to N-losses (volatilisation, denitrification, leaching) and soil-N accumulation/release in a Danish landscape. Possible non-linearities in upscaling are assessed by comparing average model results based on (i) individual farm level calculations and (ii) averaged inputs at landscape level. Effects of the non-linearities that appear when scaling up from farm to landscape are demonstrated. Especially in relation to ammonia losses the non-linearity between livestock density and N-loss is significant (p > 0.999), with around 20-30% difference compared to a scaling procedure not taking this non-linearity into account. A significant effect of farm type on soil N accumulation (p > 0.95) was also identified and needs to be included when modelling landscape level N-fluxes and greenhouse gas emissions. - Highlights: > Farm-N balances and the distribution on types of N-losses are modelled for 56 farms. > Farm type significantly affects N-losses and soil-N accumulation. > A non-linear relation between livestock density and ammonia loss is identified. > Approaches for upscaling from farm to landscape level are discussed. > Accounting farm heterogeneity is important when upscaling N-losses. - This study illustrates the importance of including non-linear effects of farm and landscape heterogeneity on the modelling and upscaling of farm nitrogen losses and greenhouse gas emissions in agricultural landscapes.

  1. Effects of farm heterogeneity and methods for upscaling on modelled nitrogen losses in agricultural landscapes

    International Nuclear Information System (INIS)

    Dalgaard, T.; Hutchings, N.; Dragosits, U.; Olesen, J.E.; Kjeldsen, C.; Drouet, J.L.; Cellier, P.

    2011-01-01

    The aim of this study is to illustrate the importance of farm scale heterogeneity on nitrogen (N) losses in agricultural landscapes. Results are exemplified with a chain of N models calculating farm-N balances and distributing the N-surplus to N-losses (volatilisation, denitrification, leaching) and soil-N accumulation/release in a Danish landscape. Possible non-linearities in upscaling are assessed by comparing average model results based on (i) individual farm level calculations and (ii) averaged inputs at landscape level. Effects of the non-linearities that appear when scaling up from farm to landscape are demonstrated. Especially in relation to ammonia losses the non-linearity between livestock density and N-loss is significant (p > 0.999), with around 20-30% difference compared to a scaling procedure not taking this non-linearity into account. A significant effect of farm type on soil N accumulation (p > 0.95) was also identified and needs to be included when modelling landscape level N-fluxes and greenhouse gas emissions. - Highlights: → Farm-N balances and the distribution on types of N-losses are modelled for 56 farms. → Farm type significantly affects N-losses and soil-N accumulation. → A non-linear relation between livestock density and ammonia loss is identified. → Approaches for upscaling from farm to landscape level are discussed. → Accounting farm heterogeneity is important when upscaling N-losses. - This study illustrates the importance of including non-linear effects of farm and landscape heterogeneity on the modelling and upscaling of farm nitrogen losses and greenhouse gas emissions in agricultural landscapes.

  2. Assessing biodiversity on the farm scale as basis for ecosystem service payments.

    Science.gov (United States)

    von Haaren, Christina; Kempa, Daniela; Vogel, Katrin; Rüter, Stefan

    2012-12-30

    Ecosystem services payments must be based on a standardised transparent assessment of the goods and services provided. This is especially relevant in the context of EU agri-environmental programs, but also for organic-food companies that foster environmental services on their contractor farms. Addressing the farm scale is important because land users/owners are major recipients of payments and they could be more involved in data generation and conservation management. A standardised system for measuring on-farm biodiversity does not yet exist that concentrates on performance indicators and includes farmers in generating information. A method is required that produces ordinal or metric scaled assessment results as well as management measures. Another requirement is the ease of application, which includes the ease of gathering input data and understandability. In order to respond to this need, we developed a method which is designed for automated application in an open source farm assessment system named MANUELA. The method produces an ordinal scale assessment of biodiversity that includes biotopes, species, biotope connectivity and the influence of land use. In addition, specific measures for biotope types are proposed. The open source geographical information system OpenJump is used for the implementation of MANUELA. The results of the trial applications and robustness tests show that the assessment can be implemented, for the most part, using existing information as well as data available from farmers or advisors. The results are more sensitive for showing on-farm achievements and changes than existing biotope-type classifications. Such a differentiated classification is needed as a basis for ecosystem service payments and for designing effective measures. The robustness of the results with respect to biotope connectivity is comparable to that of complex models, but it should be further improved. Interviews with the test farmers substantiate that the assessment

  3. Effects of farm heterogeneity and methods for upscaling on modelled nitrogen losses in agricultural landscapes

    DEFF Research Database (Denmark)

    Dalgaard, Tommy; Hutchings, Nicholas John; Dragosits, U

    2011-01-01

    The aim of this study is to illustrate the importance of farm scale heterogeneity on nitrogen (N) losses in agricultural landscapes. Results are exemplified with a chain of N models calculating farm-N balances and distributing the N-surplus to N-losses (volatilisation, denitrification, leaching......) and soil-N accumulation/release in a Danish landscape. Possible non-linearities in upscaling are assessed by comparing average model results based on (i) individual farm level calculations and (ii) averaged inputs at landscape level. Effects of the non-linearities that appear when scaling up from farm...... to landscape are demonstrated. Especially in relation to ammonia losses the non-linearity between livestock density and N-loss is significant (p > 0.999), with around 20–30% difference compared to a scaling procedure not taking this non-linearity into account. A significant effect of farm type on soil N...

  4. Studies of Sub-Synchronous Oscillations in Large-Scale Wind Farm Integrated System

    Science.gov (United States)

    Yue, Liu; Hang, Mend

    2018-01-01

    With the rapid development and construction of large-scale wind farms and grid-connected operation, the series compensation wind power AC transmission is gradually becoming the main way of power usage and improvement of wind power availability and grid stability, but the integration of wind farm will change the SSO (Sub-Synchronous oscillation) damping characteristics of synchronous generator system. Regarding the above SSO problem caused by integration of large-scale wind farms, this paper focusing on doubly fed induction generator (DFIG) based wind farms, aim to summarize the SSO mechanism in large-scale wind power integrated system with series compensation, which can be classified as three types: sub-synchronous control interaction (SSCI), sub-synchronous torsional interaction (SSTI), sub-synchronous resonance (SSR). Then, SSO modelling and analysis methods are categorized and compared by its applicable areas. Furthermore, this paper summarizes the suppression measures of actual SSO projects based on different control objectives. Finally, the research prospect on this field is explored.

  5. Dairy Wise, A Whole-Farm Dairy Model

    NARCIS (Netherlands)

    Schils, R.L.M.; Haan, de M.H.A.; Hemmer, J.G.A.; Pol, van den A.; Boer, de J.A.; Evers, A.G.; Holshof, G.; Middelkoop, van J.C.; Zom, R.L.G.

    2007-01-01

    A whole-farm dairy model was developed and evaluated. The DairyWise model is an empirical model that simulated technical, environmental, and financial processes on a dairy farm. The central component is the FeedSupply model that balanced the herd requirements, as generated by the DairyHerd model,

  6. Complete wind farm electromagnetic transient modelling for grid integration studies

    International Nuclear Information System (INIS)

    Zubia, I.; Ostolaza, X.; Susperregui, A.; Tapia, G.

    2009-01-01

    This paper presents a modelling methodology to analyse the impact of wind farms in surrounding networks. Based on the transient modelling of the asynchronous generator, the multi-machine model of a wind farm composed of N generators is developed. The model incorporates step-up power transformers, distribution lines and surrounding loads up to their connection to the power network. This model allows the simulation of symmetric and asymmetric short-circuits located in the distribution network and the analysis of transient stability of wind farms. It can be also used to study the islanding operation of wind farms

  7. Wind farm related mortality among avian migrants - a remote sensing study and model analysis

    DEFF Research Database (Denmark)

    Desholm, M.

    -2006) of migrating birds at the Nysted offshore wind farm in the Baltic Sea, Denmark. This thesis poses and answers the following questions: a) what hazard factors do offshore wind farming pose to wild birds, b) how should one choose the key focal species to study, c) how can remote sensing techniques be applied......This thesis is the result of a PhD study on bird-wind farm collisions and consists of a synopsis, five published papers, one submitted manuscript and another ready for submission. The papers describe the fi ndings from pre- and post-construction visual, radar and thermal imaging studies (1999...... to the study of bird wind farm interactions, and d) specifi cally, how do waterbirds react when approaching an offshore wind farm? The main aim of the study was the development of a predictive bird-wind farm collision model that incorporates the avoidance rate of birds at multiple scales. Out of 235...

  8. Optimal Selection of AC Cables for Large Scale Offshore Wind Farms

    DEFF Research Database (Denmark)

    Hou, Peng; Hu, Weihao; Chen, Zhe

    2014-01-01

    The investment of large scale offshore wind farms is high in which the electrical system has a significant contribution to the total cost. As one of the key components, the cost of the connection cables affects the initial investment a lot. The development of cable manufacturing provides a vast...... and systematical way for the optimal selection of cables in large scale offshore wind farms....

  9. Approaches for quantifying and managing diffuse phosphorus exports at the farm/small catchment scale.

    Science.gov (United States)

    McDowell, Richard W; Nash, David; George, Anja; Wang, Q J; Duncan, Ruth

    2009-01-01

    Quantifying and managing diffuse P losses from small catchments or at the farm scale requires detailed knowledge of farming practices and their interaction with catchment processes. However, detailed knowledge may not be available and hence modeling is required. This paper demonstrates two approaches to developing tools that assist P losses from New Zealand or Australian dairy farms. The first is largely empirical and separates sources of P within a paddock into soil, fertilizer, dung, and treading impacts (including damage to grazed pasture). This information is combined with expert knowledge of hydrological processes and potential point sources (e.g., stream crossings) to create a deterministic model that can be used to evaluate the most cost and labor efficient method of mitigating P losses. For instance, in one example, 45% of annual P lost was attributed to the application of superphosphate just before a runoff event for which a mitigation strategy could be to use a less water soluble P fertilizer. The second approach uses a combination of interviews, expert knowledge and relationships to develop a Bayesian Network that describes P exports. The knowledge integration process helped stakeholders develop a comprehensive understanding of the problem. The Network, presented in the form of a "cause and effect", diagram provided a simple, visual representation of current knowledge that could be easily applied to individual circumstances and isolate factors having the greatest influence on P loss. Both approaches demonstrate that modeling P losses and mitigation strategies does not have to cover every process or permutation and that a degree of uncertainty can be handled to create a working model of P losses at a farm or small catchment scale.

  10. Fate and occurrence of steroids in swine and dairy cattle farms with different farming scales and wastes disposal systems

    International Nuclear Information System (INIS)

    Liu Shan; Ying Guangguo; Zhang Ruiquan; Zhou Lijun; Lai Huajie; Chen Zhifeng

    2012-01-01

    Fate and occurrence of fourteen androgens, four estrogens, five glucocorticoids and five progestagens were investigated in three swine farms and three dairy cattle farms with different farming scales and wastes disposal systems in China. Twenty-one, 22, and 12 of total 28 steroids were detected in feces samples with concentrations ranging from below method limit of quantitation (< LOQ for estrone) to 8100 ± 444 ng/g (progesterone), in wastewater samples with concentrations ranging from < LOQ (estrone) to 20,700 ± 1490 ng/L (androsterone), in suspended particles with concentrations ranging from < LOQ (17β-trenbolone) to 778 ± 82.1 ng/g (5α-dihydrotestosterone) in the six farms, respectively. The steroids via swine farms and human sources were mainly originated from wastewater into the receiving environments while those steroids via cattle farms were mainly from cattle feces. The total contributions of steroids to the environment in China are estimated to be 139, 65.8 and 60.7 t/year from swine, dairy cattle and human sources, respectively. - Highlights: ► 28 steroids were investigated in three swine farms and three cattle farms. ► Eight detected synthetic steroids were from exogenous usage. ► Lagoon systems were more effective in removing steroids than sedimentation tanks. ► The steroids via swine and human sources were mainly from wastewater. ► The steroids via cattle were mainly originated from feces. - The swine and cattle farms contribute higher steroids masses to the environment than the human sources.

  11. A socio-hydrologic model of coupled water-agriculture dynamics with emphasis on farm size.

    Science.gov (United States)

    Brugger, D. R.; Maneta, M. P.

    2015-12-01

    Agricultural land cover dynamics in the U.S. are dominated by two trends: 1) total agricultural land is decreasing and 2) average farm size is increasing. These trends have important implications for the future of water resources because 1) growing more food on less land is due in large part to increased groundwater withdrawal and 2) larger farms can better afford both more efficient irrigation and more groundwater access. However, these large-scale trends are due to individual farm operators responding to many factors including climate, economics, and policy. It is therefore difficult to incorporate the trends into watershed-scale hydrologic models. Traditional scenario-based approaches are valuable for many applications, but there is typically no feedback between the hydrologic model and the agricultural dynamics and so limited insight is gained into the how agriculture co-evolves with water resources. We present a socio-hydrologic model that couples simplified hydrologic and agricultural economic dynamics, accounting for many factors that depend on farm size such as irrigation efficiency and returns to scale. We introduce an "economic memory" (EM) state variable that is driven by agricultural revenue and affects whether farms are sold when land market values exceed expected returns from agriculture. The model uses a Generalized Mixture Model of Gaussians to approximate the distribution of farm sizes in a study area, effectively lumping farms into "small," "medium," and "large" groups that have independent parameterizations. We apply the model in a semi-arid watershed in the upper Columbia River Basin, calibrating to data on streamflow, total agricultural land cover, and farm size distribution. The model is used to investigate the sensitivity of the coupled system to various hydrologic and economic scenarios such as increasing market value of land, reduced surface water availability, and increased irrigation efficiency in small farms.

  12. Enlarging of scale in dairy farming: Consequences for farm-bound traffic flows in the countryside

    NARCIS (Netherlands)

    Jaarsma, C.F.; Hermans, C.M.L.; Rienks, W.A.; Vries, de J.R.

    2013-01-01

    On average, farm units in the EU countryside are developing within the globalization process to an everincreasing physical and operational size. Within the last three decades, Dutch dairy farm holdings have increased their physical size by a factor of 3. This ongoing process can also be observed in

  13. Integration of Rural Aquaculture into Small Scale Farming Systems ...

    African Journals Online (AJOL)

    In many parts of Niger Delta, farming and fishing activities are the predominant occupation of the people living in the rural areas. To improve the livelihood of the people and to enhance their economy status, there is the need to integrate aquaculture (rearing of fish in ponds) into farming systems especially for the small ...

  14. Contribution of large scale coherence to wind turbine power: A large eddy simulation study in periodic wind farms

    Science.gov (United States)

    Chatterjee, Tanmoy; Peet, Yulia T.

    2018-03-01

    Length scales of eddies involved in the power generation of infinite wind farms are studied by analyzing the spectra of the turbulent flux of mean kinetic energy (MKE) from large eddy simulations (LES). Large-scale structures with an order of magnitude bigger than the turbine rotor diameter (D ) are shown to have substantial contribution to wind power. Varying dynamics in the intermediate scales (D -10 D ) are also observed from a parametric study involving interturbine distances and hub height of the turbines. Further insight about the eddies responsible for the power generation have been provided from the scaling analysis of two-dimensional premultiplied spectra of MKE flux. The LES code is developed in a high Reynolds number near-wall modeling framework, using an open-source spectral element code Nek5000, and the wind turbines have been modelled using a state-of-the-art actuator line model. The LES of infinite wind farms have been validated against the statistical results from the previous literature. The study is expected to improve our understanding of the complex multiscale dynamics in the domain of large wind farms and identify the length scales that contribute to the power. This information can be useful for design of wind farm layout and turbine placement that take advantage of the large-scale structures contributing to wind turbine power.

  15. Multi-time scale energy management of wind farms based on comprehensive evaluation technology

    Science.gov (United States)

    Xu, Y. P.; Huang, Y. H.; Liu, Z. J.; Wang, Y. F.; Li, Z. Y.; Guo, L.

    2017-11-01

    A novel energy management of wind farms is proposed in this paper. Firstly, a novel comprehensive evaluation system is proposed to quantify economic properties of each wind farm to make the energy management more economical and reasonable. Then, a combination of multi time-scale schedule method is proposed to develop a novel energy management. The day-ahead schedule optimizes unit commitment of thermal power generators. The intraday schedule is established to optimize power generation plan for all thermal power generating units, hydroelectric generating sets and wind power plants. At last, the power generation plan can be timely revised in the process of on-line schedule. The paper concludes with simulations conducted on a real provincial integrated energy system in northeast China. Simulation results have validated the proposed model and corresponding solving algorithms.

  16. Modelling potential production of macroalgae farms in UK and Dutch coastal waters

    Directory of Open Access Journals (Sweden)

    J. van der Molen

    2018-02-01

    Full Text Available There is increasing interest in macroalgae farming in European waters for a range of applications, including food, chemical extraction for biofuel production. This study uses a 3-D numerical model of hydrodynamics and biogeochemistry to investigate potential production and environmental effects of macroalgae farming in UK and Dutch coastal waters. The model included four experimental farms in different coastal settings in Strangford Lough (Northern Ireland, in Sound of Kerrera and Lynn of Lorne (north-west Scotland and in the Rhine plume (the Netherlands, as well as a hypothetical large-scale farm off the UK north Norfolk coast. The model could not detect significant changes in biogeochemistry and plankton dynamics at any of the farm sites averaged over the farming season. The results showed a range of macroalgae growth behaviours in response to simulated environmental conditions. These were then compared with in situ observations where available, showing good correspondence for some farms and less good correspondence for others. At the most basic level, macroalgae production depended on prevailing nutrient concentrations and light conditions, with higher levels of both resulting in higher macroalgae production. It is shown that under non-elevated and interannually varying winter nutrient conditions, farming success was modulated by the timings of the onset of increasing nutrient concentrations in autumn and nutrient drawdown in spring. Macroalgae carbohydrate content also depended on nutrient concentrations, with higher nutrient concentrations leading to lower carbohydrate content at harvest. This will reduce the energy density of the crop and thus affect its suitability for conversion into biofuel. For the hypothetical large-scale macroalgae farm off the UK north Norfolk coast, the model suggested high, stable farm yields of macroalgae from year to year with substantial carbohydrate content and limited environmental effects.

  17. Modelling potential production of macroalgae farms in UK and Dutch coastal waters

    Science.gov (United States)

    van der Molen, Johan; Ruardij, Piet; Mooney, Karen; Kerrison, Philip; O'Connor, Nessa E.; Gorman, Emma; Timmermans, Klaas; Wright, Serena; Kelly, Maeve; Hughes, Adam D.; Capuzzo, Elisa

    2018-02-01

    There is increasing interest in macroalgae farming in European waters for a range of applications, including food, chemical extraction for biofuel production. This study uses a 3-D numerical model of hydrodynamics and biogeochemistry to investigate potential production and environmental effects of macroalgae farming in UK and Dutch coastal waters. The model included four experimental farms in different coastal settings in Strangford Lough (Northern Ireland), in Sound of Kerrera and Lynn of Lorne (north-west Scotland) and in the Rhine plume (the Netherlands), as well as a hypothetical large-scale farm off the UK north Norfolk coast. The model could not detect significant changes in biogeochemistry and plankton dynamics at any of the farm sites averaged over the farming season. The results showed a range of macroalgae growth behaviours in response to simulated environmental conditions. These were then compared with in situ observations where available, showing good correspondence for some farms and less good correspondence for others. At the most basic level, macroalgae production depended on prevailing nutrient concentrations and light conditions, with higher levels of both resulting in higher macroalgae production. It is shown that under non-elevated and interannually varying winter nutrient conditions, farming success was modulated by the timings of the onset of increasing nutrient concentrations in autumn and nutrient drawdown in spring. Macroalgae carbohydrate content also depended on nutrient concentrations, with higher nutrient concentrations leading to lower carbohydrate content at harvest. This will reduce the energy density of the crop and thus affect its suitability for conversion into biofuel. For the hypothetical large-scale macroalgae farm off the UK north Norfolk coast, the model suggested high, stable farm yields of macroalgae from year to year with substantial carbohydrate content and limited environmental effects.

  18. Modeling greenhouse gas emissions from dairy farms

    Science.gov (United States)

    Dairy farms have been identified as an important source of greenhouse gas emissions. Within the farm, important emissions include enteric methane (CH4) from the animals, CH4 and nitrous oxide (N2O) from manure in housing facilities, during long-term storage and during field application, and N2O from...

  19. Accurate wind farm development and operation. Advanced wake modelling

    Energy Technology Data Exchange (ETDEWEB)

    Brand, A.; Bot, E.; Ozdemir, H. [ECN Unit Wind Energy, P.O. Box 1, NL 1755 ZG Petten (Netherlands); Steinfeld, G.; Drueke, S.; Schmidt, M. [ForWind, Center for Wind Energy Research, Carl von Ossietzky Universitaet Oldenburg, D-26129 Oldenburg (Germany); Mittelmeier, N. REpower Systems SE, D-22297 Hamburg (Germany))

    2013-11-15

    The ability is demonstrated to calculate wind farm wakes on the basis of ambient conditions that were calculated with an atmospheric model. Specifically, comparisons are described between predicted and observed ambient conditions, and between power predictions from three wind farm wake models and power measurements, for a single and a double wake situation. The comparisons are based on performance indicators and test criteria, with the objective to determine the percentage of predictions that fall within a given range about the observed value. The Alpha Ventus site is considered, which consists of a wind farm with the same name and the met mast FINO1. Data from the 6 REpower wind turbines and the FINO1 met mast were employed. The atmospheric model WRF predicted the ambient conditions at the location and the measurement heights of the FINO1 mast. May the predictability of the wind speed and the wind direction be reasonable if sufficiently sized tolerances are employed, it is fairly impossible to predict the ambient turbulence intensity and vertical shear. Three wind farm wake models predicted the individual turbine powers: FLaP-Jensen and FLaP-Ainslie from ForWind Oldenburg, and FarmFlow from ECN. The reliabilities of the FLaP-Ainslie and the FarmFlow wind farm wake models are of equal order, and higher than FLaP-Jensen. Any difference between the predictions from these models is most clear in the double wake situation. Here FarmFlow slightly outperforms FLaP-Ainslie.

  20. Wind farms providing secondary frequency regulation: Evaluating the performance of model-based receding horizon control

    International Nuclear Information System (INIS)

    Shapiro, Carl R.; Meneveau, Charles; Gayme, Dennice F.; Meyers, Johan

    2016-01-01

    We investigate the use of wind farms to provide secondary frequency regulation for a power grid. Our approach uses model-based receding horizon control of a wind farm that is tested using a large eddy simulation (LES) framework. In order to enable real-time implementation, the control actions are computed based on a time-varying one-dimensional wake model. This model describes wake advection and interactions, both of which play an important role in wind farm power production. This controller is implemented in an LES model of an 84-turbine wind farm represented by actuator disk turbine models. Differences between the velocities at each turbine predicted by the wake model and measured in LES are used for closed-loop feedback. The controller is tested on two types of regulation signals, “RegA” and “RegD”, obtained from PJM, an independent system operator in the eastern United States. Composite performance scores, which are used by PJM to qualify plants for regulation, are used to evaluate the performance of the controlled wind farm. Our results demonstrate that the controlled wind farm consistently performs well, passing the qualification threshold for all fastacting RegD signals. For the RegA signal, which changes over slower time scales, the controlled wind farm's average performance surpasses the threshold, but further work is needed to enable the controlled system to achieve qualifying performance all of the time. (paper)

  1. Scaling up agroforestry farming systems: Lessons from the Malawi ...

    African Journals Online (AJOL)

    The study examined the factors affecting agroforestry technology upscaling and identified gaps in scaling up approaches of agroforestry technologies. One hundred and sixty-four farmers in Malawi Agroforestry Extension (MAFE) project districts of Mzimba, Ntcheu and Mangochi were interviewed. Logistic model was used in ...

  2. A survey of small-scale cattle farming systems in the North West ...

    African Journals Online (AJOL)

    Unknown

    Materials and methods. Sixty small-scale cattle farming households were selected for this study out of a total of 120 .... Income from non-farm sources enables these farmers to meet the cost of hired labour. In operating at a loss, ... Range Management Division, Ministry of Agriculture, Maseru, Lesotho. Meissner, H.H., 1982.

  3. An exploratory survey of small-scale off-farm economic activities and ...

    African Journals Online (AJOL)

    Small scale off-farm economic activities are believed to be a potential frontier for generating additional livelihoods support to sustain the farm household in rural Ghana. Despite this general belief, very little has been done to provide adequate information that might be utilized by policy makers and practitioners for possible ...

  4. Modelling and transient stability of large wind farms

    DEFF Research Database (Denmark)

    Akhmatov, Vladislav; Knudsen, Hans; Nielsen, Arne Hejde

    2003-01-01

    by a physical model of grid-connected windmills. The windmill generators ate conventional induction generators and the wind farm is ac-connected to the power system. Improvements-of short-term voltage stability in case of failure events in the external power system are treated with use of conventional generator...... technology. This subject is treated as a parameter study with respect to the windmill electrical and mechanical parameters and with use of control strategies within the conventional generator technology. Stability improvements on the wind farm side of the connection point lead to significant reduction......The paper is dealing-with modelling and short-term Voltage stability considerations of large wind farms. A physical model of a large offshore wind farm consisting of a large number of windmills is implemented in the dynamic simulation tool PSS/E. Each windmill in the wind farm is represented...

  5. Modeling and Identification of Harmonic Instability Problems In Wind Farms

    DEFF Research Database (Denmark)

    Ebrahimzadeh, Esmaeil; Blaabjerg, Frede; Wang, Xiongfei

    2016-01-01

    to identify harmonic instability problems in wind farms, where many wind turbines, cables, transformers, capacitor banks, shunt reactors, etc, typically are located. This methodology introduces the wind farm as a Multi-Input Multi-Outpur (MIMO) control system, where the linearized models of fast inner control...

  6. Urban farming model in South Jakarta

    Science.gov (United States)

    Indrawati, E.

    2018-01-01

    The development of infrastructure rapidly, large of population and large of urbanization. Meanwhile, agricultural land is decreasing and agricultural production continues to decline. The productive crops is needed for consumption and it is also to improve the environment from oxygen provisioning, antidote to air pollution and to improve soil conditions. The use of yard land for horticultural crops (vegetables, fruits and ornamental plants), spices, medicines, herbs etc. can benefit for the owners of the yard particularly and the general public. The purpose of this research is to identify the model of home yard utilization, mosque yard, office, school, urban park and main road and sub main road, which can improve environmental quality in Pesanggrahan district. The method of analysis used descriptive analysis method by observation. Then analyzed the percentage of the use of yard with productive crops as urban farming. The results showed that the most productive crops were planted in Kelurahan Pesanggrahan 67% which compared with in Kelurahan Ulujami 47%, and in Kelurahan Petukangan Utara 27%. The most types of productive crops were grown as fruit trees and vegetable crops.

  7. Analysis of small-scale biogas utilization systems on Ontario cattle farms

    International Nuclear Information System (INIS)

    White, Andrew J.; Kirk, Donald W.; Graydon, John W.

    2011-01-01

    The production of biogas through the anaerobic digestion of cattle manure and its subsequent use in the generation of electricity on larger farms in Ontario is currently economically attractive. This is a result of the Ontario Feed-In Tariff (FIT) program, which provides incentivized rates for the production of electricity from biogas. Although larger farms can take advantage of the higher rates for electricity, there are substantially more smaller farms for which individually designed and engineered biogas systems would be prohibitively expensive. By employing the concept of modular biogas plants, this analysis evaluates the economics of small-scale biogas utilization systems. Dairy farms with at least 33 animals and beef farms with at least 78 animals can operate economically attractive biogas systems. This analysis shows that approximately 9000 additional Ontario cattle farms would be able to take advantage of the FIT program, which would add 120 MW e of renewable energy capacity to the Ontario electrical grid. (author)

  8. Genome-Scale Models

    DEFF Research Database (Denmark)

    Bergdahl, Basti; Sonnenschein, Nikolaus; Machado, Daniel

    2016-01-01

    An introduction to genome-scale models, how to build and use them, will be given in this chapter. Genome-scale models have become an important part of systems biology and metabolic engineering, and are increasingly used in research, both in academica and in industry, both for modeling chemical pr...

  9. Dynamic simulation of sustainable farm development scenarios using cognitive modeling

    Directory of Open Access Journals (Sweden)

    Tuzhyk Kateryna

    2017-03-01

    Full Text Available Dynamic simulation of sustainable farm development scenarios using cognitive modeling. The paper presents a dynamic simulation system of sustainable development scenarios on farms using cognitive modeling. The system incorporates relevant variables which affect the sustainable development of farms. Its user provides answers to strategic issues connected with the level of farm sustainability over a long-term perspective of dynamic development. The work contains a description of the model structure as well as the results of simulations carried out on 16 farms in northern Ukraine. The results show that the process of sustainability is based mainly on the potential for innovation in agricultural production and biodiversity. The user is able to simulate various scenarios for the sustainable development of a farm and visualize the influence of factors on the economic and social situation, as well as on environmental aspects. Upon carrying out a series of simulations, it was determined that the development of farms characterized by sustainable development is based on additional profit, which serves as the main motivation for transforming a conventional farm into a sustainable one. Nevertheless, additional profit is not the only driving force in the system of sustainable development. The standard of living, market condition, and legal regulations as well as government support also play a significant motivational role.

  10. Modelling representative and coherent Danish farm types based on farm accountancy data for use in enviromental assessments

    DEFF Research Database (Denmark)

    Dalgaard, Randi; Halberg, Niels; Kristensen, Ib S.

    2006-01-01

    is established in order to report Danish agro-economical data to the ‘Farm Accountancy Data Network’ (FADN), and to produce ‘The annual Danish account statistics for agriculture’. The farm accounts are selected and weighted to be representative for the Danish agricultural sector, and similar samples of farm......, homegrown feed, manure production, fertilizer use and crop production. The set of farm types was scaled up to national level thus representing the whole Danish agricultural sector and the resulting production, resource use and land use was checked against the national statistics. Nutrient balance....... The methane emission was higher from dairy farm types compared with all other farm types. In general the conventional dairy farms emitted more nitrate, ammonia, and nitrous oxi de, compared with organic dairy farms....

  11. Whole-farm models to quantify greenhouse gas emissions and their potential use for linking climate change mitigation and adaptation in temperate grassland ruminant-based farming systems

    DEFF Research Database (Denmark)

    del Prado, A; Crosson, P; Olesen, Jørgen E

    2013-01-01

    to quantify GHG emissions and explore climate change mitigation strategies for livestock systems. This paper analyses the limitations and strengths of the different existing approaches for modelling GHG mitigation by considering basic model structures, approaches for simulating GHG emissions from various farm...... components and the sensitivity of GHG outputs and mitigation measures to different approaches. Potential challenges for linking existing models with the simulation of impacts and adaptation measures under climate change are explored along with a brief discussion of the effects on other ecosystem services.......The farm level is the most appropriate scale for evaluating options for mitigating greenhouse gas (GHG) emissions, because the farm represents the unit at which management decisions in livestock production are made. To date, a number of whole farm modelling approaches have been developed...

  12. Whole-farm models to quantify greenhouse gas emissions and their potential use for linking climate change mitigation and adaptation in temperate grassland ruminant-based farming systems.

    Science.gov (United States)

    Del Prado, A; Crosson, P; Olesen, J E; Rotz, C A

    2013-06-01

    The farm level is the most appropriate scale for evaluating options for mitigating greenhouse gas (GHG) emissions, because the farm represents the unit at which management decisions in livestock production are made. To date, a number of whole farm modelling approaches have been developed to quantify GHG emissions and explore climate change mitigation strategies for livestock systems. This paper analyses the limitations and strengths of the different existing approaches for modelling GHG mitigation by considering basic model structures, approaches for simulating GHG emissions from various farm components and the sensitivity of GHG outputs and mitigation measures to different approaches. Potential challenges for linking existing models with the simulation of impacts and adaptation measures under climate change are explored along with a brief discussion of the effects on other ecosystem services.

  13. IEA-Task 31 WAKEBENCH: Towards a protocol for wind farm flow model evaluation. Part 2: Wind farm wake models

    DEFF Research Database (Denmark)

    Moriarty, Patrick; Rodrigo, Javier Sanz; Gancarski, Pawel

    2014-01-01

    .windbench.net). This paper provides an overview of the building-block validation approach applied to wind farm wake models, including best practices for the benchmarking and data processing procedures for validation datasets from wind farm SCADA and meteorological databases. A hierarchy of test cases has been proposed...

  14. How do farm models compare when estimating greenhouse gas emissions from dairy cattle production?

    DEFF Research Database (Denmark)

    Hutchings, Nicholas John; Özkan, Şeyda; de Haan, M

    2018-01-01

    feed imported. This was because the models differed in their description of biophysical responses and feedback mechanisms, and in the extent to which management functions were internalised. We conclude that comparing the results of different farm-scale models when applied to a range of scenarios would...

  15. Analysis of farm household technical efficiency in small-scale ...

    African Journals Online (AJOL)

    Data Envelopment Analysis (DEA) was applied to farm-level cross-sectional data collected in mid-2013 after the implementation of CIP activities. Our empirical results indicate that CIP participants and improved farmers (using using both traditional and modern hives) had the highest average levels of technical efficiencies.

  16. A Hybrid Wind-Farm Parametrization for Mesoscale and Climate Models

    Science.gov (United States)

    Pan, Yang; Archer, Cristina L.

    2018-04-01

    To better understand the potential impact of wind farms on weather and climate at the regional to global scales, a new hybrid wind-farm parametrization is proposed for mesoscale and climate models. The proposed parametrization is a hybrid model because it is not based on physical processes or conservation laws, but on the multiple linear regression of the results of large-eddy simulations (LES) with the geometric properties of the wind-farm layout (e.g., the blockage ratio and blockage distance). The innovative aspect is that each wind turbine is treated individually based on its position in the farm and on the wind direction by predicting the velocity upstream of each turbine. The turbine-induced forces and added turbulence kinetic energy (TKE) are first derived analytically and then implemented in the Weather Research and Forecasting model. Idealized simulations of the offshore Lillgrund wind farm are conducted. The wind-speed deficit and TKE predicted with the hybrid model are in excellent agreement with those from the LES results, while the wind-power production estimated with the hybrid model is within 10% of that observed. Three additional wind farms with larger inter-turbine spacing than at Lillgrund are also considered, and a similar agreement with LES results is found, proving that the hybrid parametrization works well with any wind farm regardless of the spacing between turbines. These results indicate the wind-turbine position, wind direction, and added TKE are essential in accounting for the wind-farm effects on the surroundings, for which the hybrid wind-farm parametrization is a promising tool.

  17. Small Signal Model for VSC-HVDC Connected DFIG-Based Offshore Wind Farms

    Directory of Open Access Journals (Sweden)

    Kai Liao

    2014-01-01

    Full Text Available Large-scale offshore wind farms are integrated with onshore ac grids through the voltage source converter based high voltage direct current (VSC-HVDC transmission system. The impact on the stability of the ac grids will be significant. The small signal model of a wind farm connected with voltage source converter based dc transmission system is studied in this paper. A suitable model for small signal stability analysis is presented. The control system of wind generator and the HVDC system has also been modeled in this model for small signal stability analysis. The impact of the control parameters on the network stability is investigated.

  18. Economic and agricultural transformation through large-scale farming : impacts of large-scale farming on local economic development, household food security and the environment in Ethiopia

    NARCIS (Netherlands)

    Bekele, M.S.

    2016-01-01

    This study examined impacts of large-scale farming in Ethiopia on local economic development, household food security, incomes, employment, and the environment. The study adopted a mixed research approach in which both qualitative and quantitative data were generated from secondary and primary

  19. On wake modeling, wind-farm gradients, and AEP predictions at the Anholt wind farm

    Directory of Open Access Journals (Sweden)

    A. Peña

    2018-04-01

    Full Text Available We investigate wake effects at the Anholt offshore wind farm in Denmark, which is a farm experiencing strong horizontal wind-speed gradients because of its size and proximity to land. Mesoscale model simulations are used to study the horizontal wind-speed gradients over the wind farm. From analysis of the mesoscale simulations and supervisory control and data acquisition (SCADA, we show that for westerly flow in particular, there is a clear horizontal wind-speed gradient over the wind farm. We also use the mesoscale simulations to derive the undisturbed inflow conditions that are coupled with three commonly used wake models: two engineering approaches (the Park and G. C. Larsen models and a linearized Reynolds-averaged Navier–Stokes approach (Fuga. The effect of the horizontal wind-speed gradient on annual energy production estimates is not found to be critical compared to estimates from both the average undisturbed wind climate of all turbines' positions and the undisturbed wind climate of a position in the middle of the wind farm. However, annual energy production estimates can largely differ when using wind climates at positions that are strongly influenced by the horizontal wind-speed gradient. When looking at westerly flow wake cases, where the impact of the horizontal wind-speed gradient on the power of the undisturbed turbines is largest, the wake models agree with the SCADA fairly well; when looking at a southerly flow case, where the wake losses are highest, the wake models tend to underestimate the wake loss. With the mesoscale-wake model setup, we are also able to estimate the capacity factor of the wind farm rather well when compared to that derived from the SCADA. Finally, we estimate the uncertainty of the wake models by bootstrapping the SCADA. The models tend to underestimate the wake losses (the median relative model error is 8.75 % and the engineering wake models are as uncertain as Fuga. These results are specific for

  20. Wind energy potential in Chile: Assessment of a small scale wind farm for residential clients

    International Nuclear Information System (INIS)

    Becerra, Miguel; Morán, José; Jerez, Alejandro; Cepeda, Francisco; Valenzuela, Miguel

    2017-01-01

    Highlights: • An assessment of a small scale wind farm was carried out. • Two Chilean locations were selected, which are geographically dissimilar. • The software tool selected for the project’s evaluation was HOMER. • All the project’s financial evaluations were negative. • Government policy tools and their applications were discussed. - Abstract: This work presents a techno-financial evaluation of two Chilean locations with promising wind potential: Laguna Verde placed in the central region of the country, and Porvenir in the southern region. A small scale wind farm was studied, considering a nominal electrical production capacity of 90 kW. This facility is comprised of three wind turbine models, all available in the national market. Currently, the tariff method used in Chile is the net billing scheme, where the energy bought and sold to the grid has different prices. The study is based on 300 hypothetical residential households. The software tool used to perform the assessment was the Hybrid Optimization of Multiple Energy Resources (HOMER). For all the scenarios the results showed a Net Present Cost (NPC), instead of a financial profit from the proposed projects. A sensitivity analysis was also carried out. From the group of variables studied, the NPC exhibited itself as more sensitive to the price of buying energy from the grid and to the annual average wind speed. Finally, a few government policies and their applications are discussed.

  1. Equivalent models of wind farms by using aggregated wind turbines and equivalent winds

    International Nuclear Information System (INIS)

    Fernandez, L.M.; Garcia, C.A.; Saenz, J.R.; Jurado, F.

    2009-01-01

    As a result of the increasing wind farms penetration on power systems, the wind farms begin to influence power system, and therefore the modeling of wind farms has become an interesting research topic. In this paper, new equivalent models of wind farms equipped with wind turbines based on squirrel-cage induction generators and doubly-fed induction generators are proposed to represent the collective behavior on large power systems simulations, instead of using a complete model of wind farms where all the wind turbines are modeled. The models proposed here are based on aggregating wind turbines into an equivalent wind turbine which receives an equivalent wind of the ones incident on the aggregated wind turbines. The equivalent wind turbine presents re-scaled power capacity and the same complete model as the individual wind turbines, which supposes the main feature of the present equivalent models. Two equivalent winds are evaluated in this work: (1) the average wind from the ones incident on the aggregated wind turbines with similar winds, and (2) an equivalent incoming wind derived from the power curve and the wind incident on each wind turbine. The effectiveness of the equivalent models to represent the collective response of the wind farm at the point of common coupling to grid is demonstrated by comparison with the wind farm response obtained from the detailed model during power system dynamic simulations, such as wind fluctuations and a grid disturbance. The present models can be used for grid integration studies of large power system with an important reduction of the model order and the computation time

  2. Improving farm management by modeling the contamination of farm tank milk with butyric acid bacteria

    NARCIS (Netherlands)

    Vissers, M.M.M.; Driehuis, F.; Giffel, te M.C.; Jong, de P.; Lankveld, J.M.G.

    2006-01-01

    Control of contamination of farm tank milk (FTM) with the spore-forming butyric acid bacteria (BAB) is important to prevent the late-blowing defect in semi-hard cheeses. The risk of late blowing can be decreased via control of the contamination level of FTM with BAB. A modeling approach was applied

  3. Alberta Essay Scales: Models.

    Science.gov (United States)

    Nyberg, Verner R.; Nyberg, Adell M.

    The Alberta Essay Scales were developed to assist teachers in the grading of essays. They represent a standard based on written compositions at the 12th grade level in 1964 to be compared with current composition writing achievement. A scale for mechanics in English and one for writing style and content are defined through model essays and…

  4. Risk management strategies on small-scale commercial farms in three zobatat of Eritrea

    Directory of Open Access Journals (Sweden)

    MA Mohammed

    2014-05-01

    Full Text Available In this study the perceptions of small-scale commercial farmers in Eritrea of the importance of various risk responses are ascertained and analysed to gain insight into their risk-management strategies.  Data were elicited through a survey of 186 small-scale commercial farmers conducted in three zobatat (regions of Eritrea. Factor Analysis is used to investigate heterogeneity in sample farmers’ responses.  Results indicate that relatively more important risk responses include the use of internal and external sources of information, on-farm and off-farm diversification, choice of production system and product marketing arrangements. Farmers’ perceptions of risk responses vary according to farm type, geographical location, farm and farmer characteristics, as well as the existence of enterprise specific risk responses (e.g. livestock insurance and differences in the marketing regulations of various agricultural products.

  5. Antimicrobial use and antimicrobial susceptibility in Escherichia coli on small- and medium-scale pig farms in north-eastern Thailand

    Directory of Open Access Journals (Sweden)

    G. Ström

    2017-07-01

    Full Text Available Abstract Background Intensification of livestock production seen in many low- and middle-income countries is often believed to be associated with increased use of antimicrobials, and may hence contribute to the emergence of antimicrobial resistance. The aim of this study was to map antimicrobial use on small- (n = 25 and medium-scale (n = 27 pig farms in north-eastern Thailand, and to compare antimicrobial susceptibility of commensal Escherichia coli isolated from sows on these farms. Methods Information regarding pig husbandry and antimicrobial treatment regimens was obtained by the use of semi-structured questionnaires. Faecal samples were collected from three healthy sows at each farm, and Escherichia coli was cultured and analysed for antimicrobial susceptibility using the broth microdilution method. Multilevel regression models were used to compare antimicrobial susceptibility between isolates from small- and medium-scale farms. Results All farms included in the study administered antimicrobials to their sows. Small-scale farmers most commonly (64% decided themselves when to give antimicrobials and the majority (60% bought the medicines at the local store or pharmacy, whereas farmers on medium-scale farms always discussed antimicrobial treatment with a veterinarian. Medium-scale farms used a greater diversity of antimicrobials than small-scale farms and did also administer antimicrobials in feed to a higher extent. High levels of antimicrobial resistance to several critically important antimicrobials for human medicine (including ciprofloxacin, streptomycin and ampicillin were found in isolates from both small- and medium-scale farms. Resistance levels were significantly (P < 0.05 higher in isolates from medium-scale farms for several of the antimicrobials tested, as well as the level of multidrug-resistance (P = 0.026. Conclusion The routines regarding access and administration of antimicrobials differed between the small- and

  6. A survey of small-scale cattle farming systems in the North West ...

    African Journals Online (AJOL)

    A questionnaire-based survey was conducted among a purposive sample of 60 small-scale cattle farmers in the Mopeane Rustenburg district, all of whom owned five or more head of cattle. Results showed that small-scale cattle farming is a part-time activity for most farmers in this district, and a way of investing or saving ...

  7. Wind farm electrical power production model for load flow analysis

    International Nuclear Information System (INIS)

    Segura-Heras, Isidoro; Escriva-Escriva, Guillermo; Alcazar-Ortega, Manuel

    2011-01-01

    The importance of renewable energy increases in activities relating to new forms of managing and operating electrical power: especially wind power. Wind generation is increasing its share in the electricity generation portfolios of many countries. Wind power production in Spain has doubled over the past four years and has reached 20 GW. One of the greatest problems facing wind farms is that the electrical power generated depends on the variable characteristics of the wind. To become competitive in a liberalized market, the reliability of wind energy must be guaranteed. Good local wind forecasts are therefore essential for the accurate prediction of generation levels for each moment of the day. This paper proposes an electrical power production model for wind farms based on a new method that produces correlated wind speeds for various wind farms. This method enables a reliable evaluation of the impact of new wind farms on the high-voltage distribution grid. (author)

  8. Fuzzy generation scheduling for a generation company (GenCo) with large scale wind farms

    International Nuclear Information System (INIS)

    Siahkali, H.; Vakilian, M.

    2010-01-01

    Wind power is a promising alternative in power generation because of its tremendous environmental and social benefits. Generation scheduling (GS) is more important in a power system integrating wind farms. Unlike conventional power generation sources, wind power generators supply intermittent power because of uncertainty in resource. This paper presents a fuzzy approach to the generation scheduling problem of a GenCo considering uncertainties in parameters or constraints such as load, reserve and available wind power generation. The modeling of constraints is an important issue in power system scheduling. A fuzzy optimization approach is an approach that can be used to obtain the generation scheduling under an uncertain environment. In this paper, a fuzzy optimization-based method is developed to solve power system GS problem with fuzzy objective and constraints. The crisp formulation of this GS problem is firstly defined and is rearranged by introduction of a membership function of some constraints and objective function. Then, this fuzzy optimization problem is converted to a crisp optimization and solved using GAMS software by mixed integer nonlinear programming. Employing the fuzzy optimization GS, it is expected that in practice a higher profit would be achieved in the operation and cost management of a real power system with large scale wind farms in different level of constraints' satisfaction. The proposed approach is applied to a sample system (including six conventional units and two wind farms) and the results are compared with the results of crisp solution. This approach is also applied to a larger test case to demonstrate the robustness of this fuzzy optimization method.

  9. Assessing the Economic Situation of Small-Scale Farm Forestry in Mountain Regions: A Case Study in Austria

    Directory of Open Access Journals (Sweden)

    Philipp Toscani

    2017-08-01

    Full Text Available Austria is one of the few countries with a long tradition of monitoring the economic performance of forest holdings. The national Farm Accountancy Data Network also addresses some forestry-specific issues, given the high significance of farm forestry in this country. However, it is not possible to assess the profitability of small-scale farm forestry in mountainous regions based on a representative sample. In this paper, we demonstrate how information gaps can be overcome by means of economic modeling and present results of this approach for mountain forestry for the first time. In spite of the unfavorable conditions of an alpine setting, forestry tends to be of special significance for the viability and resilience of family farms in these regions. Sustainable forest management that safeguards the ecosystem services provided by forests relies mostly on the profitability of timber production. Thus, the economic development of farm forestry is a key factor in achieving targets 15.1 and 15.4 of the United Nations Sustainable Development Goals in mountain regions.

  10. Wind farm related mortality among avian migrants - a remote sensing study and model analysis

    Energy Technology Data Exchange (ETDEWEB)

    Desholm, M.

    2006-11-15

    This thesis is the result of a PhD study on bird-wind farm collisions and consists of a synopsis, five published papers, one submitted manuscript and another ready for submission. The papers describe the findings from pre- and post-construction visual, radar and thermal imaging studies (1999-2006) of migrating birds at the Nysted offshore wind farm in the Baltic Sea, Denmark. This thesis poses and answers the following questions: a) what hazard factors do offshore wind farming pose to wild birds, b) how should one choose the key focal species to study, c) how can remote sensing techniques be applied to the study of bird wind farm interactions, and d) specifically, how do water birds react when approaching an offshore wind farm? The main aim of the study was the development of a predictive bird-wind farm collision model that incorporates the avoidance rate of birds at multiple scales. Out of 235,136 migrating sea ducks only 47 individuals were predicted to collide with the wind turbine rotor-blades, equivalent to an overall mean collision risk of c. 0.02%. This thesis shows the added value of modelling in supplementing sound empirical studies in accessing the effects of major human development pressures on migratory bird populations. (au)

  11. Limited usage of mechanical equipment in small-scale rice farming: a cause for concern

    Directory of Open Access Journals (Sweden)

    Gaudiose Mujawamariya

    2017-06-01

    Full Text Available The role of mechanization in agriculture is well documented in terms of improving productivity of farm labour and land and sustaining income status and welfare of small-scale farmers. In rice production, there is a high cost associated with labour intensive production practices especially in land preparation, weeding and harvesting, the limited adoption of mechanical equipment in these operations remains an issue of concern. The current study investigates the usage of mechanical equipment in a setting where majority of farmers are exposed to technologies but cases of non-usage/adoption are observed. The choice of usage of mechanical equipment is analysed through probit and poisson models. Mechanization generally has a positive effect on production. However, the cost associated with its usage high. The equipment should be made available and affordable to farmers especially because demand for rent is not met. Awareness is essential for adoption and ease of use of mechanization.

  12. SWEET CORN FARMING: THE EFFECT OF PRODUCTION FACTOR, EFFICIENCY AND RETURN TO SCALE

    Directory of Open Access Journals (Sweden)

    Dwijatenaya I.B.M.A.

    2017-10-01

    Full Text Available This research aims to determine the effect of production factors on the sweet corn production, the efficiency of sweet corn farming, and the return to scale of sweet corn production. The sampling technique was taken by proportionate stratified random sampling method with the sample number of 57 people while the analyzer used was the program of Frointer 4.1c. The results show that the production factors of the land farm, seed, and fertilizer have a positive and significant effect on sweet corn production. On the other hand, labor production factors have a positive but not significant effect on sweet corn production. It also found that technical efficiency, price efficiency, and economic efficiency of sweet corn farming in Muara Wis Sub-district of Kutai Kartanegara Regency are not efficient yet. The return to scale of sweet corn yield has an increasing return to scale condition.

  13. Proteomics in farm animals models of human diseases.

    Science.gov (United States)

    Ceciliani, Fabrizio; Restelli, Laura; Lecchi, Cristina

    2014-10-01

    The need to provide in vivo complex environments to understand human diseases strongly relies on the use of animal models, which traditionally include small rodents and rabbits. It is becoming increasingly evident that the few species utilised to date cannot be regarded as universal. There is a great need for new animal species that are naturally endowed with specific features relevant to human diseases. Farm animals, including pigs, cows, sheep and horses, represent a valid alternative to commonly utilised rodent models. There is an ample scope for the application of proteomic techniques in farm animals, and the establishment of several proteomic maps of plasma and tissue has clearly demonstrated that farm animals provide a disease environment that closely resembles that of human diseases. The present review offers a snapshot of how proteomic techniques have been applied to farm animals to improve their use as biomedical models. Focus will be on specific topics of biomedical research in which farm animal models have been characterised through the application of proteomic techniques. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. IEA-Task 31 WAKEBENCH: Towards a protocol for wind farm flow model evaluation. Part 2: Wind farm wake models

    International Nuclear Information System (INIS)

    Moriarty, Patrick; Rodrigo, Javier Sanz; Gancarski, Pawel; Chuchfield, Matthew; Naughton, Jonathan W; Hansen, Kurt S; Machefaux, Ewan; Maguire, Eoghan; Castellani, Francesco; Terzi, Ludovico; Breton, Simon-Philippe; Ueda, Yuko

    2014-01-01

    Researchers within the International Energy Agency (IEA) Task 31: Wakebench have created a framework for the evaluation of wind farm flow models operating at the microscale level. The framework consists of a model evaluation protocol integrated with a web-based portal for model benchmarking (www.windbench.net). This paper provides an overview of the building-block validation approach applied to wind farm wake models, including best practices for the benchmarking and data processing procedures for validation datasets from wind farm SCADA and meteorological databases. A hierarchy of test cases has been proposed for wake model evaluation, from similarity theory of the axisymmetric wake and idealized infinite wind farm, to single-wake wind tunnel (UMN-EPFL) and field experiments (Sexbierum), to wind farm arrays in offshore (Horns Rev, Lillgrund) and complex terrain conditions (San Gregorio). A summary of results from the axisymmetric wake, Sexbierum, Horns Rev and Lillgrund benchmarks are used to discuss the state-of-the-art of wake model validation and highlight the most relevant issues for future development

  15. Impacts of large-scale offshore wind farm integration on power systems through VSC-HVDC

    DEFF Research Database (Denmark)

    Liu, Hongzhi; Chen, Zhe

    2013-01-01

    the impacts of integrating a large-scale offshore wind farm into the transmission system of a power grid through VSC-HVDC connection. The concerns are focused on steady-state voltage stability, dynamic voltage stability and transient angle stability. Simulation results based on an exemplary power system......, an offshore wind farm could have a capacity rating to hundreds of MWs or even GWs that is large enough to compete with conventional power plants. Thus the impacts of a large offshore wind farm on power system operation and security should be thoroughly studied and understood. This paper investigates......The potential of offshore wind energy has been commonly recognized and explored globally. Many countries have implemented and planned offshore wind farms to meet their increasing electricity demands and public environmental appeals, especially in Europe. With relatively less space limitation...

  16. Environmental impacts of innovative dairy farming systems aiming at improved internal nutrient cycling: A multi-scale assessment.

    Science.gov (United States)

    de Vries, W; Kros, J; Dolman, M A; Vellinga, Th V; de Boer, H C; Gerritsen, A L; Sonneveld, M P W; Bouma, J

    2015-12-01

    Several dairy farms in the Netherlands aim at reducing environmental impacts by improving the internal nutrient cycle (INC) on their farm by optimizing the use of available on-farm resources. This study evaluates the environmental performance of selected INC farms in the Northern Friesian Woodlands in comparison to regular benchmark farms using a Life Cycle Assessment. Regular farms were selected on the basis of comparability in terms of milk production per farm and per hectare, soil type and drainage conditions. In addition, the environmental impacts of INC farming at landscape level were evaluated with the integrated modelling system INITIATOR, using spatially explicit input data on animal numbers, land use, agricultural management, meteorology and soil, assuming that all farms practised the principle of INC farming. Impact categories used at both farm and landscape levels were global warming potential, acidification potential and eutrophication potential. Additional farm level indicators were land occupation and non-renewable energy use, and furthermore all farm level indicators were also expressed per kg fat and protein corrected milk. Results showed that both on-farm and off-farm non-renewable energy use was significantly lower at INC farms as compared with regular farms. Although nearly all other environmental impacts were numerically lower, both on-farm and off-farm, differences were not statistically significant. Nitrogen losses to air and water decreased by on average 5 to 10% when INC farming would be implemented for the whole region. The impact of INC farming on the global warming potential and eutrophication potential was, however, almost negligible (cycle. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Farmworkers' Irrigation Schools: An Extension Model for Hispanic Farm Laborers.

    Science.gov (United States)

    Youmans, David; And Others

    1982-01-01

    Describes a model for Hispanic farm laborer irrigation schools that was developed, implemented, and evaluated by cooperative extension personnel. Success of the approach was due to attention to critical elements in the model, which is applicable to other adult basic education programs. (JOW)

  18. Modelling and measurements of wakes in large wind farms

    DEFF Research Database (Denmark)

    Barthelmie, Rebecca Jane; Rathmann, Ole; Frandsen, Sten Tronæs

    2007-01-01

    The paper presents research conducted in the Flow workpackage of the EU funded UPWIND project which focuses on improving models of flow within and downwind of large wind farms in complex terrain and offshore. The main activity is modelling the behaviour of wind turbine wakes in order to improve p...

  19. Models for simulation of transient events in a wind farm

    DEFF Research Database (Denmark)

    Sørensen, P.; Hansen, A. D.; Bindner, H.

    2002-01-01

    with different tools with each other and with measurements. This present paper limits to describe the models including our reflections on which effects we expect to be essential for obtaining useful simulation results. The models comprise the substation, where the wind farm is connected, the power collection...

  20. Spectral coherence model for power fluctuations in a wind farm

    DEFF Research Database (Denmark)

    Vigueras-Rodriguez, A.; Sørensen, Poul Ejnar; Viedma, A.

    2012-01-01

    This paper provides a model for the coherence between wind speeds located in a horizontal plane corresponding to hub height of wind turbines in a large wind farm. The model has been developed using wind speed and power measurements from the 72 Wind Turbines and two of the meteorological masts from...

  1. Large-Eddy Simulation of Waked Turbines in a Scaled Wind Farm Facility

    Science.gov (United States)

    Wang, J.; McLean, D.; Campagnolo, F.; Yu, T.; Bottasso, C. L.

    2017-05-01

    The aim of this paper is to present the numerical simulation of waked scaled wind turbines operating in a boundary layer wind tunnel. The simulation uses a LES-lifting-line numerical model. An immersed boundary method in conjunction with an adequate wall model is used to represent the effects of both the wind turbine nacelle and tower, which are shown to have a considerable effect on the wake behavior. Multi-airfoil data calibrated at different Reynolds numbers are used to account for the lift and drag characteristics at the low and varying Reynolds conditions encountered in the experiments. The present study focuses on low turbulence inflow conditions and inflow non-uniformity due to wind tunnel characteristics, while higher turbulence conditions are considered in a separate study. The numerical model is validated by using experimental data obtained during test campaigns conducted with the scaled wind farm facility. The simulation and experimental results are compared in terms of power capture, rotor thrust, downstream velocity profiles and turbulence intensity.

  2. Development and validation of a work stressor scale for Australian farming families.

    Science.gov (United States)

    McShane, Connar J; Quirk, Frances; Swinbourne, Anne

    2016-08-01

    The aim of this research was to gain insight into the key stressors for Australian farming families. It is well established that the farming work environment consists of a number of unique stressors which arise from dependency on factors beyond an individual's control (e.g. climate conditions) as well as the overlap between work and family environments. Despite this, limited research has included family factors in the assessment of stress felt by farmers and their families. This research sought to develop a scale of stressors for farming families in an Australian sample. A survey design was used for validity and reliability studies. The validity study involved assessment of factor structure, concurrent validity and discriminant validity. The reliability study used a test-retest reliability design. Participants were recruited from across Australia (38% Queensland; 30% New South Wales) and multiple industries (43% beef; 27% broadacre cropping; 26% horticulture). The validity study involved 278 participants and the reliability study involved 53 participants. Development of a Farming Family Stressor scale. The generated Farming Family Stressor scale presented satisfactory levels of concurrent validity (e.g. r = .73 against the Farm Stress Survey total score), discriminant validity (e.g. r = -.42 to r = .53 against the Satisfaction with Life and Kessler-10 total scores, respectively), internal consistency (Cronbach's alpha >.90) and test-retest reliability (rho > .66). This research lends insight into the complexity of stressors for farming families and has implications for occupational health and mental health programs that seek to reduce stress and improve health outcomes for that group. © 2015 National Rural Health Alliance Inc.

  3. Wind Speed Estimation and Parametrization of Wake Models for Downregulated Offshore Wind Farms within the scope of PossPOW Project

    DEFF Research Database (Denmark)

    Göçmen Bozkurt, Tuhfe; Giebel, Gregor; Poulsen, Niels Kjølstad

    2014-01-01

    With increasing installed capacity, wind farms are requested to downregulate more frequently, especially in the offshore environment. Determination and verification of possible (or available) power of downregulated offshore wind farms are the aims of the PossPOW project (see PossPOW.dtu.dk). Two ...... period. The re-calibrated model has to be further parametrized to include dynamic effects such as wind direction variability and meandering also considering different averaging time scales before implemented in full scale wind farms....

  4. A noise generation and propagation model for large wind farms

    DEFF Research Database (Denmark)

    Bertagnolio, Franck

    2016-01-01

    A wind turbine noise calculation model is combined with a ray tracing method in order to estimate wind farm noise in its surrounding assuming an arbitrary topography. The wind turbine noise model is used to generate noise spectra for which each turbine is approximated as a point source. However......, the detailed three-dimensional directivity features are taken into account for the further calculation of noise propagation over the surrounding terrain. An arbitrary number of turbines constituting a wind farm can be spatially distributed. The noise from each individual turbine is propagated into the far......-field using the ray tracing method. These results are added up assuming the noise from each turbine is uncorrelated. The methodology permits to estimate a wind farm noise map over the surrounding terrain in a reasonable amount of computational time on a personal computer....

  5. Determinants of wind and solar energy system adoption by U.S. farms: A multilevel modeling approach

    International Nuclear Information System (INIS)

    Borchers, Allison M.; Xiarchos, Irene; Beckman, Jayson

    2014-01-01

    This article offers the first national examination of the determinants of adoption of wind and solar energy generation on U.S. farming operations. The inclusion of state policies and characteristics in a multilevel modeling approach distinguishes this study from past research utilizing logit models of technology adoption which focus only on the characteristics of the farm operation. Results suggest the propensity to adopt is higher for livestock operations, larger farms, operators with internet access, organic operations, and newer farmers. The results find state characteristics such as solar resources, per capita income levels, and predominantly democratic voting increasing the odds of farm adoption. This research suggests the relevance of state policy variables in explaining farm level outcomes is limited, although in combination best practice net metering and interconnection policies—policies designed to encourage the development of small scale distributed applications—are shown to increase the likelihood of farm solar and wind adoption. The prevalence of electric cooperatives—which are often not subject to state renewable energy policies and often service farms—is negatively related with the propensity to adopt and suggests that policy design may be a factor. - Highlights: • This is the first national examination of wind and solar energy adoption on U.S. farms. • Controlling for state policies distinguishes this study from past research of technology adoption. • We find net metering and interconnection policies increase the likelihood of farm adoption. • Results suggest that the design of renewable energy policies may limit their impact on farms

  6. High-resolution computational algorithms for simulating offshore wind turbines and farms: Model development and validation

    Energy Technology Data Exchange (ETDEWEB)

    Calderer, Antoni [Univ. of Minnesota, Minneapolis, MN (United States); Yang, Xiaolei [Stony Brook Univ., NY (United States); Angelidis, Dionysios [Univ. of Minnesota, Minneapolis, MN (United States); Feist, Chris [Univ. of Minnesota, Minneapolis, MN (United States); Guala, Michele [Univ. of Minnesota, Minneapolis, MN (United States); Ruehl, Kelley [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Guo, Xin [Univ. of Minnesota, Minneapolis, MN (United States); Boomsma, Aaron [Univ. of Minnesota, Minneapolis, MN (United States); Shen, Lian [Univ. of Minnesota, Minneapolis, MN (United States); Sotiropoulos, Fotis [Stony Brook Univ., NY (United States)

    2015-10-30

    The present project involves the development of modeling and analysis design tools for assessing offshore wind turbine technologies. The computational tools developed herein are able to resolve the effects of the coupled interaction of atmospheric turbulence and ocean waves on aerodynamic performance and structural stability and reliability of offshore wind turbines and farms. Laboratory scale experiments have been carried out to derive data sets for validating the computational models.

  7. Does limited data availability prevent adequate water use estimates on farm scale?

    Science.gov (United States)

    Kayatz, Benjamin; Kuster, Benjamin; Percy, Barbara; Hillier, Jonathan; Freese, Dirk; Wattenbach, Martin

    2015-04-01

    Increasing food production for a growing world population and at the same time mitigating climate change as well as adapting to its consequences is one of the key global challenges. Therefore producing crops with fewer resources such as water and fertilizers and less emissions of greenhouse gases is an important question that has to be answered on farm scale. The cool farm tool (CFT) is a farm scale emission calculator and was developed in 2010 to help farmers to reduce their carbon footprint. In order to adapt to future climate change an easy to use and at the same time robust water footprinting tool is needed for the CFT to take a more holistic approach on environmental sustainability. However data on farm level is often scarce. We investigated the effect of limited data on actual evapotranspiration using the FAO56 standard to assess the quality of farm water footprint estimates. Calculations are based on various agricultural sites from the Fluxnet database and estimates are compared to eddy covariance measurements. Results show that higher data availability is not directly linked to more accurate estimates of actual evapotranspiration. Estimates based only on temperature and relative humidity are still able to reproduce daily patterns. However cumulative values over one growing season show a considerable offset to eddy covariance observations for all data input levels. Finding the optimum between data requirements and an accuracy that fulfills farmer needs is crucial. Engagement of farmers and using a global network as the Fluxnet database will help to achieve this goal.

  8. Fuel From Farms: A Guide to Small-Scale Ethanol Production.

    Science.gov (United States)

    Solar Energy Research Inst., Golden, CO.

    Ethanol and blends of ethanol and gasoline (such as gasohol) offer a near-term fuel alternative to oil. The focus of this handbook is upon the small-scale production of ethanol using farm crops as the source of raw materials. Provided are chapters on ethanol production procedures, feedstocks, plant design, and financial planning. Also presented…

  9. EFFECTS OF LARGE-SCALE POULTRY FARMS ON AQUATIC MICROBIAL COMMUNITIES: A MOLECULAR INVESTIGATION.

    Science.gov (United States)

    The effects of large-scale poultry production operations on water quality and human health are largely unknown. Poultry litter is frequently applied as fertilizer to agricultural lands adjacent to large poultry farms. Run-off from the land introduces a variety of stressors into t...

  10. A SIMULATION OF CONTRACT FARMING USING AGENT BASED MODELING

    Directory of Open Access Journals (Sweden)

    Yuanita Handayati

    2016-12-01

    Full Text Available This study aims to simulate the effects of contract farming and farmer commitment to contract farming on supply chain performance by using agent based modeling as a methodology. Supply chain performance is represented by profits and service levels. The simulation results indicate that farmers should pay attention to customer requirements and plan their agricultural activities in order to fulfill these requirements. Contract farming helps farmers deal with demand and price uncertainties. We also find that farmer commitment is crucial to fulfilling contract requirements. This study contributes to this field from a conceptual as well as a practical point of view. From the conceptual point of view, our simulation results show that different levels of farmer commitment have an impact on farmer performance when implementing contract farming. From a practical point of view, the uncertainty faced by farmers and the market can be managed by implementing cultivation and harvesting scheduling, information sharing, and collective learning as ways of committing to contract farming.

  11. Mesoscale to microscale wind farm flow modeling and evaluation

    DEFF Research Database (Denmark)

    Sanz Rodrigo, Javier; Chávez Arroyo, Roberto Aurelio; Moriarty, Patrick

    2017-01-01

    The increasing size of wind turbines, with rotors already spanning more than 150m diameter and hub heights above 100m, requires proper modeling of the atmospheric boundary layer (ABL) from the surface to the free atmosphere. Furthermore, large wind farm arrays create their own boundary layer stru...

  12. Micro-economic panel data models for Dutch dairy farming

    NARCIS (Netherlands)

    Ooms, D.L.

    2007-01-01

    Keywords:micro-economic models, panel data, GMM, CAP reform, dairy farmingIn The Netherlands, thedairy sector is the largest agricultural sub-sector based on both gross production value and number of

  13. Reducing Turbine Mechanical Loads Using Flow Model-Based Wind Farm Controller

    DEFF Research Database (Denmark)

    Kazda, Jonas; Cutululis, Nicolaos Antonio

    WindFarm [2]. SimWindFarm allows for the simultaneous simulation of the turbulent hub height flow field in the wind farm, the turbine dynamics and the wind farm control. The tests show a reduction of loads when compared to other optimal wind farm control approaches. Future work shall enhance the controller......Cumulated O&M costs of offshore wind farms are comparable with wind turbine CAPEX of such wind farm. In wind farms, wake effects can result in up to 80% higher fatigue loads at downstream wind turbines [1] and consequently larger O&M costs. The present work therefore investigates to reduce...... these loads during the provision of grid balancing services using optimal model-based wind farm control. Wind farm controllers coordinate the operating point of wind turbines in a wind farm in order to achieve a given objective. The investigated objective of the control in this work is to follow a total wind...

  14. Fuel from farms: a guide to small-scale ethanol production

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-02-01

    A guide on fermentation processes with emphasis on small-scale production of ethanol using farm crops as a source of raw material is published. The current status of on-farm ethanol production as well as an overview of some of the technical and economic factors is presented. Decision and planning worksheets and a sample business plan for use in decision making are included. Specifics in production including information on the raw materials, system components, and operational requirements are also provided. Diagrams of fermentors and distilling apparatus are included. (DC)

  15. A Methodological Approach to Evaluate Livestock Innovations on Small-Scale Farms in Developing Countries

    Directory of Open Access Journals (Sweden)

    Antón García-Martínez

    2016-06-01

    Full Text Available The aim of the study was deepening the knowledge of livestock innovations knowledge on small-scale farms in developing countries. First, we developed a methodology focused on identifying potential appropriate livestock innovations for smallholders and grouped them in innovation areas, defined as a set of well-organized practices with a business purpose. Finally, a process management program (PMP was evaluated according to the livestock innovation level and viability of the small-scale farms. Logistic regression was used to evaluate the impact of PMP on the economic viability of the farm. Information from 1650 small-scale livestock farms in Mexico was collected and the innovations were grouped in five innovation areas: A1. Management, A2. Feeding, A3. Genetic, A4. Reproduction and A5. Animal Health. The resulting innovation level in the system was low at 45.7% and heterogeneous among areas. This study shows the usefulness of the methodology described and confirms that implementing a PMP allows improving the viability an additional 21%, due to a better integration of processes, resulting in more efficient management.

  16. Microbial Indicators, Pathogens, and Antibiotic Resistance in Groundwater Impacted by Animal Farming: Field Scale to Basin Scale

    Science.gov (United States)

    Harter, T.; Li, X.; Atwill, E. R.; Packman, A. I.

    2015-12-01

    Several surveys of microbial indicators and pathogens were conducted to determine the impact of confined animal farming operations (CAFOs) on shallow, local, and regional groundwater quality in the Central Valley aquifer system, California. The aquifer system consists of highly heterogeneous, alluvial, unconsolidated coarse- to fine-grained sediments and is among the largest aquifers in the U.S.. Overlying landuse includes 3 million ha of irrigated agriculture and 1.7 million mature dairy cows in nearly 1,500 CAFOs. A multi-scale survey of water-borne indicator pathogens (Enterococcus spp. and generic E. coli) and of three water-borne pathogens (Campylobacter, Salmonella, and E. coli O157:H7) was conducted at five different spatial scales, increasing with distance from animal sources of these enteric microbial organisms: moist surfaces within individual CAFO sub-systems (calf-hutches, heifer corrals, mature cow stalls, hospital barn etc.), first encountered (shallow) groundwater immediately below these sub-systems, production aquifer below CAFOs, production aquifer near CAFOs, and production aquifer away from CAFOs. Where found, indicator pathogens were tested for antibiotic resistance. Hundreds of samples were collected at each scale: continuously during irrigation events and seasonally over a multi-year period at the three smaller site-scales; and in a one-time survey at the two larger, regional scales. All three pathogens were frequently detected in moist surface samples across CAFO sub-systems, albeit at concentrations several orders of magnitude lower than enteric indicators. Two of the three pathogens (but not Campylobacter) were also detected in first encountered groundwater, at 3-9 m below ground surface, in 1% of samples. No pathogens were found at the production aquifer scales. Generic E. coli was detected in ¼ of first encountered groundwater samples, and in 4% of production aquifer samples, while Enterococcus spp. was ubiquitously present across the

  17. Uncertainty quantification in wind farm flow models

    DEFF Research Database (Denmark)

    Murcia Leon, Juan Pablo

    uncertainties through a model chain are presented and applied to several wind energy related problems such as: annual energy production estimation, wind turbine power curve estimation, wake model calibration and validation, and estimation of lifetime equivalent fatigue loads on a wind turbine. Statistical...

  18. PORFLOW Modeling Supporting The H-Tank Farm Performance Assessment

    International Nuclear Information System (INIS)

    Jordan, J. M.; Flach, G. P.; Westbrook, M. L.

    2012-01-01

    Numerical simulations of groundwater flow and contaminant transport in the vadose and saturated zones have been conducted using the PORFLOW code in support of an overall Performance Assessment (PA) of the H-Tank Farm. This report provides technical detail on selected aspects of PORFLOW model development and describes the structure of the associated electronic files. The PORFLOW models for the H-Tank Farm PA, Rev. 1 were updated with grout, solubility, and inventory changes. The aquifer model was refined. In addition, a set of flow sensitivity runs were performed to allow flow to be varied in the related probabilistic GoldSim models. The final PORFLOW concentration values are used as input into a GoldSim dose calculator

  19. PORFLOW Modeling Supporting The H-Tank Farm Performance Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, J. M.; Flach, G. P.; Westbrook, M. L.

    2012-08-31

    Numerical simulations of groundwater flow and contaminant transport in the vadose and saturated zones have been conducted using the PORFLOW code in support of an overall Performance Assessment (PA) of the H-Tank Farm. This report provides technical detail on selected aspects of PORFLOW model development and describes the structure of the associated electronic files. The PORFLOW models for the H-Tank Farm PA, Rev. 1 were updated with grout, solubility, and inventory changes. The aquifer model was refined. In addition, a set of flow sensitivity runs were performed to allow flow to be varied in the related probabilistic GoldSim models. The final PORFLOW concentration values are used as input into a GoldSim dose calculator.

  20. Agricultural Incentives: Implications for Small-Scale and Subsistence Farming in the US Caribbean Islands

    Science.gov (United States)

    Alvarez-Berrios, N.; Parés-Ramos, I.; Gould, W. A.

    2017-12-01

    The effects of climate change threaten the world's most sensitive agroecosystems and our potential to reach agricultural productivity levels needed to feed a projected global population of 9.7 billion people by 2050. The US Caribbean agriculture is especially vulnerable to the effects of climate change, due to the region's frequent exposure to extreme weather events, its geographic and economic scale, shortage of labor force, and rapid urban expansion. Currently, agriculture contributes less than 1% of the island's GDP, and over 80% of the food consumed in the region is imported. Despite low production levels, there is widespread interest in reinvigorating the agricultural sector's contribution to the economy. Local and federal institutions play a major role strengthening the agricultural sector by providing access to incentives, loans, and education for best management practices. However, many of these efforts conform to agricultural systems of larger scale of production and temperate environments. In this study, we explore agricultural incentives programs and their implication for highly diverse, small-scale, and subsistence operations that characterize agricultural systems in Puerto Rico and the US Virgin Islands. We analyze records and maps from the USDA Farm Service Agency, to typify participating farms, and to track changes in land cover, farm size, crop diversity, practices, and production levels resulting from their enrollment in such programs. Preliminary results indicate that many incentives programs are not tailored to agricultural tropical systems and prescribe alternatives that exclude traditional farming methods employed in small-scale and subsistence farms (e.g. crop insurance that benefit monoculture over intercropped systems). Moreover, many of the incentives are contradictory in their recommendations (e.g., crop insurance benefit sun-grown coffee production, while best agricultural practices recommend agroforestry with shade-grown coffee

  1. Spatial downscaling of soil prediction models based on weighted generalized additive models in smallholder farm settings.

    Science.gov (United States)

    Xu, Yiming; Smith, Scot E; Grunwald, Sabine; Abd-Elrahman, Amr; Wani, Suhas P; Nair, Vimala D

    2017-09-11

    Digital soil mapping (DSM) is gaining momentum as a technique to help smallholder farmers secure soil security and food security in developing regions. However, communications of the digital soil mapping information between diverse audiences become problematic due to the inconsistent scale of DSM information. Spatial downscaling can make use of accessible soil information at relatively coarse spatial resolution to provide valuable soil information at relatively fine spatial resolution. The objective of this research was to disaggregate the coarse spatial resolution soil exchangeable potassium (K ex ) and soil total nitrogen (TN) base map into fine spatial resolution soil downscaled map using weighted generalized additive models (GAMs) in two smallholder villages in South India. By incorporating fine spatial resolution spectral indices in the downscaling process, the soil downscaled maps not only conserve the spatial information of coarse spatial resolution soil maps but also depict the spatial details of soil properties at fine spatial resolution. The results of this study demonstrated difference between the fine spatial resolution downscaled maps and fine spatial resolution base maps is smaller than the difference between coarse spatial resolution base maps and fine spatial resolution base maps. The appropriate and economical strategy to promote the DSM technique in smallholder farms is to develop the relatively coarse spatial resolution soil prediction maps or utilize available coarse spatial resolution soil maps at the regional scale and to disaggregate these maps to the fine spatial resolution downscaled soil maps at farm scale.

  2. Small-Scale Variability in the Soil Microbial Community Structure in a Semideveloped Farm in Zambia

    Directory of Open Access Journals (Sweden)

    Toru Hamamoto

    2018-01-01

    Full Text Available The conversion of natural lands into agricultural lands can lead to changes in the soil microbial community structure which, in turn, can affect soil functions. However, few studies have examined the effect of land use changes on the soil microbial community structure in sub-Saharan Africa. Therefore, the aim of this research was to investigate the relationships among soil characteristics and microbial communities in natural and agricultural ecosystems in a semideveloped lowland farm in the central region of Zambia, within which small-scale wetlands had been partly developed as watermelon (Citrullus lanatus and/or maize (Zea mays farms. We sampled soils from four different land use types within this farm: “native forest,” “grassland,” “watermelon farm,” and “maize farm.” We found that the land use type had a significant effect on the soil bacterial community structure at the class level, with the class Bacilli having significantly higher relative abundances in the forest sites and Gammaproteobacteria having significantly higher relative abundances in the maize sites than in the other land use types. These findings indicate that these bacterial classes may be sensitive to changes in soil ecosystems, and so further studies are required to investigate microbial indicators for the sustainable development of wetlands in sub-Saharan Africa.

  3. Large scale model testing

    International Nuclear Information System (INIS)

    Brumovsky, M.; Filip, R.; Polachova, H.; Stepanek, S.

    1989-01-01

    Fracture mechanics and fatigue calculations for WWER reactor pressure vessels were checked by large scale model testing performed using large testing machine ZZ 8000 (with a maximum load of 80 MN) at the SKODA WORKS. The results are described from testing the material resistance to fracture (non-ductile). The testing included the base materials and welded joints. The rated specimen thickness was 150 mm with defects of a depth between 15 and 100 mm. The results are also presented of nozzles of 850 mm inner diameter in a scale of 1:3; static, cyclic, and dynamic tests were performed without and with surface defects (15, 30 and 45 mm deep). During cyclic tests the crack growth rate in the elastic-plastic region was also determined. (author). 6 figs., 2 tabs., 5 refs

  4. Effectiveness of Hub and Spoke Model for Dissemination of Innovative Farm Technologies to the Farming Community

    Directory of Open Access Journals (Sweden)

    N. Sriram

    2016-05-01

    Full Text Available Hub and Spoke Model was established for dissemination of the innovative farming technologies at farmers’ doorstep. The study was conducted to measure the Effectiveness of Hub and Spoke Model for dissemination of innovative farm technologies at Tiruvannamalai district of Tamil Nadu. The respondents were selected by adopting purposive random sampling technique. A sample of 75 respondents from five villages of Polur block was selected for this study. The hub and spoke model was established and the knowledge gain of the subjects both at the pre and post exposure stages were collected using teacher made knowledge tests respectively. The data were collected using a well structured and pre-tested interview schedule. The data were analyzed by using appropriate statistical tools. The percentage of knowledge gained before the exposure to treatment was 40.20 per cent and after exposed it was 76.70 per cent. The mean knowledge gain is 36.50 per cent. The ‘t’ value 19.93 per cent indicates that the knowledge gained by the respondents was found to be significant at one per cent level. It was identified that there existed a significant differences in the effectiveness of the hub and spoke services in imparting knowledge.

  5. Modelling Waste Output from Trout Farms

    DEFF Research Database (Denmark)

    Frier, J. O.; From, J.; Larsen, Torben

    1995-01-01

    to calculate waste discharge from existing and planned aquaculture activities. A special purpose is simulating outcome of waste water treatment and altered feeding programmes. Different submodels must be applied for P, N, and organics, as well as for the different phases of food and waste treatment. Altogether......The aim of waste modelling in aquaculture is to provide tools for simulating input, transformation, output and subsidiary degradation in recipients of organic compounds, nitrogen, and phosphorus. The direct purpose of this modelling is to make it possible for caretakers and water authorities...

  6. A Multistate Model of Reliability of Farming Machinery

    Directory of Open Access Journals (Sweden)

    Durczak Karol

    2018-01-01

    Full Text Available The article describes a multistate model of reliability of farming machinery as a deductive stochastic model of the process of changes in the technical conditions observed during operation. These conditions determine the capacity of machinery to fulfil functions, simultaneously keeping safety and maintaining acceptable costs of possible repairs. The theory of semi-Markov processes was used to solve the problem. After detailed analysis of the symptoms of damage to exemplary groups of farming machinery (rotary mowers, rotary harrows and harvesting presses we obligatorily and arbitrarily proposed an optimal four-state reliability model to describe changes in technical conditions. In contrast to the classic reliability theory, which allows only two states of technical usability (either a machine is fit to function or not, we also allowed intermediate states, because not all types of damage affect the functionality of machinery. This approach increases the probability of technical usability of machinery and rationally delays the moment of premature repair.

  7. Design considerations for a farm-scale biogas plant based on pilot-scale anaerobic digesters loaded with rice straw and piggery wastewater

    International Nuclear Information System (INIS)

    Mussoline, Wendy; Esposito, Giovanni; Lens, Piet; Garuti, Gilberto; Giordano, Andrea

    2012-01-01

    Two pilot-scale (1 m 3 ) digesters filled with untreated rice straw and co-digested with raw pig wastewater were operated to obtain design parameters for a farm-scale biogas plant. Both digesters contained 50 kg of dry straw mixed with diluted pig wastewater to create dry digestion conditions (20% TS) and operated for 189 days with leachate recirculation. Digester A was designed for optimum performance (150 L of pig wastewater and mesophilic temperatures) while Digester B was designed to establish minimum inputs (60 L of pig wastewater at ambient temperatures). The pig wastewater provided sufficient buffering capacity to maintain appropriate pH values (between 7.0 and 8.1) and nutrient balances (TOC to TKN ratios of 20 in Digester A and 32 in Digester B). Total biogas production was 22,859 L in Digester A and 1420 L from Digester B, resulting in specific methane yields of 231 and 12 L CH 4 /kgVS added, respectively. Gas production in Digester A was directly correlated with temperature, but the overall lack of methanogenic activity was caused primarily by the reduced wastewater volume. Two theoretical farm-scale scenarios (considering both untreated and pretreated rice straw) were developed for a 100-ha rice farm. Either scenario can produce 100,000 m 3 CH 4 per year, yielding 328 MWh. Major differences including heat input, space requirements, loading frequency, digester volume, engine size, wastewater quantities, and additives are quantitatively defined. The appropriate choice for a farm-scale operation is the simplest model using untreated rice straw without additives, although six times more heat and twice as much reactor volume is required. -- Highlights: ► The co-digestion of untreated rice straw and piggery wastewater is investigated. ► Gas production increases with the volume of pig wastewater added and temperature. ► Pig wastewater alone can provide appropriate buffering capacity and nutrient balance. ► Pilot-scale results are used to establish

  8. Steady-state Performance Analysis of Collector System Designs for Large-scale Offshore Wind Farms

    Energy Technology Data Exchange (ETDEWEB)

    Quinonez-Varela, G.; Ault, G.W.; McDonald, J.R. [Institute for Energy and Environment, University of Strathclyde, 204 George St., Glasgow G1 1XW, Scotland (United Kingdom)

    2006-07-01

    This paper presents a comparative analysis of the steady-state performance of various designs for the electrical collector system of offshore wind farms and discusses the advantages and disadvantages of each of these designs and their application within large-scale offshore developments. A series of power systems studies were carried out for a proposed 1 GW wind farm off the northeast coast of Scotland, with the plant set to generate at a range of power outputs in order to investigate the impact on the loading and losses of the collector system. The impact on voltage level changes on the busbars within the wind farm under various conditions of reactive power demand, i.e. considering both typical squirrel-cage machines (with typically low lagging power factors) and modern doubly-fed generators (with capability to vary power factor in lagging/leading ranges), was also investigated. In addition, for collector system designs with redundant cables, contingency conditions of losing one of the cables to the hub end were investigated. The overall results have lead to consider the application of 'single-sided ring' designs for large-scale offshore wind farms since it achieves fewer losses and also provides greater adequacy and reliability. Finally, the authors introduce an alternative design based on 'single-sided ring' arrangement which seems a more suitable option taking into account potential economic barriers from the original one-to-one design.

  9. Socioeconomic implications of biosecurity practices in small-scale dairy farms.

    Science.gov (United States)

    Can, Mehmet Ferit; Altuğ, Nuri

    2014-01-01

    Biosecurity plays a crucial role in preventing contagious diseases and in increasing farm productivity. To determine technical and economic biosecurity scores of farms, and to examine the associations between biosecurity practices (BP) and producers' socioeconomic characteristics. The study was conducted on a total of 50 small-scale dairy farms that were randomly selected in Hatay, Turkey. A checklist consisting of 19 biosecurity practices was addressed to the farms. The technical and economic scoring systems were developed by the authors according to presence and cost of the each of the biosecurity practices. The mean of the technical and economic scores were found to be 9.30 and 17.04, respectively. 'Treatment of sick animals' (98%), 'vaccination against the most common contagious diseases' (90%), and 'barn lime' (86%) were found to be the most commonly used applications. 'Testing for the most common contagious diseases before buying' (10%) was used at the lowest rate. Significant differences were found among the groups regarding education level (Biosecurity scores were significantly positively correlated with herd size (biosecurity practices. Training programs should be arranged to change the attitudes and perception of small-scale producers concerning poor biosecurity practices. In order to encourage producers to increase biosecurity scores, regulations regarding financial support and penalties could be quite useful at both the regional and national levels.

  10. WHOLE FARM RISK-RATING MICROCOMPUTER MODEL

    OpenAIRE

    Anderson, Kim B.; Ikerd, John E.

    1985-01-01

    The Risk-Rating Model is designed to give extension specialists, teachers, and producers a method to analyze production, marketing, and financial risks. These risks may be analyzed either individually or simultaneously. The risk associated with each enterprise, for all combinations of enterprises, and for any combination of marketing strategies is estimated. Optimistic, expected, and pessimistic returns above variable cost and/or total cost are presented in the results. The probability that t...

  11. Spatiotemporal distribution of nitrogen dioxide within and around a large-scale wind farm - a numerical case study

    Science.gov (United States)

    Mo, Jingyue; Huang, Tao; Zhang, Xiaodong; Zhao, Yuan; Liu, Xiao; Li, Jixiang; Gao, Hong; Ma, Jianmin

    2017-12-01

    As a renewable and clean energy source, wind power has become the most rapidly growing energy resource worldwide in the past decades. Wind power has been thought not to exert any negative impacts on the environment. However, since a wind farm can alter the local meteorological conditions and increase the surface roughness lengths, it may affect air pollutants passing through and over the wind farm after released from their sources and delivered to the wind farm. In the present study, we simulated the nitrogen dioxide (NO2) air concentration within and around the world's largest wind farm (Jiuquan wind farm in Gansu Province, China) using a coupled meteorology and atmospheric chemistry model WRF-Chem. The results revealed an edge effect, which featured higher NO2 levels at the immediate upwind and border region of the wind farm and lower NO2 concentration within the wind farm and the immediate downwind transition area of the wind farm. A surface roughness length scheme and a wind turbine drag force scheme were employed to parameterize the wind farm in this model investigation. Modeling results show that both parameterization schemes yield higher concentration in the immediate upstream of the wind farm and lower concentration within the wind farm compared to the case without the wind farm. We infer this edge effect and the spatial distribution of air pollutants to be the result of the internal boundary layer induced by the changes in wind speed and turbulence intensity driven by the rotation of the wind turbine rotor blades and the enhancement of surface roughness length over the wind farm. The step change in the roughness length from the smooth to rough surfaces (overshooting) in the upstream of the wind farm decelerates the atmospheric transport of air pollutants, leading to their accumulation. The rough to the smooth surface (undershooting) in the downstream of the wind farm accelerates the atmospheric transport of air pollutants, resulting in lower concentration

  12. Sustainable Organic Farming For Environmental Health A Social Development Model

    Directory of Open Access Journals (Sweden)

    Ijun Rijwan Susanto

    2015-05-01

    Full Text Available ABSTRACT In this study the researcher attempted 1 to understand the basic features of organic farming in The Paguyuban Pasundans Cianjur 2 to describe and understand how the stakeholders were are able to internalize the challenges of organic farming on their lived experiences in the community 3 to describe and understand how the stakeholders were are able to internalize and applied the values of benefits of organic farming in support of environmental health on their lived experiences in the community 4 The purpose was to describe and understand how the stakeholders who are able to articulate their ideas regarding the model of sustainable organic farming 5 The Policy Recommendation for Organic Farming. The researcher employed triangulation thorough finding that provides breadth and depth to an investigation offering researchers a more accurate picture of the phenomenon. In the implementation of triangulation researchers conducted several interviews to get saturation. After completion of the interview results are written compiled and shown to the participants to check every statement by every participant. In addition researchers also checked the relevant documents and direct observation in the field The participants of this study were the stakeholders namely 1 The leader of Paguyuban Pasundans Organic Farmer Cianjur PPOFC 2 Members of Paguyuban Pasundans Organic FarmersCianjur 3 Leader of NGO 4 Government officials of agriculture 5 Business of organic food 6 and Consumer of organic food. Generally the findings of the study revealed the following 1 PPOFC began to see the reality as the impact of modern agriculture showed in fertility problems due to contaminated soil by residues of agricultural chemicals such as chemical fertilizers and chemical pesticides. So he wants to restore the soil fertility through environmentally friendly of farming practices 2 the challenges of organic farming on their lived experiences in the community farmers did not

  13. Processor farming method for multi-scale analysis of masonry structures

    Science.gov (United States)

    Krejčí, Tomáš; Koudelka, Tomáš

    2017-07-01

    This paper describes a processor farming method for a coupled heat and moisture transport in masonry using a two-level approach. The motivation for the two-level description comes from difficulties connected with masonry structures, where the size of stone blocks is much larger than the size of mortar layers and very fine finite element mesh has to be used. The two-level approach is suitable for parallel computing because nearly all computations can be performed independently with little synchronization. This approach is called processor farming. The master processor is dealing with the macro-scale level - the structure and the slave processors are dealing with a homogenization procedure on the meso-scale level which is represented by an appropriate representative volume element.

  14. Management of broadleaved weeds in small-scale in an on-farm perspective

    International Nuclear Information System (INIS)

    Ooro, P.A.; Kamwaga, J.N.; Kipkemoi, P.L.; Bor, P.K.; Mbanda, G.O.; Rogoncho; Ochieng', J.O.

    2001-01-01

    An on-farm trial was conducted at eight different sites in Rongai and Njoro areas of Nakuru district and only six of the sites were finally harvested. The study was mainly to evaluate different weed control methods to offer a variety of recommendations for small scale wheat farmers. Of the treatments tested Buctril Mc out performed all the treatments except for Ariane. Cultural methods of control seemed to be inferior to almost all the chemical control. (author)

  15. Organic Farming and Small-Scale Farmers: Main Opportunities and Challenges

    OpenAIRE

    Jouzi, Zeynab; Azadi, Hossein; Taheri, Fatemeh; Zarafshani, Kiumars; Gebrehiwot, Kindeya; Van Passel, Steven; Lebailly, Philippe

    2017-01-01

    Producing enough food to meet the needs of a growing population has always been the greatest concern of food policy-makers around the world. Given the increasing attention to organic farming (OF), we conducted this study to investigate the main opportunities and challenges of the food production system of small-scale farmers in developing countries with an emphasis on their livelihoods. The study showed that the most significant advantages of OF are environmental protection and a higher resil...

  16. Modeling of the maintenance policy of an offshore wind farm

    International Nuclear Information System (INIS)

    Maddens, L.; Labeau, P.E.

    2004-01-01

    Wind energy has a key position in the market of renewable electricity production means. Offshore wind farms offer additional surfaces to exploit this form of energy, together with more favourable wind conditions. Yet offshore windmills ask for higher investment and maintenance costs. Optimising the latter costs should therefore turn out to be particularly beneficial for this technology. The present paper summarizes the main modelling aspects of the maintenance of a typical offshore wind farm, such as the accessibility of the wind turbines and the impact of weather conditions, the cost of the different transport resources, the number of maintenance teams, a tolerated unavailability of part of the windmills, the opportunity to combine corrective and preventive maintenance actions on one or several windmills. All these features were embedded in a Petri net model of the maintenance policy of the farm, allowing to estimate the maintenance costs entailed by several strategies. Advantages and drawbacks of using Petri nets for the modelling of such a maintenance strategy are finally discussed. (authors)

  17. Reducing Agricultural Water Footprints at the Farm Scale: A Case Study in the Beijing Region

    Directory of Open Access Journals (Sweden)

    Jing Huang

    2015-12-01

    Full Text Available Beijing is one of the most water-stressed regions in the world. Reducing agricultural water use has long been the basis of local policy for sustainable water use. In this article, the potential to reduce the life cycle (cradle to gate water footprints of wheat and maize that contribute to 94% of the local cereal production was assessed. Following ISO 14046, consumptive and degradative water use for the wheat-maize rotation system was modeled under different irrigation and nitrogen (N application options. Reducing irrigation water volume by 33.3% compared to current practice did not cause a significant yield decline, but the water scarcity footprint and water eutrophication footprint were decreased by 27.5% and 23.9%, respectively. Similarly, reducing the N application rate by 33.3% from current practice did not cause a significant yield decline, but led to a 52.3% reduction in water eutrophication footprint while maintaining a similar water scarcity footprint. These results demonstrate that improving water and fertilizer management has great potential for reducing the crop water footprints at the farm scale. This situation in Beijing is likely to be representative of the challenge facing many of the water-stressed regions in China, where a sustainable means of agricultural production must be found.

  18. Occurrence of Eimeria species parasites on small-scale commercial chicken farms in Africa and indication of economic profitability.

    Science.gov (United States)

    Fornace, Kimberly M; Clark, Emily L; Macdonald, Sarah E; Namangala, Boniface; Karimuribo, Esron; Awuni, Joseph A; Thieme, Olaf; Blake, Damer P; Rushton, Jonathan

    2013-01-01

    Small-scale commercial poultry production is emerging as an important form of livestock production in Africa, providing sources of income and animal protein to many poor households, yet the occurrence and impact of coccidiosis on this relatively new production system remains unknown. The primary objective of this study was to examine Eimeria parasite occurrence on small-scale commercial poultry farms in Ghana, Tanzania and Zambia. Additionally, farm economic viability was measured by calculating the farm gross margin and enterprise budget. Using these economic measures as global assessments of farm productivity, encompassing the diversity present in regional husbandry systems with a measure of fundamental local relevance, we investigated the detection of specific Eimeria species as indicators of farm profitability. Faecal samples and data on production parameters were collected from small-scale (less than 2,000 birds per batch) intensive broiler and layer farms in peri-urban Ghana, Tanzania and Zambia. All seven Eimeria species recognised to infect the chicken were detected in each country. Furthermore, two of the three genetic variants (operational taxonomic units) identified previously in Australia have been described outside of Australia for the first time. Detection of the most pathogenic Eimeria species associated with decreased farm profitability and may be considered as an indicator of likely farm performance. While a causal link remains to be demonstrated, the presence of highly pathogenic enteric parasites may pose a threat to profitable, sustainable small-scale poultry enterprises in Africa.

  19. Occurrence of Eimeria species parasites on small-scale commercial chicken farms in Africa and indication of economic profitability.

    Directory of Open Access Journals (Sweden)

    Kimberly M Fornace

    Full Text Available Small-scale commercial poultry production is emerging as an important form of livestock production in Africa, providing sources of income and animal protein to many poor households, yet the occurrence and impact of coccidiosis on this relatively new production system remains unknown. The primary objective of this study was to examine Eimeria parasite occurrence on small-scale commercial poultry farms in Ghana, Tanzania and Zambia. Additionally, farm economic viability was measured by calculating the farm gross margin and enterprise budget. Using these economic measures as global assessments of farm productivity, encompassing the diversity present in regional husbandry systems with a measure of fundamental local relevance, we investigated the detection of specific Eimeria species as indicators of farm profitability. Faecal samples and data on production parameters were collected from small-scale (less than 2,000 birds per batch intensive broiler and layer farms in peri-urban Ghana, Tanzania and Zambia. All seven Eimeria species recognised to infect the chicken were detected in each country. Furthermore, two of the three genetic variants (operational taxonomic units identified previously in Australia have been described outside of Australia for the first time. Detection of the most pathogenic Eimeria species associated with decreased farm profitability and may be considered as an indicator of likely farm performance. While a causal link remains to be demonstrated, the presence of highly pathogenic enteric parasites may pose a threat to profitable, sustainable small-scale poultry enterprises in Africa.

  20. Sustaining Small Scale Farming: Evidence of Poverty and income Disparity among Rural Farming Households in South-South Region of Nigeria

    Directory of Open Access Journals (Sweden)

    Sunday B. Akpan

    2016-09-01

    Full Text Available The incidence of poverty is evidenced among rural farm households in developing societies. As a result of persistence poverty among rural farm households, there is a sudden upsurge in agricultural livelihood diversification and rural-urban migration resulting in high rate of urban unemployment. To help generate suitable policy variables to help tackle this rampaging issue in the South- south region of Nigeria, this study specifically analyses poverty and income inequality as well as identified determinants of poverty among rural farm households in Akwa Ibom State, Nigeria. Data were collected from 390 rural farm household heads spread across the rural areas of the State. Combination of sampling methods was employed to sample cross-sectional data from respondents. The study used descriptive tools and regression analysis (Tobit regressions to analyse information collected. The socio-economic analysis reveals that most farming household heads were male; an average of 12.3 years of formal was discovered; social capital formation was poor, while average age stood at 42.5 years. About 33.08 % of male headed households and 22.05 % of female-headed households live below poverty line in the study area. Income inequality index revealed 0.4210 for male headed households and 0.4531 for the female counterpart. The Tobit model estimates revealed that, household head farming experience, years in the social organisation, a level of formal education, farm and non-farm income were negative drivers of rural poverty in the region. Household’s age, household size, structure of land ownership and gender were positive drivers of poverty among rural farming households. It is recommended that sound family welfare packages should be implemented in the rural communities. Also, the social capital formation should be promoted among rural farming households, while adult education policies should be re-visited. The government of the region should also improve educational

  1. Eradication of Aujeszky's disease from a large-scale pig farm.

    Science.gov (United States)

    Komáromi, M; Szabó, I

    2005-01-01

    Eradication of Aujeszky's disease from a large-scale pig farm by the 'test-and-cull' eradication procedure based on the use of gene-deleted vaccines and serological monitoring using gE ELISA is described. Aujeszky's disease free status was successfully achieved on a farrow-to-finish type farm characterised by three difficulties interfering with the success of eradication: (i) weaned (30-day-old) piglets remained in the farrowing house until 65 days of age; (ii) the farm did not use nursery rearing; (iii) fatteners were kept together with the breeding gilts. Thus, the immunisation programme had to be adjusted to the management technology used on the farm, and by regular serological monitoring it had to be periodically modified to make it suitable for attaining the goals. This meant that breeding animal candidates of a wide age range and kept in the same air space had to be provided with a continuously high-level immunity by regular vaccination sufficient even for rectifying potential human errors. The immunisation programme was designed by taking into consideration the disappearance of maternal immunity, and a strict vaccination programme was applied during the rearing of breeding gilts kept together with the fattening pigs. Frequent immunisation applied during the rearing of the own breeding animal replacements proved to be of decisive importance for the eradication of Aujeszky's disease from the entire herd. In addition to the accurate implementation of the vaccination programme, regular serological monitoring also made a major contribution to the success of eradication.

  2. Dissemination and persistence of Pseudomonas spp. in small-scale dairy farms

    Directory of Open Access Journals (Sweden)

    Daniele Michele Nucera

    2016-05-01

    Full Text Available This study was aimed at collecting data on presence, dissemination and persistence of Pseudomonas in small-scale dairy farms. Six farms (located in Piedmont were visited three times over 2014: 116 waters (wells and different faucets/pipes and 117 environmental samples (milking equipments and drains were collected. Enumeration of Pseudomonadaceae was performed, 3-5 colonies/samples were selected for identification via 16SrDNA/oprI polymerase chain reaction (PCR, and typed by enterobacterial-repetitive- intergenic-consensus (ERIC-PCR. Pseudomonadaceae were detected in 77% of samples. No statistical differences were found among proportions of positives across farms, sample typologies and seasons. Most isolates were Pseudomonas fluorescens (45%, and ERIC-PCR showed 32 persistent types diffused across farms. All in all, Pseudomonas spp. represents a challenge, considering its presence over time in water as well as in teat cups, indicating a continuous source of contamination. Moreover, persistency of strains may indicate biofilm-formation and/or sanitisers resistance, therefore emphasising the role of primary production for preventing milk contamination by Pseudomonas spp.

  3. Farm-specific carbon footprinting to the farm gate for agricultural co-products using the OVERSEER® model.

    Science.gov (United States)

    Wheeler, D M; Ledgard, S F; Boyes, M

    2013-06-01

    The user inputs to OVERSEER® Nutrient Budgets (Overseer) allow farm-specific greenhouse gas (GHG) emissions to be estimated. Since the development of the original model, life cycle assessment standards (e.g. PAS 2050) have been proposed and adopted for determining GHG or carbon footprints, which are usually reported as emissions per unit of product, for example, per kg milk, meat or wool. New Zealand pastoral farms frequently generate a range of products with different management practices. A robust system is required to allocate the individual sources of GHGs (e.g. methane, nitrous oxide, direct carbon dioxide and embodied carbon dioxide emissions for inputs used on the farm) to each product from a farm. This paper describes a method for allocating emissions to co-products from New Zealand farms. The method requires allocating the emissions, first, to an animal enterprise, separating the emissions between breeding and trading animals, and then allocating to a specific product to give product (e.g. milk, meat, wool, velvet) footprints from the 'cradle-to-farm-gate'. The meat product was based on live-weight gain. Procedures were adopted so that emissions associated with rearing of young stock used in live-weight gain systems, both as a by-product or a primary product could be estimated. This allows the possibility of total emissions for a meat product to be built up from contributing farms along the production chain.

  4. Drift Scale THM Model

    Energy Technology Data Exchange (ETDEWEB)

    J. Rutqvist

    2004-10-07

    This model report documents the drift scale coupled thermal-hydrological-mechanical (THM) processes model development and presents simulations of the THM behavior in fractured rock close to emplacement drifts. The modeling and analyses are used to evaluate the impact of THM processes on permeability and flow in the near-field of the emplacement drifts. The results from this report are used to assess the importance of THM processes on seepage and support in the model reports ''Seepage Model for PA Including Drift Collapse'' and ''Abstraction of Drift Seepage'', and to support arguments for exclusion of features, events, and processes (FEPs) in the analysis reports ''Features, Events, and Processes in Unsaturated Zone Flow and Transport and Features, Events, and Processes: Disruptive Events''. The total system performance assessment (TSPA) calculations do not use any output from this report. Specifically, the coupled THM process model is applied to simulate the impact of THM processes on hydrologic properties (permeability and capillary strength) and flow in the near-field rock around a heat-releasing emplacement drift. The heat generated by the decay of radioactive waste results in elevated rock temperatures for thousands of years after waste emplacement. Depending on the thermal load, these temperatures are high enough to cause boiling conditions in the rock, resulting in water redistribution and altered flow paths. These temperatures will also cause thermal expansion of the rock, with the potential of opening or closing fractures and thus changing fracture permeability in the near-field. Understanding the THM coupled processes is important for the performance of the repository because the thermally induced permeability changes potentially effect the magnitude and spatial distribution of percolation flux in the vicinity of the drift, and hence the seepage of water into the drift. This is important because

  5. A process-based emission model of volatile organic compounds from silage sources on farms

    DEFF Research Database (Denmark)

    Bonifacio, H. F.; Rotz, C. A.; Hafner, S. D.

    2017-01-01

    such as those from dairy farms. A process-based model for predicting VOC emissions from silage was developed and incorporated into the Integrated Farm System Model (IFSM, v. 4.3), a whole-farm simulation of crop, dairy, and beef production systems. The performance of the IFSM silage VOC emission model...... performance, economics, and environmental impacts of farm production. As a component of IFSM, the silage VOC emission model was used to simulate a representative dairy farm in central California. The simulation showed most silage VOC emissions were from feed lying in feed lanes and not from the exposed face...

  6. Cost optimization of wind turbines for large-scale offshore wind farms

    International Nuclear Information System (INIS)

    Fuglsang, P.; Thomsen, K.

    1998-02-01

    This report contains a preliminary investigation of site specific design of off-shore wind turbines for a large off-shore wind farm project at Roedsand that is currently being proposed by ELKRAFT/SEAS. The results were found using a design tool for wind turbines that involve numerical optimization and aeroelastic calculations of response. The wind climate was modeled in detail and a cost function was used to estimate costs from manufacture and installation. Cost of energy is higher for off-shore installations. A comparison of an off-shore wind farm site with a typical stand alone on-shore site showed an increase of the annual production of 28% due to the difference in wind climate. Extreme loads and blade fatigue loads were nearly identical, however,fatigue loads on other main components increased significantly. Optimizations were carried out to find the optimum overall off-shore wind turbine design. A wind turbine for the off-shore wind farm should be different compared with a stand-alone on-shore wind turbine. The overall design changed were increased swept area and rated power combined with reduced rotor speed and tower height. Cost was reduced by 12% for the final 5D/14D off-shore wind turbine from 0.306 DKr/kWh to 0.270 DKr/kWh. These figures include capital costs from manufacture and installation but not on-going costs from maintenance. These results make off-shore wind farms more competitive and comparable to the reference on-shore stand-alone wind turbine. A corresponding reduction of cost of energy could not be found for the stand alone on-shore wind turbine. Furthermore the fatigue loads on wind turbines in on-shore wind farms will increase and cost of energy will increase in favor of off-shore wind farms. (au) EFP-95; EU-JOULE-3; 21 tabs., 7 ills., 8 refs

  7. Mathematical model of the Savannah River Site waste tank farm

    International Nuclear Information System (INIS)

    Smith, F.G. III.

    1991-01-01

    A mathematical model has been developed to simulate operation of the waste tank farm and the associated evaporator systems at the Savannah River Site. The model solves material balance equations to predict the volumes of liquid waste, salt, and sludge for all of the tanks within each of the evaporator systems. Additional logic is included to model the behavior of waste tanks not directly associated with the evaporators. Input parameters include the Material Management Plan forecast of canyon operations, specification of other waste sources for the evaporator systems, evaporator operating characteristics, and salt and sludge removal schedules. The model determines how the evaporators will operate, when waste transfers can be made, and waste accumulation rates. Output from the model includes waste tank contents, summaries of systems operations, and reports of space gain and the remaining capacity to store waste materials within the tank farm. Model simulations can be made to predict waste tank capacities on a daily basis for up to 20 years. The model is coded as a set of three computer programs designed to run on either IBM compatible or Apple Macintosh II personal computers

  8. Systematic Wind Farm Measurement Data Filtering Tool for Wake Model Calibration

    DEFF Research Database (Denmark)

    Rethore, Pierre-Elouan Mikael; Johansen, Nicholas Alan; Frandsen, Sten Tronæs

    A set of systematic methods for characterizing the sensors of a wind farm and using these sensors to filter more accurately large volumes of measurement data is proposed. These methods are based on the experience accumulated while processing datasets from two large offshore wind farms in Denmark....... Both wake model developers and wind farm operators seeking to determine how the wind farm operates under specific conditions can find these methods valuable. The methods are general and can be applied successfully to any wind farm by taking into consideration the specific aspects of each wind farm....

  9. Prevalence and concentration of Salmonella and Campylobacter in the processing environment of small-scale pastured broiler farms.

    Science.gov (United States)

    Trimble, Lisa M; Alali, Walid Q; Gibson, Kristen E; Ricke, Steven C; Crandall, Philip; Jaroni, Divya; Berrang, Mark; Habteselassie, Mussie Y

    2013-11-01

    A growing niche in the locally grown food movement is the small-scale production of broiler chickens using the pasture-raised poultry production model. Limited research exists that focuses on Salmonella and Campylobacter contamination in the environment associated with on-farm processing of pasture-raised broilers. The objective of this study was to establish data relative to Salmonella and Campylobacter prevalence and concentration in soil and mortality compost resulting from prior processing waste disposal in the small-scale, on-farm broiler processing environment. Salmonella and Campylobacter concentrations were determined in soil (n = 42), compost (n = 39), and processing wastewater (PWW; n = 46) samples from 4 small broiler farms using a 3-tube most probable number (MPN) method for Salmonella and direct plating method for Campylobacter. Salmonella prevalence and concentration (mean log10 MPN per sample weight or volume) in soil [60%, 0.97 (95% CI: 0.66 to 1.27)], compost [64%, 0.95 (95% CI: 0.66 to 1.24)], and wastewater [48%, 1.29 (95% CI: 0.87 to 1.71)] were not significantly different (P > 0.05). Although Campylobacter prevalence was not significantly different by sample type (64.3, 64.3, and 45.7% in soil, compost, and PWW, respectively), the concentration (mean log10 cfu) of this pathogen was significantly lower (P poultry production waste disposal practices and provides a record of data that may serve as a guide for future improvement of these practices. Further research is needed regarding the small-scale broiler production environment in relation to improving disposal of processing waste for optimum control of human pathogens.

  10. Simultaneous nested modeling from the synoptic scale to the LES scale for wind energy applications

    DEFF Research Database (Denmark)

    Liu, Yubao; Warner, Tom; Liu, Yuewei

    2011-01-01

    This paper describes an advanced multi-scale weather modeling system, WRF–RTFDDA–LES, designed to simulate synoptic scale (~2000 km) to small- and micro-scale (~100 m) circulations of real weather in wind farms on simultaneous nested grids. This modeling system is built upon the National Center...... experiments are conducted to investigate the impacts of subgrid scale (SGS) mixing parameters and nesting approaches. This study demonstrates that the WRF–RTFDDA–LES system is a valuable tool for simulating real world microscale weather flows and for development of future real-time forecasting system...

  11. Integrative modeling and novel particle swarm-based optimal design of wind farms

    Science.gov (United States)

    Chowdhury, Souma

    allowing simultaneous optimization of the type and the location of the turbines. Layout optimization (using UWFLO) of a hypothetical 25-turbine commercial-scale wind farm provides a remarkable 4.4% increase in capacity factor compared to a conventional array layout. A further 2% increase in capacity factor is accomplished when the types of turbines are also optimally selected. The scope of turbine selection and placement however depends on the land configuration and the nameplate capacity of the farm. Such dependencies are not clearly defined in the existing literature. We develop response surface-based models, which implicitly employ UWFLO, to quantify and analyze the roles of these other crucial design factors in optimal wind farm planning. The wind pattern at a site can vary significantly from year to year, which is not adequately captured by conventional wind distribution models. The resulting ill-predictability of the annual distribution of wind conditions introduces significant uncertainties in the estimated energy output of the wind farm. A new method is developed to characterize these wind resource uncertainties and model the propagation of these uncertainties into the estimated farm output. The overall wind pattern/regime also varies from one region to another, which demands turbines with capabilities uniquely suited for different wind regimes. Using the UWFLO method, we model the performance potential of currently available turbines for different wind regimes, and quantify their feature-based expected market suitability. Such models can initiate an understanding of the product variation that current turbine manufacturers should pursue, to adequately satisfy the needs of the naturally diverse wind energy market. The wind farm design problems formulated in this dissertation involve highly multimodal objective and constraint functions and a large number of continuous and discrete variables. An effective modification of the PSO algorithm is developed to address such

  12. Aeolus Toolbox for Dynamics Wind Farm Model, Simulation and Control

    DEFF Research Database (Denmark)

    Grunnet, Jacob Deleuran; Soltani, Mohsen; Knudsen, Torben

    2010-01-01

    This paper presents the wind farm simulation modeldeveloped in the EU-FP7 project, AEOLUS. Theidea is to provide a publicly available simulationpackage for researchers developing farm level controlsolutions. With the software it is possible toauto generate a wind farm simulation model in Matlab...

  13. Modelling of offshore wind turbine wakes with the wind farm program FLaP

    DEFF Research Database (Denmark)

    Lange, B.; Waldl, H.P.; Guerrero, A.G.

    2003-01-01

    The wind farm layout program FLaP estimates the wind speed at any point in a wind farm and the power output of the turbines. The ambient flow conditions and the properties of the turbines and the farm are used as input. The core of the program is an axisymmetric wake model describing the wake...

  14. Environmental consequence analyses of fish farm emissions related to different scales and exemplified by data from the Baltic--a review.

    Science.gov (United States)

    Gyllenhammar, Andreas; Håkanson, Lars

    2005-08-01

    The aim of this work is to review studies to evaluate how emissions from fish cage farms cause eutrophication effects in marine environments. The focus is on four different scales: (i) the conditions at the site of the farm, (ii) the local scale related to the coastal area where the farm is situated, (iii) the regional scale encompassing many coastal areas and (iv) the international scale including several regional coastal areas. The aim is to evaluate the role of nutrient emissions from fish farms in a general way, but all selected examples come from the Baltic Sea. An important part of this evaluation concerns the method to define the boundaries of a given coastal area. If this is done arbitrarily, one would obtain arbitrary results in the environmental consequence analysis. In this work, the boundary lines between the coast and the sea are drawn using GIS methods (geographical information systems) according to the topographical bottleneck method, which opens a way to determine many fundamental characteristics in the context of mass balance calculations. In mass balance modelling, the fluxes from the fish farm should be compared to other fluxes to, within and from coastal areas. Results collected in this study show that: (1) at the smallest scale (impact areas of fish cage farm often corresponds to the size of a "football field" (50-100 m) if the annual fish production is about 50 ton, (2) at the local scale (1 ha to 100 km2), there exists a simple load diagram (effect-load-sensitivity) to relate the environmental response and effects from a specific load from a fish cage farm. This makes it possible to obtain a first estimate of the maximum allowable fish production in a specific coastal area, (3) at the regional scale (100-10,000 km2), it is possible to create negative nutrient fluxes, i.e., use fish farming as a method to reduce the nutrient loading to the sea. The breaking point is to use more than about 1.1 g wet weight regionally caught wild fish per gram

  15. An industry-scale mass marking technique for tracing farmed fish escapees.

    Directory of Open Access Journals (Sweden)

    Fletcher Warren-Myers

    Full Text Available Farmed fish escape and enter the environment with subsequent effects on wild populations. Reducing escapes requires the ability to trace individuals back to the point of escape, so that escape causes can be identified and technical standards improved. Here, we tested if stable isotope otolith fingerprint marks delivered during routine vaccination could be an accurate, feasible and cost effective marking method, suitable for industrial-scale application. We tested seven stable isotopes, (134Ba, (135Ba, (136Ba, (137Ba, (86Sr, (87Sr and (26Mg, on farmed Atlantic salmon reared in freshwater, in experimental conditions designed to reflect commercial practice. Marking was 100% successful with individual Ba isotopes at concentrations as low as 0.001 µg. g-1 fish and for Sr isotopes at 1 µg. g-1 fish. Our results suggest that 63 unique fingerprint marks can be made at low cost using Ba (0.0002 - 0.02 $US per mark and Sr (0.46 - 0.82 $US per mark isotopes. Stable isotope fingerprinting during vaccination is feasible for commercial application if applied at a company level within the world's largest salmon producing nations. Introducing a mass marking scheme would enable tracing of escapees back to point of origin, which could drive greater compliance, better farm design and improved management practices to reduce escapes.

  16. Differential Protection for an Outgoing Transformer of Large-Scale Doubly Fed Induction Generator-Based Wind Farms

    Directory of Open Access Journals (Sweden)

    Bingtuan Gao

    2014-08-01

    Full Text Available With the rapid development of wind energy, relay protection for large-scale wind farms has been attracting some researchers, due to the absence of standards. Based on the large-scale doubly fed induction generator (DFIG-based wind farms located in Gansu Province, China, this paper studies the differential protection for the outgoing power transformer of large-scale DFIG-based wind farms. According to the equivalent circuit of the power grid integrated with wind farms, the main frequency components of current and voltage during faults are identified mathematically and then verified by simulations. The results show that the frequencies of current and voltage at the terminals of outgoing transmission lines are inconsistent. Following the feature of frequency inconsistency, the adaptability of differential protection is analyzed, and it is found that differential protection for an outgoing transformer in large-scale wind farms may fail once ignoring the frequency inconsistency. Simulation studies demonstrate that inconsistent frequency characteristics will deteriorate the sensitivity and reliability of differential protection. Finally, several suggestions are provided for improving the performance of relay protections for large-scale DFIG-based wind farms.

  17. Ecologies of Scale: Multifunctionality Connects Conservation and Agriculture across Fields, Farms, and Landscapes

    Directory of Open Access Journals (Sweden)

    Devan Allen McGranahan

    2014-07-01

    Full Text Available Agroecology and landscape ecology are two land-use sciences based on ecological principles, but have historically focused on fine and broad spatial scales, respectively. As global demand for food strains current resources and threatens biodiversity conservation, concepts such as multifunctional landscapes and ecologically-analogous agroecosystems integrate ecological concepts across multiple spatial scales. This paper reviews ecological principles behind several concepts crucial to the reconciliation of food production and biodiversity conservation, including relationships between biodiversity and ecosystem functions such as productivity and stability; insect pest and pollinator management; integrated crop and livestock systems; countryside biogeography and heterogeneity-based rangeland management. Ecological principles are integrated across three spatial scales: fields, farms, and landscapes.

  18. On-farm characteristics and biosecurity protocols for small-scale swine producers in eastern Australia.

    Science.gov (United States)

    Schembri, N; Hernandez-Jover, M; Toribio, J-A L M L; Holyoake, P K

    2015-01-01

    Pigs are considered high risk for the introduction and spread of foot and mouth disease (FMD) in Australia. Facilities where animals from different origins are commingled, such as saleyards, pose a high risk for disease spread. Sound on-farm management practices and biosecurity protocols are the first line of defence against a potential on-farm disease outbreak. This study evaluated the practices of 104 producers (vendors who sold pigs and purchasers of live pigs for grow-out) who traded pigs at 6 peri-urban and rural saleyards in eastern Australia. Specifically, management and on-farm biosecurity practices were assessed using an in-depth questionnaire. Univariable and multivariable logistic regression analyses were used to investigate (1) producer associations: producer type, State, motivation to keep pigs, farm type, gender, years having owned pigs, and the acquisition of formal livestock qualifications; and (2) pig associations: herd size, housing, management (husbandry and feeding) practices and biosecurity (including pig movement) practices. Backyard operations (footwear precautions (P=0.007) and ask visitors about prior pig contacts (P=0.004). Approximately 40% of backyard and small-scale producers reported not having any quarantine practices in place for incoming pigs, compared to only 9.1% among larger producers. The main reasons cited for not adopting on-farm biosecurity practices in this study included having no need on their property (43.1%) and a lack of information and support (by the industry and/or authorities; 18.5%). Up to three-quarters of all producers maintained an open breeding herd, regularly introducing new pigs to the main herd. Saleyards are an important source of income for backyard and small-scale producers as well as an important risk factor for the introduction and dissemination of endemic and emerging animal diseases. Differing management and biosecurity practices as well as the motivations of these producers keeping pigs in small

  19. On Electrical Design and Technical Performance Requirements for Large Scale Wind Farms

    DEFF Research Database (Denmark)

    Gordon, Mark; Keerthipala, W.; Fernando, A.

    2009-01-01

    plant operating limits for ensuring power system security at the high voltage point of connection. Experiences presented here refer mainly to few of the selected technical requirements and issues encountered during the process of wind farms connections into Eastern Australian power system. In particular......This paper presents and discusses technical performance requirements for connection of large scale wind turbine generating systems into HV transmission networks. Requirements have been presented for the purpose of achieving performance enhanced operation, reliability and assessment of the power...

  20. Prevalence and risk factors for carriage of antimicrobial-resistant Escherichia coli on household and small-scale chicken farms in the Mekong Delta of Vietnam

    NARCIS (Netherlands)

    Nguyen, V.T.; Carrique-Mas, J.J.; Ngo, T.H; Ho, H.M.; Ha, T.T.; Campbell, J.I.; Nguyen, T.N.; Hoang, N.N.; Pham, V.M.; Wagenaar, J.A.; Hardon, A.; Thai, Q.H.; Schultsz, C.

    2015-01-01

    Objectives: To describe the prevalence of antimicrobial resistance among commensal Escherichia coli isolates on household and small-scale chicken farms, common in southern Vietnam, and to investigate the association of antimicrobial resistance with farming practices and antimicrobial usage. Methods:

  1. Prevalence and risk factors for carriage of antimicrobial-resistant Escherichia coli on household and small-scale chicken farms in the Mekong Delta of Vietnam

    NARCIS (Netherlands)

    Trung, Nguyen Vinh; Carrique-Mas, Juan J; Thi Hoa, Ngo; Mai, Ho Huynh; Tuyen, Ha Thanh; Campbell, James I; Nhung, Nguyen Thi; Nhung, Hoang Ngoc; Van Minh, Pham; Wagenaar, Jaap A; Hardon, Anita; Hieu, Thai Quoc; Schultsz, Constance

    2015-01-01

    OBJECTIVES: To describe the prevalence of antimicrobial resistance among commensal Escherichia coli isolates on household and small-scale chicken farms, common in southern Vietnam, and to investigate the association of antimicrobial resistance with farming practices and antimicrobial usage. METHODS:

  2. Is the increase of scale in the tropics a pathway to smallholders? Dimension and ecological zone effect on the mixed crop-livestock farms

    Directory of Open Access Journals (Sweden)

    Jaime Rangel

    2017-07-01

    Full Text Available Mixed crop-livestock farms are widely spread in different tropical regions in the world; they contribute to food security, rural development, sustainability and poverty alleviation. The effect of scale on performance of dual purpose (DP cattle farms was evaluated in two Mexican ecological zones: dry (DT and wet tropics (WT. In 2011, a questionnaire of 184 items distributed into technical and social characteristics was applied to a representative sample of 3,285 farms with 50 or less cows (0.97%. The farms were classified into three groups according to their dimension: very small (1-9 cows, small (10-19 cows and medium (20-50 cows. A general linear model (GLM with two factors and their interactions was applied. Significant effects in dimension and ecological zone were found as well as seven interactions between both factors (p<0.05. Native pastures were used in all farms for grazing. However, small farms’ herds frequently grazed on cultivated pastures and on crop residues (p<0.05. Medium farms showed the highest grazing surface, but in the WT silage and green fodder were used while in the DT dry fodders were used (p<0.001. The interactions between factors showed a bigger specialization in milk production in DT farms, whereas WT farms were more specialized in meat production. The mixed crop-livestock system in tropic region requires an increase in herd size according to farm’s own productive structure, which is strongly influenced by the ecological zone. The systems would improve with the active participation of smallholders to identify and achieve best practices, higher technological adoption level and with an effective support from public and private Institutions.

  3. A Farm Information Model for Development and Configuration of Interoperable ICT Components to support Collaborative Business Processes

    NARCIS (Netherlands)

    Kruize, J.W.; Goense, D.; Wolfert, J.; Verdouw, C.N.; Scholten, H.; Beulens, A.J.M.

    2015-01-01

    Farm enterprises2
    The objective of this paper is to describe a farm information model and a proof of concept that demonstrates how a collaborative Business Process for farming can be configured using this farm information model. Knowledge to develop this model and a proof of concept is obtained

  4. Modelling farm vulnerability to flooding: A step toward vulnerability mitigation policies appraisal

    Science.gov (United States)

    Brémond, P.; Abrami, G.; Blanc, C.; Grelot, F.

    2009-04-01

    flood. In the case of farm activities, vulnerability mitigation consists in implementing measures which can be: physical (equipment or electric power system elevation), organizational (emergency or recovery plan) or financial (insurance). These measures aim at decreasing the total damage incurred by farmers in case of flooding. For instance, if equipment is elevated, it will not suffer direct damage such as degradation. As a consequence, equipment will be available to continue production or recovery tasks, thus, avoiding indirect damage such as delays, indebtedness… The effects of these policies on farms, in particular vulnerability mitigation cannot be appraised using current methodologies mainly because they do not consider farm as a whole and focus on direct damage at the land plot scale (loss of yield). Moreover, since vulnerability mitigation policies are quite recent, few examples of implementation exist and no feedback experience can be processed. Meanwhile, decision makers and financial actors require more justification of the efficiency of public fund by economic appraisal of the projects. On the Rhône River, decision makers asked for an economic evaluation of the program of farm vulnerability mitigation they plan to implement. This implies to identify the effects of the measures to mitigate farm vulnerability, and to classify them by comparing their efficacy (avoided damage) and their cost of implementation. In this presentation, we propose and discuss a conceptual model of vulnerability at the farm scale. The modelling, in Unified Modelling Language, enabled to represent the ties between spatial, organizational and temporal dimensions, which are central to understanding of farm vulnerability and resilience to flooding. Through this modelling, we encompass three goals: To improve the comprehension of farm vulnerability and create a framework that allow discussion with experts of different disciplines as well as with local farmers; To identify data which

  5. The Explicit Wake Parametrisation V1.0: a wind farm parametrisation in the mesoscale model WRF

    Directory of Open Access Journals (Sweden)

    P. J. H. Volker

    2015-11-01

    Full Text Available We describe the theoretical basis, implementation, and validation of a new parametrisation that accounts for the effect of large offshore wind farms on the atmosphere and can be used in mesoscale and large-scale atmospheric models. This new parametrisation, referred to as the Explicit Wake Parametrisation (EWP, uses classical wake theory to describe the unresolved wake expansion. The EWP scheme is validated for a neutral atmospheric boundary layer against filtered in situ measurements from two meteorological masts situated a few kilometres away from the Danish offshore wind farm Horns Rev I. The simulated velocity deficit in the wake of the wind farm compares well to that observed in the measurements, and the velocity profile is qualitatively similar to that simulated with large eddy simulation models and from wind tunnel studies. At the same time, the validation process highlights the challenges in verifying such models with real observations.

  6. Validation of the dynamic wake meander model for loads and power production in the Egmond aan Zee wind farm

    DEFF Research Database (Denmark)

    Larsen, Torben J.; Aagaard Madsen, Helge; Larsen, Gunner Chr.

    2013-01-01

    is excellent regarding power production in both free and wake sector, and a very good agreement is seen for the load comparisons too. This enables the conclusion that wake meandering, caused by large scale ambient turbulence, is indeed an important contribution to wake loading in wind farms. Copyright © 2012......This paper investigates wake effects on load and power production by using the dynamic wake meander (DWM) model implemented in the aeroelastic code HAWC2. The instationary wind farm flow characteristics are modeled by treating the wind turbine wakes as passive tracers transported downstream using...... a meandering process driven by the low frequent cross-wind turbulence components. The model complex is validated by comparing simulated and measured loads for the Dutch Egmond aan Zee wind farm consisting of 36 Vestas V90 turbine located outside the coast of the Netherlands. Loads and production are compared...

  7. Summary Report: The Shadow effect of large wind farms: measurements, data analysis and modelling

    DEFF Research Database (Denmark)

    Frandsen, Sten Tronæs; Barthelmie, Rebecca Jane; Rathmann, Ole

    It was the goal of the project – by means of data from the demonstration wind farms Horns Rev and Nysted, analyses of these data and modelling – to facilitate prediction of the power losses from a wind farm should a new wind farm be built upwind relative to the prevailing wind direction......: • Measurements were carried out at the Nysted and Horns Rev demonstration wind farms for several years. Doing so included design, installation and operation of the measurement system • A data base was built from the incoming data. The data have been organized to facilitate verification of the models developed....... Or conversely, predict with adequate accuracy the production of a new wind farm built downwind of an existing wind farm. The project should be seen in the perspective of the two existing demonstration wind farms that extend 5-10 km in each direction. In order to e.g. use the existing electrical infrastructure...

  8. International Symposia on Scale Modeling

    CERN Document Server

    Ito, Akihiko; Nakamura, Yuji; Kuwana, Kazunori

    2015-01-01

    This volume thoroughly covers scale modeling and serves as the definitive source of information on scale modeling as a powerful simplifying and clarifying tool used by scientists and engineers across many disciplines. The book elucidates techniques used when it would be too expensive, or too difficult, to test a system of interest in the field. Topics addressed in the current edition include scale modeling to study weather systems, diffusion of pollution in air or water, chemical process in 3-D turbulent flow, multiphase combustion, flame propagation, biological systems, behavior of materials at nano- and micro-scales, and many more. This is an ideal book for students, both graduate and undergraduate, as well as engineers and scientists interested in the latest developments in scale modeling. This book also: Enables readers to evaluate essential and salient aspects of profoundly complex systems, mechanisms, and phenomena at scale Offers engineers and designers a new point of view, liberating creative and inno...

  9. Raising surface water levels in peat areas with dairy farming upscaling hydrological, agronomical and economic effects from farm-scale to local scale.

    NARCIS (Netherlands)

    Vos, de J.A.; Bakel, van P.J.T.; Hoving, I.E.; Smidt, R.A.

    2010-01-01

    Raising surface water levels in peat areas is a measure to reduce soil subsidence, to prevent decay of wooden foundations and to stimulate wet nature restoration and reduce greenhouse gas emissions. However, in these areas dairy farms are present and farming at wetter soils is difficult due to lower

  10. Coupling the Weather Research and Forecasting (WRF) model and Large Eddy Simulations with Actuator Disk Model: predictions of wind farm power production

    Science.gov (United States)

    Garcia Cartagena, Edgardo Javier; Santoni, Christian; Ciri, Umberto; Iungo, Giacomo Valerio; Leonardi, Stefano

    2015-11-01

    A large-scale wind farm operating under realistic atmospheric conditions is studied by coupling a meso-scale and micro-scale models. For this purpose, the Weather Research and Forecasting model (WRF) is coupled with an in-house LES solver for wind farms. The code is based on a finite difference scheme, with a Runge-Kutta, fractional step and the Actuator Disk Model. The WRF model has been configured using seven one-way nested domains where the child domain has a mesh size one third of its parent domain. A horizontal resolution of 70 m is used in the innermost domain. A section from the smallest and finest nested domain, 7.5 diameters upwind of the wind farm is used as inlet boundary condition for the LES code. The wind farm consists in six-turbines aligned with the mean wind direction and streamwise spacing of 10 rotor diameters, (D), and 2.75D in the spanwise direction. Three simulations were performed by varying the velocity fluctuations at the inlet: random perturbations, precursor simulation, and recycling perturbation method. Results are compared with a simulation on the same wind farm with an ideal uniform wind speed to assess the importance of the time varying incoming wind velocity. Numerical simulations were performed at TACC (Grant CTS070066). This work was supported by NSF, (Grant IIA-1243482 WINDINSPIRE).

  11. An assessment of the commercial cost of farm scale wood fuel procurement and processing

    International Nuclear Information System (INIS)

    1996-01-01

    The capital cost of small scale biomass fired systems is currently significantly higher than equivalent rated fossil fuel fired systems. If the cost of producing willow or poplar coppice derived fuel can be shown to offer significant savings over the cost of conventional fossil fuel alternatives, the resultant total cost of energy production could in fact be less. The production of ''home grown'' fuel should always, in theory, be cheaper than bought in supplies due to the removal of cost components such as profit and risk and the possible use of labour during traditionally quiet periods on the farm. However, it has not been shown to date that small scale coppice plantations can successfully produce cost effective wood fuel to displace fuel that would otherwise be 'bought in'. It is likely that fuel from coppice will be harvested on a semi-manual basis using brush cutters and farm loaders etc. This report identifies appropriate systems and provides estimates of the key costs to a grower. Particular emphasis is given to operations surrounding cut-back, harvesting and comminution. The report provides an outline of the statutory requirements of employers engaged in coppice management. Key costs have been presented in their most useful form for a potential grower to compile enterprise gross margins. (Author)

  12. A farm-scale pilot plant for biohydrogen and biomethane production by two-stage fermentation

    Directory of Open Access Journals (Sweden)

    R. Oberti

    2013-09-01

    Full Text Available Hydrogen is considered one of the possible main energy carriers for the future, thanks to its unique environmental properties. Indeed, its energy content (120 MJ/kg can be exploited virtually without emitting any exhaust in the atmosphere except for water. Renewable production of hydrogen can be obtained through common biological processes on which relies anaerobic digestion, a well-established technology in use at farm-scale for treating different biomass and residues. Despite two-stage hydrogen and methane producing fermentation is a simple variant of the traditional anaerobic digestion, it is a relatively new approach mainly studied at laboratory scale. It is based on biomass fermentation in two separate, seuqential stages, each maintaining conditions optimized to promote specific bacterial consortia: in the first acidophilic reactorhydrogen is produced production, while volatile fatty acids-rich effluent is sent to the second reactor where traditional methane rich biogas production is accomplished. A two-stage pilot-scale plant was designed, manufactured and installed at the experimental farm of the University of Milano and operated using a biomass mixture of livestock effluents mixed with sugar/starch-rich residues (rotten fruits and potatoes and expired fruit juices, afeedstock mixture based on waste biomasses directly available in the rural area where plant is installed. The hydrogenic and the methanogenic reactors, both CSTR type, had a total volume of 0.7m3 and 3.8 m3 respectively, and were operated in thermophilic conditions (55 2 °C without any external pH control, and were fully automated. After a brief description of the requirements of the system, this contribution gives a detailed description of its components and of engineering solutions to the problems encountered during the plant realization and start-up. The paper also discusses the results obtained in a first experimental run which lead to production in the range of previous

  13. Numerical simulation of the aerodynamic field in complex terrain wind farm based on actuator disk model

    DEFF Research Database (Denmark)

    Xu, Chang; Li, Chen Qi; Han, Xing Xing

    2015-01-01

    Study on the aerodynamic field in complex terrain is significant to wind farm micro-sitting and wind power prediction. This paper modeled the wind turbine through an actuator disk model, and solved the aerodynamic field by CFD to study the influence of meshing, boundary conditions and turbulence...... model on the calculation results. Comparison with the measured data of a wind farm was applied to find an appropriate method for simulating the aerodynamic field in the complex terrain wind farm. Related research can provide reference for wind farm micro-siting and wind power prediction....

  14. 8th international workshop on large-scale integration of wind power into power systems as well as on transmission networks for offshore wind farms. Proceedings

    International Nuclear Information System (INIS)

    Betancourt, Uta; Ackermann, Thomas

    2009-01-01

    Within the 8th International Workshop on Large-Scale Integration of Wind Power into Power Systems as well as on Transmission Networks for Offshore Wind Farms at 14th to 15th October, 2009 in Bremen (Federal Republic of Germany), lectures and posters were presented to the following sessions: (1) Keynote session and panel; (2) Grid integration studies and experience: Europe; (3) Connection of offshore wind farms; (4) Wind forecast; (5) High voltage direct current (HVDC); (6) German grid code issues; (7) Offshore grid connection; (8) Grid integration studies and experience: North America; (9) SUPWIND - Decision support tools for large scale integration of wind; (10) Windgrid - Wind on the grid: An integrated approach; (11) IEA Task 25; (12) Grid code issues; (13) Market Issues; (14) Offshore Grid; (15) Modelling; (16) Wind power and storage; (17) Power system balancing; (18) Wind turbine performance; (19) Modelling and offshore transformer.

  15. Combination of Deterministic and Probabilistic Meteorological Models to enhance Wind Farm Power Forecasts

    International Nuclear Information System (INIS)

    Bremen, Lueder von

    2007-01-01

    Large-scale wind farms will play an important role in the future worldwide energy supply. However, with increasing wind power penetration all stakeholders on the electricity market will ask for more skilful wind power predictions regarding save grid integration and to increase the economic value of wind power. A Neural Network is used to calculate Model Output Statistics (MOS) for each individual forecast model (ECMWF and HIRLAM) and to model the aggregated power curve of the Middelgrunden offshore wind farm. We showed that the combination of two NWP models clearly outperforms the better single model. The normalized day-ahead RMSE forecast error for Middelgrunden can be reduced by 1% compared to single ECMWF. This is a relative improvement of 6%. For lead times >24h it is worthwhile to use a more sophisticated model combination approach than simple linear weighting. The investigated principle component regression is able to extract the uncorrelated information from two NWP forecasts. The spread of Ensemble Predictions is related to the skill of wind power forecasts. Simple contingency diagrams show that low spread corresponds is more often related to low forecast errors and high spread to large forecast errors

  16. Using heterogeneity in the population structure of U.S. swine farms to compare transmission models for porcine epidemic diarrhoea

    Science.gov (United States)

    O’Dea, Eamon B.; Snelson, Harry; Bansal, Shweta

    2016-01-01

    In 2013, U.S. swine producers were confronted with the disruptive emergence of porcine epidemic diarrhoea (PED). Movement of animals among farms is hypothesised to have played a role in the spread of PED among farms. Via this or other mechanisms, the rate of spread may also depend on the geographic density of farms and climate. To evaluate such effects on a large scale, we analyse state-level counts of outbreaks with variables describing the distribution of farm sizes and types, aggregate flows of animals among farms, and an index of climate. Our first main finding is that it is possible for a correlation analysis to be sensitive to transmission model parameters. This finding is based on a global sensitivity analysis of correlations on simulated data that included a biased and noisy observation model based on the available PED data. Our second main finding is that flows are significantly associated with the reports of PED outbreaks. This finding is based on correlations of pairwise relationships and regression modeling of total and weekly outbreak counts. These findings illustrate how variation in population structure may be employed along with observational data to improve understanding of disease spread. PMID:26947420

  17. Using heterogeneity in the population structure of U.S. swine farms to compare transmission models for porcine epidemic diarrhoea.

    Science.gov (United States)

    O'Dea, Eamon B; Snelson, Harry; Bansal, Shweta

    2016-03-07

    In 2013, U.S. swine producers were confronted with the disruptive emergence of porcine epidemic diarrhoea (PED). Movement of animals among farms is hypothesised to have played a role in the spread of PED among farms. Via this or other mechanisms, the rate of spread may also depend on the geographic density of farms and climate. To evaluate such effects on a large scale, we analyse state-level counts of outbreaks with variables describing the distribution of farm sizes and types, aggregate flows of animals among farms, and an index of climate. Our first main finding is that it is possible for a correlation analysis to be sensitive to transmission model parameters. This finding is based on a global sensitivity analysis of correlations on simulated data that included a biased and noisy observation model based on the available PED data. Our second main finding is that flows are significantly associated with the reports of PED outbreaks. This finding is based on correlations of pairwise relationships and regression modeling of total and weekly outbreak counts. These findings illustrate how variation in population structure may be employed along with observational data to improve understanding of disease spread.

  18. Phosphorus management in cropping systems of the Paris Basin: From farm to regional scale.

    Science.gov (United States)

    Le Noë, Julia; Garnier, Josette; Billen, Gilles

    2018-01-01

    The sustainability of phosphorus (P) fertilization in cropping systems is an important issue because P resources on earth are limited and excess P in soils can lead to ecological damage such as eutrophication. Worldwide, there is an increasing interest in organic farming (OF) due to its good environmental performance. However, organic cropping systems are suspected of generating negative P budgets, which questions their ability to provide sustainable P management. The design of agricultural systems at a broader scale also largely influences the shape of the P cycle and the possibility of its recycling to cropland. In this context, the aim of this study was to assess the relative influence of (i) OF versus conventional farming (CF) practices and (ii) the structure of agro-food systems at the regional scale, on P cycling and availability on cropland. For this purpose, we examined P budgets and soil P status of 14 organic and conventional cropping systems in commercial farms located in the Paris Basin. Available P was analyzed using two different methods: resin P and Olsen P. The results revealed no significant differences between CF and OF in available P stocks. Phosphorus budgets were always negative and significantly lower in CF systems, indicating that P was mined from soil reserves. In parallel, we estimated P budgets over cropland in all French regions for two distinct periods, 2004-2014 and 1970-1981, and showed that specialized intensive cropping systems in the Paris Basin led to a high, positive P budget in the latter period. However, this trend was reversed in the 2004-2014 period due to a sharp reduction of the mineral fertilizer application rate. The shift from very high P budgets to much lower and sometimes negative P budgets would not be a threat for agriculture due to the current high level of Olsen P in these regions, which was consistent with our measurements at the plot scale. Overall, these results suggest that OF would not lead to more P deficiency

  19. Consequential environmental life cycle assessment of a farm-scale biogas plant.

    Science.gov (United States)

    Van Stappen, Florence; Mathot, Michaël; Decruyenaere, Virginie; Loriers, Astrid; Delcour, Alice; Planchon, Viviane; Goffart, Jean-Pierre; Stilmant, Didier

    2016-06-15

    Producing biogas via anaerobic digestion is a promising technology for meeting European and regional goals on energy production from renewable sources. It offers interesting opportunities for the agricultural sector, allowing waste and by-products to be converted into bioenergy and bio-based materials. A consequential life cycle assessment (cLCA) was conducted to examine the consequences of the installation of a farm-scale biogas plant, taking account of assumptions about processes displaced by biogas plant co-products (power, heat and digestate) and the uses of the biogas plant feedstock prior to plant installation. Inventory data were collected on an existing farm-scale biogas plant. The plant inputs are maize cultivated for energy, solid cattle manure and various by-products from surrounding agro-food industries. Based on hypotheses about displaced electricity production (oil or gas) and the initial uses of the plant feedstock (animal feed, compost or incineration), six scenarios were analyzed and compared. Digested feedstock previously used in animal feed was replaced with other feed ingredients in equivalent feed diets, designed to take account of various nutritional parameters for bovine feeding. The displaced production of mineral fertilizers and field emissions due to the use of digestate as organic fertilizer was balanced against the avoided use of manure and compost. For all of the envisaged scenarios, the installation of the biogas plant led to reduced impacts on water depletion and aquatic ecotoxicity (thanks mainly to the displaced mineral fertilizer production). However, with the additional animal feed ingredients required to replace digested feedstock in the bovine diets, extra agricultural land was needed in all scenarios. Field emissions from the digestate used as organic fertilizer also had a significant impact on acidification and eutrophication. The choice of displaced marginal technologies has a huge influence on the results, as have the

  20. A farm-scale framework for assessing vineyard soil fertility and restoration practices

    Science.gov (United States)

    Vaudour, Emmanuelle; Gilliot, Jean-Marc; Leclercq, Léa

    2015-04-01

    The design of sustainable vineyard management is needed at varied scales and particularly at farm-scale. More and more winegrowers wish to adopt environmental-friendly practices while better controlling harvest composition. This leads to question complex issues with regard to sustainability of winegrowing agroecosystem and the adoption of new soil and vineyard management practices that are likely to favour a long-term preservation of quality production together with soil ecosystem functions. This study aims at elaborating a multivariate approach framework for vineyard soil fertility assessment over a 6 ha-farm planted with rainfed black Grenache and Syrah varieties in the Southern Rhone Valley. In a previous study carried out at the regional scale, soil landscape and potential terroir units had been characterized. A new field survey comprising ~20 soil pits, physico-chemical analyses for all soil profile horizons, and a series of additional soil surface samples analyzed for several parameters including soil organic carbon, calcium carbonate, copper and the major mineral nutrients, is here carried out. Along with soil parameters and soil surface condition, vine biological parameters including vigour, presence of diseases, stock-unearthing are collected. Very high resolution multispectral satellite data and resistivity EMI data are acquired and processed in order to characterize spatial variations in both physiological responses, soil surface conditions, soil depth and/or the presence of coarse elements. Multi-temporal historical aerial photographs are used in order to complement farmer's surveys regarding past management practices. The farm is characterized by a diversity of soils including Red Mediterranean soils (chromic luvisols), colluvic calcisols, arenosols, fluvisols, and regosols, which develop from top to slope then bottom of a Neogene molassic and conglomeratic plateau. Soil management past practices are marked by the absence of chemical/organic manuring

  1. Modelling the Spread of Farming in the Bantu-Speaking Regions of Africa: An Archaeology-Based Phylogeography

    OpenAIRE

    Russell, Thembi; Silva, Fabio; Steele, James

    2014-01-01

    We use archaeological data and spatial methods to reconstruct the dispersal of farming into areas of sub-Saharan Africa now occupied by Bantu language speakers, and introduce a new large-scale radiocarbon database and a new suite of spatial modelling techniques. We also introduce a method of estimating phylogeographic relationships from archaeologically-modelled dispersal maps, with results produced in a format that enables comparison with linguistic and genetic phylogenies. Several hypothese...

  2. Updraft gasification of poultry litter at farm-scale--A case study.

    Science.gov (United States)

    Taupe, N C; Lynch, D; Wnetrzak, R; Kwapinska, M; Kwapinski, W; Leahy, J J

    2016-04-01

    Farm and animal wastes are increasingly being investigated for thermochemical conversion, such as gasification, due to the urgent necessity of finding new waste treatment options. We report on an investigation of the use of a farm-scale, auto-thermal gasification system for the production of a heating gas using poultry litter (PL) as a feedstock. The gasification process was robust and reliable. The PL's ash melting temperature was 639°C, therefore the reactor temperature was kept around this value. As a result of the low reactor temperature the process performance parameters were low, with a cold gas efficiency (CGE) of 0.26 and a carbon conversion efficiency (CCE) of 0.44. The calorific value of the clean product gas was 3.39 MJ m(-3)N (LHV). The tar was collected as an emulsion containing 87 wt.% water and the extracted organic compounds were identified. The residual char exceeds thresholds for Zn and Cu to obtain European biochar certification; however, has potential to be classified as a pyrogenic carbonaceous material (PCM), which resembles a high nutrient biochar. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Productive, economic and environmental effects of optimised feeding strategies in small-scale dairy farms in the Highlands of Mexico

    Directory of Open Access Journals (Sweden)

    José Velarde-Guillén

    2017-06-01

    Full Text Available Since most dairy production in developing countries comes from small farms, there is scope to reduce their contribution to greenhouse gas (GHG emissions. In the highlands of Mexico, the limitations in these systems are high feeding costs. This paper assessed the production, economics and estimated methane emissions from traditional feeding strategies (TFS in 22 small-scale dairy farms compared to optimised feeding strategies (OFS evaluated through on-farm research in eight participating farms in the dry (DS and in the rainy (RS seasons. Results were analysed with a completely randomized design. There were no differences (P>0.05 in milk fat, body condition score (BCS or live weight between TFS and OFS, but there was higher (P

  4. THE COMMUNITY MENTORING IN ORGANIC WASTE MANAGEMENT AT COMMUNAL SCALE TO SUPPORT THE URBAN FARMING PROGRAM

    Directory of Open Access Journals (Sweden)

    Reni Amaranti

    2017-04-01

    Full Text Available The waste management in urban areas should get treatment from various parties (communities, governments, and businesses to prevent environmental damage increases. Waste management can be done in the management area of the Rukun Tetangga (RT and Rukun Warga (RW level, also the village level. The main problem for the current partner that doesn’t spread evenly of knowledge and the capabilities in utilizing waste into something that has economic valuable and the low level of public participation in the program launched by the government especially Kampung Berkebun programs that have been implemented at the level of Rukun Warga (RW. Community Service activity is done by providing assistance to communities to manage organic waste in the local environment (communal scale-Rukun Tetangga program to support the Urban Farming to utilize all potentials and resources that have been owned and has not been utilized properly.

  5. Farm-scale anaerobic digestion of beef and dairy cattle manure for energy cogeneration at two farms in Canada

    Energy Technology Data Exchange (ETDEWEB)

    Patni, N.; Monreal, C. [Agriculture and Agri-Food Canada, Quebec City, PQ (Canada); Li, X. [Highmark Renewables Research, Calgary, AB (Canada); Crolla, A.; Kinsley, C. [Guelph Univ., Alfred Campus, Alfred, ON (Canada); Barclay, J. [Environment Canada, Ottawa, ON (Canada). Emerging Fuel Issues Div.

    2010-07-01

    This paper reported on a study that was conducted in 2003 to 2005 at beef and diary cattle farms in Canada, where cattle manure was anaerobically digested for biogas production. The biogas was used for electrical and thermal energy cogeneration. Manure from about 7500 beef cattle at a feedlot was digested at a thermophilic temperature of 55 degrees C in two 1800 m{sup 3} above-ground digesters with a hydraulic retention time (HRT) of 14 days. The biogas had an average 58 per cent methane content and was combusted in a General Electric Jenbacher 999 kW cogeneration system. At the second farm, manure from about 165 lactating cows, 110 heifers and 40 calves was digested at a mesophilic temperature of 40 degrees C in a 500 m{sup 3} below-ground digester with a HRT of 28 days. The unique feature of this digester was that it was retrofitted in a pre-existing larger slurry storage tank. The biogas had an average 65 per cent methane content and was combusted in a 75 kW Perkins dual fuel diesel engine connected to a 65 kW Schnell generator. In 2007, when fats, oils and grease (FOG) from restaurant waste residue was added to the manure, biogas production increased by about 300 per cent and electrical energy generation increased by 180 per cent. Both systems have operated year-round from December to February at average ambient temperatures that ranged from -9 to -12 degrees Celsius. This paper addressed the long-term sustainability options for animal farm operations in terms of biogas production for electricity and thermal energy cogeneration.

  6. Methane Emission Quantification at the Farm Scale Using Boundary-Layer Volume Budgets

    Science.gov (United States)

    Stieger, J.; Eugster, W.; Siegwolf, R. T.; Buchmann, N. C.

    2012-12-01

    Agriculture plays an important role in the global greenhouse gas budget. Especially emissions of CH4 from livestock and manure management are of key importance. In Switzerland, roughly 80% of all national methane emissions originate from the agricultural sector. However, methane emissions in Switzerland so far were not measured but were estimated via emission factors for enteric fermentation of livestock and for manure management. This results in high uncertainties associated with emission estimates (up to 55%). Our study aims at quantifying methane emissions at the farm scale. We explored whether boundary-layer budget quantifications of methane can be used for the validation of emission estimates, and hence for the reduction of associated uncertainties in national inventory reports under the Kyoto Protocol. We will present methane emission budgets based on concentration profiles obtained from tethered balloon measurements from several campaigns carried out over two consecutive years (2011 and 2012). We will show how CH4 emissions at the farm scale (0.5 - 5 km2) were quantified using this boundary-layer budgeting approach. Clear diurnal courses of CH4 fluxes showed, that the temporal and spatial variability of emissions and atmospheric processes played an important role for source strength estimation. As an effect of these processes, budget quantifications differed up to 45% compared to the national inventory estimates. While the major determinants of methane emission budgets are still unclear, we will show that the δ13C ratios in CH4 concentrations did provide additional information about the processes responsible for the CH4 fluxes obtained.

  7. Gasification of Kentucky bluegrass (Poa pratensis l.) straw in a farm-scale reactor

    Energy Technology Data Exchange (ETDEWEB)

    Boateng, A.A.; Hicks, K.B. [US Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 E. Mermaid Lane, Wyndmoor, PA 19038 (United States); Banowetz, G.M.; Steiner, J.J.; El-Nashaar, H. [US Department of Agriculture, Agricultural Research Service, National Forage Seed Production Research Center, 3450 Southwest Campus Way, Corvallis, OR 97331 (United States); Barton, T.F.; Sethi, V.K. [Western Regional Research Institute, Laramie, 365 North 9th Street, Laramie, WY 82072 (United States); Taylor, D.G. [Taylor Energy, LLC, 46 Oakhurst, Irvine, CA 92620 (United States)

    2007-02-15

    A novel gasification reactor was designed for conversion of grass straw to synthesis gas. Our design goal was to improve synthetic gas yield and thermal stability at a scale suitable for on-farm use at a cost similar to that of a combine harvester. The reactor that was constructed and tested in this study follows the newly emerging design technique whereby the endothermic pyrolysis or gasification and exothermic char combustion co-exist in the same reactor. It operates in a dual mode where straw gasification occurs in the annulus of an outer tube and an inner (draft) tube. Our trials established that the dual-mode operation could be performed without material flow problems. Sustained tests demonstrated reactor stability at gasification temperatures up to 650 C and successful gasification of Kentucky bluegrass straw utilizing combustion heat from the inner tube. Calculated equivalence ratios of combustion in the inner tube ranged from 0.3 to 0.78 indicating fuel lean combustion of residual char without slagging. Carbon conversion ranged between 35.4 and 44.8%. Energy recovery, estimated as the ratio of the heat of combustion of the gas to that of the dry-ash-free feedstock, ranged from 14.7% to 30.92%. The estimated heating value for the synthesis gas ranged from 1.27 to 2.85 MJ m{sup -3}. Although these conversion parameters are low, a proof of the design concept was established. They can be improved with little modification by increasing the residence time in the draft tube and complete isolation of the gaseous products of combustion and the gasification. More tests are required to evaluate the economic feasibility of the farm-scale unit. (author)

  8. A Response Surface-Based Cost Model for Wind Farm Design

    International Nuclear Information System (INIS)

    Zhang Jie; Chowdhury, Souma; Messac, Achille; Castillo, Luciano

    2012-01-01

    A Response Surface-Based Wind Farm Cost (RS-WFC) model is developed for the engineering planning of wind farms. The RS-WFC model is developed using Extended Radial Basis Functions (E-RBF) for onshore wind farms in the U.S. This model is then used to explore the influences of different design and economic parameters, including number of turbines, rotor diameter and labor cost, on the cost of a wind farm. The RS-WFC model is composed of three components that estimate the effects of engineering and economic factors on (i) the installation cost, (ii) the annual Operation and Maintenance (O and M) cost, and (iii) the total annual cost of a wind farm. The accuracy of the cost model is favorably established through comparison with pertinent commercial data. The final RS-WFC model provided interesting insights into cost variation with respect to critical engineering and economic parameters. In addition, a newly developed analytical wind farm engineering model is used to determine the power generated by the farm, and the subsequent Cost of Energy (COE). This COE is optimized for a unidirectional uniform “incoming wind speed” scenario using Particle Swarm Optimization (PSO). We found that the COE could be appreciably minimized through layout optimization, thereby yielding significant cost savings. - Highlights: ► We present a Response Surface-Based Wind Farm Cost (RS-WFC) model for wind farm design. ► The model could estimate installation cost, Operation and Maintenance cost, and total annual cost of a wind farm. ► The Cost of Energy is optimized using Particle Swarm Optimization. ► Layout optimization could yield significant cost savings.

  9. Assessment of biosecurity measures against highly pathogenic avian influenza risks in small-scale commercial farms and free-range poultry flocks in the northcentral Nigeria.

    Science.gov (United States)

    Alhaji, N B; Odetokun, I A

    2011-04-01

    There is considerable global concern over the emergence of highly pathogenic avian influenza (HPAI) that has affected domestic poultry flocks in Nigeria and other parts of the world. There have been little investigations on the proposition that free-range flocks are potentially at higher risk of HPAI than confined small-scale commercial enterprises. The objective is to analyse the biosecurity measures instituted in the small-scale commercial poultry farms and established free-range bird flocks owned by households in the rural areas and qualitatively assess the risk status at the two levels of poultry management systems in northcentral Nigeria. We used data collected through questionnaire administration to farms and flock owners and subjected them to a traffic light system model to test for relative risks of HPAI infection based on the biosecurity measures put in place at the farm and flock levels. The results indicate that free-range flocks are at lower risk compared to small-scale commercial operations. These findings are plausible as birds from free-range flocks have more opportunities to contact wild bird reservoirs of low-pathogenic avian influenza (LPAI) strains than small-scale commercial poultry, thus providing them with constant challenge and maintenance of flock immunity. The development of efficient and effective biosecurity measures against poultry diseases on small-scale commercial farms requires adequate placement of barriers to provide segregation, cleaning and disinfection, while concerted community-led sanitary measures are required for free-range poultry flocks in the developing topical and subtropical economies. © 2011 Blackwell Verlag GmbH.

  10. Bio-economic farm modelling to analyse agricultural land productivity in Rwanda

    NARCIS (Netherlands)

    Bidogeza, J.C.

    2011-01-01

    Keywords: Rwanda; farm household typology; sustainable technology adoption; multivariate analysis;
    land degradation; food security; bioeconomic model; crop simulation models; organic fertiliser; inorganic fertiliser; policy incentives

    In Rwanda, land degradation contributes to the

  11. Bio-economic farm modelling to analyse agricultural land productivity in Rwanda

    NARCIS (Netherlands)

    Bidogeza, J.C.

    2011-01-01

    Keywords: Rwanda; farm household typology; sustainable technology adoption; multivariate analysis;
    land degradation; food security; bioeconomic model; crop simulation models; organic fertiliser; inorganic fertiliser; policy incentives In Rwanda, land degradation contributes to the low and

  12. O&M Modeling of Offshore Wind Farms - State of the Art and Future Developments

    DEFF Research Database (Denmark)

    Asgarpour, Masoud; Sørensen, John Dalsgaard

    2016-01-01

    In this paper the state of the art in O&M models for O&M cost estimation of offshore wind farms is discussed and then, a case study for O&M cost estimation of an 800 MW reference offshore wind farm is given. Moreover, a framework for an ideal O&M strategy optimizer to achieve the maximum possible...

  13. The k-ε-fP model applied to wind farms

    DEFF Research Database (Denmark)

    Laan, van der, Paul Maarten; Sørensen, Niels N.; Réthoré, Pierre-Elouan

    2015-01-01

    The recently developed k-ε-fP eddy-viscosity model is applied to one on-shore and two off-shore wind farms. The results are compared with power measurements and results of the standard k-ε eddy-viscosity model. In addition, the wind direction uncertainty of the measurements is used to correct...... by the turbulence models becomes smaller for wind turbines that are located further downstream. Moreover, the difference between the capability of the turbulence models to estimate the wind farm efficiency reduces with increasing wind farm size and wind turbine spacing. Copyright © 2014 John Wiley & Sons, Ltd....

  14. Sandia Wake Imaging System Field Test Report: 2015 Deployment at the Scaled Wind Farm Technology (SWiFT) Facility.

    Energy Technology Data Exchange (ETDEWEB)

    Naughton, Brian Thomas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Herges, Thomas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-10-01

    This report presents the objectives, configuration, procedures, reporting , roles , and responsibilities and subsequent results for the field demonstration of the Sandia Wake Imaging System (SWIS) at the Sandia Scaled Wind Farm Technology (SWiFT) facility near Lubbock, Texas in June and July 2015.

  15. Optimising the use of plastic protective covers in field grown melon on a farm scale

    Directory of Open Access Journals (Sweden)

    Paolo Benincasa

    2014-01-01

    Full Text Available This in-farm research study was aimed at evaluating new strategies in the use of plastic protective covers in field grown melon in order to expand the production period and reduce costs. Four experiments were set up in 2010 and repeated in 2011 in Central Italy, in an inland region with a temperate climate. We evaluated: i the use of high tunnels for two growing cycles per year, i.e. for very early and very late production (target transplanting in late winter and mid-summer, respectively, for either one year or two consecutive years, and the use of grafted plants in the second year as an alternative to normal plants to prevent soil born diseases; ii the use of ethylene-vinyl-acetate film low tunnels alone or combined with non-woven floating row covers for transplanting in early spring; iii the use of non-woven low tunnels for transplanting in mid-spring; iv the use of biodegradable and conventional polyethylene ground mulch films, both in the presence of nonwoven low tunnels. As far as the non-woven cover is concerned, we adopted the strategy of removing later with respect to usual practices, i.e. ten days after the onset of first pistillate flowers. This was based on the evidence that covers hamper honeybee circulation, which may be exploited on a farm-scale to delay pollination until an adequate number of pistillate flowers set, in order to shorten scaled fruit ripening and harvest. Our results demonstrate that high tunnels may be used for at least four consecutive melon growing cycles (early and late productions for two years with good off-season yields and no appreciable drawbacks in terms of disease scale-up, irrespective of the use of normal or grafted plants. The non-woven low tunnel was effective in hampering honeybee circulation and its delayed removal allowed the harvest period to be halved, a more uniform fruit size to be obtained, and labour productivity of harvest to be increased. This had positive implications on the management of

  16. Fishing farmers or farming fishers? Fishing typology of inland small-scale fishing households and fisheries management in singkarak lake, west sumatra, indonesia.

    Science.gov (United States)

    Yuerlita; Perret, Sylvain Roger; Shivakoti, Ganesh P

    2013-07-01

    Technical and socio-economic characteristics are known to determine different types of fishers and their livelihood strategies. Faced with declining fish and water resources, small-scale fisheries engage into transformations in livelihood and fishing practices. The paper is an attempt to understand these changes and their socio-economic patterns, in the case of Singkarak Lake in West Sumatra, Indonesia. Based upon the hypothesis that riparian communities have diverse, complex yet structured and dynamic livelihood systems, the paper's main objective is to study, document and model the actual diversity in livelihood, practices and performance of inland small-scale fisheries along the Singkarak Lake, to picture how households are adapted to the situation, and propose an updated, workable model (typology) of those for policy. Principal component analysis and cluster analysis were used to develop a typology of fishing households. The results show that small-scale fishers can be classified into different types characterized by distinct livelihood strategies. Three household types are identified, namely "farming fishers" households (type I, 30 %), "fishing farmers" households (type II, 30 %), and "mainly fishers" households (type III, 40 %). There are significant differences among these groups in the number of boats owned, annual fishing income, agriculture income and farming experience. Type I consists of farming fishers, well equipped, with high fishing costs and income, yet with the lowest return on fishing assets. They are also landowners with farming income, showing the lowest return on land capital. Type II includes poor fishing farmers, landowners with higher farming income; they show the highest return on land asset. They have less fishing equipment, costs and income. Type III (mainly fishers) consists of poorer, younger fishers, with highest return on fishing assets and on fishing costs. They have little land, low farming income, and diversified livelihood

  17. Fishing Farmers or Farming Fishers? Fishing Typology of Inland Small-Scale Fishing Households and Fisheries Management in Singkarak Lake, West Sumatra, Indonesia

    Science.gov (United States)

    Yuerlita; Perret, Sylvain Roger; Shivakoti, Ganesh P.

    2013-07-01

    Technical and socio-economic characteristics are known to determine different types of fishers and their livelihood strategies. Faced with declining fish and water resources, small-scale fisheries engage into transformations in livelihood and fishing practices. The paper is an attempt to understand these changes and their socio-economic patterns, in the case of Singkarak Lake in West Sumatra, Indonesia. Based upon the hypothesis that riparian communities have diverse, complex yet structured and dynamic livelihood systems, the paper's main objective is to study, document and model the actual diversity in livelihood, practices and performance of inland small-scale fisheries along the Singkarak Lake, to picture how households are adapted to the situation, and propose an updated, workable model (typology) of those for policy. Principal component analysis and cluster analysis were used to develop a typology of fishing households. The results show that small-scale fishers can be classified into different types characterized by distinct livelihood strategies. Three household types are identified, namely "farming fishers" households (type I, 30 %), "fishing farmers" households (type II, 30 %), and "mainly fishers" households (type III, 40 %). There are significant differences among these groups in the number of boats owned, annual fishing income, agriculture income and farming experience. Type I consists of farming fishers, well equipped, with high fishing costs and income, yet with the lowest return on fishing assets. They are also landowners with farming income, showing the lowest return on land capital. Type II includes poor fishing farmers, landowners with higher farming income; they show the highest return on land asset. They have less fishing equipment, costs and income. Type III (mainly fishers) consists of poorer, younger fishers, with highest return on fishing assets and on fishing costs. They have little land, low farming income, and diversified livelihood

  18. Institutional and Socioeconomic Model of Farm Mechanization and Foreign Workers

    OpenAIRE

    Napasintuwong, Orachos; Emerson, Robert D.

    2005-01-01

    A multi-output cost function approach to induced innovation is adopted to analyze the impact of socioeconomic variables and institutional factors on technological change in agriculture. Focusing on the impact of immigration policy and farm mechanization, the study includes variables such as H-2A or guest workers, deportable Mexicans working in agriculture representing the percentage of unauthorized workers, the public and private research expenditures on farm mechanization and other research ...

  19. On the Evolution of the Integral Length Scale in the Wake of Wind Turbines and within Wind Farms

    Science.gov (United States)

    Liu, Huiwen; Jin, Yaqing; Hayat, Imran; Chamorro, Leonardo P.

    2017-11-01

    Wind tunnel experiments were performed to characterize the evolution of integral length scale in the wake of a single turbine, and around wind farms. Hotwire anemometry was used to obtain high-resolution measurements of the streamwise velocity fluctuation at various locations. Negligible and high freestream turbulence levels were considered in the case of single turbine. The integral length scale along the rotor axis is found to grow nearly linearly with distance independent of the incoming turbulence levels, and appears to reach the incoming level in the high turbulence case at about 35-40 rotor diameters downstream. In the wind farm, results suggest that the distribution of integral length scale can be roughly described by a power-law growth with distance within consecutive turbines. Approximately past the third row, the integral length scale appears to reach equilibrium of the spatial distribution.

  20. Spatial allocation of farming systems and farming indicators in Europe

    DEFF Research Database (Denmark)

    Kempen, Markus; Elbersen, Berien S.; Staritsky, Igor

    2011-01-01

    In this article an approach to spatially allocate farm information to a specific environmental context is presented. At this moment the European wide farm information is only available at a rather aggregated administrative level. The suggested allocation approach adds a spatial dimension to all...... sample farms making it possible to aggregate farm types both to natural and to lower scale administrative regions. This spatial flexibility allows providing input data to economic or bio-physical models at their desired resolution. The allocation approach is implemented as a constrained optimization...... model searching for an optimal match between farm attributes and spatial characteristics subject to consistency constraints. The objective functions are derived from a Bayesian highest posterior density framework. The allocation procedure recovers the spatial farm type distributions satisfactorilly...

  1. Farm scale greenhouse gas accounting as basis for emissions trading or financial support

    DEFF Research Database (Denmark)

    Olesen, Jørgen E; Svendsen, Gert Tinggaard

    2013-01-01

    also farm productivity, through adoption of the efficiency measures that increase production per unit emissions, or through changes in land use, farm management or technologies that target reduction in GHG emissions. Different farm types may have very different options for emissions reductions...... under farm management control. CO2 is released largely from microbial decay or burning of plant litter and soil organic matter. CH4 is produced when organic materials decompose under anoxic conditions, notably from fermentative digestion by ruminant livestock, stored manures, wetlands and rice grown...... depending on farm type, farm structure, agroecological conditions, infrastructure and available financing. The usual practice within the Common Agricultural Policy (CAP) in terms of incentivizing GHG emissions in agriculture is to support certain practices or technologies based on a list of approved...

  2. Modeling and investigation of Gulf El-Zayt wind farm for stability studying during extreme

    Directory of Open Access Journals (Sweden)

    Omar Noureldeen

    2014-03-01

    Full Text Available This paper investigates the impact of extreme gust wind as a case of wind speed variation on a wind farm interconnected electrical grid. The impact of extreme gust wind speed variation on active and reactive power of the wind farms is studied for variable speed wind farm equipped with Doubly Fed Induction Generators (DFIGs. A simulation model of the under implementation 120 MW wind farm at Gulf El-Zayt region, Red Sea, Egypt, is simulated as a case study. A detailed model of extreme gust wind speed variation is implemented and simulated, using MATLAB/Simulink toolbox, based on International Electrotechnical Commission IEC 61400-1 and climate characteristic of Gulf El-Zayt site. The simulation results show the influence of different extreme gust wind speed variations on the fluctuation of active power and reactive power at the Point of Common Coupling (PCC of the studied wind farm.

  3. A rule-of-thumb approach to estimate annual deep percolation and runoff in irrigated landscapes at field to farm scales

    Science.gov (United States)

    Selle, B.; Githui, F.; Thayalakumaran, T.

    2009-04-01

    The rootzone of a field or farm in irrigated landscapes is the logical unit that can be managed or influenced by farmers, catchment managers and water authorities. Increasing scarcity, variability and expensive nature of water supplies necessitates better understanding of the rootzone water balance in irrigated landscapes. The major terms of the annual water balance in the rootzone include rainfall, irrigation, evapotranspiration, deep percolation below the rootzone and runoff. While information on annual rainfall, irrigation and evapotranspiration can often be readily obtained at field to farm scales, deep percolation and runoff are typically unavailable as their continuous measurement is difficult and/or uneconomical. Consequently, these terms are often calculated using models that are able to simulate the rootzone water balance. In this case study, we developed a rule-of-thumb approach to estimate annual deep percolation and runoff for the Barr Creek catchment in northern Victoria, Australia. Firstly, annual deep percolation and runoff were calculated at field to farm scales using an integrated SWAT-MODFLOW model calibrated against a comprehensive data set including drain flows and salinity, remotely sensed evapotranspiration and watertable levels. Secondly, a rule-of-thumb approach was developed to approximate annual deep percolation and runoff from readily available information on annual irrigation, rainfall, evapotranspiration, soils, watertable levels and landuse. This rule-of-thumb approach can be applied to continuously estimate deep percolation and runoff.

  4. Characterization and evaluation of agro-ecosystems on a farm scale a study case: The Paysandu farming center (Medellin. Colombia)

    International Nuclear Information System (INIS)

    Juan Camilo de los Rios Cardona; Andres Felipe Gallego Zapata; Leon Dario Velez Vargas; Agudelo Otalvaro, Jose Ignacio; Toro Restrepo, Luis Jairo; Lema Tapias, Alvaro de Jesus; Acevedo Agudelo, Luis Ignacio

    2004-01-01

    The state, condition, and tendencies of the agro-ecosystems (AE) of the Paysandu farming center of the Universidad Nacional de Colombia, sede Medellin were characterized and evaluated by means of parameterization and analysis of the various technological receptivity (RT, after the Spanish initials) and technological intensity (IT), based upon a methodological proposal of Velez and Gasto (1999), in terms of AE diversity and of the uses, management, and technological acceptance, techno-structural and hydro-structural endowment, potential productivity and services to the local, regional, and national society. The results showed that the greater part of the center (72%) has very low RT; which does not permit the establishment of mechanized advanced agro-technological management systems (SMA) however, 69.8% of the area is managed with SMA adequate for the restrictions imposed by the RT sixty-two percent of the area of the center, principally under pasture cover for dairy cattle production, is managed with advanced SMA. As a result of the interaction between RT and the SMA employed, six AE were identified, of which three, that represent 69.8% of the area (100.2 ha.), are managed with technologies adequate for their biophysical conditions or with technological receptivity (adequate IT), and the other three, that represent 28,57% of the are (43.1 ha.) ore managed with technologies that do not correspond to their RT conditions (tradition IT) which leads to a deterioration of their biophysical and ecological conditions

  5. Modeling Commercial Freshwater Turtle Production on US Farms for Pet and Meat Markets

    Science.gov (United States)

    Mali, Ivana; Wang, Hsiao-Hsuan; Grant, William E.; Feldman, Mark; Forstner, Michael R. J.

    2015-01-01

    Freshwater turtles are being exploited for meat, eggs, traditional medicine, and pet trade. As a response, turtle farming became a booming aquaculture industry in the past two decades, specifically in the southeastern states of the United States of America (US) and across Southeast Asia. However, US turtle farms are currently producing turtles only for the pet trade while commercial trappers remain focused on catching the largest individuals from the wild. In our analyses we have created a biological and economic model that describes farming operations on a representative turtle farm in Louisiana. We first modeled current production of hatchling and yearling red-eared slider turtles (Trachemys scripta elegans) (i.e., traditional farming) for foreign and domestic pet markets, respectively. We tested the possibility of harvesting adult turtles from the breeding stock for sale to meat markets to enable alternative markets for the farmers, while decreasing the continued pressures on wild populations (i.e., non-traditional farming). Our economic model required current profit requirements of ~$13/turtle or ~$20.31/kg of meat from non-traditional farming in order to acquire the same profit as traditional farming, a value which currently exceeds market values of red-eared sliders. However, increasing competition with Asian turtle farms and decreasing hatchling prices may force the shift in the US toward producing turtles for meat markets. In addition, our model can be modified and applied to more desirable species on the meat market once more knowledge is acquired about species life histories and space requirements under farmed conditions. PMID:26407157

  6. Modeling Commercial Freshwater Turtle Production on US Farms for Pet and Meat Markets.

    Science.gov (United States)

    Mali, Ivana; Wang, Hsiao-Hsuan; Grant, William E; Feldman, Mark; Forstner, Michael R J

    2015-01-01

    Freshwater turtles are being exploited for meat, eggs, traditional medicine, and pet trade. As a response, turtle farming became a booming aquaculture industry in the past two decades, specifically in the southeastern states of the United States of America (US) and across Southeast Asia. However, US turtle farms are currently producing turtles only for the pet trade while commercial trappers remain focused on catching the largest individuals from the wild. In our analyses we have created a biological and economic model that describes farming operations on a representative turtle farm in Louisiana. We first modeled current production of hatchling and yearling red-eared slider turtles (Trachemys scripta elegans) (i.e., traditional farming) for foreign and domestic pet markets, respectively. We tested the possibility of harvesting adult turtles from the breeding stock for sale to meat markets to enable alternative markets for the farmers, while decreasing the continued pressures on wild populations (i.e., non-traditional farming). Our economic model required current profit requirements of ~$13/turtle or ~$20.31/kg of meat from non-traditional farming in order to acquire the same profit as traditional farming, a value which currently exceeds market values of red-eared sliders. However, increasing competition with Asian turtle farms and decreasing hatchling prices may force the shift in the US toward producing turtles for meat markets. In addition, our model can be modified and applied to more desirable species on the meat market once more knowledge is acquired about species life histories and space requirements under farmed conditions.

  7. Modeling Commercial Freshwater Turtle Production on US Farms for Pet and Meat Markets.

    Directory of Open Access Journals (Sweden)

    Ivana Mali

    Full Text Available Freshwater turtles are being exploited for meat, eggs, traditional medicine, and pet trade. As a response, turtle farming became a booming aquaculture industry in the past two decades, specifically in the southeastern states of the United States of America (US and across Southeast Asia. However, US turtle farms are currently producing turtles only for the pet trade while commercial trappers remain focused on catching the largest individuals from the wild. In our analyses we have created a biological and economic model that describes farming operations on a representative turtle farm in Louisiana. We first modeled current production of hatchling and yearling red-eared slider turtles (Trachemys scripta elegans (i.e., traditional farming for foreign and domestic pet markets, respectively. We tested the possibility of harvesting adult turtles from the breeding stock for sale to meat markets to enable alternative markets for the farmers, while decreasing the continued pressures on wild populations (i.e., non-traditional farming. Our economic model required current profit requirements of ~$13/turtle or ~$20.31/kg of meat from non-traditional farming in order to acquire the same profit as traditional farming, a value which currently exceeds market values of red-eared sliders. However, increasing competition with Asian turtle farms and decreasing hatchling prices may force the shift in the US toward producing turtles for meat markets. In addition, our model can be modified and applied to more desirable species on the meat market once more knowledge is acquired about species life histories and space requirements under farmed conditions.

  8. Coupling Dairy Manure Storage with Injection to Improve Nitrogen Management: Whole-Farm Simulation Using the Integrated Farm System Model

    Directory of Open Access Journals (Sweden)

    E. W. Duncan

    2017-02-01

    Full Text Available Application of livestock manure to farm soils represents a priority nutrient management concern in the Chesapeake Bay watershed. Historically, strong emphasis has been placed on adding manure storage to dairy operations, with the recognition that manure application methods can be improved. The Integrated Farm System Model was used to simulate manure management on a typical Pennsylvania dairy farm (100 milking cows, 80 ha. Converting the operation from daily haul to 6 mo of storage with broadcast application did not substantially change nitrogen (N losses to the environment. However, switching to manure injection conserved ammonium N and improved manure N use efficiency by crops, even though it increased N leaching by 27% with 6-mo storage and 13% with 12-mo storage. Increasing manure storage from 6 to 12 mo with manure injection reduced nitrate N leaching by 38%, due to better timing of manure application to crop growth, but lowered annual net returns. Overall, manure injection and 6 mo of storage resulted in the best combination of profit and environmental outcome.

  9. ANEMOS: Development of a next generation wind power forecasting system for the large-scale integration of onshore and offshore wind farms.

    Science.gov (United States)

    Kariniotakis, G.; Anemos Team

    2003-04-01

    Objectives: Accurate forecasting of the wind energy production up to two days ahead is recognized as a major contribution for reliable large-scale wind power integration. Especially, in a liberalized electricity market, prediction tools enhance the position of wind energy compared to other forms of dispatchable generation. ANEMOS, is a new 3.5 years R&D project supported by the European Commission, that resembles research organizations and end-users with an important experience on the domain. The project aims to develop advanced forecasting models that will substantially outperform current methods. Emphasis is given to situations like complex terrain, extreme weather conditions, as well as to offshore prediction for which no specific tools currently exist. The prediction models will be implemented in a software platform and installed for online operation at onshore and offshore wind farms by the end-users participating in the project. Approach: The paper presents the methodology of the project. Initially, the prediction requirements are identified according to the profiles of the end-users. The project develops prediction models based on both a physical and an alternative statistical approach. Research on physical models gives emphasis to techniques for use in complex terrain and the development of prediction tools based on CFD techniques, advanced model output statistics or high-resolution meteorological information. Statistical models (i.e. based on artificial intelligence) are developed for downscaling, power curve representation, upscaling for prediction at regional or national level, etc. A benchmarking process is set-up to evaluate the performance of the developed models and to compare them with existing ones using a number of case studies. The synergy between statistical and physical approaches is examined to identify promising areas for further improvement of forecasting accuracy. Appropriate physical and statistical prediction models are also developed for

  10. Empirical comparison of pollution generating technologies in nonparametric modelling : The case of greenhouse gas emissions in French meat sheep farming

    OpenAIRE

    Dakpo, K Hervé; Jeanneaux, Philippe; Latruffe, Laure

    2015-01-01

    In this paper we consider different models that assess eco - efficiency with production frontier estimation when both desirable outputs and undesirable outputs (or residuals) are considered. These models are confronted to livestock farm data (sheep meat farms) and greenho use gas (GHG) emissions, to discuss their suitability in eco - efficiency measurement. The application is to French sheep meat farms. Our results show t...

  11. Effects of the 2003 CAP Reform on Investments of Dutch Dairy Farms Simulations with a Household Production Model

    NARCIS (Netherlands)

    Peerlings, J.H.M.; Ooms, D.L.

    2005-01-01

    This paper develops a non-separable household production model capable of analyzing the effects of the 2003 CAP reform, and especially EU farm payments, on individual Dutch dairy farms. Model results show that the 2003 CAP reform farm payments do not fully compensate the income loss caused by the

  12. Detecting Land-Use Change and On-Farm Investments at the Plot Scale

    Science.gov (United States)

    Burney, J. A.; Goldblatt, R.; Amezaga, K. Y.; Sanford, L.; Nichols, M. M.

    2017-12-01

    The ability to remotely monitor agro-ecosystems over large spatial scales, at high spatial and temporal resolution, promises to open new and previously un-tractable lines of inquiry about the relationships between management practices, welfare, and resilience in coupled human-natural systems. We use several sources of remotely sensed data (from vegetation indices to synthetic aperture radar) and new analysis methods to infer when and where land-use and management changes take place at the farm level, including processes leading to degradation, like overgrazing or tree removal, as well as processes intended to boost resilience, like irrigation and conservation agriculture. Here, we first show how ecosystem health metrics can be used as indicators of both poverty and vulnerability. This is especially important because many other remotely-sensed economic proxies exhibit hysteresis in one direction; that is, they may respond quickly to positive income shocks (e.g., a change in income may rapidly lead to more construction and an expansion of the urban environment), but little if at all to negative shocks (a drop in income does not lead to deconstruction of buildings). We then present results from three field projects that show how these techniques can be used to detect management changes — reflecting changes in household welfare — in both field and quasi/natural experiments.

  13. Methane production and energy evaluation of a farm scaled biogas plant in cold climate area.

    Science.gov (United States)

    Fjørtoft, Kristian; Morken, John; Hanssen, Jon Fredrik; Briseid, Tormod

    2014-10-01

    The aim of this study was to investigate the specific methane production and the energy balance at a small farm scaled mesophilic biogas plant in a cold climate area. The main substrate was dairy cow slurry. Fish silage was used as co-substrate for two of the three test periods. Energy production, substrate volumes and thermal and electric energy consumption was monitored. Methane production depended mainly on type and amount of substrates, while energy consumption depended mainly on the ambient temperature. During summer the main thermal energy consumption was caused by heating of new substrates, while covering for thermal energy losses from digester and pipes required most thermal energy during winter. Fish silage gave a total energy production of 1623 k Wh/m(3), while the dairy cow slurry produced 79 k Wh/m(3) slurry. Total energy demand at the plant varied between 26.9% and 88.2% of the energy produced. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. A simple rule based model for scheduling farm management operations in SWAT

    Science.gov (United States)

    Schürz, Christoph; Mehdi, Bano; Schulz, Karsten

    2016-04-01

    For many interdisciplinary questions at the watershed scale, the Soil and Water Assessment Tool (SWAT; Arnold et al., 1998) has become an accepted and widely used tool. Despite its flexibility, the model is highly demanding when it comes to input data. At SWAT's core the water balance and the modeled nutrient cycles are plant growth driven (implemented with the EPIC crop growth model). Therefore, land use and crop data with high spatial and thematic resolution, as well as detailed information on cultivation and farm management practices are required. For many applications of the model however, these data are unavailable. In order to meet these requirements, SWAT offers the option to trigger scheduled farm management operations by applying the Potential Heat Unit (PHU) concept. The PHU concept solely takes into account the accumulation of daily mean temperature for management scheduling. Hence, it contradicts several farming strategies that take place in reality; such as: i) Planting and harvesting dates are set much too early or too late, as the PHU concept is strongly sensitivity to inter-annual temperature fluctuations; ii) The timing of fertilizer application, in SWAT this often occurs simultaneously on the same date in in each field; iii) and can also coincide with precipitation events. Particularly, the latter two can lead to strong peaks in modeled nutrient loads. To cope with these shortcomings we propose a simple rule based model (RBM) to schedule management operations according to realistic farmer management practices in SWAT. The RBM involves simple strategies requiring only data that are input into the SWAT model initially, such as temperature and precipitation data. The user provides boundaries of time periods for operation schedules to take place for all crops in the model. These data are readily available from the literature or from crop variety trials. The RBM applies the dates by complying with the following rules: i) Operations scheduled in the

  15. Farm scale application of EMI and FDR sensors to measuring and mapping soil water content

    Science.gov (United States)

    Rallo, Giovanni; Provenzano, Giuseppe

    2017-04-01

    Soil water content (SWC) controls most water exchange processes within and between the soil-plants-atmosphere continuum and can therefore be considered as a practical variable for irrigation farmer choices. A better knowledge of spatial SWC patterns could improve farmer's awareness about critical crop water status conditions and enhance their capacity to characterize their behavior at the field or farm scale. However, accurate soil moisture measurement across spatial and temporal scales is still a challenging task and, specifically at intermediate spatial (0.1-100 ha) and temporal (minutes to days) scales, a data gap remains that limits our understanding over reliability of the SWC spatial measurements and its practical applicability in irrigation scheduling. In this work we compare the integrated EM38 (Geonics Ltd. Canada) response, collected at different sensor positions above ground to that obtained by integrating the depth profile of volumetric SWC measured with Diviner 2000 (Sentek) in conjunction with the depth response function of the EM38 when operated in both horizontal and vertical dipole configurations. On a 1.0-ha Olive grove site in Sicliy (Italy), 200 data points were collected before and after irrigation or precipitation events following a systematic sampling grid with focused measurements around the tree. Inside two different zone of the field, characterized from different soil physical properties, two Diviner 2000 access tube (1.2 m) were installed and used for the EM38 calibration. After calibration, the work aimed to propose the combined use of the FDR and EMI sensors to measuring and mapping root zone soil water content. We found strong correlations (R2 = 0.66) between Diviner 2000 SWC averaged to a depth of 1.2 m and ECa from an EM38 held in the vertical mode above the soil surface. The site-specific relationship between FDR-based SWC and ECa was linear for the purposes of estimating SWC over the explored range of ECa monitored at field levels

  16. Modelization of a large wind farm, considering the modification of the atmospheric boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Crespo, A.; Gomez-Elvira, R. [Univ. Politecnica de Madrid, Mecanica de Fluidos, E.T.S.I. Industriales, Madrid (Spain); Frandsen, S.; Larsen, S.E. [Risoe National Lab., Roskilde (Denmark)

    1999-03-01

    A method is presented to adapt existing models of wind farms to very large ones that may affect the whole planetary boundary layer. An internal boundary layer is considered that starts developing at the leading edge of the farm until it reaches, sufficiently far downstream, the top of the planetary boundary layer, and a new equilibrium region is reached. The wind farm is simulated by an artificial roughness that is function of the turbine spacing, drag and height. From this model the flow conditions are calculated at a certain reference height and then are used as boundary conditions for a numerical code used to model a wind farm. Three-dimensional effects are considered by applying appropriate conditions at the sides of the farm. Calculations are carried out to estimate the energy production in large wind farms, and it is found that additional losses due to modification of the planetary boundary layer may be of importance for wind farms of size larger than about 100 km. (au)

  17. Metabolic Profile and Inflammatory Responses in Dairy Cows with Left Displaced Abomasum Kept under Small-Scaled Farm Conditions

    Directory of Open Access Journals (Sweden)

    Fenja Klevenhusen

    2015-10-01

    Full Text Available Left displaced abomasum (LDA is a severe metabolic disease of cattle with a strong negative impact on production efficiency of dairy farms. Metabolic and inflammatory alterations associated with this disease have been reported in earlier studies, conducted mostly in large dairy farms. This research aimed to: (1 evaluate metabolic and inflammatory responses in dairy cows affected by LDA in small-scaled dairy farms; and (2 establish an Animals 2015, 5 1022 association between lactation number and milk production with the outcome of metabolic variables. The cows with LDA had lower serum calcium (Ca, but greater concentrations of non-esterified fatty acids (NEFA and beta-hydroxy-butyrate (BHBA, in particular when lactation number was >2. Cows with LDA showed elevated levels of aspartate aminotransferase, glutamate dehydrogenase, and serum amyloid A (SAA, regardless of lactation number. In addition, this study revealed strong associations between milk yield and the alteration of metabolic profile but not with inflammation in the sick cows. Results indicate metabolic alterations, liver damage, and inflammation in LDA cows kept under small-scale farm conditions. Furthermore, the data suggest exacerbation of metabolic profile and Ca metabolism but not of inflammation and liver health with increasing lactation number and milk yield in cows affected by LDA.

  18. Plot-, farm-, and watershed-scale effects of coffee cultivation in runoff and sediment production in western Puerto Rico.

    Science.gov (United States)

    Ramos-Scharrón, Carlos E; Figueroa-Sánchez, Yasiel

    2017-11-01

    The combination of a topographically abrupt wet-tropical setting with the high level of soil exposure that typifies many sun-grown coffee farms represents optimal conditions for high erosion rates. Although traditionally considered as a main cause for water resource degradation, limited empirical evidence has existed to document its true contribution. This study relies on plot-scale experimental results conducted in western Puerto Rico to assess the impact of cultivated surfaces and farm access roads on runoff and sediment production from the plot to the farm and watershed scales. Results show that unsurfaced and graveled road surfaces produce one- to two-orders of magnitude more per unit area runoff than cultivated lands. Similarly, erosion rates from unsurfaced roads are about 102 g m -2 per cm of rainfall and these are two-orders of magnitude greater than from actively cultivated surfaces. Mitigation practices such as uncompacting road surfaces by ripping and gravel application reduce onsite erosion rates to 0.6% and 8% of unsurfaced conditions, respectively. At the farm scale, coffee farms are estimated to produce sediment at a rate of 12-18 Mg ha -1 yr -1 , and roads are undoubtedly the dominant sediment source responsible for 59-95% of the total sediment produced. The costs associated to ameliorating erosion problems through road graveling are high. Therefore, a combined approach that treats road erosion onsite with one that traps sediment before it reaches river networks is the viable solution to this problem. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. OPTIMIZATION MODEL FOR VEHICLE ROUTING AND EQUIPMENT REPLACEMENT IN FARM MACHINERY

    OpenAIRE

    Grano, Carolina; Abensur, Eder

    2017-01-01

    ABSTRACT: An equipment replacement decision takes into account economic engineering models based on discounted cash flow (DCF) such as the Annual Equivalent Cost (AEC). Despite a large number of researches on industrial assets replacement, there is a lack of studies applied to farm goods. This study aimed at assessing an alternative model for economic decision analysis on farm machinery replacement, with no restrictions on the number of replacements and assessed goods during a defined timelin...

  20. Fatigue reliability and effective turbulence models in wind farms

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Frandsen, Sten Tronæs; Tarp-Johansen, N.J.

    2007-01-01

    Offshore wind farms with 100 or more wind turbines are expected to be installed many places during the next years. Behind a wind turbine a wake is formed where the mean wind speed decreases slightly and the turbulence intensity increases significantly. This increase in turbulence intensity in wak...

  1. The farm household model based on Lexicographic utilities

    African Journals Online (AJOL)

    Yigezu A. Yigezu

    2012-08-05

    Aug 5, 2012 ... In the face of large seasonal price swings of cereal staples, resource- poor farmers with limited liquidity often sell most ... better access to land, animal power and off farm incomes was taken. Detailed household and plot ... function with a trade-off between expected income and risk. Risk is proxied by some.

  2. Developing COMET-Farm and the DayCent Model for California Specialty Crops

    Science.gov (United States)

    Steenwerth, K. L.; Barker, X. Z.; Carlson, M.; Killian, K.; Easter, M.; Swan, A.; Thompson, L.; Williams, S.; Paustian, K.

    2016-12-01

    Specialty crops are hugely important to the agricultural economy of California, which grows over 400 specialty crops and produces at least a third of the nations' vegetables and more than two thirds of its fruit and nut tree crops. Since the passage of AB32 Global Warming Solutions Act in 2006, the state has made strong investments in reducing greenhouse gas emissions and developing climate adaptation solutions. Most recently, Governor J. Brown (CA) has issued an executive order to establish reductions to 40% below 1990 levels. While agriculture in California is not regulated for greenhouse gas emissions under AB32, efforts are being made to develop tools to support practices that can enhance soil health and reduce greenhouse gas emissions. USDA-NRCS supports one such tool known as COMET-Farm, which is intended for future use with incentive programs and soil conservation plans managed by the agency. The underlying model that that simulates entity-scale greenhouse gas emissions in COMET-Farm is DayCent. Members of the California Climate Hub are collaborating with the Natural Resource Ecology Laboratory at Colorado State University in Fort Collins, CO to develop DayCent for 15 California specialty crops. These specialty crops include woody perennials like stone fruit like almonds and peaches, walnuts, citrus, wine grapes, raisins and table grapes. Annual specialty crops include cool season vegetables like lettuce and broccoli, tomatoes, and strawberries. DayCent has been parameterized for these crops using existing published and unpublished studies. Practice based information has also been gathered in consultation with growers. Aspects of the model have been developed for woody biomass production and competition between herbaceous vegetation and woody perennial crops. We will report on model performance for these crops and opportunities for model improvement.

  3. Adoption Model of Falcataria-Based Farm Forestry: A Duration Analysis Approach

    Directory of Open Access Journals (Sweden)

    Evi Irawan

    2016-06-01

    Full Text Available Integrating perennial plant, such as Falcataria moluccana, in farming system can provide economic and environmental benefits, especially in marginal areas. Indonesian governments at all levels have been employing a number of efforts to speed-up adoption of tree planting on farm.  However, the establishment of farm forestry on private land in Indonesia, especially in Java, is widely varied.  While the farm forestry in some locations has been well adopted, the farmers or land users in other location are reluctant to adopt them, although the traits of farmers and farm land in both locations are similar. Most adoption studies have employed cross-sectional data in a static discrete choice modeling framework to analyze why some farmers adopt at a certain point in time.  The static approach does not consider the dynamic environment in which the adoption decision is made and thus does not incorporate speed of adoption.  The information of adoption speed of an innovation is important in designing extension policies as well as reengineering innovations in order to align with socio-economic conditions of the farmers.  Based on data from a survey of a random sample of 117 smallholder households in Wonosobo Regency, Central Java, Indonesia, this study investigated determinants of time to adoption of farm forestry using duration analysis. Results revealed that factors that accelerate the adoption varied include age of household head, level of education of household head, off-farm employment and output price. Older farmers tend to adopt faster than the younger farmers. The other interesting findings are that off-farm employment and membership to farmers group are two most influential factors in speeding-up adoption of Falcataria-based farm forestry. The policy implications of this research are that government should design policies that promote farmers’ participation in off-farm income activities and strengthening farmer groups in addition to extension

  4. Coordinated Voltage Control of a Wind Farm based on Model Predictive Control

    DEFF Research Database (Denmark)

    Zhao, Haoran; Wu, Qiuwei; Guo, Qinglai

    2016-01-01

    This paper presents an autonomous wind farm voltage controller based on Model Predictive Control (MPC). The reactive power compensation and voltage regulation devices of the wind farm include Static Var Compensators (SVCs), Static Var Generators (SVGs), Wind Turbine Generators (WTGs) and On...... are calculated based on an analytical method to improve the computation efficiency and overcome the convergence problem. Two control modes are designed for both voltage violated and normal operation conditions. A wind farm with 20 wind turbines was used to conduct case studies to verify the proposed coordinated...

  5. Combined Active and Reactive Power Control of Wind Farms based on Model Predictive Control

    DEFF Research Database (Denmark)

    Zhao, Haoran; Wu, Qiuwei; Wang, Jianhui

    2017-01-01

    This paper proposes a combined wind farm controller based on Model Predictive Control (MPC). Compared with the conventional decoupled active and reactive power control, the proposed control scheme considers the significant impact of active power on voltage variations due to the low X=R ratio...... of wind farm collector systems. The voltage control is improved. Besides, by coordination of active and reactive power, the Var capacity is optimized to prevent potential failures due to Var shortage, especially when the wind farm operates close to its full load. An analytical method is used to calculate...

  6. Evaluating nitrogen taxation scenarios using the dynamic whole farm simulation model FASSET

    DEFF Research Database (Denmark)

    Berntsen, J.; Petersen, B.M.; Jacobsen, Brian H.

    2003-01-01

    The whole farm model FASSET ver. 1.0 was used for evaluation of the environmental and economic consequences of implementing different nitrogen taxes. The taxation policies analysed were a tax on nitrogen in mineral fertiliser, a tax on nitrogen in mineral fertiliser and imported animal feedstuff...... leaching varied between 1 and 9 € kg N−1. None of the taxation policies was the most cost-effective for all farm types. Tax on mineral fertiliser favours pig producers, whereas the tax on nitrogen surplus favours arable farms. Thus efficient taxation schemes for reduction of nitrate leaching should...

  7. Weed control practices on Costa Rican coffee farms: is herbicide use necessary for small-scale producers?

    OpenAIRE

    Bellamy, Angelina Sanderson

    2010-01-01

    Abstract This paper presents research conducted during two coffee farming seasons in Costa Rica. The study examined coffee farmers? weed management practices and is presented in the form of a case study of small-scale farmers? use of labor and herbicides in weed management practices. Over 200 structured interviews were conducted with coffee farmers concerning their use of hired labor and family labor, weed management activities, support services, and expectations about the future o...

  8. Development of a Hybrid Uav Sensor Platform Suitable for Farm-Scale Applications in Precision Agriculture

    Science.gov (United States)

    Pircher, M.; Geipel, J.; Kusnierek, K.; Korsaeth, A.

    2017-08-01

    Today's modern precision agriculture applications have a huge demand for data with high spatial and temporal resolution. This leads to the need of unmanned aerial vehicles (UAV) as sensor platforms providing both, easy use and a high area coverage. This study shows the successful development of a prototype hybrid UAV for practical applications in precision agriculture. The UAV consists of an off-the-shelf fixed-wing fuselage, which has been enhanced with multi-rotor functionality. It was programmed to perform pre-defined waypoint missions completely autonomously, including vertical take-off, horizontal flight, and vertical landing. The UAV was tested for its return-to-home (RTH) accuracy, power consumption and general flight performance at different wind speeds. The RTH accuracy was 43.7 cm in average, with a root-mean-square error of 39.9 cm. The power consumption raised with an increase in wind speed. An extrapolation of the analysed power consumption to conditions without wind resulted in an estimated 40 km travel range, when we assumed a 25 % safety margin of remaining battery capacity. This translates to a maximal area coverage of 300 ha for a scenario with 18 m/s airspeed, 50 minutes flight time, 120 m AGL altitude, and a desired 70 % of image side-lap and 85 % forward-lap. The ground sample distance with an in-built RGB camera was 3.5 cm, which we consider sufficient for farm-scale mapping missions for most precision agriculture applications.

  9. DEVELOPMENT OF A HYBRID UAV SENSOR PLATFORM SUITABLE FOR FARM-SCALE APPLICATIONS IN PRECISION AGRICULTURE

    Directory of Open Access Journals (Sweden)

    M. Pircher

    2017-08-01

    Full Text Available Today’s modern precision agriculture applications have a huge demand for data with high spatial and temporal resolution. This leads to the need of unmanned aerial vehicles (UAV as sensor platforms providing both, easy use and a high area coverage. This study shows the successful development of a prototype hybrid UAV for practical applications in precision agriculture. The UAV consists of an off-the-shelf fixed-wing fuselage, which has been enhanced with multi-rotor functionality. It was programmed to perform pre-defined waypoint missions completely autonomously, including vertical take-off, horizontal flight, and vertical landing. The UAV was tested for its return-to-home (RTH accuracy, power consumption and general flight performance at different wind speeds. The RTH accuracy was 43.7 cm in average, with a root-mean-square error of 39.9 cm. The power consumption raised with an increase in wind speed. An extrapolation of the analysed power consumption to conditions without wind resulted in an estimated 40 km travel range, when we assumed a 25 % safety margin of remaining battery capacity. This translates to a maximal area coverage of 300 ha for a scenario with 18 m/s airspeed, 50 minutes flight time, 120 m AGL altitude, and a desired 70 % of image side-lap and 85 % forward-lap. The ground sample distance with an in-built RGB camera was 3.5 cm, which we consider sufficient for farm-scale mapping missions for most precision agriculture applications.

  10. Modelling of rate effects at multiple scales

    DEFF Research Database (Denmark)

    Pedersen, R.R.; Simone, A.; Sluys, L. J.

    2008-01-01

    , the length scale in the meso-model and the macro-model can be coupled. In this fashion, a bridging of length scales can be established. A computational analysis of  a Split Hopkinson bar test at medium and high impact load is carried out at macro-scale and meso-scale including information from  the micro-scale....

  11. Mukhabarah as Sharia Financing Model in Beef Cattle Farm Entrepise

    Science.gov (United States)

    Asnawi, A.; Amrawaty, A. A.; Nirwana

    2018-02-01

    Financing constraints on beef cattle farm nowadays have received attention by the government through distributed various assistance programs and program loans through implementing banks. The existing financing schemes are all still conventional yet sharia-based. The purpose of this research is to formulate financing pattern for sharia beef cattle farm. A qualitative and descriptive approach is used to formulate the pattern by considering the profit-sharing practices of the beef cattle farmers. The results of this study have formulated a financing pattern that integrates government, implementing banks, beef cattle farmers group and cooperative as well as breeders as its members. This pattern of financing is very accommodating of local culture that develops in rural communities. It is expected to be an input, especially in formulating a business financing policy Sharia-based beef cattle breeding.

  12. Enhancing methane production in a farm-scale biogas production system

    Energy Technology Data Exchange (ETDEWEB)

    Kaparaju, P.

    2003-07-01

    Biogas technology with utilisation of biogas is increasingly applied in the agricultural sector to produce renewable energy and to minimise environmental emissions both resulting in reduction in greenhouse gas (GHG) emissions. The main objective of this thesis was to evaluate methods to enhance the methane production in a farm-scale biogas production system. Semi-continuous digestion of pig and dairy cow manures produced methane yields (m{sup 3} kg{sup -1} volatile solids (VS)) of about 0.31 and 0.14 respectively at 2 kgVS m{sup -3} d{sup -1} loading rate, 30 d hydraulic retention time (HRT) and 6.0% feed VS while in batches yields were 0.14, and 0.36 m3 kg{sup -1} VS for dairy cow and pig and manures respectively. These yields were lower than the theoretical yield of 0.4 m3 kg{sup -1} VS reported for cow manure. Possible co-substrates to enhance the methane production were investigated. Methane yields (m{sup 3} kg{sup -1} VS) in batch assays were 0.14 to 0.35 for three different energy crops and 0.32-0.39 for confectionery by-products. On full-scale application, cow manure alone and co-digestion with energy crops produced 0.22 m{sup 3} CH{sub 4} kg{sup -1} VS and co-digestion with confectionery by-products (20% of feed biomass) about 0.28 m{sup 3} kg{sup -1} VS. Laboratory co-digestion of pig manure with potato tuber or its industrial by- products (potato peel or potato stillage) at loading rate of 2 kg VS m-3 d-1 produced methane yields (m{sup 3} kg{sup -1} VS) of about 0.22 at 85:15 and 0.31 at 80:20 feed VS ratio (VS% pig manure to potato co-substrate) compared to 0.14 for pig manure alone. The batch incubation of digested materials from a farm biogas digester (35 deg C) and its associated post-storage tank indicated that both materials could still produce up to 0.20 m{sup 3} kg{sup -1} VS. The amount and rate was highly dependent on temperature. These results suggest that the untapped methane potential in the digested manure cannot effectively be recovered at

  13. Statistical modeling of the power grid from a wind farm standpoint

    DEFF Research Database (Denmark)

    Farajzadehbibalan, Saber; Ramezani, Mohammad H.; Nielsen, Peter

    2017-01-01

    In this study, we derive a statistical model of a power grid from the wind farm's standpoint based on dynamic principal component analysis. The main advantages of our model compared to the previously developed models are twofold. Firstly, our proposed model benefits from logged data of an offshor...

  14. Impacts of Wake Effect and Time Delay on the Dynamic Analysis of Wind Farms Models

    Science.gov (United States)

    El-Fouly, Tarek H. M.; El-Saadany, Ehab F.; Salama, Magdy M. A.

    2008-01-01

    This article investigates the impacts of proper modeling of the wake effects and wind speed delays, between different wind turbines' rows, on the dynamic performance accuracy of the wind farms models. Three different modeling scenarios were compared to highlight the impacts of wake effects and wind speed time-delay models. In the first scenario,…

  15. Modelling as a tool to redesign livestock farming systems: a literature review.

    Science.gov (United States)

    Gouttenoire, L; Cournut, S; Ingrand, S

    2011-12-01

    Livestock farming has recently come under close scrutiny, in response especially to environmental issues. Farmers are encouraged to redesign their livestock farming systems in depth to improve their sustainability. Assuming that modelling can be a relevant tool to address such systemic changes, we sought to answer the following question: 'How can livestock farming systems be modelled to help farmers redesign their whole farming systems?' To this end, we made a literature review of the models of livestock farming systems published from 2000 to mid-2009 (n = 79). We used an analysis grid based on three considerations: (i) system definition, (ii) the intended use of the model and (iii) the way in which farmers' decision-making processes were represented and how agricultural experts and farmers were involved in the modelling processes. Consistent rationales in approaches to supporting changes in livestock farming were identified in three different groups of models, covering 83% of the whole set. These could be defined according to (i) the way in which farmers' decisions were represented and (ii) the model's type of contribution to supporting changes. The first type gathered models that dynamically simulated the system according to different management options; the farmers' decision-making processes are assumed to consist in choosing certain values for management factors. Such models allow long-term simulations and endorse different disciplinary viewpoints, but the farmers are weakly involved in their design. Models of the second type can indicate the best combination of farm activities under given constraints, provided the farmers' objectives are profit maximisation. However, when used to support redesigning processes, they address neither how to implement the optimal solution nor its long-term consequences. Models of the third type enable users to dynamically simulate different options for the farming system, the management of which is assumed to be planned according

  16. Prevalence and risk factors for carriage of antimicrobial-resistant Escherichia coli on household and small-scale chicken farms in the Mekong Delta of Vietnam

    NARCIS (Netherlands)

    Nguyen, Vinh Trung; Carrique-Mas, Juan J.; Ngo, Thi Hoa; Ho, Huynh Mai; Ha, Thanh Tuyen; Campbell, James I.; Nguyen, Thi Nhung; Hoang, Ngoc Nhung; Pham, Van Minh; Wagenaar, Jaap A.; Hardon, Anita; Thai, Quoc Hieu; Schultsz, Constance

    2015-01-01

    To describe the prevalence of antimicrobial resistance among commensal Escherichia coli isolates on household and small-scale chicken farms, common in southern Vietnam, and to investigate the association of antimicrobial resistance with farming practices and antimicrobial usage. We collected data on

  17. Atmospheric stability-dependent infinite wind-farm models and the wake-decay coefficient

    OpenAIRE

    Peña, Alfredo; Rathmann, Ole

    2014-01-01

    We extend the infinite wind-farm boundary-layer (IWFBL) model of Frandsen to take into account atmospheric static stability effects. This extended model is compared with the IWFBL model of Emeis and to the Park wake model used inWind Atlas Analysis and Application Program (WAsP), which is computed for an infinite wind farm. The models show similar behavior for the wind-speed reduction when accounting for a number of surface roughness lengths, turbine to turbine separations and wind speeds und...

  18. A CFD model of the wake of an offshore wind farm: using a prescribed wake inflow

    International Nuclear Information System (INIS)

    Rethore, P-E; Bechmann, A; Soerensen, N N; Frandsen, S T; Mann, J; Joergensen, H E; Rathmann, O; Larsen, S E

    2007-01-01

    An CFD model of the wake of an offshore wind farm, expanding existing measurements is proposed. The method is based on solving the Navier Stokes equation in a large domain downstream an offshore wind farm. The inflow of the domain is estimated using existing met mast measurements from both free stream and directly in-wake conditions. A comparison between the simulation results and measurements from a met mast are presented and the shortcomings of the methods are discussed

  19. Modelling Wind for Wind Farm Layout Optimization Using Joint Distribution of Wind Speed and Wind Direction

    OpenAIRE

    Ju Feng; Wen Zhong Shen

    2015-01-01

    Reliable wind modelling is of crucial importance for wind farm development. The common practice of using sector-wise Weibull distributions has been found inappropriate for wind farm layout optimization. In this study, we propose a simple and easily implementable method to construct joint distributions of wind speed and wind direction, which is based on the parameters of sector-wise Weibull distributions and interpolations between direction sectors. It is applied to the wind measurement data a...

  20. Fast simulation approaches for power fluctuation model of wind farm based on frequency domain

    DEFF Research Database (Denmark)

    Lin, Jin; Gao, Wen-zhong; Sun, Yuan-zhang

    2012-01-01

    This paper discusses one model developed by Riso, DTU, which is capable of simulating the power fluctuation of large wind farms in frequency domain. In the original design, the “frequency-time” transformations are time-consuming and might limit the computation speed for a wind farm of large size....... is more than 300 times if all these approaches are adopted, in any low, medium and high wind speed test scenarios....

  1. Enhanced Voltage Control of VSC-HVDC Connected Offshore Wind Farms Based on Model Predictive Control

    OpenAIRE

    Guo, Yifei; Gao, Houlei; Wu, Qiuwei; Zhao, Haoran; Østergaard, Jacob; Shahidehpour, Mohammad

    2018-01-01

    This paper proposes an enhanced voltage control strategy (EVCS) based on model predictive control (MPC) for voltage source converter based high voltage direct current (VSCHVDC) connected offshore wind farms (OWFs). In the proposed MPC based EVCS, all wind turbine generators (WTGs) as well as the wind farm side VSC are optimally coordinated to keep voltages within the feasible range and reduce system power losses. Considering the high ratio of the OWF collector system, the effects of active po...

  2. Adoption of Small-Scale Irrigation Farming as a Climate-Smart Agriculture Practice and Its Influence on Household Income in the Chinyanja Triangle, Southern Africa

    Directory of Open Access Journals (Sweden)

    Nelson Mango

    2018-04-01

    Full Text Available This article is concerned with the adoption of small-scale irrigation farming as a climate-smart agriculture practice and its influence on household income in the Chinyanja Triangle. Chinyanja Triangle is a region that is increasingly experiencing mid-season dry spells and an increase in occurrence of drought, which is attributed largely to climate variability and change. This poses high agricultural production risks, which aggravate poverty and food insecurity. For this region, adoption of small-scale irrigation farming as a climate-smart agriculture practice is very important. Through a binary logistic and ordinary least squares regression, this article determines factors that influence the adoption of small-scale irrigation farming as a climate-smart agriculture practice and its influence on income among smallholder farmers. The results show that off-farm employment, access to irrigation equipment, access to reliable water sources and awareness of water conservation practices, such as rainwater harvesting, have a significant influence on the adoption of small-scale irrigation farming. On the other hand, the farmer’s age, distance travelled to the nearest market and nature of employment negatively influence the adoption of small-scale irrigation farming decisions. Ordinary least squares regression results showed that the adoption of small-scale irrigation farming as a climate-smart agriculture practice has a significant positive influence on agricultural income. We therefore conclude that to empower smallholder farmers to respond quickly to climate variability and change, practices that will enhance the adoption of small-scale irrigation farming in the Chinyanja Triangle are critical, as this will significantly affect agricultural income. In terms of policy, we recommend that the governments of Zambia, Malawi and Mozambique, which cover the Chinyanja Triangle, formulate policies that will enhance the adoption of sustainable small scale

  3. Business models in urban farming: A comparative analysis of case studies from Spain, Italy and Germany

    Directory of Open Access Journals (Sweden)

    Pölling Bernd

    2017-09-01

    Full Text Available The “Urban Agriculture Europe” EU COST-Action (2012–2016 has shown that the complexity of urban agriculture (UA is hardly compressible into classic business management models and has proposed new management models, such as the Business Model Canvas (BMC. Business models of UA have to be different from rural ones. In particular, factors such as differentiation and diversification, but also low cost-oriented specialisation, are characteristic and necessary business models for UA to stay profitable in the long term under challenging city conditions. This paper aims to highlight how farm enterprises have to adjust to urban conditions by stepping into appropriate business models aiming to stay competitive and profitable, and how the BMC is useful to analyse their organisation and performance, both economically and socially. The paper offers an inter-regional analysis of UA enterprises located in Spain, Italy, and Germany, which are further subdivided into: local food, leisure, educational, social, therapeutic, agri-environmental, cultural heritage and experimental farms. The analysis demonstrates that UA is differentially adjusted to specific urban conditions and that the BMC is useful for analysing urban farming. Heterogeneous local food farms and the integration of local and organic food production in social farming business models are most frequent in our case studies.

  4. Potential climatic impacts and reliability of large-scale offshore wind farms

    International Nuclear Information System (INIS)

    Wang Chien; Prinn, Ronald G

    2011-01-01

    The vast availability of wind power has fueled substantial interest in this renewable energy source as a potential near-zero greenhouse gas emission technology for meeting future world energy needs while addressing the climate change issue. However, in order to provide even a fraction of the estimated future energy needs, a large-scale deployment of wind turbines (several million) is required. The consequent environmental impacts, and the inherent reliability of such a large-scale usage of intermittent wind power would have to be carefully assessed, in addition to the need to lower the high current unit wind power costs. Our previous study (Wang and Prinn 2010 Atmos. Chem. Phys. 10 2053) using a three-dimensional climate model suggested that a large deployment of wind turbines over land to meet about 10% of predicted world energy needs in 2100 could lead to a significant temperature increase in the lower atmosphere over the installed regions. A global-scale perturbation to the general circulation patterns as well as to the cloud and precipitation distribution was also predicted. In the later study reported here, we conducted a set of six additional model simulations using an improved climate model to further address the potential environmental and intermittency issues of large-scale deployment of offshore wind turbines for differing installation areas and spatial densities. In contrast to the previous land installation results, the offshore wind turbine installations are found to cause a surface cooling over the installed offshore regions. This cooling is due principally to the enhanced latent heat flux from the sea surface to lower atmosphere, driven by an increase in turbulent mixing caused by the wind turbines which was not entirely offset by the concurrent reduction of mean wind kinetic energy. We found that the perturbation of the large-scale deployment of offshore wind turbines to the global climate is relatively small compared to the case of land

  5. Antibiotic Resistance in Animal and Environmental Samples Associated with Small-Scale Poultry Farming in Northwestern Ecuador.

    Science.gov (United States)

    Braykov, Nikolay P; Eisenberg, Joseph N S; Grossman, Marissa; Zhang, Lixin; Vasco, Karla; Cevallos, William; Muñoz, Diana; Acevedo, Andrés; Moser, Kara A; Marrs, Carl F; Foxman, Betsy; Trostle, James; Trueba, Gabriel; Levy, Karen

    2016-01-01

    The effects of animal agriculture on the spread of antibiotic resistance (AR) are cross-cutting and thus require a multidisciplinary perspective. Here we use ecological, epidemiological, and ethnographic methods to examine populations of Escherichia coli circulating in the production poultry farming environment versus the domestic environment in rural Ecuador, where small-scale poultry production employing nontherapeutic antibiotics is increasingly common. We sampled 262 "production birds" (commercially raised broiler chickens and laying hens) and 455 "household birds" (raised for domestic use) and household and coop environmental samples from 17 villages between 2010 and 2013. We analyzed data on zones of inhibition from Kirby-Bauer tests, rather than established clinical breakpoints for AR, to distinguish between populations of organisms. We saw significantly higher levels of AR in bacteria from production versus household birds; resistance to either amoxicillin-clavulanate, cephalothin, cefotaxime, and gentamicin was found in 52.8% of production bird isolates and 16% of household ones. A strain jointly resistant to the 4 drugs was exclusive to a subset of isolates from production birds (7.6%) and coop surfaces (6.5%) and was associated with a particular purchase site. The prevalence of AR in production birds declined with bird age (P < 0.01 for all antibiotics tested except tetracycline, sulfisoxazole, and trimethoprim-sulfamethoxazole). Farming status did not impact AR in domestic environments at the household or village level. Our results suggest that AR associated with small-scale poultry farming is present in the immediate production environment and likely originates from sources outside the study area. These outside sources might be a better place to target control efforts than local management practices. IMPORTANCE In developing countries, small-scale poultry farming employing antibiotics as growth promoters is being advanced as an inexpensive source of

  6. Centralized configuration system for a large scale farm of network booted computers

    Science.gov (United States)

    Ballestrero, S.; Brasolin, F.; Dârlea, G.-L.; Dumitru, I.; Scannicchio, D. A.; Twomey, M. S.; Vâlsan, M. L.; Zaytsev, A.

    2012-12-01

    The ATLAS trigger and data acquisition online farm is composed of nearly 3,000 computing nodes, with various configurations, functions and requirements. Maintaining such a cluster is a big challenge from the computer administration point of view, thus various tools have been adopted by the System Administration team to help manage the farm efficiently. In particular, a custom central configuration system, ConfDBv2, was developed for the overall farm management. The majority of the systems are network booted, and are running an operating system image provided by a Local File Server (LFS) via the local area network (LAN). This method guarantees the uniformity of the system and allows, in case of issues, very fast recovery of the local disks which could be used as scratch area. It also provides greater flexibility as the nodes can be reconfigured and restarted with a different operating system in a very timely manner. A user-friendly web interface offers a quick overview of the current farm configuration and status, allowing changes to be applied on selected subsets or on the whole farm in an efficient and consistent manner. Also, various actions that would otherwise be time consuming and error prone can be quickly and safely executed. We describe the design, functionality and performance of this system and its web-based interface, including its integration with other CERN and ATLAS databases and with the monitoring infrastructure.

  7. Enhanced Kalman Filtering for a 2D CFD NS Wind Farm Flow Model

    International Nuclear Information System (INIS)

    Doekemeijer, B M; Van Wingerden, J W; Boersma, S; Pao, L Y

    2016-01-01

    Wind turbines are often grouped together for financial reasons, but due to wake development this usually results in decreased turbine lifetimes and power capture, and thereby an increased levelized cost of energy (LCOE). Wind farm control aims to minimize this cost by operating turbines at their optimal control settings. Most state-of-the-art control algorithms are open-loop and rely on low fidelity, static flow models. Closed-loop control relying on a dynamic model and state observer has real potential to further decrease wind's LCOE, but is often too computationally expensive for practical use. In this paper two time-efficient Kalman filter (KF) variants are outlined incorporating the medium fidelity, dynamic flow model “WindFarmSimulator” (WFSim). This model relies on a discretized set of Navier-Stokes equations in two dimensions to predict the flow in wind farms at low computational cost. The filters implemented are an Ensemble KF and an Approximate KF. Simulations in which a high fidelity simulation model represents the true wind farm show that these filters are 10"1 —10"2 times faster than a regular KF with comparable or better performance, correcting for wake dynamics that are not modeled in WFSim (noticeably, wake meandering and turbine hub effects). This is a first big step towards real-time closed-loop control for wind farms. (paper)

  8. Development of a wind farm noise propagation prediction model - project progress to date

    International Nuclear Information System (INIS)

    Robinson, P.; Bullmore, A.; Bass, J.; Sloth, E.

    1998-01-01

    This paper describes a twelve month measurement campaign which is part of a European project (CEC Project JOR3-CT95-0051) with the aim to substantially reduce the uncertainties involved in predicting environmentally radiated noise levels from wind farms (1). This will be achieved by comparing noise levels measure at varying distances from single and multiple sources over differing complexities of terrain with those predicted using a number of currently adopted sound propagation models. Specific objectives within the project are to: establish the important parameters controlling the propagation of wind farm noise to the far field; develop a planning tool for predicting wind farm noise emission levels under practically encountered conditions; place confidence limits on the upper and lower bounds of the noise levels predicted, thus enabling developers to quantify the risk whether noise emission from wind farms will cause nuisance to nearby residents. (Author)

  9. Stackelberg Game Model of Wind Farm and Electric Vehicle Battery Switch Station

    Science.gov (United States)

    Jiang, Zhe; Li, Zhimin; Li, Wenbo; Wang, Mingqiang; Wang, Mengxia

    2017-05-01

    In this paper, a cooperation method between wind farm and Electric vehicle battery switch station (EVBSS) was proposed. In the pursuit of maximizing their own benefits, the cooperation between wind farm and EVBSS was formulated as a Stackelberg game model by treating them as decision makers in different status. As the leader, wind farm will determine the charging/discharging price to induce the charging and discharging behavior of EVBSS reasonably. Through peak load shifting, wind farm could increase its profits by selling more wind power to the power grid during time interval with a higher purchase price. As the follower, EVBSS will charge or discharge according to the price determined by wind farm. Through optimizing the charging /discharging strategy, EVBSS will try to charge with a lower price and discharge with a higher price in order to increase its profits. Since the possible charging /discharging strategy of EVBSS is known, the wind farm will take the strategy into consideration while deciding the charging /discharging price, and will adjust the price accordingly to increase its profits. The case study proved that the proposed cooperation method and model were feasible and effective.

  10. A high performance finite element model for wind farm modeling in forested areas

    Science.gov (United States)

    Owen, Herbert; Avila, Matias; Folch, Arnau; Cosculluela, Luis; Prieto, Luis

    2015-04-01

    Wind energy has grown significantly during the past decade and is expected to continue growing in the fight against climate change. In the search for new land where the impact of the wind turbines is small several wind farms are currently being installed in forested areas. In order to optimize the distribution of the wind turbines within the wind farm the Reynolds Averaged Navier Stokes equations are solved over the domain of interest using either commercial or in house codes. The existence of a canopy alters the Atmospheric Boundary Layer wind profile close to the ground. Therefore in order to obtain a more accurate representation of the flow in forested areas modification to both the Navier Stokes and turbulence variables equations need to be introduced. Several existing canopy models have been tested in an academic problem showing that the one proposed by Sogachev et. al gives the best results. This model has been implemented in an in house CFD solver named Alya. It is a high performance unstructured finite element code that has been designed from scratch to be able to run in the world's biggest supercomputers. Its scalabililty has recently been tested up to 100000 processors in both American and European supercomputers. During the past three years the code has been tuned and tested for wind energy problems. Recent efforts have focused on the canopy model following industry needs. In this work we shall benchmark our results in a wind farm that is currently being designed by Scottish Power and Iberdrola in Scotland. This is a very interesting real case with extensive experimental data from five different masts with anemometers at several heights. It is used to benchmark both the wind profiles and the speed up obtained between different masts. Sixteen different wind directions are simulated. The numerical model provides very satisfactory results for both the masts that are affected by the canopy and those that are not influenced by it.

  11. Assessing the impact of marine wind farms on birds through movement modelling.

    Science.gov (United States)

    Masden, Elizabeth A; Reeve, Richard; Desholm, Mark; Fox, Anthony D; Furness, Robert W; Haydon, Daniel T

    2012-09-07

    Advances in technology and engineering, along with European Union renewable energy targets, have stimulated a rapid growth of the wind power sector. Wind farms contribute to carbon emission reductions, but there is a need to ensure that these structures do not adversely impact the populations that interact with them, particularly birds. We developed movement models based on observed avoidance responses of common eider Somateria mollissima to wind farms to predict, and identify potential measures to reduce, impacts. Flight trajectory data that were collected post-construction of the Danish Nysted offshore wind farm were used to parameterize competing models of bird movements around turbines. The model most closely fitting the observed data incorporated individual variation in the minimum distance at which birds responded to the turbines. We show how such models can contribute to the spatial planning of wind farms by assessing their extent, turbine spacing and configurations on the probability of birds passing between the turbines. Avian movement models can make new contributions to environmental assessments of wind farm developments, and provide insights into how to reduce impacts that can be identified at the planning stage.

  12. A process-based emission model of volatile organic compounds from silage sources on farms

    Science.gov (United States)

    Bonifacio, H. F.; Rotz, C. A.; Hafner, S. D.; Montes, F.; Cohen, M.; Mitloehner, F. M.

    2017-03-01

    Silage on dairy farms can emit large amounts of volatile organic compounds (VOCs), a precursor in the formation of tropospheric ozone. Because of the challenges associated with direct measurements, process-based modeling is another approach for estimating emissions of air pollutants from sources such as those from dairy farms. A process-based model for predicting VOC emissions from silage was developed and incorporated into the Integrated Farm System Model (IFSM, v. 4.3), a whole-farm simulation of crop, dairy, and beef production systems. The performance of the IFSM silage VOC emission model was evaluated using ethanol and methanol emissions measured from conventional silage piles (CSP), silage bags (SB), total mixed rations (TMR), and loose corn silage (LCS) at a commercial dairy farm in central California. With transport coefficients for ethanol refined using experimental data from our previous studies, the model performed well in simulating ethanol emission from CSP, TMR, and LCS; its lower performance for SB could be attributed to possible changes in face conditions of SB after silage removal that are not represented in the current model. For methanol emission, lack of experimental data for refinement likely caused the underprediction for CSP and SB whereas the overprediction observed for TMR can be explained as uncertainty in measurements. Despite these limitations, the model is a valuable tool for comparing silage management options and evaluating their relative effects on the overall performance, economics, and environmental impacts of farm production. As a component of IFSM, the silage VOC emission model was used to simulate a representative dairy farm in central California. The simulation showed most silage VOC emissions were from feed lying in feed lanes and not from the exposed face of silage storages. This suggests that mitigation efforts, particularly in areas prone to ozone non-attainment status, should focus on reducing emissions during feeding. For

  13. Statistical meandering wake model and its application to yaw-angle optimisation of wind farms

    DEFF Research Database (Denmark)

    Thøgersen, Emil; Tranberg, Bo; Herp, Jürgen

    2017-01-01

    wakes are treated as independently and identically distributed random variables. When carefully calibrated to the Nysted wind farm, the ensemble average of the statistical model produces the same wind-direction dependence of the power efficiency as obtained from the standard Jensen model. Upon using...... the JWM to perform a yaw-angle optimisation of wind-farm power output, we find an optimisation gain of 6.7% for the Nysted wind farm when compared to zero yaw angles and averaged over all wind directions. When applying the obtained JWM-based optimised yaw angles to the SMWM, the ensemble-averaged gain......The wake produced by a wind turbine is dynamically meandering and of rather narrow nature. Only when looking at large time averages, the wake appears to be static and rather broad, and is then well described by simple engineering models like the Jensen wake model (JWM). We generalise the latter...

  14. Farm-scale thermophilic co-digestion of dairy manure with a biodiesel byproduct in cold regions

    International Nuclear Information System (INIS)

    Andriamanohiarisoamanana, Fetra J.; Yamashiro, Takaki; Ihara, Ikko; Iwasaki, Masahiro; Nishida, Takehiro; Umetsu, Kazutaka

    2016-01-01

    Highlights: • Co-digestion of dairy manure and crude glycerin was conducted using a 60 m 3 reactor. • The highest methane yield was 0.323 m 3 /kgVS obtained at 4.2% (v/v) of crude glycerin. • The optimum organic loading rate for crude glycerol was 1.32 kgVS CG /m 3 d. • Reactor energy self-sufficiency was observed with net energy output of 25 kW h/d. - Abstract: Conversion of organic wastes into applicable energy sources is the best way to improve organic waste management. In this study, the performance of thermophilic co-digestion of dairy manure (DM) and crude glycerol (CG) in a 60-m 3 farm-scale biogas digester located in a cold region was investigated during the winter. Compared to the anaerobic digestion of DM alone, the methane production increased by approximately twofold during co-digestion of DM and CG. The highest methane yield was 0.323 m 3 /kgVS obtained at 4.2% (v/v) of CG. Despite the increase in methane production with organic loading rate, the methane yield of CG reduced remarkably at 2.64 kgVS CG /m 3 d, while the highest was at 1.32 kgVS CG /m 3 d. During the co-digestion, a net energy at an average of 25 kWh/d was obtained for farm operation, whereas a supply of kerosene and electricity from national grid were required for the digester and farm operations during anaerobic digestion of DM. During winter, the improvement of biogas yield through the addition of CG enabled the sustainability of a farm-scale biogas production system and reduced its environmental impact.

  15. Canadian Whole-Farm Model Holos - Development, Stakeholder Involvement, and Model Application

    Science.gov (United States)

    Kroebel, R.; Janzen, H.; Beauchemin, K. A.

    2017-12-01

    Agriculture and Agri-Food Canada's Holos model, based mostly on emission factors, aims to explore the effect of management on Canadian whole-farm greenhouse gas emissions. The model includes 27 commonly grown annual and perennial crops, summer fallow, grassland, and 8 types of tree plantings, along with beef, dairy, sheep, swine and other livestock or poultry operations. Model outputs encompass net emissions of CO2, CH4, and N2O (in CO2 equivalents), calculated for various farm components. Where possible, algorithms are drawn from peer-reviewed publications. For consistency, Holos is aligned with the Canadian sustainability indicator and national greenhouse gas inventory objectives. Although primarily an exploratory tool for research, the model's design makes it accessible and instructive also to agricultural producers, educators, and policy makers. Model development, therefore, proceeds iteratively, with extensive stakeholder feedback from training sessions or annual workshops. To make the model accessible to diverse users, the team developed a multi-layered interface, with general farming scenarios for general use, but giving access to detailed coefficients and assumptions to researchers. The model relies on extensive climate, soil, and agronomic databases to populate regionally-applicable default values thereby minimizing keyboard entries. In an initial application, the model was used to assess greenhouse gas emissions from the Canadian beef production system; it showed that enteric methane accounted for 63% of total GHG emissions and that 84% of emissions originated from the cow-calf herd. The model further showed that GHG emission intensity per kg beef, nationally, declined by 14% from 1981 to 2011, owing to gains in production efficiency. Holos is now being used to consider further potential advances through improved rations or other management options. We are now aiming to expand into questions of grazing management, and are developing a novel carbon

  16. Antimicrobials in small-scale urban pig farming in a lower middle-income country - arbitrary use and high resistance levels.

    Science.gov (United States)

    Ström, G; Boqvist, S; Albihn, A; Fernström, L-L; Andersson Djurfeldt, A; Sokerya, S; Sothyra, T; Magnusson, U

    2018-01-01

    Administration of antimicrobials to food-producing animals is regarded as a major contributor to the overall emergence of resistance in bacteria worldwide. However, few data are available on global antimicrobial use and resistance (AMR) in livestock, especially from low- and middle-income countries. We conducted a structured survey of 91 small-scale pig farms in the urban and peri-urban areas of Phnom Penh, Cambodia, to assess the farmers' knowledge, attitudes and practices related to antimicrobial use in their pig production. Commensal Escherichia coli was isolated from three healthy pigs from each farm ( n  = 261) and susceptibility testing was performed against 14 antimicrobials, using broth microdilution. Univariable logistic regression and generalized linear mixed models were used to investigate potential associations between farm characteristics, management factors and resistance to different types of antimicrobials. We found a widespread and arbitrary use of antimicrobials, often based on the farmer's own judgment. Around 66% of the farmers reported frequently self-adjusting treatment duration and dosage, and 45% had not heard about the term 'antimicrobial resistance'. The antimicrobials most commonly mentioned or kept by the farmers were amoxicillin, tylosin, gentamicin and colistin. Around 37% used a feed concentrate that contained antimicrobials, while antimicrobials for humans were used as a last-line treatment by 10% of the farmers. Commensal E. coli exhibited high prevalence of resistance to several antimicrobials considered to be of critical importance for human medicine, including ampicillin, ciprofloxacin and colistin, and multidrug-resistance was found in 79% of the samples. Higher prevalence of resistance was observed on farms that administered prophylactic antimicrobials and on farms that treated the entire group or herd in the event of disease. The widespread and arbitrary use of antimicrobials in pig farming in Cambodia is highly worrisome

  17. Zoonotic Transmission of mcr-1 Colistin Resistance Gene from Small-Scale Poultry Farms, Vietnam

    NARCIS (Netherlands)

    Trung, N.V.; Matamoros, S.; Carrique-Mas, J.J.; Nghia, N.H.; Nhung, N.T.; Chieu, T.T.B.; Mai, H.H.; Van Rooijen, W.; Campbell, J.; Wagenaar, J.A.; Hardon, A.; Mai, N.T.N.; Hieu, T.Q.; Thwaites, G.; de Jong, M.D.; Schultsz, C.; Hoa, N.T.

    We investigated the consequences of colistin use in backyard chicken farms in Vietnam by examining the prevalence of mcr-1 in fecal samples from chickens and humans. Detection of mcr-1–carrying bacteria in chicken samples was associated with colistin use and detection in human samples with exposure

  18. Zoonotic Transmission of mcr-1 Colistin Resistance Gene from Small-Scale Poultry Farms, Vietnam

    NARCIS (Netherlands)

    Trung, Nguyen Vinh; Matamoros, Sébastien; Carrique-Mas, Juan J.; Nghia, Nguyen Huu; Nhung, Nguyen Thi; Chieu, Tran Thi Bich; Mai, Ho Huynh; van Rooijen, Willemien; Campbell, James; Wagenaar, Jaap A.; Hardon, Anita; Mai, Nguyen Thi Nhu; Hieu, Thai Quoc; Thwaites, Guy; de Jong, Menno D.; Schultsz, Constance; Hoa, Ngo Thi

    2017-01-01

    We investigated the consequences of colistin use in backyard chicken farms in Vietnam by examining the prevalence of mcr-1 in fecal samples from chickens and humans. Detection of mcr-1-carrying bacteria in chicken samples was associated with colistin use and detection in human samples with exposure

  19. Evaluation of Four Farm-scale Systems for the Treatment of Liquid Pig Manure

    NARCIS (Netherlands)

    Melse, R.W.; Verdoes, N.

    2005-01-01

    In some regions in the Netherlands, high pig concentrations and limited availability of arable land have led to a surplus of manure which results in high off-farm manure disposal costs. The aim of manure treatment is to lower manure transport costs by reducing the volume and to improve market

  20. The economic value of Acacia karroo in small-scale farming systems ...

    African Journals Online (AJOL)

    Due to the prevailing soil acidity problems and extensive land degradation, it is suggested that the tree has potential in agroforestry to change and improve the sustainability and profitability of both agriculture and ecotourism through game farming in the area. It is also acknowledged that for any land use to expand in a ...

  1. Ascariasis in Humans and Pigs on Small-Scale Farms, Maine, USA, 2010–2013

    Science.gov (United States)

    Colby, Kate; Manning, Susan E.; Hoenig, Donald; McEvoy, Elizabeth; Montgomery, Susan; Mathison, Blaine; de Almeida, Marcos; Bishop, Henry; Dasilva, Alexandre; Sears, Stephen

    2015-01-01

    Ascaris is a genus of parasitic nematodes that can cause infections in humans and pigs. During 2010–2013, we identified 14 cases of ascariasis in persons who had contact with pigs in Maine, USA. Ascaris spp. are important zoonotic pathogens, and prevention measures are needed, including health education, farming practice improvements, and personal and food hygiene. PMID:25626125

  2. Bringing ISFM to scale through an integrated farm planning approach: a case study from Burundi

    NARCIS (Netherlands)

    Kessler, A.; Duivenbooden, van N.; Nsabimana, F.; Beek, van C.L.

    2016-01-01

    Integrated soil fertility management (ISFM) is generally accepted as the most relevant paradigm for soil fertility improvement in the tropics. Successes however are mainly reported at plot level, while real impact at farm level and beyond remains scattered. As a consequence, many Sub-Saharan African

  3. Agricultural marketing systems and sustainability : study of small scale Andean hillside farms

    NARCIS (Netherlands)

    Castaño, J.

    2001-01-01

    A better understanding of the way in which marketing systems can contribute to the adoption of sustainable agricultural practices (ASAP) on small-farms constitutes the aim of this study. In particular, the study examines the contribution of vertical

  4. Modeling large offshore wind farms under different atmospheric stability regimes with the Park wake model

    DEFF Research Database (Denmark)

    Pena Diaz, Alfredo; Réthoré, Pierre-Elouan; Rathmann, Ole

    2014-01-01

    We evaluate a modified version of the Park wake model against power data from a west-east row in the middle of the Horns Rev I offshore wind farm. The evaluation is performed on data classified in four different atmospheric stability conditions, for a narrow wind speed range, and a wide range...... turbines on the row and those using the WAsP recommended value closer to the data for the first turbines. It is generally seen that under stable and unstable atmospheric conditions the power deficits are the highest and lowest, respectively, but the wind conditions under both stability regimes...

  5. Modeling large offshore wind farms under different atmospheric stability regimes with the Park wake model

    DEFF Research Database (Denmark)

    Peña, Alfredo; Réthoré, Pierre-Elouan; Rathmann, Ole

    2013-01-01

    Here, we evaluate a modified version of the Park wake model against power data from a west-east row in the middle of the Horns Rev I offshore wind farm. The evaluation is performed on data classified in four different atmospheric stability conditions, for a narrow wind speed range, and a wide range...... turbines and those using the WAsP recommended value closer to the data for the first turbines. It is generally seen that under stable and unstable atmospheric conditions the power deficits are the highest and lowest, respectively, but the wind conditions under both stability regimes are different...

  6. The effect of a giant wind farm on precipitation in a regional climate model

    International Nuclear Information System (INIS)

    Fiedler, B H; Bukovsky, M S

    2011-01-01

    The Weather Research and Forecasting (WRF) model is employed as a nested regional climate model to study the effect of a giant wind farm on warm-season precipitation in the eastern two-thirds of the USA. The boundary conditions for WRF are supplied by 62 years of NCEP/NCAR (National Center for Environmental Prediction/National Center for Atmospheric Research) global reanalysis. In the model, the presence of a mid-west wind farm, either giant or small, can have an enormous impact on the weather and the amount of precipitation for one season, which is consistent with the known sensitivity of long-term weather forecasts to initial conditions. The effect on climate is less strong. In the average precipitation of 62 warm seasons, there is a statistically significant 1.0% enhancement of precipitation in a multi-state area surrounding and to the south-east of the wind farm.

  7. Modelling and Measuring Flow and Wind Turbine Wakes in Large Wind Farms Offshore

    DEFF Research Database (Denmark)

    Barthelmie, Rebecca Jane; Hansen, Kurt Schaldemose; Frandsen, Sten Tronæs

    2009-01-01

    Average power losses due to wind turbine wakes are of the order of 10 to 20% of total power output in large offshore wind farms. Accurately quantifying power losses due to wakes is, therefore, an important part of overall wind farm economics. The focus of this research is to compare different types...... power losses due to wakes and loads. The research presented is part of the EC-funded UpWind project, which aims to radically improve wind turbine and wind farm models in order to continue to improve the costs of wind energy. Reducing wake losses, or even reduce uncertainties in predicting power losses...... from wakes, contributes to the overall goal of reduced costs. Here, we assess the state of the art in wake and flow modelling for offshore wind forms, the focus so for has been cases at the Horns Rev wind form, which indicate that wind form models require modification to reduce under-prediction of wake...

  8. New Models for Maintenance of Offshore Wind Farms

    DEFF Research Database (Denmark)

    Petersen, Kristian R.

    . The approach was tested on an offshore wind farm. The findings showed that the approach can help the asset owner identify possible future events that influence the assets both negatively and positively. Evaluating the events in a life-cycle plan may reveal how the asset owner can mitigate negative events...... shown that such approaches should be multidisciplinary; however, previous attempts have mainly considered technical and economic aspects of the operation of assets. Thus, a truly multidisciplinary approach that includes technical, economic, customer, compliance, and organisational aspects was developed......&M of an asset, it is important to consider three decision-making perspectives: short-term operational, medium-term tactical, and long-term strategic. However, the main focus has been on day-to-day operational issues, which leaves no room for longer-term thinking. Through three research projects, one on each...

  9. A model for optimal fleet composition of vessels for offshore wind farm maintenance

    NARCIS (Netherlands)

    Alcoba, A.G.; Ortega, G.; Hendrix, E.M.T.; Halvorsen-Waere, E.E.; Haugland, Dag

    2017-01-01

    We present a discrete optimisation model that chooses an optimal fleet of vessels to support maintenance operations at Offshore Wind Farms (OFWs). The model is presented as a bi-level problem. On the first (tactical) level, decisions are made on the fleet composition for a certain time horizon. On

  10. Actuator disk model of wind farms based on the rotor average wind speed

    DEFF Research Database (Denmark)

    Han, Xing Xing; Xu, Chang; Liu, De You

    2016-01-01

    Due to difficulty of estimating the reference wind speed for wake modeling in wind farm, this paper proposes a new method to calculate the momentum source based on the rotor average wind speed. The proposed model applies volume correction factor to reduce the influence of the mesh recognition...

  11. An integrated model for estimating energy cost of a tidal current turbine farm

    International Nuclear Information System (INIS)

    Li, Ye; Lence, Barbara J.; Calisal, Sander M.

    2011-01-01

    A tidal current turbine is a device for harnessing energy from tidal currents and functions in a manner similar to a wind turbine. A tidal current turbine farm consists of a group of tidal current turbines distributed in a site where high-speed current is available. The accurate prediction of energy cost of a tidal current turbine farm is important to the justification of planning and constructing such a farm. However, the existing approaches used to predict energy cost of tidal current turbine farms oversimplify the hydrodynamic interactions between turbines in energy prediction and oversimplify the operation and maintenance strategies involved in cost estimation as well as related fees. In this paper, we develop a model, which integrates a marine hydrodynamic model with high accuracy for predicting energy output and a comprehensive cost-effective operation and maintenance model for estimating the cost that may be incurred in producing the energy, to predict energy cost from a tidal current turbine farm. This model is expected to be able to simulate more complicated cases and generate more accurate results than existing models. As there is no real tidal current turbine farm, we validate this model with offshore wind studies. Finally, case studies about Vancouver are conducted with a scenario-based analysis. We minimize the energy cost by minimizing the total cost and maximizing the total power output under constraints related to the local conditions (e.g., geological and labor information) and the turbine specifications. The results suggest that tidal current energy is about ready to penetrate the electricity market in some major cities in North America if learning curve for the operational and maintenance is minimum. (author)

  12. Regional-scale variation in the distribution and abundance of farming damselfishes on Australia's Great Barrier Reef

    KAUST Repository

    Emslie, Michael J.

    2012-03-15

    Territorial damselfishes that manipulate ("farm") the algae in their territories can have a marked effect on benthic community structure and may influence coral recovery following disturbances. Despite the numerical dominance of farming species on many reefs, the importance of their grazing activities is often overlooked, with most studies only examining their roles over restricted spatial and temporal scales. We used the results of field surveys covering 9.5° of latitude of the Great Barrier Reef to describe the distribution, abundance and temporal dynamics of farmer communities. Redundancy analysis revealed unique subregional assemblages of farming species that were shaped by the combined effects of shelf position and, to a lesser extent, by latitude. These spatial patterns were largely stable through time, except when major disturbances altered the benthic community. Such disturbances affected the functional guilds of farmers in different ways. Since different guilds of farmers modify benthic community structure and affect survival of juvenile corals in different ways, these results have important implications for coral recovery following disturbances. © 2012 Springer-Verlag.

  13. Long Island Solar Farm

    Energy Technology Data Exchange (ETDEWEB)

    Anders, R.

    2013-05-01

    The Long Island Solar Farm (LISF) is a remarkable success story, whereby very different interest groups found a way to capitalize on unusual circumstances to develop a mutually beneficial source of renewable energy. The uniqueness of the circumstances that were necessary to develop the Long Island Solar Farm make it very difficult to replicate. The project is, however, an unparalleled resource for solar energy research, which will greatly inform large-scale PV solar development in the East. Lastly, the LISF is a superb model for the process by which the project developed and the innovation and leadership shown by the different players.

  14. Transforming ex-small scale mining land as farming areas for sustainable development and poverty alleviation

    Science.gov (United States)

    Nampa, I. W.; Markus, J. E. R.; Mudita, I. W.; Natonis, R. L.; Bunga, W.; Kaho, N. R.

    2018-03-01

    When the price of manganese ores in 2012, mining activities declined or even terminated. Ex-miners lose an important source of income, but they did not have any other alternative except going back to slash and burn cultivation, producing enough only for their own food. Their hope for a better live was gone and at the same time they faced stigmatisation as causing environmental degradation from the rest of the community. We carried out this case study to followex-miners in the Tubuhue village who organised themselves to do post-mining rehabilitation by turning the former mining site into an area of productive farming. In-depth interview, field observation and focus group discussion were conducted from 2015 to 2017. We found that during the period of mining boom, slash and burn cultivation decrease significantly but began to increase after no mining activities. Various social transformations took place along with this land use change, but the most important was the miners’ decision to do mining as an organised activity. A strong leader of this organization played a pivotal role in turning the former mining site into an area of productive sedentary farming. This was carried out by organizing the ex-miners into farmers groups and together, constructing drip and sprinkler irrigation networks to water their crops using rain water collected in the mining holes that they had turned into small check-dams. The leader expected that this farming could provide an alternative for ex-miners to obtain cash income to limit them going back doing swidden farming.

  15. Modelling Wind for Wind Farm Layout Optimization Using Joint Distribution of Wind Speed and Wind Direction

    DEFF Research Database (Denmark)

    Feng, Ju; Shen, Wen Zhong

    2015-01-01

    Reliable wind modelling is of crucial importance for wind farm development. The common practice of using sector-wise Weibull distributions has been found inappropriate for wind farm layout optimization. In this study, we propose a simple and easily implementable method to construct joint distribu......Reliable wind modelling is of crucial importance for wind farm development. The common practice of using sector-wise Weibull distributions has been found inappropriate for wind farm layout optimization. In this study, we propose a simple and easily implementable method to construct joint...... quite well in terms of the coefficient of determination R-2. Then, the best of these joint distributions is used in the layout optimization of the Horns Rev 1 wind farm and the choice of bin sizes for wind speed and wind direction is also investigated. It is found that the choice of bin size for wind...... direction is especially critical for layout optimization and the recommended choice of bin sizes for wind speed and wind direction is finally presented....

  16. The possibility of functioning micro-scale biogas plant in selected farm

    Directory of Open Access Journals (Sweden)

    Czekała Wojciech

    2017-12-01

    Full Text Available Renewable energy sources (RES become more and more popular. In Poland, biomass has the highest energy potential among all RES. Methane fermentation is one of possible ways to use it. The aim of the study was to perform energy and economic calculations for the biogas plant installation project in an existing farm situated in the Wielkopolska voivodeship. Because of the small area of the farm and the type of production, the calculations were carried out for micro-installation biogas plants. During the preparation of the project the production potential of the substrates was determined, allowing for further analyses. It was calculated that the electrical power of the designed biogas plant was 8.10 kW, with a total annual production of biogas at 29 471 m3. The obtained amount allows to generate in the cogeneration system 66 450 kWh of electricity and 71 190 kWh of heat energy. Some of the energy produced can be used on the farm and its surplus sold to the grid, which will allow for financial and environmental benefits.

  17. Prediction of Fecal Nitrogen and Fecal Phosphorus Content for Lactating Dairy Cows in Large-scale Dairy Farms

    Directory of Open Access Journals (Sweden)

    QU Qing-bo

    2017-05-01

    Full Text Available To facilitate efficient and sustainable manure management and reduce potential pollution, it's necessary for precise prediction of fecal nutrient content. The aim of this study is to build prediction models of fecal nitrogen and phosphorus content by the factors of dietary nutrient composition, days in milk, milk yield and body weight of Chinese Holstein lactating dairy cows. 20 kinds of dietary nutrient composition and 60 feces samples were collected from lactating dairy cows from 7 large-scale dairy farms in Tianjin City; The fecal nitrogen and phosphorus content were analyzed. The whole data set was divided into training data set and testing data set. The training data set, including 14 kinds of dietary nutrient composition and 48 feces samples, was used to develop prediction models. The relationship between fecal nitrogen or phosphorus content and dietary nutrient composition was illustrated by means of correlation and regression analysis using SAS software. The results showed that fecal nitrogen(FN content was highly positively correlated with organic matter intake(OMI and crude fat intake(CFi, and correlation coefficients were 0. 836 and 0. 705, respectively. Negative correlation coefficient was found between fecal phosphorus(FP content and body weight(BW, and the correlation coefficient was -0.525. Among different approaches to develop prediction models, the results indicated that determination coefficients of multiple linear regression equations were higher than those of simple linear regression equations. Specially, fecal nitrogen content was excellently predicted by milk yield(MY, days in milk(DIM, organic matter intake(OMI and nitrogen intake(NI, and the model was as follows:y=0.43+0.29×MY+0.02×DIM+0.92×OMI-13.01×NI (R2=0.96. Accordingly, the highest determination coefficient of prediction equation of FP content was 0.62, when body weight(BW, phosphorus intake(PI and nitrogen intake(NI were combined as predictors. The prediction

  18. Technical Report on Alberta Essay Scales: Models.

    Science.gov (United States)

    Nyberg, Verner R.; Nyberg, Adell M.

    The supplementary information on "Alberta Essay Scales: Models" presented here includes similar models to employ in grading essays, the background and development of the scales, and the rationale for developing two scales of English mechanics and style/content. A standard is presented for evaluating current writing achievement by…

  19. Environmental impacts of innovative dairy farming systems aiming at improved internal nutrient cycling: a multi-scale assessment

    NARCIS (Netherlands)

    Vries, de W.; Kros, J.; Dolman, M.A.; Vellinga, Th.V.; Boer, de H.C.; Sonneveld, M.P.W.; Bouma, J.

    2015-01-01

    Several dairy farms in the Netherlands aim at reducing environmental impacts by improving the internal nutrient cycle (INC) on their farm by optimizing the use of available on-farm resources. This study evaluates the environmental performance of selected INC farms in the Northern Friesian Woodlands

  20. Impacts of climate change on farm income security in Central Asia: An integrated modeling approach

    OpenAIRE

    Bobojonov, Ihtiyor; Aw-Hassan, Aden

    2014-01-01

    Increased risk due to global warming has already become embedded in agricultural decision making in Central Asia and uncertainties are projected to increase even further. Agro-ecology and economies of Central Asia are heterogenous and very little is known about the impact of climate change at the sub-national levels. The bio-economic farm model (BEFM) is used for ex ante assessment of climate change impacts at sub-national levels in Central Asia. The BEFM is calibrated to 10 farming systems i...

  1. Generalized coupled wake boundary layer model: applications and comparisons with field and LES data for two wind farms

    NARCIS (Netherlands)

    Stevens, Richard Johannes Antonius Maria; Gayme, Dennice F.; Meneveau, Charles

    2016-01-01

    We describe a generalization of the coupled wake boundary layer (CWBL) model for wind farms that can be used to evaluate the performance of wind farms under arbitrary wind inflow directions, whereas the original CWBL model (Stevens et al., J. Renewable and Sustainable Energy 7, 023115 (2015))

  2. Guest Editorial Modeling and Advanced Control of Wind Turbines/Wind Farms

    Energy Technology Data Exchange (ETDEWEB)

    Hu, J.; Hou, Y.; Zhu, Z.; Xu, D.; Xu, D.; Muljadi, E.; Liu, F.; Iwanski, G.; Geng, H.; Erlich, I.; Wen, J.; Harnefors, L.; Fan, L.; El Moursi, M. S.; Kjaer, P. C.; Nelson, R. J.; Cardenas, R.; Feng, S.; Islam, S.; Qiao, W.; Yuan, X.

    2017-09-01

    The papers in this special section brings together papers focused on the recent advancements and breakthroughs in the technology of modeling and enhanced active/reactive power control of wind power conversion systems, ranging from components of wind turbines to wind farms.

  3. Integrated Organic Farm; a model aimed at contributing to food security for indigenous communities in Talamanca

    Directory of Open Access Journals (Sweden)

    Ricardo Salazar-Díaz

    2015-06-01

    Traditional farming in Talamanca comes from the continuous and balanced relationship between humans and their natural environment; however, there is evidence of deterioration in this relationship. As a result of this initiative, this proposal intends to be a model to be replicated in neighboring communities and so contribute to sustainable human development in the region of Talamanca.

  4. On-farm evaluation of the Salmon Welfare Index Model (SWIM 1.0)

    NARCIS (Netherlands)

    Folkedal, O.; Pettersen, J.M.; Bracke, M.B.; Stien, L.H.; Nilsson, J.; Martins, C.; Breck, O.; Midtlyng, P.J.; Kristiansen, T.

    2016-01-01

    The present study investigated the operational feasibility of the recently developed Salmon Welfare Index Model (SWIM 1.0) designed for Atlantic salmon (Salmo salar L) in production cages. Ten salmon farms containing spring smolts were visited twice, first between May and June the first year in

  5. Simulation of a 7.7 MW onshore wind farm with the Actuator Line Model

    Science.gov (United States)

    Guggeri, A.; Draper, M.; Usera, G.

    2017-05-01

    Recently, the Actuator Line Model (ALM) has been evaluated with coarser resolution and larger time steps than what is generally recommended, taking into account an atmospheric sheared and turbulent inflow condition. The aim of the present paper is to continue these studies, assessing the capability of the ALM to represent the wind turbines’ interactions in an onshore wind farm. The ‘Libertad’ wind farm, which consists of four 1.9MW Vestas V100 wind turbines, was simulated considering different wind directions, and the results were compared with the wind farm SCADA data, finding good agreement between them. A sensitivity analysis was performed to evaluate the influence of the spatial resolution, finding acceptable agreement, although some differences were found. It is believed that these differences are due to the characteristics of the different Atmospheric Boundary Layer (ABL) simulations taken as inflow condition (precursor simulations).

  6. Potential climatic impacts and reliability of very large-scale wind farms

    Directory of Open Access Journals (Sweden)

    C. Wang

    2010-02-01

    Full Text Available Meeting future world energy needs while addressing climate change requires large-scale deployment of low or zero greenhouse gas (GHG emission technologies such as wind energy. The widespread availability of wind power has fueled substantial interest in this renewable energy source as one of the needed technologies. For very large-scale utilization of this resource, there are however potential environmental impacts, and also problems arising from its inherent intermittency, in addition to the present need to lower unit costs. To explore some of these issues, we use a three-dimensional climate model to simulate the potential climate effects associated with installation of wind-powered generators over vast areas of land or coastal ocean. Using wind turbines to meet 10% or more of global energy demand in 2100, could cause surface warming exceeding 1 °C over land installations. In contrast, surface cooling exceeding 1 °C is computed over ocean installations, but the validity of simulating the impacts of wind turbines by simply increasing the ocean surface drag needs further study. Significant warming or cooling remote from both the land and ocean installations, and alterations of the global distributions of rainfall and clouds also occur. These results are influenced by the competing effects of increases in roughness and decreases in wind speed on near-surface turbulent heat fluxes, the differing nature of land and ocean surface friction, and the dimensions of the installations parallel and perpendicular to the prevailing winds. These results are also dependent on the accuracy of the model used, and the realism of the methods applied to simulate wind turbines. Additional theory and new field observations will be required for their ultimate validation. Intermittency of wind power on daily, monthly and longer time scales as computed in these simulations and inferred from meteorological observations, poses a demand for one or more options to ensure

  7. Trade-offs between pasture production and farmland bird conservation: exploration of options using a dynamic farm model.

    Science.gov (United States)

    Sabatier, R; Teillard, F; Rossing, W A H; Doyen, L; Tichit, M

    2015-05-01

    In European grassland landscapes, grazing and mowing play a key role for the maintenance of high-quality habitats that host important bird populations. As grasslands are also key resources for cattle feeding, there is a need to develop management strategies that achieve the double objective of production and biodiversity conservation. The objective of this study was to use a modelling approach to generate recognisable patterns of bird dynamics in farms composed of different land use proportions, and to compare their production and ecological dimensions. We developed a dynamic model, which linked grassland management to bird population dynamics at the field and farm levels. The model was parameterised for two types of suckling farms corresponding to contrasting levels of grassland intensification and for two bird species of high conservation value. A viability algorithm was used to define and assess viable management strategies for production and ecological performance so as to draw the shape of the relationship between both types of performances for the two types of farms. Our results indicated that, at the farm level, there was a farming system effect with a negative and non-linear relationship linking performance. Improving bird population maintenance was less costly in extensive farms compared with intensive farms. At the field level, the model predicted the timing and intensity of land use, maximising either production or ecological performance. The results suggested that multi-objective grassland management would benefit from public policies that consider levels of organisation higher than the field level, such as the farm or the landscape.

  8. Fuel from farms: A guide to small-scale ethanol production: Second edition

    Energy Technology Data Exchange (ETDEWEB)

    1982-05-01

    This guide presents the current status of on-farm fermentation ethanol production as well as an overview of some of the technical and economic factors. Tools such as decision and planning worksheets and a sample business plan for use in exploring whether or not to go into ethanol production are given. Specifics in production including information on the raw materials, system components, and operational requirements are also provided. Recommendation of any particular process is deliberately avoided because the choice must be tailored to the needs and resources of each individual producer. The emphasis is on providing the facts necessary to make informed judgments. 98 refs., 14 figs., 9 tabs.

  9. Comparison of the effectiveness of analytical wake models for wind farm with constant and variable hub heights

    International Nuclear Information System (INIS)

    Wang, Longyan; Tan, Andy C.C.; Cholette, Michael; Gu, Yuantong

    2016-01-01

    Highlights: • The effectiveness of three analytical wake models is studied. • The results of the analytical wake models are compared with the CFD simulations. • The results of CFD simulation are verified by comparison to the offshore wind farm observation data. • The onshore wind farm with both constant and different hub height turbines are analyzed. • PARK model is able to predict the total wind farm power production well with tuned surface roughness value. - Abstract: Extensive power losses of wind farm have been witnessed due to the wake interactions between wind turbines. By applying analytical wake models which describe the wind speed deficits in the wake quantitatively, the power losses can be regained to a large extent through wind farm layout optimization, and this has been extensively reported in literature. Nevertheless, the effectiveness of the analytical wake models in predicting the wind farm power production have rarely been studied and compared for wind farm with both constant and variable wind turbine hub heights. In this study, the effectiveness of three different analytical wake models (PARK model, Larsen model and B-P model) is thoroughly compared over a wide range of wake properties. After the validation with the observation data from offshore wind farm, CFD simulations are used to verify the effectiveness of the analytical wake models for an onshore wind farm. The results show that when using the PARK model the surface roughness value (z 0 ) must be carefully tuned to achieve good performance in predicting the wind farm power production. For the other two analytical wake models, their effectiveness varies depending on the situation of wind farm (offshore or onshore) and the wind turbine hub heights (constant or variable). It was found that the results of B-P model agree well with the CFD simulations for offshore wind farm, but not for the onshore wind farm. The Larsen model is more accurate for the wind farm with variable wind turbine

  10. Economics of small-scale on-farm use of canola and soybean for biodiesel and straight vegetable oil biofuels

    International Nuclear Information System (INIS)

    Fore, Seth R.; Porter, Paul; Jordan, Nicholas; Lazarus, William

    2011-01-01

    While the cost competitiveness of vegetable oil-based biofuels (VOBB) has impeded extensive commercialization on a large-scale, the economic viability of small-scale on-farm production of VOBB is unclear. This study assessed the cost competitiveness of small-scale on-farm production of canola- [Brassica napus (L.)] and soybean-based [Glycine max (L.)] biodiesel and straight vegetable oil (SVO) biofuels in the upper Midwest at 2007 price levels. The effects of feedstock type, feedstock valuation (cost of production or market price), biofuel type, and capitalization level on the cost L -1 of biofuel were examined. Valuing feedstock at the cost of production, the cost of canola-based biodiesel ranged from 0.94 to 1.13 L -1 and SVO from 0.64 to 0.83 L -1 depending on capitalization level. Comparatively, the cost of soybean-based biodiesel and SVO ranged from 0.40 to 0.60 L -1 and from 0.14 to 0.33 L -1 , respectively, depending on capitalization level. Valuing feedstock at the cost of production, soybean biofuels were cost competitive whereas canola biofuels were not. Valuing feedstock at its market price, canola biofuels were more cost competitive than soybean-based biofuels, though neither were cost competitive with petroleum diesel. Feedstock type proved important in terms of the meal co-product credit, which decreased the cost of biodiesel by 1.39 L -1 for soybean and 0.44 L -1 for canola. SVO was less costly to produce than biodiesel due to reduced input costs. At a small scale, capital expenditures have a substantial impact on the cost of biofuel, ranging from 0.03 to 0.25 L -1 . (author)

  11. A mechanistic model for electricity consumption on dairy farms: definition, validation, and demonstration.

    Science.gov (United States)

    Upton, J; Murphy, M; Shalloo, L; Groot Koerkamp, P W G; De Boer, I J M

    2014-01-01

    Our objective was to define and demonstrate a mechanistic model that enables dairy farmers to explore the impact of a technical or managerial innovation on electricity consumption, associated CO2 emissions, and electricity costs. We, therefore, (1) defined a model for electricity consumption on dairy farms (MECD) capable of simulating total electricity consumption along with related CO2 emissions and electricity costs on dairy farms on a monthly basis; (2) validated the MECD using empirical data of 1yr on commercial spring calving, grass-based dairy farms with 45, 88, and 195 milking cows; and (3) demonstrated the functionality of the model by applying 2 electricity tariffs to the electricity consumption data and examining the effect on total dairy farm electricity costs. The MECD was developed using a mechanistic modeling approach and required the key inputs of milk production, cow number, and details relating to the milk-cooling system, milking machine system, water-heating system, lighting systems, water pump systems, and the winter housing facilities as well as details relating to the management of the farm (e.g., season of calving). Model validation showed an overall relative prediction error (RPE) of less than 10% for total electricity consumption. More than 87% of the mean square prediction error of total electricity consumption was accounted for by random variation. The RPE values of the milk-cooling systems, water-heating systems, and milking machine systems were less than 20%. The RPE values for automatic scraper systems, lighting systems, and water pump systems varied from 18 to 113%, indicating a poor prediction for these metrics. However, automatic scrapers, lighting, and water pumps made up only 14% of total electricity consumption across all farms, reducing the overall impact of these poor predictions. Demonstration of the model showed that total farm electricity costs increased by between 29 and 38% by moving from a day and night tariff to a flat

  12. Spatiotemporal Dispersal and Deposition of Fish Farm Wastes: A Model Study from Central Norway

    Directory of Open Access Journals (Sweden)

    Ole J. Broch

    2017-06-01

    Full Text Available A spatially explicit coupled hydrodynamic-mass transport model system was used to simulate dispersal of particulate organic matter from Atlantic salmon (Salmo salar farming in central Norway. Model setups of 32 m horizontal resolution were run for periods of up to 650 days for 3 sites of different oceanographic characteristics: one fjord location, one medium-exposed location influenced by fjord water, and one coastal location. Records on feed used for each cage at each location were converted to feces released based on a published mass balance model. The results from the simulations were compared with scores from corresponding mandatory benthic surveys (MOM-B of the sediment layer beneath the farms. The correspondence between simulated and measured thickness of the sediment layer was good, and improved with the inclusion of resuspension processes. At all sites the distribution of organic matter in the bottom layer was non-homogeneous, with significant temporal variation and transport and settling of matter up to at least 0.5 km away from one of the farms. Our results indicate that the monitoring practice used in Norway until now, with a few sediment grab samples taken mainly within the fish farm, may not adequately determine the areal impacts of all salmon farming operations. The patchy distribution of organic matter and the correspondence between simulation and survey results is attributed to the use of full 3D current fields of a high spatiotemporal resolution and a good model for resuspension processes that some previous model studies have failed to properly account for.

  13. A dynamic simulation model of the Savannah River High Level Waste Tank Farm

    International Nuclear Information System (INIS)

    Gregory, M.V.; Shanahan, K.L.; Hang, T.

    1993-01-01

    A detailed, dynamic simulation model of a 51-tank high level radioactive waste storage and processing complex is being developed using SPEEDUP TM software. The initial model represents mass transfer, evaporation, precipitation, and sludge washing unit operation processes in about one-third of the tank farm complex through the solution of more than of 1000 coupled differential and algebraic equations, Eight discrete chemical constituents are tracked throughout the unit operations. The model is built upon FORTRAN both automatically generated by SPEEDUP TM to represent continuous processes, and custom-tailored by ourselves to control batched unit operations. The current model requires under 4 CPU seconds per simulated day on a VAX 8810. Strategies have been developed for expanding the model to the full tank farm complex

  14. Finance and the global land rush : Understanding the growing role of investment funds in land deals and large-scale farming

    NARCIS (Netherlands)

    O. Visser (Oane)

    2015-01-01

    markdownabstractIn the wake of the 2007–08 food crisis, we have seen the combined development of a rapid financialization of agriculture with the expansion of large-scale corporate farming through large-scale land deals, in particular in developing countries and emerging economies. The rapidly

  15. Factors influencing adoption of farm management practices in three agrobiodiversity hotspots in India: an analysis using the Count Data Model

    Directory of Open Access Journals (Sweden)

    Prabhakaran T. Raghu

    2014-07-01

    Full Text Available Sustainable agricultural practices require, among other factors, adoption of improved nutrient management techniques, pest mitigation technology and soil conservation measures. Such improved management practices can be tools for enhancing crop productivity. Data on micro-level farm management practices from developing countries is either scarce or unavailable, despite the importance of their policy implications with regard to resource allocation. The present study investigates adoption of some farm management practices and factors influencing the adoption behavior of farm households in three agrobiodiversity hotspots in India: Kundra block in the Koraput district of Odisha, Meenangadi panchayat in the Wayanad district of Kerala and Kolli Hills in the Namakkal district of Tamil Nadu. Information on farm management practices was collected from November 2011 to February 2012 from 3845 households, of which the data from 2726 farm households was used for analysis. The three most popular farm management practices adopted by farmers include: application of chemical fertilizers, farm yard manure and green manure for managing nutrients; application of chemical pesticides, inter-cropping and mixed cropping for mitigating pests; and contour bunds, grass bunds and trenches for soil conservation. A Negative Binomial count data regression model was used to estimate factors influencing decision-making by farmers on farm management practices. The regression results indicate that farmers who received information from agricultural extension are statistically significant and positively related to the adoption of farm management practices. Another key finding shows the negative relationship between cultivation of local varieties and adoption of farm management practices.

  16. Co-digestion of energy crops and industrial confectionery by-products with cow manure: batch-scale and farm-scale evaluation.

    Science.gov (United States)

    Kaparaju, P; Luostarinen, S; Kalmari, E; Kalmari, J; Rintala, J

    2002-01-01

    The possible co-digestion of energy crops and industrial confectionery by-products with cow manure was evaluated firstly, through long-term batch experiments and secondly, in a farm-scale digester. In batch assays, digestion with mesophilically digested cow manure as inoculum resulted in specific methane yields (m3 kg(-1) VS added waste) of 0.35 for grass hay (particle size confectionery by-products were 0.37 for chocolate, 0.39 for black candy and 0.32 for confectionery raw material. Out the three particle sizes (2.0, 1.0 and 0.5 cm) tested, particle size of 1.0 cm was found ideal for digestion of grass hay and clover while, particle size reduction did not influence methane production from oats. Stage of the crop influenced the methane yields, with clover harvested at vegetative stage yielding 33% higher methane than when harvested at flowering stage. An approximate 60% enhancement in methane yield was noticed with the co-digestion of industrial confectionery wastes with cow manure in a full-scale farm digester.

  17. 33 CFR 157.104 - Scale models.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Scale models. 157.104 Section 157... Oil Washing (COW) System on Tank Vessels General § 157.104 Scale models. If the pattern under § 157.100(a)(4) or § 157.102(d) cannot be shown on a plan, a scale model of each tank must be built for...

  18. The shadow effect of large wind farms: measurements, data analysis and modelling. Summary report[Final summary report

    Energy Technology Data Exchange (ETDEWEB)

    Frandsen, Steen; Barthelmie, R.; Rathmann, O.; Joergensen, Hans E.; Badger, J.; Hansen, Kurt; Ott, S.; Rethore, P.-E.; Larsen, Soeren E.; Jensen, Leo E.

    2007-07-15

    It was the goal of the project by means of data from the demonstration wind farms Horns Rev and Nysted, analyses of these data and modelling to facilitate prediction of the power losses from a wind farm should a new wind farm be built upwind relative to the prevailing wind direction. Or conversely, predict with adequate accuracy the production of a new wind farm built downwind of an existing wind farm. The project should be seen in the perspective of the two existing demonstration wind farms that extend 5-10 km in each direction. In order to e.g. use the existing electrical infrastructure it may be appropriate to build new wind farms rather close to the existing wind farms. A relevant question is therefore how far away new wind farms must be placed to avoid too large power losses. Measurements have been carried out for several years at the two sites, and databases have been prepared. The databases one for each site include production and operational statistics for the wind turbines and statistics for the meteorological measurements carries out in the vicinity of the wind farms. Several different modelling activities were carried out, which intentionally to some extent are redundant. Thus, if different modelling efforts results in comparable results, the quality of the models will be tested outside the physical range where data are available. All project participants find that the project has been immensely successful. The main achievements of the project are: 1) Measurements were carried out at the Nysted and Horns Rev demonstration wind farms for several years. Doing so included design, installation and operation of the measurement system 2) A data base was built from the incoming data. The data have been organized to facilitate verification of the models developed as part of the project 3) 6-7 different models have been developed and compared. 4) Approximately 20 journal and conference papers have resulted directly from the project (au)

  19. Emergence of highly pathogenic porcine reproductive and respiratory syndrome (HP-PRRS) in medium-scale swine farms in southeastern Cambodia.

    Science.gov (United States)

    Tornimbene, B; Frossard, J-P; Chhim, V; Sorn, S; Guitian, J; Drew, T W

    2015-01-01

    Since 2006, reports from China and Viet Nam have alerted of an emergent highly pathogenic variant of porcine reproductive and respiratory syndrome virus (HP-PRRSV) in that region. The frequent occurrence of outbreaks in these countries puts Cambodian pig farms at high risk of infection, but no study had been conducted to investigate the presence of HP-PRRS in Cambodian farms. We investigated the presence of HP-PRRS in medium-scale (semi-commercial) swine farms in the Cambodian southeastern region. Specifically, one province bordering Viet Nam (Takeo) was selected due to the concentration of most semi-commercial farms in that province. A cross-sectional study was carried out, between July and September 2010 to assess whether the prevalence of infection in these farms was indicative of recent spread of PPRSV and to identify risk factors for infection. The number of farms to be sampled was established using methods for Lot Quality Assurance Surveys (LQAS), in order to achieve a pre-established ability to discriminate between two different prevalence settings. The target population comprised all semi-commercial farms in Takeo province from which a random sample of 35 farms was selected. Selected farms were visited and questionnaires administered to gather information on farm characteristics and husbandry practices. Blood samples from individual pigs were collected in each of the study farms and tested for PRRSV, along with a number of other swine respiratory pathogens in order to investigate potential interactions. Our results showed that the virus was already present in Takeo semi-commercial pig population (LQAS herd prevalence ≥85%) at the time of sampling. The presence of sows in the farm and farm density were significantly associated (PPRRS - but this was an unadjusted association as small sample size precluded multivariate analysis. Spatiotemporal description of the supposed pattern of infection revealed that the 1st farms infected were closely located to major

  20. A system-level cost-of-energy wind farm layout optimization with landowner modeling

    International Nuclear Information System (INIS)

    Chen, Le; MacDonald, Erin

    2014-01-01

    Highlights: • We model the role of landowners in determining the success of wind projects. • A cost-of-energy (COE) model with realistic landowner remittances is developed. • These models are included in a system-level wind farm layout optimization. • Basic verification indicates the optimal COE is in-line with real-world data. • Land plots crucial to a project’s success can be identified with the approach. - Abstract: This work applies an enhanced levelized wind farm cost model, including landowner remittance fees, to determine optimal turbine placements under three landowner participation scenarios and two land-plot shapes. Instead of assuming a continuous piece of land is available for the wind farm construction, as in most layout optimizations, the problem formulation represents landowner participation scenarios as a binary string variable, along with the number of turbines. The cost parameters and model are a combination of models from the National Renewable Energy Laboratory (NREL), Lawrence Berkeley National Laboratory, and Windustry. The system-level cost-of-energy (COE) optimization model is also tested under two land-plot shapes: equally-sized square land plots and unequal rectangle land plots. The optimal COEs results are compared to actual COE data and found to be realistic. The results show that landowner remittances account for approximately 10% of farm operating costs across all cases. Irregular land-plot shapes are easily handled by the model. We find that larger land plots do not necessarily receive higher remittance fees. The model can help site developers identify the most crucial land plots for project success and the optimal positions of turbines, with realistic estimates of costs and profitability

  1. Modelling heavy metal and phosphorus balances for farming systems

    NARCIS (Netherlands)

    Keller, A.N.; Schulin, R.

    2003-01-01

    Accounting for agricultural activities such as P fertilization in regional models of heavy metal accumulation provides suitable sustainable management strategies to reduce nutrient surpluses and metal inputs in agricultural soils. Using the balance model PROTERRA-S, we assessed the phosphorus ( P),

  2. Impacts of Small-Scale Industrialized Swine Farming on Local Soil, Water and Crop Qualities in a Hilly Red Soil Region of Subtropical China

    Science.gov (United States)

    Zhang, Di; Wang, Xingxiang; Zhou, Zhigao

    2017-01-01

    Industrialized small-scale pig farming has been rapidly developed in developing regions such as China and Southeast Asia, but the environmental problems accompanying pig farming have not been fully recognized. This study investigated 168 small-scale pig farms and 29 example pig farms in Yujiang County of China to examine current and potential impacts of pig wastes on soil, water and crop qualities in the hilly red soil region, China. The results indicated that the small-scale pig farms produced considerable annual yields of wastes, with medians of 216, 333 and 773 ton yr−1 per pig farm for manure, urine and washing wastewater, respectively, which has had significant impact on surface water quality. Taking NH4+-N, total nitrogen (TN) or total phosphorus (TP) as a criterion to judge water quality, the proportions of Class III and below Class III waters in the local surface waters were 66.2%, 78.7% and 72.5%. The well water (shallow groundwater) quality near these pig farms met the water quality standards by a wide margin. The annual output of pollutants from pig farms was the most important factor correlated with the nutrients and heavy metals in soils, and the relationship can be described by a linear equation. The impact on croplands was marked by the excessive accumulation of available phosphorus and heavy metals such as Cu and Zn. For crop safety, the over-limit ratio of Zn in vegetable samples reached 60%, other heavy metals in vegetable and rice samples tested met the food safety standard at present. PMID:29211053

  3. Impacts of Small-Scale Industrialized Swine Farming on Local Soil, Water and Crop Qualities in a Hilly Red Soil Region of Subtropical China.

    Science.gov (United States)

    Zhang, Di; Wang, Xingxiang; Zhou, Zhigao

    2017-12-06

    Industrialized small-scale pig farming has been rapidly developed in developing regions such as China and Southeast Asia, but the environmental problems accompanying pig farming have not been fully recognized. This study investigated 168 small-scale pig farms and 29 example pig farms in Yujiang County of China to examine current and potential impacts of pig wastes on soil, water and crop qualities in the hilly red soil region, China. The results indicated that the small-scale pig farms produced considerable annual yields of wastes, with medians of 216, 333 and 773 ton yr -1 per pig farm for manure, urine and washing wastewater, respectively, which has had significant impact on surface water quality. Taking NH₄⁺-N, total nitrogen (TN) or total phosphorus (TP) as a criterion to judge water quality, the proportions of Class III and below Class III waters in the local surface waters were 66.2%, 78.7% and 72.5%. The well water (shallow groundwater) quality near these pig farms met the water quality standards by a wide margin. The annual output of pollutants from pig farms was the most important factor correlated with the nutrients and heavy metals in soils, and the relationship can be described by a linear equation. The impact on croplands was marked by the excessive accumulation of available phosphorus and heavy metals such as Cu and Zn. For crop safety, the over-limit ratio of Zn in vegetable samples reached 60%, other heavy metals in vegetable and rice samples tested met the food safety standard at present.

  4. Impacts of Small-Scale Industrialized Swine Farming on Local Soil, Water and Crop Qualities in a Hilly Red Soil Region of Subtropical China

    Directory of Open Access Journals (Sweden)

    Di Zhang

    2017-12-01

    Full Text Available Industrialized small-scale pig farming has been rapidly developed in developing regions such as China and Southeast Asia, but the environmental problems accompanying pig farming have not been fully recognized. This study investigated 168 small-scale pig farms and 29 example pig farms in Yujiang County of China to examine current and potential impacts of pig wastes on soil, water and crop qualities in the hilly red soil region, China. The results indicated that the small-scale pig farms produced considerable annual yields of wastes, with medians of 216, 333 and 773 ton yr−1 per pig farm for manure, urine and washing wastewater, respectively, which has had significant impact on surface water quality. Taking NH4+-N, total nitrogen (TN or total phosphorus (TP as a criterion to judge water quality, the proportions of Class III and below Class III waters in the local surface waters were 66.2%, 78.7% and 72.5%. The well water (shallow groundwater quality near these pig farms met the water quality standards by a wide margin. The annual output of pollutants from pig farms was the most important factor correlated with the nutrients and heavy metals in soils, and the relationship can be described by a linear equation. The impact on croplands was marked by the excessive accumulation of available phosphorus and heavy metals such as Cu and Zn. For crop safety, the over-limit ratio of Zn in vegetable samples reached 60%, other heavy metals in vegetable and rice samples tested met the food safety standard at present.

  5. Integrated Farm System Model Version 4.3 and Dairy Gas Emissions Model Version 3.3 Software development and distribution

    Science.gov (United States)

    Modeling routines of the Integrated Farm System Model (IFSM version 4.2) and Dairy Gas Emission Model (DairyGEM version 3.2), two whole-farm simulation models developed and maintained by USDA-ARS, were revised with new components for: (1) simulation of ammonia (NH3) and greenhouse gas emissions gene...

  6. Modelling the interactions between regional farming structure, nitrogen losses and environmental regulation

    DEFF Research Database (Denmark)

    Happe, Kathrin; Hutchings, Nick; Dalgaard, Tommy

    2011-01-01

    by one livestock unit. Substantial changes in the structure of agricultural production were shown for both scenarios. The effect on the regional nitrogen surpluses was predicted to differ between scenarios and the contribution of the different farm types to change with time. Predicted ammonia emission......Changes in the structure of agriculture are known to affect emissions of environmental pollutants from agriculture. Such changes are often driven by structural changes in agricultural production, so structural changes are likely to have indirect effects on emissions. In a pilot study, we consider...... how linking two complementary simulation models might be used to explore these effects. The agent-based AgriPoliS model was used to simulate the structural dynamics of agricultural production. The results from AgriPoliS were passed via a number of intermediate models to the Farm-N model, which...

  7. A Bayesian network approach to knowledge integration and representation of farm irrigation: 1. Model development

    Science.gov (United States)

    Wang, Q. J.; Robertson, D. E.; Haines, C. L.

    2009-02-01

    Irrigation is important to many agricultural businesses but also has implications for catchment health. A considerable body of knowledge exists on how irrigation management affects farm business and catchment health. However, this knowledge is fragmentary; is available in many forms such as qualitative and quantitative; is dispersed in scientific literature, technical reports, and the minds of individuals; and is of varying degrees of certainty. Bayesian networks allow the integration of dispersed knowledge into quantitative systems models. This study describes the development, validation, and application of a Bayesian network model of farm irrigation in the Shepparton Irrigation Region of northern Victoria, Australia. In this first paper we describe the process used to integrate a range of sources of knowledge to develop a model of farm irrigation. We describe the principal model components and summarize the reaction to the model and its development process by local stakeholders. Subsequent papers in this series describe model validation and the application of the model to assess the regional impact of historical and future management intervention.

  8. Modeling and simulation of offshore wind farm O&M processes

    International Nuclear Information System (INIS)

    Joschko, Philip; Widok, Andi H.; Appel, Susanne; Greiner, Saskia; Albers, Henning; Page, Bernd

    2015-01-01

    This paper describes a holistic approach to operation and maintenance (O&M) processes in the domain of offshore wind farm power generation. The acquisition and process visualization is followed by a risk analysis of all relevant processes. Hereafter, a tool was designed, which is able to model the defined processes in a BPMN 2.0 notation, as well as connect and simulate them. Furthermore, the notation was enriched with new elements, representing other relevant factors that were, to date, only displayable with much higher effort. In that regard a variety of more complex situations were integrated, such as for example new process interactions depending on different weather influences, in which case a stochastic weather generator was combined with the business simulation or other wind farm aspects important to the smooth running of the offshore wind farms. In addition, the choices for different methodologies, such as the simulation framework or the business process notation will be presented and elaborated depending on the impact they had on the development of the approach and the software solution. - Highlights: • Analysis of operation and maintenance processes of offshore wind farms • Process modeling with BPMN 2.0 • Domain-specific simulation tool

  9. Change in Farm Production Structure Within Different CAP Schemes – an LP Modelling Approach

    Directory of Open Access Journals (Sweden)

    Jaka ŽGAJNAR

    2008-01-01

    Full Text Available After accession to European Union in 2004 direct payments became veryimportant income source also for farmers in Slovenia. But agricultural policy inplace at accession changed significantly in year 2007 as result of CAP reformimplementation. The objective of this study was to evaluate decision makingimpacts of direct payments scheme implemented with the reform: regional or morelikely hybrid scheme. The change in farm production structure was simulated withmodel, applying gross margin maximisation, based on static linear programmingapproach. The model has been developed in a spreadsheet framework in MS Excelplatform. A hypothetical farm has been chosen to analyse different scenarios andspecializations. Focus of the analysis was on cattle sector, since it is expected thatdecoupling is going to have significant influence on its optimal productionstructure. The reason is high level of direct payments that could in pre-reformscheme rise up to 70 % of total gross margin. Model results confirm that the reformshould have unfavourable impacts on cattle farms with intensive productionpractice. The results show that hybrid scheme has minor negative impacts in allcattle specializations, while regional scheme would be better option for sheepspecialized farm. Analysis has also shown growing importance of CAP pillar IIpayments, among them particularly agri-environmental measures. In all threeschemes budgetary payments enable farmers to improve financial results and inboth reform schemes they alleviate economic impacts of the CAP reform.

  10. Modeling and simulation of offshore wind farm O&M processes

    Energy Technology Data Exchange (ETDEWEB)

    Joschko, Philip, E-mail: joschko@informatik.uni-hamburg.de [University of Hamburg, Dept. of Informatics, Vogt-Kölln-Straße 30, 22527 Hamburg (Germany); Widok, Andi H., E-mail: a.widok@htw-berlin.de [University of Hamburg, Dept. of Informatics, Vogt-Kölln-Straße 30, 22527 Hamburg (Germany); Appel, Susanne, E-mail: susanne.appel@hs-bremen.de [HSB Bremen, Institute for Environment and Biotechnology, Neustadtswall 30, 28199 Bremen (Germany); Greiner, Saskia, E-mail: saskia.greiner@hs-bremen.de [HSB Bremen, Institute for Environment and Biotechnology, Neustadtswall 30, 28199 Bremen (Germany); Albers, Henning, E-mail: henning.albers@hs-bremen.de [HSB Bremen, Institute for Environment and Biotechnology, Neustadtswall 30, 28199 Bremen (Germany); Page, Bernd, E-mail: page@informatik.uni-hamburg.de [University of Hamburg, Dept. of Informatics, Vogt-Kölln-Straße 30, 22527 Hamburg (Germany)

    2015-04-15

    This paper describes a holistic approach to operation and maintenance (O&M) processes in the domain of offshore wind farm power generation. The acquisition and process visualization is followed by a risk analysis of all relevant processes. Hereafter, a tool was designed, which is able to model the defined processes in a BPMN 2.0 notation, as well as connect and simulate them. Furthermore, the notation was enriched with new elements, representing other relevant factors that were, to date, only displayable with much higher effort. In that regard a variety of more complex situations were integrated, such as for example new process interactions depending on different weather influences, in which case a stochastic weather generator was combined with the business simulation or other wind farm aspects important to the smooth running of the offshore wind farms. In addition, the choices for different methodologies, such as the simulation framework or the business process notation will be presented and elaborated depending on the impact they had on the development of the approach and the software solution. - Highlights: • Analysis of operation and maintenance processes of offshore wind farms • Process modeling with BPMN 2.0 • Domain-specific simulation tool.

  11. Amaranth farming

    DEFF Research Database (Denmark)

    Bjarklev, Araceli; Kjær, Tyge; Kjærgård, Bente

    2008-01-01

    natural resources that small-scale farmers have to combat the abovementioned problems. The study identified several local and regional barriers for increasing the level of farming, production, processing and consumption. A striking and paradoxical limitation is the monopolization practices developed...

  12. Mark Online, a Full Scale GIS-based Danish Farm Management Information System

    Directory of Open Access Journals (Sweden)

    Jens Bligaard

    2015-01-01

    Full Text Available With its oceanic climate with moderate summers and mild winters in combination with a highly organized infrastructure, farming has traditionally been very intensive in Denmark. The cultivated land constitutes 26,000 km² out of a total of 43,000 km². Most of the arable land is used for intensive plant production with a high level of mechanization and management practices. For more than three decades The Knowledge Centre for Agriculture (KCA has developed and implemented ICT Farm Management Information Systems (FMIS for planning and documentation of all aspects of crop production. Today, updated field specific information on field size, soil type, crops, varieties, soil tillage, sowing, fertilization, pesticide usage etc. is now hosted in the GIS-based FMIS, Mark Online covering more than 80% of the arable land. A centralized Microsoft SQL data base forms the core base for all the information. Based on a MS .NET framework a number of multi-tier client-server applications have been developed. Most of the desk top applications consist of relative thick clients based on Win forms, whereas HTML5 apps and Android/IOS native apps are used for the mobile platform. Data exchange between the clients and server are based on a web service layer using data compression to improve performance. Farmers are one of the two primary target groups. Local agricultural advisors working on behalf of farmers not having their own software is the other primary target group. Nonetheless, both groups are mainly focusing on field record planning, decision making and documentation. Data is transferred between the Mark Online system and the authorities by XML-based web services or ordinary file upload to official websites. The Open Geospatial Consortium’s Web Feature Service (WFS provides another interface allowing requests for geospatial features, which is used between Mark Online and external GIS.

  13. Agribusiness and Contract Farming: the Case of Small-Scale Cucumber Producers in Mexico

    Directory of Open Access Journals (Sweden)

    Flavia Echánove Huacuja

    2010-11-01

    Full Text Available La agricultura por contrato constituye un mecanismo de abasto de las agroindustrias que se ha expandido rápidamente en los últimos años. Entre los factores que han motivado esta expansión se encuentran los cambios en el consumo alimentario, el crecimiento y fortalecimiento de las agroindustrias y otros distribuidores y la aplicación de políticas de ajuste estructural. El objetivo de este artículo es el análisis de las características del régimen contractual bajo el cual se produce cierta hortaliza de exportación ('el pepinillo', así como sus efectos en los productores, en los mercados de trabajo y tierras, y en el medio ambiente. Encontramos que el ingreso obtenido por los productores contratados no los ha exentado de la necesidad de diversificar sus actividades y que, en general, su situación como productores de bienes no-tradicionales es vulnerable y dependiente de los cambios en los mercados mundiales. English: Contract farming comprises an agribusiness supply mechanism that has undergone rapid expansion in recent years. Among the factors influencing that expansion are changes in consumption, the growth and strengthening of agribusinesses and other distributors, and the application of structural adjustment policies. The objective of this article is the analysis of the characteristics of the type of contract farming practiced with regard to the production of an export vegetable crop (pickling cucumbers, as well as its effects on producers, labor and land markets, and the environment. We find that the income obtained by contracted producers has not freed them from the necessity of diversifying their activities, and that in general, their situation as producers of non-traditional commodities is vulnerable and dependent upon the changing scenarios of global markets.

  14. Engineering models for merging wakes in wind farm optimization applications

    DEFF Research Database (Denmark)

    Machefaux, Ewan; Larsen, Gunner Chr.; Murcia Leon, Juan Pablo

    2015-01-01

    The present paper deals with validation of 4 different engineering wake superposition approaches against detailed CFD simulations and covering different turbine interspacing, ambient turbulence intensities and mean wind speeds. The first engineering model is a simple linear superposition of wake ...

  15. Labour Quality Model for Organic Farming Food Chains

    OpenAIRE

    Gassner, B.; Freyer, B.; Leitner, H.

    2008-01-01

    The debate on labour quality in science is controversial as well as in the organic agriculture community. Therefore, we reviewed literature on different labour quality models and definitions, and had key informant interviews on labour quality issues with stakeholders in a regional oriented organic agriculture bread food chain. We developed a labour quality model with nine quality categories and discussed linkages to labour satisfaction, ethical values and IFOAM principles.

  16. Photovoltaic solar array technology required for three wide scale generating systems for terrestrial applications: rooftop, solar farm, and satellite

    Science.gov (United States)

    Berman, P. A.

    1972-01-01

    Three major options for wide-scale generation of photovoltaic energy for terrestrial use are considered: (1) rooftop array, (2) solar farm, and (3) satellite station. The rooftop array would use solar cell arrays on the roofs of residential or commercial buildings; the solar farm would consist of large ground-based arrays, probably in arid areas with high insolation; and the satellite station would consist of an orbiting solar array, many square kilometers in area. The technology advancement requirements necessary for each option are discussed, including cost reduction of solar cells and arrays, weight reduction, resistance to environmental factors, reliability, and fabrication capability, including the availability of raw materials. The majority of the technology advancement requirements are applicable to all three options, making possible a flexible basic approach regardless of the options that may eventually be chosen. No conclusions are drawn as to which option is most advantageous, since the feasibility of each option depends on the success achieved in the technology advancement requirements specified.

  17. Model to evaluate welfare in dairy cow farms

    Directory of Open Access Journals (Sweden)

    Luigi Calamari

    2010-01-01

    Full Text Available The assessment of herd welfare is a scientific discipline that is rapidly developing. The scientific community plays an important role in delivering appropriate, repeatable, valid and feasible models for this assessment. Unfortunately, there are different feelings regarding the welfare of animals and it is imperative for its assessment that certain agreement on the meaning of animal welfare is accepted. Then it is necessary to look at the goals of the models of welfare assessment because different goals require a different combination of welfare indicators. The different models for welfare assessment can be categorized broadly into research, legislative requirements, certification systems, and advisory/management tools. These models may have various goals: quantification of welfare, provision of welfare assurance or welfare management. However, it is widely accepted that welfare is best assessed with multiple different measures; therefore, a welfare assessment model for a livestock herd can include two types of measure: a description of the housing system and management (indirect indicators and data recording on how the animals react to the system (direct indicators. The first type provides information on risk factors for welfare problems. Direct measures on the animals provide information on their response to the environment and are more direct measures of welfare than their counterparts, but direct welfare indicators alone do not point out the causes of impaired welfare. Because welfare is a complex construct, different approaches for the aggregation of the different aspects of welfare have been proposed, although the aggregation in an overall welfare value is not sufficient. The thresholds between acceptable and unacceptable welfare levels have to be included in the model of welfare assessment but it seems useful to set certain minimum standards for each single welfare aspect. Afterward, judging the validity of a common welfare assessment

  18. The Relationship of Dairy Farm Eco-Efficiency with Intensification and Self-Sufficiency. Evidence from the French Dairy Sector Using Life Cycle Analysis, Data Envelopment Analysis and Partial Least Squares Structural Equation Modelling.

    Directory of Open Access Journals (Sweden)

    Andreas Diomedes Soteriades

    Full Text Available We aimed at quantifying the extent to which agricultural management practices linked to animal production and land use affect environmental outcomes at a larger scale. Two practices closely linked to farm environmental performance at a larger scale are farming intensity, often resulting in greater off-farm environmental impacts (land, non-renewable energy use etc. associated with the production of imported inputs (e.g. concentrates, fertilizer; and the degree of self-sufficiency, i.e. the farm's capacity to produce goods from its own resources, with higher control over nutrient recycling and thus minimization of losses to the environment, often resulting in greater on-farm impacts (eutrophication, acidification etc.. We explored the relationship of these practices with farm environmental performance for 185 French specialized dairy farms. We used Partial Least Squares Structural Equation Modelling to build, and relate, latent variables of environmental performance, intensification and self-sufficiency. Proxy indicators reflected the latent variables for intensification (milk yield/cow, use of maize silage etc. and self-sufficiency (home-grown feed/total feed use, on-farm energy/total energy use etc.. Environmental performance was represented by an aggregate 'eco-efficiency' score per farm derived from a Data Envelopment Analysis model fed with LCA and farm output data. The dataset was split into two spatially heterogeneous (bio-physical conditions, production patterns regions. For both regions, eco-efficiency was significantly negatively related with milk yield/cow and the use of maize silage and imported concentrates. However, these results might not necessarily hold for intensive yet more self-sufficient farms. This requires further investigation with latent variables for intensification and self-sufficiency that do not largely overlap- a modelling challenge that occurred here. We conclude that the environmental 'sustainability' of intensive

  19. Large Scale Computations in Air Pollution Modelling

    DEFF Research Database (Denmark)

    Zlatev, Z.; Brandt, J.; Builtjes, P. J. H.

    Proceedings of the NATO Advanced Research Workshop on Large Scale Computations in Air Pollution Modelling, Sofia, Bulgaria, 6-10 July 1998......Proceedings of the NATO Advanced Research Workshop on Large Scale Computations in Air Pollution Modelling, Sofia, Bulgaria, 6-10 July 1998...

  20. A model for the optimal risk management of (farm) firms

    DEFF Research Database (Denmark)

    Rasmussen, Svend

    Current methods of risk management focus on efficiency and do not provide operational answers to the basic question of how to optimise and balance the two objectives, maximisation of expected income and minimisation of risk. This paper uses the Capital Asset Pricing Model (CAPM) to derive...

  1. Statistical Modeling of Energy Production by Photovoltaic Farms

    Czech Academy of Sciences Publication Activity Database

    Brabec, Marek; Pelikán, Emil; Krč, Pavel; Eben, Kryštof; Musílek, P.

    2011-01-01

    Roč. 5, č. 9 (2011), s. 785-793 ISSN 1934-8975 Grant - others:GA AV ČR(CZ) M100300904 Institutional research plan: CEZ:AV0Z10300504 Keywords : electrical energy * solar energy * numerical weather prediction model * nonparametric regression * beta regression Subject RIV: BB - Applied Statistics, Operational Research

  2. Interactive design of farm conversion : linking agricultural research and farmer learning for sustainable small scale horticulture production in Colombia

    NARCIS (Netherlands)

    Lee, R.A.

    2002-01-01

    Key words: interactive conversion design / vegetable production / small farms / sustainable farming / Colombia / learning processes / facilitation / agricultural research methods

  3. Gis-Based Wind Farm Site Selection Model Offshore Abu Dhabi Emirate, Uae

    Science.gov (United States)

    Saleous, N.; Issa, S.; Mazrouei, J. Al

    2016-06-01

    The United Arab Emirates (UAE) government has declared the increased use of alternative energy a strategic goal and has invested in identifying and developing various sources of such energy. This study aimed at assessing the viability of establishing wind farms offshore the Emirate of Abu Dhabi, UAE and to identify favourable sites for such farms using Geographic Information Systems (GIS) procedures and algorithms. Based on previous studies and on local requirements, a set of suitability criteria was developed including ocean currents, reserved areas, seabed topography, and wind speed. GIS layers were created and a weighted overlay GIS model based on the above mentioned criteria was built to identify suitable sites for hosting a new offshore wind energy farm. Results showed that most of Abu Dhabi offshore areas were unsuitable, largely due to the presence of restricted zones (marine protected areas, oil extraction platforms and oil pipelines in particular). However, some suitable sites could be identified, especially around Delma Island and North of Jabal Barakah in the Western Region. The environmental impact of potential wind farm locations and associated cables on the marine ecology was examined to ensure minimal disturbance to marine life. Further research is needed to specify wind mills characteristics that suit the study area especially with the presence of heavy traffic due to many oil production and shipping activities in the Arabian Gulf most of the year.

  4. Oscillation Performance and Wide‐area Coordination Control of Power System with Large‐scale Wind Farms

    DEFF Research Database (Denmark)

    Su, Chi

    in the power system; investigating the possible influence of large‐scale wind power integration on system oscillation performance; developing oscillation mitigation strategies for wind farms; and coordinating various damping controllers in the power system. For the power system operation aspect, an optimal...... and a residue identification technique is used. Furthermore, a particle swarm optimization (PSO) based coordinating strategy to select the locations, input signals and parameters of multiple PSSs is proposed. Simulation results show that this method is able to find a group of PSSs to improve the target mode...... by observing the oscillation damping change in relation with the change of the ancillary controller parameters. Furthermore, the forced oscillation in the power system activated by the wind power oscillation due to wind shear and tower shadow effects is analyzed. The forced oscillation amplitude is found...

  5. Test Plan for the Wake Steering Experiment at the Scaled Wind Farm Technology (SWiFT) Facility.

    Energy Technology Data Exchange (ETDEWEB)

    Naughton, Brian Thomas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-02-01

    This document is a test plan describing the objectives, configuration, procedures, reporting, roles, and responsibilities for conducting the joint Sandia National Laboratories and National Renewable Energy Laboratory Wake Steering Experiment at the Sandia Scaled Wind Farm Technology (SWiFT) facility near Lubbock, Texas in 2016 and 2017 . The purpose of this document is to ensure the test objectives and procedures are sufficiently detailed such that al l involved personnel are able to contribute to the technical success of the test. This document is not intended to address safety explicitly which is addressed in a separate document listed in the references titled Sandia SWiFT Facility Site Operations Manual . Both documents should be reviewed by all test personnel.

  6. Reliability model for offshore wind farms; Paalidelighedsmodel for havvindmoelleparker

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, P.; Lundtang Paulsen, J.; Lybech Toegersen, M.; Krogh, T. [Risoe National Lab., Roskilde (Denmark); Raben, N.; Donovan, M.H.; Joergensen, L. [SEAS (Denmark); Winther-Jensen, M.

    2002-05-01

    A method for the prediction of the mean availability for an offshore windfarm has been developed. Factors comprised are the reliability of the single turbine, the strategy for preventive maintenance the climate, the number of repair teams, and the type of boats available for transport. The mean availability is defined as the sum of the fractions of time, where each turbine is available for production. The project has been carried out together with SEAS Wind Technique, and their site Roedsand has been chosen as the example of the work. A climate model has been created based on actual site measurements. The prediction of the availability is done with a Monte Carlo-simulation. Software was developed for the preparation of the climate model from weather measurements as well as for the Monte carlo-simulation. Three examples have been simulated, one with guessed parametres, and the other two with parameters more close to the Roedsand case. (au)

  7. Multi-scale modeling of composites

    DEFF Research Database (Denmark)

    Azizi, Reza

    A general method to obtain the homogenized response of metal-matrix composites is developed. It is assumed that the microscopic scale is sufficiently small compared to the macroscopic scale such that the macro response does not affect the micromechanical model. Therefore, the microscopic scale...... is analyzed using a Representative Volume Element (RVE), while the homogenized data are saved and used as an input to the macro scale. The dependence of fiber size is analyzed using a higher order plasticity theory, where the free energy is stored due to plastic strain gradients at the micron scale. Hill...... to plastic deformation. The macroscopic operators found, can be used to model metal matrix composites on the macroscopic scale using a hierarchical multi-scale approach. Finally, decohesion under tension and shear loading is studied using a cohesive law for the interface between matrix and fiber....

  8. Meat Quality Characteristics of Small East African Goats and Norwegian Crosses Finished under Small Scale Farming Conditions.

    Science.gov (United States)

    Hozza, W A; Mtenga, L A; Kifaro, G C; Shija, D S N; Mushi, D E; Safari, J G; Shirima, E J M

    2014-12-01

    The aim of the experiment was to study the effect of feeding system on meat quality characteristics of Small East African (SEA) goats and their crosses with Norwegian (SEA×N) goats finished under small scale farming conditions. Twenty four castrated goats at the age of 18 months with live body weight of 16.7±0.54 kg from each breed (SEA and SEA×N) were distributed in a completely randomized design in a 2×3 factorial arrangement (two breed, and three dietary treatments). The dietary treatments were; no access to concentrate (T0), 66% access to ad libitum concentrate allowance (T66) and 100% access to ad libitum concentrate allowance with 20% refusal (T100) and the experimental period was for 84 days. In addition, all goats were allowed to graze for 2 hours daily and later fed grass hay on ad libitum basis. Daily feed intakes were recorded for all 84-days of experiment after which the animals were slaughtered. Feed intake of T100 animals was 536 g/d, which was 183 g/d higher than that of T66 group. Supplemented goats had significantly (pconversion efficiency. The SEA had higher (p0.05) for dressing percentage and carcass conformation among supplemented goats except fatness score, total fat depots and carcass fat which increased (pgoats fed concentrate declined rapidly and reached below 6 at 6 h post-mortem but temperature remained at 28°C. Cooking loss and meat tenderness improved (pgoats and their crosses with Norwegian breeds finished under small scale farming conditions in rural areas. Therefore, concentrate supplementation of goats of both breeds improves meat quality attributes.

  9. Degradation of cefquinome in spiked milk as a model for bioremediation of dairy farm waste milk containing cephalosporin residues.

    Science.gov (United States)

    Horton, R A; Randall, L P; Bailey-Horne, V; Heinrich, K; Sharman, M; Brunton, L A; La Ragione, R M; Jones, J R

    2015-04-01

    The aims of this work were to develop a model of dairy farm waste milk and to investigate methods for the bioremediation of milk containing cefquinome residues. Unpasteurized milk and UHT milk that had both been spiked with cefquinome at a concentration of 2 μg ml(-1) were used as a model for waste milk containing cephalosporin residues. Adjustment of the spiked UHT milk to pH 10 or treatment with conditioned medium from bacterial growth producing cefotaximase, were the most effective methods for decreasing the cefquinome concentrations within 24 h. A large-scale experiment (10 l of cefquinome-spiked unpasteurized milk) suggested that fermentation for 22 h at 37°C followed by heating at 60°C for 2 h was sufficient to decrease cefquinome concentrations to below the limit of quantification (milk. Treatment of waste milk to decrease cephalosporin residue concentrations and also to kill bacteria prior to feeding to dairy calves could decrease the risk of selection for ESBL bacteria on dairy farms. © 2015 Crown copyright. Journal of Applied Microbiology © 2015 The Society for Applied Microbiology. This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland.

  10. Projecting carbon footprint of Canadian dairy farms under future climate conditions with the integrated farm system model

    Science.gov (United States)

    Dairy farms are an important sector of Canadian agriculture, and there is an on-going effort to assess their environmental impact. In Canada, like many northern areas of the world, climate change is expected to increase agricultural productivity. This will likely come along with changes in environme...

  11. Maize Residue as a Viable Substrate for Farm Scale Cultivation of Oyster Mushroom (Pleurotus ostreatus

    Directory of Open Access Journals (Sweden)

    Abena O. Adjapong

    2015-01-01

    Full Text Available In the search for alternatives to sawdust as growing media in commercial mushroom cultivation, three organic substrates obtainable as crop residue, maize husk, maize cob, and maize stalk, with each being supplemented with rice bran, were evaluated as growth media for the oyster mushroom, Pleurotus ostreatus (Kummer. For the tested alternatives to sawdust, the harvested weight of fruiting bodies that sprouted on a kilogram maize husk media per crop (32.99 g was the highest. Sawdust media supported significantly (P<0.001 heavier fruiting bodies (42.18 than the maize residues. The peak mushroom harvests for the various substrates were obtained between the first and seventh fruiting body flushes. The biological efficiency of the substrates, which measured usable nutrients indicated that maize stalk supplemented with rice bran, was 39% compared to that of the sawdust media (60%. The maize husk media and the maize cob media had biological efficiencies of 32% and 9.5%, respectively. These results indicate that two of the tested growing media (maize stalk or husk produced mushrooms with yield characteristics that were comparable to the well-used sawdust in the cultivation of oyster mushrooms. The environmental and economic parameters involved in the use and carting of sawdust make these on-farm crop residues a viable alternative for mushroom cultivation in especially nonforest zones of Ghana.

  12. Functional Scaling of Musculoskeletal Models

    DEFF Research Database (Denmark)

    Lund, Morten Enemark; Andersen, Michael Skipper; de Zee, Mark

    specific to the patient. This is accomplished using optimisation methods to determine patient-specific joint positions and orientations, which minimise the least-squares error between model markers and the recorded markers from a motion capture experiment. Functional joint positions and joint axis...... geometry, without the need for MR/CT scans. However, more validation activities are needed to better understand the effect of morphing musculoskeletal models based on functional joint parameters....

  13. Wind resource modelling for micro-siting - Validation at a 60-MW wind farm site

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, J.C.; Gylling Mortensen, N. [Risoe National Lab., Wind Energy and Atmospheric Physics Dept., Roskilde (Denmark); Said, U.S. [New and Renewable Energy Authority, Cairo (Egypt)

    1999-03-01

    This paper investigates and validates the applicability of the WAsP-model for layout optimization and micro-siting of wind turbines at a given site for a 60-MW wind farm at Zafarana at the Gulf of Suez in Egypt. Previous investigations show large gradients in the wind climate within the area. For the design and optimization of the wind farm it was found necessary to verify the WAsP extrapolation of wind atlas results from 2 existing meteorological masts located 5 and 10 km, respectively, from the wind farm site. On-site measurements at the 3.5 x 3.5 km{sup 2} wind farm site in combination with 7 years of near-site wind atlas measurements offer significant amounts of data for verification of wind conditions for micro-siting. Wind speeds, wind directions, turbulence intensities and guests in 47.5 m a.g.l. have been measured at 9 locations across the site. Additionally, one of the site masts is equipped as a reference mast, measuring both vertical profiles of wind speed and temperature as well as air pressure and temperature. The exercise is further facilitated by the fact that winds are highly uni-directional; the north direction accounting for 80-90% of the wind resource. The paper presents comparisons of 5 months of on-site measurements and modeled predictions from 2 existing meteorological masts located at distances of 5 and 10 km, respectively, from the wind farm site. Predictions based on terrain descriptions of the Wind Atlas for the Gulf of Suez 1991-95 showed over-predictions of wind speeds of 4-10%. With calibrated terrain descriptions, made based on measured data and a re-visit to critical parts of the terrain, the average prediction error of wind speeds was reduced to about 1%. These deviations are smaller than generally expected for such wind resource modeling, clearly documenting the validity of using WAsP modeling for micro-siting and layout optimization of the wind farm. (au)

  14. Atmospheric stability-dependent infinite wind-farm models and the wake-decay coefficient

    DEFF Research Database (Denmark)

    Peña, Alfredo; Rathmann, Ole

    2014-01-01

    We extend the infinite wind-farm boundary-layer (IWFBL) model of Frandsen to take into account atmospheric static stability effects. This extended model is compared with the IWFBL model of Emeis and to the Park wake model used inWind Atlas Analysis and Application Program (WAsP), which is computed......) larger than the adjusted values for a wide range of neutral to stable atmospheric stability conditions, a number of roughness lengths and turbine separations lower than _ 10 rotor diameters and (ii) too large compared with those obtained by a semiempirical formulation (relating the ratio of the friction...

  15. Bayesian based Prognostic Model for Predictive Maintenance of Offshore Wind Farms

    DEFF Research Database (Denmark)

    Asgarpour, Masoud; Sørensen, John Dalsgaard

    2018-01-01

    monitoring, fault prediction and predictive maintenance of offshore wind components is defined. The diagnostic model defined in this paper is based on degradation, remaining useful lifetime and hybrid inspection threshold models. The defined degradation model is based on an exponential distribution......The operation and maintenance costs of offshore wind farms can be significantly reduced if existing corrective actions are performed as efficient as possible and if future corrective actions are avoided by performing sufficient preventive actions. In this paper a prognostic model for degradation...

  16. Bayesian based Prognostic Model for Predictive Maintenance of Offshore Wind Farms

    DEFF Research Database (Denmark)

    Asgarpour, Masoud

    2017-01-01

    monitoring, fault detection and predictive maintenance of offshore wind components is defined. The diagnostic model defined in this paper is based on degradation, remaining useful lifetime and hybrid inspection threshold models. The defined degradation model is based on an exponential distribution......The operation and maintenance costs of offshore wind farms can be significantly reduced if existing corrective actions are performed as efficient as possible and if future corrective actions are avoided by performing sufficient preventive actions. In this paper a prognostic model for degradation...

  17. An evaluation of a farm scale biogas plant with a micro turbine for combined heat and power production; Utvaerdering av gaardsbiogasanlaeggning med mikroturbin foer kraftvaermeproduktion

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Nils; Edstroem, Mats; Hansson, Mikael (Swedish Inst. of Agricultural and Environmental Engineering, Uppsala (Sweden)); Algerbo, Per-Anders (HIR Malmoehus, Bjaerred (Sweden))

    2010-03-15

    The purpose of this study was to: To evaluate a farm scale biogas plant digesting energy and nutrient rich substrates at a high organic loading rate and biogas production using the biogas for combined heat and power production with a micro turbine. Put together technical, biological and economical documentation which can help farmers to investigate presumption to invest in a farm scale biogas plant for heat and power production. The farm scale biogas plant has an active digester volume of 450 m3 and the process temperature is ca 37 deg C. A micro turbine with 105 kW electrical and 160 kW thermal power is used for heat and power production. The produced electricity is sold to the grid and the heat is used on the farm for drying grain and heating two houses. The plant is digesting poultry manure and 2 substrates from the agriculture industry. All together the plant is digesting 3140 metric tons of substrates/yr and the substrates costs 160 k SEK/yr. Total investment for the plant is 4.7 M SEK. Produced head reduces the oil consumption at the farm with 15 m3 (value 100 k SEK/yr). There is a surplus of heat production of 600 MWh/yr. The production cost for the electricity is close to 0,66 SEK/kWh based on a value of the digestate of 100 SEK/ton together with an investment subsidy of 30 %. The production cost for the electricity is strongly depending on the value of the digestate. Hagavik is a crop production farm based on organic farming. If the valuation of the digestate is reduced to 50 SEK/ton, the production cost for the electricity increases to approx. 0.84 SEK/kWh (1 SEK is about 0.14 USD)

  18. Dynamic modelling of VSC-HVDC for connection of offshore wind farms

    DEFF Research Database (Denmark)

    Rios, Bardo; Garcia-Valle, Rodrigo

    2011-01-01

    A VSC-HVDC (Voltage Source Converter – High Voltage Direct Current) dynamic model with a set of control strategies is developed in DIgSILENT Power-Factory with the objective of analyzing the converter’s operating capability for grid support during grid faults. The investigation is carried out based...... on a 165 MW offshore wind farm with induction generators and a Low Voltage Ride-Through solution of the offshore wind turbines and Static Voltage Compensator units in the point of connection with a grid represented by a reduced four-generator power grid model. VSC-HVDC promises to be a reliable alternative...... solution for interconnection with off-shore wind farms as they become larger, with a higher installed power capacity, increased number of wind turbines, and geographically situated at larger distances from suitable connection points in the transmission grids....

  19. Enhanced Voltage Control of VSC-HVDC Connected Offshore Wind Farms Based on Model Predictive Control

    DEFF Research Database (Denmark)

    Guo, Yifei; Gao, Houlei; Wu, Qiuwei

    2018-01-01

    This paper proposes an enhanced voltage control strategy (EVCS) based on model predictive control (MPC) for voltage source converter based high voltage direct current (VSCHVDC) connected offshore wind farms (OWFs). In the proposed MPC based EVCS, all wind turbine generators (WTGs) as well...... as the wind farm side VSC are optimally coordinated to keep voltages within the feasible range and reduce system power losses. Considering the high ratio of the OWF collector system, the effects of active power outputs of WTGs on voltage control are also taken into consideration. The predictive model of VSC...... with a typical cascaded control structure is derived in details. The sensitivity coefficients are calculated by an analytical method to improve the computational efficiency. A VSC-HVDC connected OWF with 64 WTGs was used to validate the proposed voltage control strategy....

  20. Can Livestock Farming and Tourism Coexist in Mountain Regions? A New Business Model for Sustainability

    Directory of Open Access Journals (Sweden)

    Dino Genovese

    2017-11-01

    Full Text Available European Mediterranean mountain regions have been characterized by a sort of competition between the tourism sector and the agro-silvo-pastoral system, which in recent years has contributed to generate a continuous decline of the second one. Nevertheless, Pasture-based Livestock Farming Systems (PLSFS are relevant for their role in the management and conservation of large High Nature Value (HNV farmlands in Europe. The goal of our research is therefore to analyze what are the main features of farming organizations in the Italian alpine mountains and how they may be combined into inovative and sustainable business models (BM, characterized by the coexistence of agro-silvo-pastoral and touristic activities. By drawing upon the BM definition suggested by the Bocken’s et al. (2014, an exploratory case study has been analyzed; in particular, we propose the case study of the Lanzo Valleys, an alpine mountain region in the northwest of Italy, and the Toma di Lanzo Producers Association. The way a concrete and sustainable innovation in the more traditional BM could be supported only by the proactive intervention of a supra-farm dimension, while maintaining the peculiarities of the individual farms, is clearly shown in the article. A system of firms and institutions linked together in a collaborative relationship may represent a strong network, able to achieve the common goal of producing a sustainable development for the territory. Indeed, environment and cultural heritage may be preserved, as well as the economic perspective of farms reinforced, while the PLSFS could become more attractive for the tourism phenomenon. Interesting implications for farmers, policy makers and local institutions are identified.

  1. Modelling impacts of offshore wind farms on trophic web: the Courseulles-sur-Mer case study

    Science.gov (United States)

    Raoux, Aurore; Pezy, Jean-Philippe; Dauvin, Jean-Claude; Tecchio, samuele; Degraer, Steven; Wilhelmsson, Dan; Niquil, Nathalie

    2016-04-01

    The French government is planning the construction of three offshore wind farms in Normandy. These offshore wind farms will integrate into an ecosystem already subject to a growing number of anthropogenic disturbances such as transportation, fishing, sediment deposit, and sediment extraction. The possible effects of this cumulative stressors on ecosystem functioning are still unknown, but they could impact their resilience, making them susceptible to changes from one stable state to another. Understanding the behaviour of these marine coastal complex systems is essential in order to anticipate potential state changes, and to implement conservation actions in a sustainable manner. Currently, there are no global and integrated studies on the effects of construction and exploitation of offshore wind farms. Moreover, approaches are generally focused on the conservation of some species or groups of species. Here, we develop a holistic and integrated view of ecosystem impacts through the use of trophic webs modelling tools. Trophic models describe the interaction between biological compartments at different trophic levels and are based on the quantification of flow of energy and matter in ecosystems. They allow the application of numerical methods for the characterization of emergent properties of the ecosystem, also called Ecological Network Analysis (ENA). These indices have been proposed as ecosystem health indicators as they have been demonstrated to be sensitive to different impacts on marine ecosystems. We present here in detail the strategy for analysing the potential environmental impacts of the construction of the Courseulles-sur-Mer offshore wind farm (Bay of Seine) such as the reef effect through the use of the Ecopath with Ecosim software. Similar Ecopath simulations will be made in the future on the Le Tréport offshore wind farm site. Results will contribute to a better knowledge of the impacts of the offshore wind farms on ecosystems. They also allow to

  2. Energy efficiency of crops grown for biogas production in a large-scale farm in Poland

    International Nuclear Information System (INIS)

    Jankowski, Krzysztof Józef; Dubis, Bogdan; Budzyński, Wojciech Stefan; Bórawski, Piotr; Bułkowska, Katarzyna

    2016-01-01

    This article presents the results of a 3-year field study into the yield and energy efficiency of maize, sweet sorghum, giant miscanthus, Amur silver grass, Virginia fanpetals and alfalfa with timothy grass grown in a farm in north-eastern Poland. The species with the highest DMY (dry matter yield) were the giant miscanthus (25.3 Mg ha −1 y −1 ) and maize (22.7 Mg ha −1 y −1 ). The production of 1 Mg of giant miscanthus DMY was least energy-intensive (0.74 GJ). In the remaining species, the energy inputs required to produce 1 Mg of DMY ranged from 1.12 to 1.40 GJ (maize, Amur silver grass, sweet sorghum) to 2.66 GJ (Virginia fanpetals). Giant miscanthus and maize were characterized by the highest energy outputs of 468 and 404 GJ ha −1 y −1 , respectively. The biomass of the remaining crops accumulated 31–68% less energy. In the climate of north-eastern Poland, the most energy-efficient crop was giant miscanthus (25.0), followed by maize (15.8), Amur silver grass (14.7) and sweet sorghum (12.5), whereas the lowest values of the energy efficiency ratio were noted in alfalfa with timothy grass (10.0) and Virginia fanpetals (7.0). - Highlights: • Giant miscanthus and maize produced high DMY (25.3 and 22.7 Mg ha −1 y −1 ). • Giant miscanthus and maize delivered high energy outputs (468 and 404 GJ ha −1 y −1 ). • The energy input per 1 Mg of giant miscanthus DMY was determined at 0.74 GJ. • In the others crops, the production of 1 Mg DMY required 1.5–3.6-times more energy. • The highest energy efficiency ratio was obtained for giant miscanthus production.

  3. Intensive management in grasslands causes diffuse water pollution at the farm scale.

    Science.gov (United States)

    Peukert, Sabine; Griffith, Bruce A; Murray, Phillip J; Macleod, Christopher J A; Brazier, Richard E

    2014-11-01

    Arable land use is generally assumed to be the largest contributor to agricultural diffuse pollution. This study adds to the growing evidence that conventional temperate intensively managed lowland grasslands contribute significantly to soil erosion and diffuse pollution rates. This is the first grassland study to monitor hydrological characteristics and multiple pollutant fluxes (suspended sediment [SS] and the macronutrients: total oxidized nitrogen-N [TON], total phosphorus [TP], and total carbon [TC]) at high temporal resolution (monitoring up to every 15 min) over 1 yr. Monitoring was conducted across three fields (6.5-7.5 ha) on the North Wyke Farm Platform, UK. The estimated annual erosion rates (up to 527.4 kg ha), TP losses (up to 0.9 kg ha), and TC losses (up to 179 kg ha) were similar to or exceeded the losses reported for other grassland, mixed land-use, and arable sites. Annual yields of TON (up to 3 kg ha) were less than arable land-use fluxes and earlier grassland N studies, an important result as the study site is situated within a Nitrate Vulnerable Zone. The high-resolution monitoring allowed detailed "system's functioning" understanding of hydrological processes, mobilization- transport pathways of individual pollutants, and the changes of the relative importance of diffuse pollutants through flow conditions and time. Suspended sediment and TP concentrations frequently exceeded water quality guidelines recommended by the European Freshwater Fisheries Directive (25 mg L) and the European Water Framework Directive (0.04 mg soluble reactive P L), suggesting that intensively managed grasslands pose a significant threat to receiving surface waters. Such sediment and nutrient losses from intensively managed grasslands should be acknowledged in land management guidelines and advice for future compliance with surface water quality standards. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of

  4. Leininger's model for discoveries at The Farm and midwifery services to the Amish.

    Science.gov (United States)

    Finn, J

    1995-01-01

    This paper is a descriptive report and analysis of a transcultural nurse's experiences immersed in a hippie subculture at The Farm near Summertown, Tennessee. This subcultural group initially was established over 20 years ago as a community with a unique worldview which included pacifistic, vegetarian, and collective values and beliefs. This community prefers health care provided by their own community members who serve as generic care providers and also as folk midwives for home births. Leininger's (1991) Theory of Culture Care Diversity and Universality and her Sunrise Model provided the framework for discovering and understanding this unique subcultural group. The major components of Leininger's Sunrise Model including worldview, cultural values, and lifeways were used in the analysis. The important social structure factors discovered included environmental context, technological factors, religious and philosophical factors, political and legal factors, economic factors, and educational factors. The Farm community's culture care expressions, patterns and practices for health and well being were discovered including generic and folk systems of care. The farm midwives provide primary care and home birthing care to a nearby Old Order Amish community. The Amish culture and health care seeking patterns are discussed including their selective use of generic, folk, and professional care systems. The discoveries that resulted from the application of Leininger's Sunrise Model are presented including implications for transcultural nurse caregiving.

  5. The Relationship of Dairy Farm Eco-Efficiency with Intensification and Self-Sufficiency. Evidence from the French Dairy Sector Using Life Cycle Analysis, Data Envelopment Analysis and Partial Least Squares Structural Equation Modelling

    Science.gov (United States)

    Soteriades, Andreas Diomedes; Stott, Alistair William; Moreau, Sindy; Charroin, Thierry; Blanchard, Melanie; Liu, Jiayi; Faverdin, Philippe

    2016-01-01

    We aimed at quantifying the extent to which agricultural management practices linked to animal production and land use affect environmental outcomes at a larger scale. Two practices closely linked to farm environmental performance at a larger scale are farming intensity, often resulting in greater off-farm environmental impacts (land, non-renewable energy use etc.) associated with the production of imported inputs (e.g. concentrates, fertilizer); and the degree of self-sufficiency, i.e. the farm’s capacity to produce goods from its own resources, with higher control over nutrient recycling and thus minimization of losses to the environment, often resulting in greater on-farm impacts (eutrophication, acidification etc.). We explored the relationship of these practices with farm environmental performance for 185 French specialized dairy farms. We used Partial Least Squares Structural Equation Modelling to build, and relate, latent variables of environmental performance, intensification and self-sufficiency. Proxy indicators reflected the latent variables for intensification (milk yield/cow, use of maize silage etc.) and self-sufficiency (home-grown feed/total feed use, on-farm energy/total energy use etc.). Environmental performance was represented by an aggregate ‘eco-efficiency’ score per farm derived from a Data Envelopment Analysis model fed with LCA and farm output data. The dataset was split into two spatially heterogeneous (bio-physical conditions, production patterns) regions. For both regions, eco-efficiency was significantly negatively related with milk yield/cow and the use of maize silage and imported concentrates. However, these results might not necessarily hold for intensive yet more self-sufficient farms. This requires further investigation with latent variables for intensification and self-sufficiency that do not largely overlap- a modelling challenge that occurred here. We conclude that the environmental ‘sustainability’ of intensive dairy

  6. Financial analysis of brucellosis control for small-scale goat farming in the Bajio Region, Mexico

    NARCIS (Netherlands)

    Oseguera Montiel, D.; Bruce, M.; Frankena, K.; Udo, H.M.J.; Zijpp, van der A.J.; Rushton, J.

    2015-01-01

    Brucellosis is an endemic disease in small-scale goat husbandry systems in Mexico. It is a zoonosis and the economic consequences can be large, although estimates are not available for the Mexican goat sector. Our objective was to conduct a financial analysis of brucellosis control in a prominent

  7. Design and validation of field-scale anaerobic digesters treating dairy manure for small farms

    Science.gov (United States)

    Six field-scale (FS) digesters were designed, constructed, and tested using a plug-flow design used by millions of farmers in developing countries and reconfigured for a temperate climate. Digester efficiency was analyzed based on methane (CH4) production, volatile solids (VS) reduction, inoculum to...

  8. Diversity And Sustainability Of Small – Scale Farming In Cross River ...

    African Journals Online (AJOL)

    The paper examines the diversity and sustainability attributes of crops grown by small – scale farmers in Calabar Urban of Cross River State. It has as its objectives, the identification of the structure of agricultural system in Calabar- Urban, the determination of the types and diversity of crops grown by the farmers, the extent ...

  9. A multi-state model for wind farms considering operational outage probability

    DEFF Research Database (Denmark)

    Cheng, Lin; Liu, Manjun; Sun, Yuanzhang

    2013-01-01

    developed by considering the following factors: running time, operating environment, operating conditions, and wind speed fluctuations. A multi-state model for wind farms is also established. Numerical results illustrate that the proposed model can be well applied to power system reliability assessment...... power penetration levels. Therefore, a more comprehensive analysis toward WECS as well as an appropriate reliability assessment model are essential for maintaining the reliable operation of power systems. In this paper, the impact of wind turbine outage probability on system reliability is firstly...

  10. H2A Biomethane Model Documentation and a Case Study for Biogas From Dairy Farms

    Energy Technology Data Exchange (ETDEWEB)

    Saur, G.; Jalalzadeh, A.

    2010-12-01

    The new H2A Biomethane model was developed to estimate the levelized cost of biomethane by using the framework of the vetted original H2A models for hydrogen production and delivery. For biomethane production, biogas from sources such as dairy farms and landfills is upgraded by a cleanup process. The model also estimates the cost to compress and transport the product gas via the pipeline to export it to the natural gas grid or any other potential end-use site. Inputs include feed biogas composition and cost, required biomethane quality, cleanup equipment capital and operations and maintenance costs, process electricity usage and costs, and pipeline delivery specifications.

  11. A bio-economic farm household model to assess cropping systems in the Rift valley of Ethiopia : towards climate smart agriculture: do food security and mitigration goals match?

    NARCIS (Netherlands)

    Hengsdijk, H.; Verhagen, A.

    2012-01-01

    Modelling approach for rain fed farm household systems in the Central Rif Valley of Ethiopia to assess the possible effects of intensification of cereal-based cropping systems to farm income, mitigation of GHG emissions and other household indicators

  12. A lab-scale model system for cocoa bean fermentation.

    Science.gov (United States)

    Romanens, Edwina; Näf, Rebecca; Lobmaier, Tobias; Pedan, Vasilisa; Leischtfeld, Susette Freimüller; Meile, Leo; Schwenninger, Susanne Miescher

    2018-04-01

    Lab-scale systems modelling the spontaneous cocoa bean fermentation process are useful tools to research the influence of process parameters on the fermentation and the final bean quality. In this study in Honduras, a 1-kg lab-scale fermentation (LS-F) was compared to a 300-kg on-farm fermentation (OF-F) in a multiphasic approach, analysing microbial counts, microbial species diversity, physico-chemical parameters, and final dried bean quality. Yeast and total aerobic counts of up to 8 log CFU/g during the LS-F were comparable to the OF-F, while counts for lactic acid bacteria and acetic acid bacteria were up to 3 log CFU/g lower during the LS-F than during the OF-F. While species of the genera Hansenia, Saccharomyces, and Acetobacter dominated most of the fermentation processes, the genera dominating the drying phases were Pichia, Trichosporon, Pediococcus, and Acetobacter. Dried beans resulting from the LS-F, compared to the OF-F, were similar in contents of acetic acid, 6 times lower in lactic acid, up to 4 times higher in residual sugars, and 3-12 times higher in polyphenols. Dried beans processed at LS showed a similar flavour profile in terms of astringency, bitterness, acidity, and brown, fine, and cocoa flavours, but 2 units higher off-flavours than OF processed beans. With 81%, the share of well-fermented beans from the LS-F complied with industrial standards, whereas 7% over-fermented beans were above the threshold. Conclusively, the 5-day model fermentation and subsequent drying successfully mimicked the on-farm process, providing a high-throughput method to screen microbial strains to be used as starter cultures.

  13. Plot Scale Phosphorous and Potassium Balances of Newly Opened Wetland Rice Farming Originated from Wetland

    Directory of Open Access Journals (Sweden)

    Sofyan Ritung

    2012-09-01

    Full Text Available Development of newly opened wetland rice fields both from dry land and wetland in Indonesia are important to meet rice growing demand, increase soil productivity, keep rural food security and provide jobs as well as generate income. Most soils of newly opened rice fields are low in P and K contents, but the farmers do not apply P and Krecommended fertilisers. The study was conducted on newly opened wetland rice farming in Panca Agung village,Bulungan District, East Kalimantan Province, Indonesia in 2009. The aims were to evaluate phosphorous and potassium input – out of newly opened wetland rice and to validate the P and K recommendation. Six treatments were tested including farmers practices (as control, farmer practices + straw compost + dolomite, NPK with recommendation rate in which N and K was split in two applications, NPK with recommendation rate in which N and K was split three applications, NPK with recommendation rate + straw compost + Dolomite , in which N and K was split three applications, and NPK with recommendation rate + straw compost + dolomite, in which N and K were split two applications. The N, P and K rates were 250 kg urea, 100 kg SP-36 and 100 kg KCl ha-1 season-1, while the farmer practices 100 kg urea and 100 kg SP-36 ha-1 season-1. Parameters to be measured were concentration P and K in mineral fertilizer, compost, irrigation water and grains as well as straw. The results showed that surplus P ranged from 5.75 to 12.85 kg P ha-1 season-1, meaning that SP-36 application rate was more than enough to replace P removed by harvest product. In contrast,potassium application rate should be increased from 100 to 200 kg KCl ha-1 season-1 to fix K removed by harvest product. However, when the compost will also be increased to 3 Mg ha-1 season-1 K fertilizer can be increased to 150 kg KCl ha-1 season-1 to substitute K taken away by rice harvest product and to keep higher rice grain yield. These P and K recommendation rate imply

  14. Control of Groundwater Pollution from Animal Feeding Operations: A Farm-Level Dynamic Model for Policy Analysis

    Science.gov (United States)

    Wang, J.; Baerenklau, K.

    2012-12-01

    Consolidation in livestock production generates higher farm incomes due to economies of scale, but it also brings waste disposal problems. Over-application of animal waste on adjacent land produces adverse environmental and health effects, including groundwater nitrate pollution. The situation is particularly noticeable in California. In respond to this increasingly severe problem, EPA published a type of command-and-control regulation for concentrated animal feeding operations (CAFOs) in 2003. The key component of the regulation is its nutrient management plans (NMPs), which intend to limit the land application rates of animal waste. Although previous studies provide a full perspective on potential economic impacts for CAFOs to meet nutrient standards, their models are static and fail to reflect changes in management practices other than spreading manure on additional land and changing cropping patterns. We develop a dynamic environmental-economic modeling framework for representative CAFOs. The framework incorporates four models (i.e., animal model, crop model, hydrologic model, and economic model) that include various components such as herd management, manure handling system, crop rotation, water sources, irrigation system, waste disposal options, and pollutant emissions. We also include the dynamics of soil characteristics in the rootzone as well as the spatial heterogeneity of the irrigation system. The operator maximizes discounted total farm profit over multiple periods subject to environmental regulations. Decision rules from the dynamic optimization problem demonstrate best management practices for CAFOs to improve their economic and environmental performance. Results from policy simulations suggest that direct quantity restrictions of emission or incentive-based emission policies are much more cost-effective than the standard approach of limiting the amount of animal waste that may be applied to fields (as shown in the figure below); reason being

  15. Farm-scale testing of soybean peroxidase and calcium peroxide for surficial swine manure treatment and mitigation of odorous VOCs, ammonia and hydrogen sulfide

    Science.gov (United States)

    The swine industry, regulatory agencies, and the public are interested in farm-tested methods for controlling gaseous emissions from swine barns. In earlier lab- and pilot-scale studies, a renewable catalyst consisting of soybean peroxidase (SBP) mixed with calcium peroxide was found to be effective...

  16. Towards a ‘systems’ approach for guiding agricultural environmental management: a South African case study of a small-scale maize farming system

    CSIR Research Space (South Africa)

    Musvoto, Constansia D

    2009-08-01

    Full Text Available environmental management intervention points in an agricultural system, illustrated through a case study of a small-scale maize farming system in South Africa. A review of documented information on the ecological, socio-political and economic components...

  17. Dynamic wake model with coordinated pitch and torque control of wind farms for power tracking

    Science.gov (United States)

    Shapiro, Carl; Meyers, Johan; Meneveau, Charles; Gayme, Dennice

    2017-11-01

    Control of wind farm power production, where wind turbines within a wind farm coordinate to follow a time-varying power set point, is vital for increasing renewable energy participation in the power grid. Previous work developed a one-dimensional convection-diffusion equation describing the advection of the velocity deficit behind each turbine (wake) as well the turbulent mixing of the wake with the surrounding fluid. Proof-of-concept simulations demonstrated that a receding horizon controller built around this time-dependent model can effectively provide power tracking services by modulating the thrust coefficients of individual wind turbines. In this work, we extend this model-based controller to include pitch angle and generator torque control and the first-order dynamics of the drive train. Including these dynamics allows us to investigate control strategies for providing kinetic energy reserves to the grid, i.e. storing kinetic energy from the wind in the rotating mass of the wind turbine rotor for later use. CS, CM, and DG are supported by NSF (ECCS-1230788, CMMI 1635430, and OISE-1243482, the WINDINSPIRE project). JM is supported by ERC (ActiveWindFarms, 306471). This research was conducted using computational resources at MARCC.

  18. Forecasting wind power production from a wind farm using the RAMS model

    DEFF Research Database (Denmark)

    Tiriolo, L.; Torcasio, R. C.; Montesanti, S.

    2015-01-01

    The importance of wind power forecast is commonly recognized because it represents a useful tool for grid integration and facilitates the energy trading. This work considers an example of power forecast for a wind farm in the Apennines in Central Italy. The orography around the site is complex...... and the horizontal resolution of the wind forecast has an important role. To explore this point we compared the performance of two 48 h wind power forecasts using the winds predicted by the Regional Atmospheric Modeling System (RAMS) for the year 2011. The two forecasts differ only for the horizontal resolution...... of the ECMWF Integrated Forecasting System (IFS), whose horizontal resolution over Central Italy is about 25 km at the time considered in this paper. Because wind observations were not available for the site, the power curve for the whole wind farm was derived from the ECMWF wind operational analyses available...

  19. Wake interaction and power production of variable height model wind farms

    DEFF Research Database (Denmark)

    Vested, Malene Hovgaard; Hamilton, N.; Sørensen, Jens Nørkær

    2014-01-01

    Understanding wake dynamics is an ongoing research topic in wind energy, since wakes have considerable effects on the power production when wind turbines are placed in a wind farm. Wind tunnel experiments have been conducted to study the wake to wake interaction in a model wind farm in tandem...... with measurements of the extracted power. The aim is to investigate how alternating mast height influences the interaction of the wakes and the power production. Via the use of stereo-particle image velocimetry, the flow field was obtained in the first and last rows of the wind turbine array as a basis...... of comparison. It was found that downstream of the exit row wind turbine, the power was increased by 25% in the case of a staggered height configuration. This is partly due to the fact that the taller turbines reach into a flow area with a softened velocity gradient. Another aspect is that the wake downstream...

  20. On scaling of human body models

    Directory of Open Access Journals (Sweden)

    Hynčík L.

    2007-10-01

    Full Text Available Human body is not an unique being, everyone is another from the point of view of anthropometry and mechanical characteristics which means that division of the human body population to categories like 5%-tile, 50%-tile and 95%-tile from the application point of view is not enough. On the other hand, the development of a particular human body model for all of us is not possible. That is why scaling and morphing algorithms has started to be developed. The current work describes the development of a tool for scaling of the human models. The idea is to have one (or couple of standard model(s as a base and to create other models based on these basic models. One has to choose adequate anthropometrical and biomechanical parameters that describe given group of humans to be scaled and morphed among.

  1. Distributed Model Predictive Control of A Wind Farm for Optimal Active Power Control

    DEFF Research Database (Denmark)

    Zhao, Haoran; Wu, Qiuwei; Guo, Qinglai

    2015-01-01

    , which combines the clustering, linear identification and pattern recognition techniques. The developed model, consisting of 47 affine dynamics, is verified by the comparison with a widely-used nonlinear wind turbine model. It can be used as a predictive model for the Model Predictive Control (MPC......This paper presents a dynamic discrete-time Piece- Wise Affine (PWA) model of a wind turbine for the optimal active power control of a wind farm. The control objectives include both the power reference tracking from the system operator and the wind turbine mechanical load minimization. Instead...... of partial linearization of the wind turbine model at selected operating points, the nonlinearities of the wind turbine model are represented by a piece-wise static function based on the wind turbine system inputs and state variables. The nonlinearity identification is based on the clustering-based algorithm...

  2. Harmonic models of a back-to-back converter in large offshore wind farms compared with measurement data

    DEFF Research Database (Denmark)

    Kocewiak, Lukasz Hubert; Hjerrild, Jesper; Bak, Claus Leth

    2009-01-01

    The offshore wind farm with installed back-to-back power converter in wind turbines is studied. As an example the Burbo Bank offshore wind farm with Siemens Wind Power wind turbines is taken into consideration. The wind farm is simulated in DIgSILENT Power Factory software in order to determine a...... results are compared with measurement data from the Burbo Bank offshore wind farm. The delimitations of both power converter models with referent to harmonic analysis are shown in this paper....... and assess harmonic emission in the point of common coupling. Different modelling methods of power electronic devices installed in wind turbines are presented. Harmonic load flow analysis and impedance frequency characteristics calculation are conducted to present differences between the models. Simulation...

  3. A survey of modelling methods for high-fidelity wind farm simulations using large eddy simulation

    DEFF Research Database (Denmark)

    Breton, Simon-Philippe; Sumner, J.; Sørensen, Jens Nørkær

    2017-01-01

    Large eddy simulations (LES) of wind farms have the capability to provide valuable and detailed information about the dynamics of wind turbine wakes. For this reason, their use within the wind energy research community is on the rise, spurring the development of new models and methods. This review...... surveys the most common schemes available to model the rotor, atmospheric conditions and terrain effects within current state-of-the-art LES codes, of which an overview is provided. A summary of the experimental research data available for validation of LES codes within the context of single and multiple...

  4. A Simulation Model of Combined Biogas, Bioethanol and Protein Fodder Co-Production in Organic Farming

    DEFF Research Database (Denmark)

    Oleskowicz-Popiel, Piotr; Thomsen, Mette Hedegaard; Thomsen, Anne Belinda

    2009-01-01

    In order to evaluate new strategies for the production of renewable energy within sustainable organic agriculture, a process-simulation model for a 100 ha organic farm was developed. Data used for the model was obtained from laboratory trials, literature data, consultancy with experts, and results...... from the BioConcens project (http://www.bioconcens.elr.dk). Different design approaches were evaluated in order to establish the most suitable configuration. Rye grains, clover grass silage, maize silage, whey and cattle manure were selected as raw materials for co-production of fuels, feed...

  5. Investigation of sonar transponders for offshore wind farms: modeling approach, experimental setup, and results.

    Science.gov (United States)

    Fricke, Moritz B; Rolfes, Raimund

    2013-11-01

    The installation of offshore wind farms in the German Exclusive Economic Zone requires the deployment of sonar transponders to prevent collisions with submarines. The general requirements for these systems have been previously worked out by the Research Department for Underwater Acoustics and Marine Geophysics of the Bundeswehr. In this article, the major results of the research project "Investigation of Sonar Transponders for Offshore Wind Farms" are presented. For theoretical investigations a hybrid approach was implemented using the boundary element method to calculate the source directivity and a three-dimensional ray-tracing algorithm to estimate the transmission loss. The angle-dependence of the sound field as well as the weather-dependence of the transmission loss are compared to experimental results gathered at the offshore wind farm alpha ventus, located 45 km north of the island Borkum. While theoretical and experimental results are in general agreement, the implemented model slightly underestimates scattering at the rough sea surface. It is found that the source level of 200 dB re 1 μPa at 1 m is adequate to satisfy the detectability of the warning sequence at distances up to 2 NM (≈3.7 km) within a horizontal sector of ±60° if realistic assumptions about signal-processing and noise are made. An arrangement to enlarge the angular coverage is discussed.

  6. Meat Quality Characteristics of Small East African Goats and Norwegian Crosses Finished under Small Scale Farming Conditions

    Directory of Open Access Journals (Sweden)

    W. A. Hozza

    2014-12-01

    Full Text Available The aim of the experiment was to study the effect of feeding system on meat quality characteristics of Small East African (SEA goats and their crosses with Norwegian (SEA×N goats finished under small scale farming conditions. Twenty four castrated goats at the age of 18 months with live body weight of 16.7±0.54 kg from each breed (SEA and SEA×N were distributed in a completely randomized design in a 2×3 factorial arrangement (two breed, and three dietary treatments. The dietary treatments were; no access to concentrate (T0, 66% access to ad libitum concentrate allowance (T66 and 100% access to ad libitum concentrate allowance with 20% refusal (T100 and the experimental period was for 84 days. In addition, all goats were allowed to graze for 2 hours daily and later fed grass hay on ad libitum basis. Daily feed intakes were recorded for all 84-days of experiment after which the animals were slaughtered. Feed intake of T100 animals was 536 g/d, which was 183 g/d higher than that of T66 group. Supplemented goats had significantly (p0.05 for dressing percentage and carcass conformation among supplemented goats except fatness score, total fat depots and carcass fat which increased (p<0.05 with increasing concentrate levels in the diet. Increasing level of concentrate on offer increased meat dry matter with subsequent increase of fat in the meat. Muscle pH of goats fed concentrate declined rapidly and reached below 6 at 6 h post-mortem but temperature remained at 28°C. Cooking loss and meat tenderness improved (p<0.05 and thawing loss increased (p<0.05 with ageing period. Similarly, meat tenderness improved (p<0.05 with concentrate supplementation. Shear force of muscles varied from 36 to 66, the high values been associated with Semimembranosus and Gluteobiceps muscles. The present study demonstrates that there are differences in meat quality characteristics of meat from SEA goats and their crosses with Norwegian breeds finished under small scale

  7. A novel spatial and stochastic model to evaluate the within- and between-farm transmission of classical swine fever virus. I. General concepts and description of the model.

    Science.gov (United States)

    Martínez-López, B; Ivorra, B; Ramos, A M; Sánchez-Vizcaíno, J M

    2011-01-27

    A new stochastic and spatial model was developed to evaluate the potential spread of classical swine fever virus (CSFV) within- and between-farms, and considering the specific farm-to-farm contact network. Within-farm transmission was simulated using a modified SI model. Between-farm transmission was assumed to occur by direct contacts (i.e. animal movement) and indirect contacts (i.e. local spread, vehicle and person contacts) and considering the spatial location of farms. Control measures dictated by the European legislation (i.e. depopulation of infected farms, movement restriction, zoning, surveillance, contact tracing) were also implemented into the model. Model experimentation was performed using real data from Segovia, one of the provinces with highest density of pigs in Spain, and results were presented using the mean, 95% probability intervals [95% PI] and risk maps. The estimated mean [95% PI] number of infected, quarantined and depopulated farms were 3 [1,17], 23 [0,76] and 115 [0,318], respectively. The duration of the epidemic was 63 [26,177] days and the most important way of transmission was associated with local spread (61.4% of the infections). Results were consistent with the spread of previous CSFV introductions into the study region. The model and results presented here may be useful for the decision making process and for the improvement of the prevention and control programmes for CSFV. Copyright © 2010 Elsevier B.V. All rights reserved.

  8. Using models to establish the financially optimum strategy for Irish dairy farms.

    Science.gov (United States)

    Ruelle, E; Delaby, L; Wallace, M; Shalloo, L

    2018-01-01

    Determining the effect of a change in management on farm with differing characteristics is a significant challenge in the evaluation of dairy systems due to the interacting components of complex biological systems. In Ireland, milk production is increasing substantially following the abolition of the European Union milk quota regime in 2015. There are 2 main ways to increase the milk production on farm (within a fixed land base): either increase the number of animals (thus increasing the stocking rate) or increase the milk production per animal through increased feeding or increased lactation length. In this study, the effect of increased concentrate feeding or an increase in grazing intensity was simulated to determine the effect on the farm system and its economic performance. Four stocking rates (2.3, 2.6, 2.9, and 3.2 cow/ha) and 5 different concentrate supplementation strategies (0, 180, 360, 600, and 900 kg of dry matter/lactation) resulting in 20 different scenarios were evaluated across different milk, concentrate, and silage purchase prices. Each simulation was run across 10 yr of meteorological data, which had been recorded over the period 2004 to 2013. Three models-the Moorepark and St Gilles grass growth model, the pasture-based herd dynamic milk model, and the Moorepark dairy systems model-were integrated and applied to simulate the different scenarios. Overall, this study has demonstrated that the most profitable scenario was a stocking rate of 2.6 cow/ha with a concentrate supplementation of 600 kg of dry matter/cow. The factor that had the greatest influence on profitability was variability of milk price. The Authors. Published by the Federation of Animal Science Societies and Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

  9. Site-Scale Saturated Zone Flow Model

    Energy Technology Data Exchange (ETDEWEB)

    G. Zyvoloski

    2003-12-17

    The purpose of this model report is to document the components of the site-scale saturated-zone flow model at Yucca Mountain, Nevada, in accordance with administrative procedure (AP)-SIII.lOQ, ''Models''. This report provides validation and confidence in the flow model that was developed for site recommendation (SR) and will be used to provide flow fields in support of the Total Systems Performance Assessment (TSPA) for the License Application. The output from this report provides the flow model used in the ''Site-Scale Saturated Zone Transport'', MDL-NBS-HS-000010 Rev 01 (BSC 2003 [162419]). The Site-Scale Saturated Zone Transport model then provides output to the SZ Transport Abstraction Model (BSC 2003 [164870]). In particular, the output from the SZ site-scale flow model is used to simulate the groundwater flow pathways and radionuclide transport to the accessible environment for use in the TSPA calculations. Since the development and calibration of the saturated-zone flow model, more data have been gathered for use in model validation and confidence building, including new water-level data from Nye County wells, single- and multiple-well hydraulic testing data, and new hydrochemistry data. In addition, a new hydrogeologic framework model (HFM), which incorporates Nye County wells lithology, also provides geologic data for corroboration and confidence in the flow model. The intended use of this work is to provide a flow model that generates flow fields to simulate radionuclide transport in saturated porous rock and alluvium under natural or forced gradient flow conditions. The flow model simulations are completed using the three-dimensional (3-D), finite-element, flow, heat, and transport computer code, FEHM Version (V) 2.20 (software tracking number (STN): 10086-2.20-00; LANL 2003 [161725]). Concurrently, process-level transport model and methodology for calculating radionuclide transport in the saturated zone at Yucca

  10. Site-Scale Saturated Zone Flow Model

    International Nuclear Information System (INIS)

    G. Zyvoloski

    2003-01-01

    The purpose of this model report is to document the components of the site-scale saturated-zone flow model at Yucca Mountain, Nevada, in accordance with administrative procedure (AP)-SIII.lOQ, ''Models''. This report provides validation and confidence in the flow model that was developed for site recommendation (SR) and will be used to provide flow fields in support of the Total Systems Performance Assessment (TSPA) for the License Application. The output from this report provides the flow model used in the ''Site-Scale Saturated Zone Transport'', MDL-NBS-HS-000010 Rev 01 (BSC 2003 [162419]). The Site-Scale Saturated Zone Transport model then provides output to the SZ Transport Abstraction Model (BSC 2003 [164870]). In particular, the output from the SZ site-scale flow model is used to simulate the groundwater flow pathways and radionuclide transport to the accessible environment for use in the TSPA calculations. Since the development and calibration of the saturated-zone flow model, more data have been gathered for use in model validation and confidence building, including new water-level data from Nye County wells, single- and multiple-well hydraulic testing data, and new hydrochemistry data. In addition, a new hydrogeologic framework model (HFM), which incorporates Nye County wells lithology, also provides geologic data for corroboration and confidence in the flow model. The intended use of this work is to provide a flow model that generates flow fields to simulate radionuclide transport in saturated porous rock and alluvium under natural or forced gradient flow conditions. The flow model simulations are completed using the three-dimensional (3-D), finite-element, flow, heat, and transport computer code, FEHM Version (V) 2.20 (software tracking number (STN): 10086-2.20-00; LANL 2003 [161725]). Concurrently, process-level transport model and methodology for calculating radionuclide transport in the saturated zone at Yucca Mountain using FEHM V 2.20 are being

  11. Wind Power Curve Modeling Using Statistical Models: An Investigation of Atmospheric Input Variables at a Flat and Complex Terrain Wind Farm

    Energy Technology Data Exchange (ETDEWEB)

    Wharton, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bulaevskaya, V. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Irons, Z. [Enel Green Power North America, Andover, MA (United States); Qualley, G. [Infigen Energy, Dallas, TX (United States); Newman, J. F. [Univ. of Oklahoma, Norman, OK (United States); Miller, W. O. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-09-28

    The goal of our FY15 project was to explore the use of statistical models and high-resolution atmospheric input data to develop more accurate prediction models for turbine power generation. We modeled power for two operational wind farms in two regions of the country. The first site is a 235 MW wind farm in Northern Oklahoma with 140 GE 1.68 turbines. Our second site is a 38 MW wind farm in the Altamont Pass Region of Northern California with 38 Mitsubishi 1 MW turbines. The farms are very different in topography, climatology, and turbine technology; however, both occupy high wind resource areas in the U.S. and are representative of typical wind farms found in their respective areas.

  12. Optimization biogas management as alternative energy from communal scale dairy farm

    Science.gov (United States)

    Ruhiyat, R.; Siami, L.

    2018-01-01

    Cow Slurry can be the main pollution source in most villages in Indonesia. In this study, treatment of cow slurry intended to reduce pollution in Citarum river and greenhouse gases effect of CH4 and CO2. As a part of renewable energy, biogas can be one of solution to be implemented in small-scale and remote area. In Pejaten, Tarumajaya Village, the cost-effective reached when 7cattleman united to treat cow slurry in one biodigester. The breed varies cow from calf, veal to adult cattle. The installation of anaerobic-bio digester that produce biogas 28 m3/day equivalent with Rp 168,000 to be consumed for 14 households. In addition, villager also benefitted manure as 42.5 ton monthly. As a whole, the highest profit comes from adult cattle that produce 900 kg/month slurry as Rp 59,919 monthly. Furthermore, this system gives job opportunity for villagers to be biodigester operator is the main beneficial with the higher income compare to mower that only Rp 600.000 monthly as Rp 1.065.000.

  13. "An Equal Interest in the Soil": Creek Small-Scale Farming and the Work of Nationhood, 1866-1889

    Science.gov (United States)

    Chang, David A.

    2009-01-01

    After the war in 1866, slaves became the owners of the lands they once farmed for their masters. The land they farmed became their own because of the nature of Creek citizenship and land tenure. The 1866 treaty of peace between the United States federal government and the Creek Nation (also known as the Muskogee Nation) declared that freed slaves…

  14. Interactive model to assess economics of anaerobic digestion of the farm

    Science.gov (United States)

    1981-08-01

    An interactive computer model, to provide economic assessment for on the farm anaerobic digestion systems was designed. The model is accessed as part of the MASEC Models Library. It consists of two phases: engineering analysis and economic analysis. User inputs are stored in a data base and may be retained for future use. Model outputs include a recap of user inputs, calculations for gas production, digester heat requirements, system revenues, yearly cash flow, and a graph of the net present value of the investment. The model is generalized so that nonfarm applications may also be analyzed. The program will work equally well for various digester designs such as continuously stirred reactors, plug flow systems, and fluidized bed columns.

  15. Wind model for low frequency power fluctuations in offshore wind farms

    DEFF Research Database (Denmark)

    Vigueras-Rodríguez, A.; Sørensen, Poul Ejnar; Cutululis, Nicolaos Antonio

    2010-01-01

    of hours, taking into account the spectral correlation between different wind turbines. The modelling is supported by measurements from two large wind farms, namely Nysted and Horns Rev. Measurements from individual wind turbines and meteorological masts are used. Finally, the models are integrated...... into an aggregated model which is used for estimating some electrical parameters as power ramps and reserves requirements, showing a quite good agreement between simulations and measurement. The comparison with measurements generally show that the inclusion of the correlation between low frequency components...... is an improvement, but the effect is relatively small. The effect of including the low frequency components in the model is much more significant. Therefore, that aggregated model is useful in the power system planning and operation, e.g. regarding load following and regulation. Copyright © 2009 John Wiley & Sons...

  16. A Comprehensive Energy Analysis and Related Carbon Footprint of Dairy Farms, Part 2: Investigation and Modeling of Indirect Energy Requirements

    Directory of Open Access Journals (Sweden)

    Giuseppe Todde

    2018-02-01

    Full Text Available Dairy cattle farms are continuously developing more intensive systems of management, which require higher utilization of durable and non-durable inputs. These inputs are responsible for significant direct and indirect fossil energy requirements, which are related to remarkable emissions of CO2. This study focused on investigating the indirect energy requirements of 285 conventional dairy farms and the related carbon footprint. A detailed analysis of the indirect energy inputs related to farm buildings, machinery and agricultural inputs was carried out. A partial life cycle assessment approach was carried out to evaluate indirect energy inputs and the carbon footprint of farms over a period of one harvest year. The investigation highlights the importance and the weight related to the use of agricultural inputs, which represent more than 80% of the total indirect energy requirements. Moreover, the analyses carried out underline that the assumption of similarity in terms of requirements of indirect energy and related carbon emissions among dairy farms is incorrect especially when observing different farm sizes and milk production levels. Moreover, a mathematical model to estimate the indirect energy requirements of dairy farms has been developed in order to provide an instrument allowing researchers to assess the energy incorporated into farm machinery, agricultural inputs and buildings. Combining the results of this two-part series, the total energy demand (expressed in GJ per farm results in being mostly due to agricultural inputs and fuel consumption, which have the largest share of the annual requirements for each milk yield class. Direct and indirect energy requirements increased, going from small sized farms to larger ones, from 1302–5109 GJ·y−1, respectively. However, the related carbon dioxide emissions expressed per 100 kg of milk showed a negative trend going from class <5000 to >9000 kg of milk yield, where larger farms were able to

  17. Assessing the Geographic Representativity of Farm Accountancy Data

    Directory of Open Access Journals (Sweden)

    Stuart Green

    2013-02-01

    Full Text Available The environment affects agriculture, via soils, weather, etc. and agriculture affects the environment locally at farm level and via its impact on climate change. Locating agriculture within its spatial environment is thus important for farmers and policy makers. Within the EU countries collect detailed farm data to understand the technical and financial performance of farms; the Farm Accountancy Data Network. However, knowledge of the spatial-environmental context of these farms is reported at gross scale. In this paper, Irish farm accounting data is geo-referenced using address matching to a national address database. An analysis of the geographic distribution of the survey farms, illustrated through a novel 2D ranked pair plot of the coordinates, compared to the national distribution of farms shows a trend in the location of survey farms that leads to a statistical difference in the climatic variables associated with the farm. The farms in the survey have significantly higher accumulated solar radiation values than the national average. As a result, the survey may not be representative spatially of the pattern of environment x farm system. This could have important considerations when using FADN data in modelling climate change impacts on agri-economic performance.

  18. Results of Sexbierum Wind Farm: single wake measurements

    NARCIS (Netherlands)

    Cleijne, J.W.

    1993-01-01

    In the framework of the JOULE-0064 'Full-scale Measurements in Wind Turbine Arrays' in the period between June-November 1992 measurements have been performed in the Sexbierum Wind Farm. The aim of the measurements is to provide data for the validation of wake and wind farm models, which are being

  19. Measurement and Modelling of Scaling Minerals

    DEFF Research Database (Denmark)

    Villafafila Garcia, Ada

    2005-01-01

    of temperature and pressure. Reliable experimental solubility measurements under conditions similar to those found in reality will help the development of strong and consistent models. Chapter 1 is a short introduction to the problem of scale formation, the model chosen to study it, and the experiments performed......). Chapters 8 and 9 focus on the experimental part of this dissertation, analyzing different experimental procedures to determine salt solubility at high temperature and pressure, and developing a setup to perform those measurements. The motivation behind both parts of the Ph.D. project is the problem...... of scale formation found in many industrial processes, and especially in oilfield and geothermal operations. We want to contribute to the study of this problem by releasing a simple and accurate thermodynamic model capable of calculating the behaviour of scaling minerals, covering a wide range...

  20. A sample theory-based logic model to improve program development, implementation, and sustainability of Farm to School programs.

    Science.gov (United States)

    Ratcliffe, Michelle M

    2012-08-01

    Farm to School programs hold promise to address childhood obesity. These programs may increase students’ access to healthier foods, increase students’ knowledge of and desire to eat these foods, and increase their consumption of them. Implementing Farm to School programs requires the involvement of multiple people, including nutrition services, educators, and food producers. Because these groups have not traditionally worked together and each has different goals, it is important to demonstrate how Farm to School programs that are designed to decrease childhood obesity may also address others’ objectives, such as academic achievement and economic development. A logic model is an effective tool to help articulate a shared vision for how Farm to School programs may work to accomplish multiple goals. Furthermore, there is evidence that programs based on theory are more likely to be effective at changing individuals’ behaviors. Logic models based on theory may help to explain how a program works, aid in efficient and sustained implementation, and support the development of a coherent evaluation plan. This article presents a sample theory-based logic model for Farm to School programs. The presented logic model is informed by the polytheoretical model for food and garden-based education in school settings (PMFGBE). The logic model has been applied to multiple settings, including Farm to School program development and evaluation in urban and rural school districts. This article also includes a brief discussion on the development of the PMFGBE, a detailed explanation of how Farm to School programs may enhance the curricular, physical, and social learning environments of schools, and suggestions for the applicability of the logic model for practitioners, researchers, and policy makers.

  1. Modelling the fate of pesticides in paddy rice-fish pond farming system in Northern Vietnam

    Science.gov (United States)

    Lamers, M.; Nguyen, N.; Streck, T.

    2012-04-01

    During the last decade rice production in Vietnam has tremendously increased due to the introduction of new high yield, short duration rice varieties and an increased application of pesticides. Since pesticides are toxic by design, there is a natural concern on the possible impacts of their presence in the environment on human health and environment quality. In North Vietnam, lowland and upland rice fields were identified to be a major non-point source of agrochemical pollution to surface and ground water, which are often directly used for domestic purposes. Field measurements, however, are time consuming, costly and logistical demanding. Hence, quantification, forecast and risk assessment studies are hampered by a limited amount of field data. One potential way to cope with this shortcoming is the use of process-based models. In the present study we developed a model for simulating short-term pesticide dynamics in combined paddy rice field - fish pond farming systems under the specific environmental conditions of south-east Asia. Basic approaches and algorithms to describe the key underlying biogeochemical processes were mainly adopted from the literature to assure that the model reflects the current standard of scientific knowledge and commonly accepted theoretical background. The model was calibrated by means of the Gauss-Marquardt-Levenberg algorithm and validated against measured pesticide concentrations (dimethoate and fenitrothion) during spring and summer rice crop season 2008, respectively, of a paddy field - fish pond system typical for northern Vietnam. First simulation results indicate that our model is capable to simulate the fate of pesticides in such paddy - fish pond farming systems. The model efficiency for the period of calibration, for example, was 0.97 and 0.95 for dimethoate and fenitrothion, respectively. For the period of validation, however, the modeling efficiency slightly decreased to 0.96 and 0.81 for dimethoate and fenitrothion

  2. Energy Self-sufficiency from an Emergy Perspective Exemplified by a Model System of a Danish Farm Cooperative

    DEFF Research Database (Denmark)

    Østergård, Hanne; Markussen, Mads Ville

    2010-01-01

    Contemporary food production is highly dependent on fossil fuel for production of fertilizer and as diesel for field operations. One way to enhance agricultural resilience is to increase self-sufficiency at the farm level with necessities such as energy, food, fodder, nutrients and seed. It is even...... better if the farm is a net energy producer since energy used for processing, distribution and trade of farm products should be supplied also by agriculture in order to increase the resilience of food supply systems. In this project we analyze these potentials based on a model system of a multifunctional...... flow for labor in different ways. The five farms produce bioenergy (biodiesel from oil seed rape and electricity and hot water from anaerobic fermentation of grass-clover), food and fodder (cereals and legumes) and green manure (effluent from biogas production). All green manure, about half...

  3. Using the coupled wake boundary layer model to evaluate the effect of turbulence intensity on wind farm performance

    NARCIS (Netherlands)

    Stevens, Richard Johannes Antonius Maria; Gayme, Dennice F.; Meneveau, Charles

    2015-01-01

    We use the recently introduced coupled wake boundary layer (CWBL) model to predict the e ect of turbulence intensity on the performance of a wind farm. The CWBL model combines a standard wake model with a \\top-down" approach to get improved predictions for the power output compared to a stand-alone

  4. Phenomenology of Low Quantum Gravity Scale Models

    CERN Document Server

    Benakli, Karim

    1999-01-01

    We study some phenomenological implications of models where the scale of quantum gravity effects lies much below the four-dimensional Planck scale. These models arise from M-theory vacua where either the internal space volume is large or the string coupling is very small. We provide a critical analysis of ways to unify electroweak, strong and gravitational interactions in M-theory. We discuss the relations between different scales in two M-vacua: Type I strings and Ho\\v rava--Witten supergravity models. The latter allows possibilities for an eleven-dimensional scale at TeV energies with one large dimension below separating our four-dimensional world from a hidden one. Different mechanisms for breaking supersymmetry (gravity mediated, gauge mediated and Scherk-Schwarz mechanisms) are discussed in this framework. Some phenomenological issues such as dark matter (with masses that may vary in time), origin of neutrino masses and axion scale are discussed. We suggest that these are indications that the string scal...

  5. Changes in the Welfare of an Injured Working Farm Dog Assessed Using the Five Domains Model

    Directory of Open Access Journals (Sweden)

    Katherine E. Littlewood

    2016-09-01

    Full Text Available The present structured, systematic and comprehensive welfare evaluation of an injured working farm dog using the Five Domains Model is of interest in its own right. It is also an example for others wanting to apply the Model to welfare evaluations in different species and contexts. Six stages of a fictitious scenario involving the dog are considered: (1 its on-farm circumstances before one hind leg is injured; (2 its entanglement in barbed wire, cutting it free and transporting it to a veterinary clinic; (3 the initial veterinary examination and overnight stay; (4 amputation of the limb and immediate post-operative recovery; (5 its first four weeks after rehoming to a lifestyle block; and (6 its subsequent life as an amputee and pet. Not all features of the scenario represent average-to-good practice; indeed, some have been selected to indicate poor practice. It is shown how the Model can draw attention to areas of animal welfare concern and, importantly, to how welfare enhancement may be impeded or facilitated. Also illustrated is how the welfare implications of a sequence of events can be traced and evaluated, and, in relation to specific situations, how the degrees of welfare compromise and enhancement may be graded. In addition, the choice of a companion animal, contrasting its welfare status as a working dog and pet, and considering its treatment in a veterinary clinical setting, help to highlight various welfare impacts of some practices. By focussing attention on welfare problems, the Model can guide the implementation of remedies, including ways of promoting positive welfare states. Finally, wider applications of the Five Domains Model are noted: by enabling both negative and positive welfare-relevant experiences to be graded, the Model can be applied to quality of life assessments and end-of-life decisions and, with particular regard to negative experiences, the Model can also help to strengthen expert witness testimony during

  6. Scaled Experimental Modeling of VHTR Plenum Flows

    International Nuclear Information System (INIS)

    ICONE, 15

    2007-01-01

    The Very High Temperature Reactor (VHTR) is the leading candidate for the Next Generation Nuclear Power (NGNP) Project in the U.S. which has the goal of demonstrating the production of emissions free electricity and hydrogen by 2015. Various scaled heated gas and water flow facilities were investigated for modeling VHTR upper and lower plenum flows during the decay heat portion of a pressurized conduction-cooldown scenario and for modeling thermal mixing and stratification (''thermal striping'') in the lower plenum during normal operation. It was concluded, based on phenomena scaling and instrumentation and other practical considerations, that a heated water flow scale model facility is preferable to a heated gas flow facility and to unheated facilities which use fluids with ranges of density to simulate the density effect of heating. For a heated water flow lower plenum model, both the Richardson numbers and Reynolds numbers may be approximately matched for conduction-cooldown natural circulation conditions. Thermal mixing during normal operation may be simulated but at lower, but still fully turbulent, Reynolds numbers than in the prototype. Natural circulation flows in the upper plenum may also be simulated in a separate heated water flow facility that uses the same plumbing as the lower plenum model. However, Reynolds number scaling distortions will occur at matching Richardson numbers due primarily to the necessity of using a reduced number of channels connected to the plenum than in the prototype (which has approximately 11,000 core channels connected to the upper plenum) in an otherwise geometrically scaled model. Experiments conducted in either or both facilities will meet the objectives of providing benchmark data for the validation of codes proposed for NGNP designs and safety studies, as well as providing a better understanding of the complex flow phenomena in the plenums

  7. Scaled experimental modeling of VHTR plenum flows

    International Nuclear Information System (INIS)

    McCreery, Glenn E.; Condie, Keith G.; Schultz, Richard R.

    2007-01-01

    The Very High Temperature Reactor (VHTR) is the leading candidate for the Next Generation Nuclear Power (NGNP) Project in the U.S. Various scaled heated and unheated gas and water flow facilities were investigated for modeling VHTR upper and lower plenum flows during the decay heat portion of a pressurized conduction-cooldown scenario and for modeling thermal mixing and stratification ('thermal striping') in the lower plenum during normal operation. It was concluded, based on phenomena scaling and instrumentation and other practical considerations, that a heated water flow scale model facility is preferable to a heated gas flow facility and to unheated facilities which use fluids with ranges of density to simulate the buoyancy effect of heating. For a heated water flow lower plenum model, both the Richardson numbers and Reynolds numbers may be approximately matched for conduction-cooldown natural circulation conditions. Thermal mixing during normal operation may be simulated but at lower, but still fully turbulent, Reynolds numbers than in the prototype. Natural circulation flows in the upper plenum may also be simulated in a separate heated water flow facility that uses the same plumbing as the lower plenum model. However, scaling distortions will occur due primarily to the necessity of using a reduced number of channels connected to the upper plenum than in the prototype in an otherwise geometrically scaled model. Experiments conducted in either or both facilities will meet the objectives of providing benchmark data for the validation of codes proposed for NGNP designs and safety studies, as well as providing a better understanding of the complex flow phenomena in the plenums. (author)

  8. Scaled Experimental Modeling of VHTR Plenum Flows

    Energy Technology Data Exchange (ETDEWEB)

    ICONE 15

    2007-04-01

    Abstract The Very High Temperature Reactor (VHTR) is the leading candidate for the Next Generation Nuclear Power (NGNP) Project in the U.S. which has the goal of demonstrating the production of emissions free electricity and hydrogen by 2015. Various scaled heated gas and water flow facilities were investigated for modeling VHTR upper and lower plenum flows during the decay heat portion of a pressurized conduction-cooldown scenario and for modeling thermal mixing and stratification (“thermal striping”) in the lower plenum during normal operation. It was concluded, based on phenomena scaling and instrumentation and other practical considerations, that a heated water flow scale model facility is preferable to a heated gas flow facility and to unheated facilities which use fluids with ranges of density to simulate the density effect of heating. For a heated water flow lower plenum model, both the Richardson numbers and Reynolds numbers may be approximately matched for conduction-cooldown natural circulation conditions. Thermal mixing during normal operation may be simulated but at lower, but still fully turbulent, Reynolds numbers than in the prototype. Natural circulation flows in the upper plenum may also be simulated in a separate heated water flow facility that uses the same plumbing as the lower plenum model. However, Reynolds number scaling distortions will occur at matching Richardson numbers due primarily to the necessity of using a reduced number of channels connected to the plenum than in the prototype (which has approximately 11,000 core channels connected to the upper plenum) in an otherwise geometrically scaled model. Experiments conducted in either or both facilities will meet the objectives of providing benchmark data for the validation of codes proposed for NGNP designs and safety studies, as well as providing a better understanding of the complex flow phenomena in the plenums.

  9. Managing large-scale models: DBS

    International Nuclear Information System (INIS)

    1981-05-01

    A set of fundamental management tools for developing and operating a large scale model and data base system is presented. Based on experience in operating and developing a large scale computerized system, the only reasonable way to gain strong management control of such a system is to implement appropriate controls and procedures. Chapter I discusses the purpose of the book. Chapter II classifies a broad range of generic management problems into three groups: documentation, operations, and maintenance. First, system problems are identified then solutions for gaining management control are disucssed. Chapters III, IV, and V present practical methods for dealing with these problems. These methods were developed for managing SEAS but have general application for large scale models and data bases

  10. Multi-Scale Modeling of Magnetospheric Dynamics

    Science.gov (United States)

    Kuznetsova, M. M.; Hesse, M.; Toth, G.

    2012-01-01

    Magnetic reconnection is a key element in many phenomena in space plasma, e.g. Coronal mass Ejections, Magnetosphere substorms. One of the major challenges in modeling the dynamics of large-scale systems involving magnetic reconnection is to quantifY the interaction between global evolution of the magnetosphere and microphysical kinetic processes in diffusion regions near reconnection sites. Recent advances in small-scale kinetic modeling of magnetic reconnection significantly improved our understanding of physical mechanisms controlling the dissipation in the vicinity of the reconnection site in collisionless plasma. However the progress in studies of small-scale geometries was not very helpful for large scale simulations. Global magnetosphere simulations usually include non-ideal processes in terms of numerical dissipation and/or ad hoc anomalous resistivity. Comparative studies of magnetic reconnection in small scale geometries demonstrated that MHD simulations that included non-ideal processes in terms of a resistive term 11 J did not produce fast reconnection rates observed in kinetic simulations. In collisionless magnetospheric plasma, the primary mechanism controlling the dissipation in the vicinity of the reconnection site is nongyrotropic pressure effects with spatial scales comparable with the particle Larmor radius. We utilize the global MHD code BATSRUS and replace ad hoc parameters such as "critical current density" and "anomalous resistivity" with a physically motivated model of dissipation. The primary mechanism controlling the dissipation in the vicinity of the reconnection site in incorporated into MHD description in terms of non-gyrotropic corrections to the induction equation. We will demonstrate that kinetic nongyrotropic effects can significantly alter the global magnetosphere evolution. Our approach allowed for the first time to model loading/unloading cycle in response to steady southward IMF driving. The role of solar wind parameters and

  11. Opportunities of energy supply of farm holdings on the basis of small-scale renewable energy sources

    Science.gov (United States)

    Efendiev, A. M.; Nikolaev, Yu. E.; Evstaf'ev, D. P.

    2016-02-01

    One of the major national economic problems of Russia is raising of agricultural production, which will provide strategic security and sustainable supply of the population with provisions. Creation of subsidiary small holdings, farm holdings, and peasant farm holdings will require addressing issues of energy supply. At considerable distance of small farms from centralized energy systems (by fuel, electricity and thermal energy) it is proposed to create a system of local energy networks on the basis of low-powered power plants using renewable energy sources (RES). There is economic unreasonableness of use of imported components of small power plants. Creation of new combined small power plants on renewable energy sources produced by domestic manufacturers is recommended. Schemes of arrangements of small power plants based on renewable energy sources are proposed, variants and characteristics of a basic source are provided—biogas plants developed by the authors. Calculations revealed that heat and power supply of self-contained farms distant from small power plants based on renewable energy sources is 2.5-2.6 times cheaper than from centralized networks. Production of biogas through anaerobic fermentation of organic waste of cattle complexes is considered as the basis. The analysis of biowaste output in various cattle farms is carried out, and the volume of biogas is determined to meet the requirements of these farms in electrical and thermal energy. The objective of the present article is to study the possibility of creating small combined power plants in Russia based on renewable sources of energy for independent consumers.

  12. Landscape modelling at Regional to Continental scales

    Science.gov (United States)

    Kirkby, M. J.

    Most work on simulating landscape evolution has been focused at scales of about 1 Ha, there are still limitations, particularly in understanding the links between hillslope process rates and climate, soils and channel initiation. However, the need for integration with GCM outputs and with Continental Geosystems now imposes an urgent need for scaling up to Regional and Continental scales. This is reinforced by a need to incorporate estimates of soil erosion and desertification rates into national and supra-national policy. Relevant time-scales range from decadal to geological. Approaches at these regional to continental scales are critical to a fuller collaboration between geomorphologists and others interested in Continental Geosystems. Two approaches to the problem of scaling up are presented here for discussion. The first (MEDRUSH) is to embed representative hillslope flow strips into sub-catchments within a larger catchment of up to 5,000 km2. The second is to link one-dimensional models of SVAT type within DEMs at up to global scales (CSEP/SEDWEB). The MEDRUSH model is being developed as part of the EU Desertification Programme (MEDALUS project), primarily for semi-natural vegetation in southern Europe over time spans of up to 100 years. Catchments of up to 2500 km2 are divided into 50-200 sub-catchments on the basis of flow paths derived from DEMs with a horizontal resolution of 50 m or better. Within each sub-catchment a representative flow strip is selected and Hydrology, Sediment Transport and Vegetation change are simulated in detail for the flow strip, using a 1 hour time step. Changes within each flow strip are transferred back to the appropriate sub-catchment and flows of water and sediment are then routed through the channel network, generating changes in flood plain morphology.

  13. Scaling microbial physiology in global models (Invited)

    Science.gov (United States)

    Wieder, W. R.; Bonan, G. B.; Hinckley, E. S.; Allison, S. D.

    2013-12-01

    A growing chorus from the biogeochemistry, soil science, and ecosystem modeling communities calls for model structures that provide direct microbial control over soil C dynamics. Thus, we describe a new model that explicitly represents microbial physiology in its representation of soil C cycling on the global scale. Presently, the model is parameterized based on measurements of microbial enzyme kinetics, but we must make assumptions about other aspects of microbial physiology (e.g., microbial growth efficiency and microbial turnover rates). We demonstrate that, compared to traditional soil biogeochemistry modeling approaches, the microbial explicit model can simulate global soil C pools that more closely match contemporary observations (based on the Harmonized World Soils Database), but generate wildly divergent results in response to environmental perturbations. The discrepancy between projections in non-steady state simulations highlight the modeling processes, parameters, and structures that deserve greater attention from both empirical and modeling communities and provide avenues to begin exploring soil biogeochemical theory across spatial and temporal scales.

  14. Modelling large-scale hydrogen infrastructure development

    International Nuclear Information System (INIS)

    De Groot, A.; Smit, R.; Weeda, M.

    2005-08-01

    In modelling a possible H2 infrastructure development the following questions are answered in this presentation: How could the future demand for H2 develop in the Netherlands?; and In which year and where would it be economically viable to construct a H2 infrastructure in the Netherlands? Conclusions are that: A model for describing a possible future H2 infrastructure is successfully developed; The model is strongly regional and time dependent; Decrease of fuel cell cost appears to be a sensitive parameter for development of H2 demand; Cost-margin between large-scale and small-scale H2 production is a main driver for development of a H2 infrastructure; A H2 infrastructure seems economically viable in the Netherlands starting from the year 2022

  15. Modeling and Mitigation for High Frequency Switching Transients Due to Energization in Offshore Wind Farms

    Directory of Open Access Journals (Sweden)

    Yanli Xin

    2016-12-01

    Full Text Available This paper presents a comprehensive investigation on high frequency (HF switching transients due to energization of vacuum circuit breakers (VCBs in offshore wind farms (OWFs. This research not only concerns the modeling of main components in collector grids of an OWF for transient analysis (including VCBs, wind turbine transformers (WTTs, submarine cables, but also compares the effectiveness between several mainstream switching overvoltage (SOV protection methods and a new mitigation method called smart choke. In order to accurately reproduce such HF switching transients considering the current chopping, dielectric strength (DS recovery capability and HF quenching capability of VCBs, three models are developed, i.e., a user–defined VCB model, a HF transformer terminal model and a three-core (TC frequency dependent model of submarine cables, which are validated through simulations and compared with measurements. Based on the above models and a real OWF configuration, a simulation model is built and several typical switching transient cases are investigated to analyze the switching transient process and phenomena. Subsequently, according to the characteristics of overvoltages, appropriate parameters of SOV mitigation methods are determined to improve their effectiveness. Simulation results indicate that the user–defined VCB model can satisfactorily simulate prestrikes and the proposed component models display HF characteristics, which are consistent with onsite measurement behaviors. Moreover, the employed protection methods can suppress induced SOVs, which have a steep front, a high oscillation frequency and a high amplitude, among which the smart choke presents a preferable HF damping effect.

  16. Modelling, Analysis and Control of DC-connected Wind Farms to Grid

    DEFF Research Database (Denmark)

    Iov, Florin; Sørensen, Poul; Hansen, Anca Daniela

    2006-01-01

    Nowadays, there is an increasing trend to connect large MW wind farms to the transmission system. Requirements that focus on the influence of the farms on the grid stability and power quality, and on the control capabilities of wind farms have already been established. The main trends of modern...... wind turbines/farms are clearly the variable speed operation and a grid connection through a power electronic interface, especially using doubly-fed induction generators. Using power electronics the control capabilities of these wind turbines/farms are extended and thus the grid requirements...... are fulfilled.  However, the traditional squirrel-cage generators based wind turbines/wind farms directly connected to the grid have less control capabilities. These wind turbines/farms cannot regulate their production and contribute to power system stability. A DC transmission system for connection...

  17. Towards dynamic genome-scale models.

    Science.gov (United States)

    Gilbert, David; Heiner, Monika; Jayaweera, Yasoda; Rohr, Christian

    2017-10-13

    The analysis of the dynamic behaviour of genome-scale models of metabolism (GEMs) currently presents considerable challenges because of the difficulties of simulating such large and complex networks. Bacterial GEMs can comprise about 5000 reactions and metabolites, and encode a huge variety of growth conditions; such models cannot be used without sophisticated tool support. This article is intended to aid modellers, both specialist and non-specialist in computerized methods, to identify and apply a suitable combination of tools for the dynamic behaviour analysis of large-scale metabolic designs. We describe a methodology and related workflow based on publicly available tools to profile and analyse whole-genome-scale biochemical models. We use an efficient approximative stochastic simulation method to overcome problems associated with the dynamic simulation of GEMs. In addition, we apply simulative model checking using temporal logic property libraries, clustering and data analysis, over time series of reaction rates and metabolite concentrations. We extend this to consider the evolution of reaction-oriented properties of subnets over time, including dead subnets and functional subsystems. This enables the generation of abstract views of the behaviour of these models, which can be large-up to whole genome in size-and therefore impractical to analyse informally by eye. We demonstrate our methodology by applying it to a reduced model of the whole-genome metabolism of Escherichia coli K-12 under different growth conditions. The overall context of our work is in the area of model-based design methods for metabolic engineering and synthetic biology. © The Author 2017. Published by Oxford University Press.

  18. Probabilistic, meso-scale flood loss modelling

    Science.gov (United States)

    Kreibich, Heidi; Botto, Anna; Schröter, Kai; Merz, Bruno

    2016-04-01

    Flood risk analyses are an important basis for decisions on flood risk management and adaptation. However, such analyses are associated with significant uncertainty, even more if changes in risk due to global change are expected. Although uncertainty analysis and probabilistic approaches have received increased attention during the last years, they are still not standard practice for flood risk assessments and even more for flood loss modelling. State of the art in flood loss modelling is still the use of simple, deterministic approaches like stage-damage functions. Novel probabilistic, multi-variate flood loss models have been developed and validated on the micro-scale using a data-mining approach, namely bagging decision trees (Merz et al. 2013). In this presentation we demonstrate and evaluate the upscaling of the approach to the meso-scale, namely on the basis of land-use units. The model is applied in 19 municipalities which were affected during the 2002 flood by the River Mulde in Saxony, Germany (Botto et al. submitted). The application of bagging decision tree based loss models provide a probability distribution of estimated loss per municipality. Validation is undertaken on the one hand via a comparison with eight deterministic loss models including stage-damage functions as well as multi-variate models. On the other hand the results are compared with official loss data provided by the Saxon Relief Bank (SAB). The results show, that uncertainties of loss estimation remain high. Thus, the significant advantage of this probabilistic flood loss estimation approach is that it inherently provides quantitative information about the uncertainty of the prediction. References: Merz, B.; Kreibich, H.; Lall, U. (2013): Multi-variate flood damage assessment: a tree-based data-mining approach. NHESS, 13(1), 53-64. Botto A, Kreibich H, Merz B, Schröter K (submitted) Probabilistic, multi-variable flood loss modelling on the meso-scale with BT-FLEMO. Risk Analysis.

  19. Modeling and resonance issues of wind farm integration with related facts applications

    Science.gov (United States)

    Auddy, Soubhik

    shown that the performance of the TCSC is superior to SVC for damping SSR. These two FACTS devices are primarily employed for achieving other objectives, such as, power transfer improvement and are simultaneously utilized for damping SSR. This thesis also examines for the first time the potential for overvoltages due to ferroresonance and self-excitation while connecting large wind farms to EHV lines. A detailed analysis of the factors influencing self-excitation and ferroresonance has been performed. The impacts of different generator models on the overvoltage issues are examined. Different measures of alleviating these overvoltages are proposed which include line differential protection and wind turbine generator excitation system control. This study has been conducted using EMTDC/PSCAD for an upcoming large wind farm in Ontario. In an effort to validate a doubly fed induction generator (DFIG) model an additional study has been done to validate the DFIG model available in PSS/E from an extensive field validation study of Hydro One Network Inc. Keywords. Power system stability, Transient stability, Inter-area oscillations, Remote Signals, Wide Area Measurement (WAM), Subsynchronous Resonance (SSR), Flexible AC Transmission Systems (FACTS), Static VAR Compensator (SVC), Thyristor Controlled Series Capacitor (TCSC), Wind Farm, Wind Energy Conversion Systems (WECS), Wind Power Systems (WPS), Wind Turbine Generator (WTG), Self-excited induction generator (SEIG), Doubly Fed Induction Generator (DFIG), Ferroresonance, Self-excitation.

  20. Wake interaction and power production of variable height model wind farms

    International Nuclear Information System (INIS)

    Vested, M H; Sørensen, J N; Hamilton, N; Cal, R B

    2014-01-01

    Understanding wake dynamics is an ongoing research topic in wind energy, since wakes have considerable effects on the power production when wind turbines are placed in a wind farm. Wind tunnel experiments have been conducted to study the wake to wake interaction in a model wind farm in tandem with measurements of the extracted power. The aim is to investigate how alternating mast height influences the interaction of the wakes and the power production. Via the use of stereo-particle image velocimetry, the flow field was obtained in the first and last rows of the wind turbine array as a basis of comparison. It was found that downstream of the exit row wind turbine, the power was increased by 25% in the case of a staggered height configuration. This is partly due to the fact that the taller turbines reach into a flow area with a softened velocity gradient. Another aspect is that the wake downstream of a tall wind turbine to some extent passes above the standard height wind turbine. Overall the experiments show that the velocity field downstream of the exit row changes considerably when the mast height is alternating

  1. Optimal supplementary frequency controller design using the wind farm frequency model and controller parameters stability region.

    Science.gov (United States)

    Toulabi, Mohammadreza; Bahrami, Shahab; Ranjbar, Ali Mohammad

    2018-03-01

    In most of the existing studies, the frequency response in the variable speed wind turbines (VSWTs) is simply realized by changing the torque set-point via appropriate inputs such as frequency deviations signal. However, effective dynamics and systematic process design have not been comprehensively discussed yet. Accordingly, this paper proposes a proportional-derivative frequency controller and investigates its performance in a wind farm consisting of several VSWTs. A band-pass filter is deployed before the proposed controller to avoid responding to either steady state frequency deviations or high rate of change of frequency. To design the controller, the frequency model of the wind farm is first characterized. The proposed controller is then designed based on the obtained open loop system. The stability region associated with the controller parameters is analytically determined by decomposing the closed-loop system's characteristic polynomial into the odd and even parts. The performance of the proposed controller is evaluated through extensive simulations in MATLAB/Simulink environment in a power system comprising a high penetration of VSWTs equipped with the proposed controller. Finally, based on the obtained feasible area and appropriate objective function, the optimal values associated with the controller parameters are determined using the genetic algorithm (GA). Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

  2. Drift-Scale THC Seepage Model

    International Nuclear Information System (INIS)

    C.R. Bryan

    2005-01-01

    The purpose of this report (REV04) is to document the thermal-hydrologic-chemical (THC) seepage model, which simulates the composition of waters that could potentially seep into emplacement drifts, and the composition of the gas phase. The THC seepage model is processed and abstracted for use in the total system performance assessment (TSPA) for the license application (LA). This report has been developed in accordance with ''Technical Work Plan for: Near-Field Environment and Transport: Coupled Processes (Mountain-Scale TH/THC/THM, Drift-Scale THC Seepage, and Post-Processing Analysis for THC Seepage) Report Integration'' (BSC 2005 [DIRS 172761]). The technical work plan (TWP) describes planning information pertaining to the technical scope, content, and management of this report. The plan for validation of the models documented in this report is given in Section 2.2.2, ''Model Validation for the DS THC Seepage Model,'' of the TWP. The TWP (Section 3.2.2) identifies Acceptance Criteria 1 to 4 for ''Quantity and Chemistry of Water Contacting Engineered Barriers and Waste Forms'' (NRC 2003 [DIRS 163274]) as being applicable to this report; however, in variance to the TWP, Acceptance Criterion 5 has also been determined to be applicable, and is addressed, along with the other Acceptance Criteria, in Section 4.2 of this report. Also, three FEPS not listed in the TWP (2.2.10.01.0A, 2.2.10.06.0A, and 2.2.11.02.0A) are partially addressed in this report, and have been added to the list of excluded FEPS in Table 6.1-2. This report has been developed in accordance with LP-SIII.10Q-BSC, ''Models''. This report documents the THC seepage model and a derivative used for validation, the Drift Scale Test (DST) THC submodel. The THC seepage model is a drift-scale process model for predicting the composition of gas and water that could enter waste emplacement drifts and the effects of mineral alteration on flow in rocks surrounding drifts. The DST THC submodel uses a drift-scale

  3. Drift-Scale THC Seepage Model

    Energy Technology Data Exchange (ETDEWEB)

    C.R. Bryan

    2005-02-17

    The purpose of this report (REV04) is to document the thermal-hydrologic-chemical (THC) seepage model, which simulates the composition of waters that could potentially seep into emplacement drifts, and the composition of the gas phase. The THC seepage model is processed and abstracted for use in the total system performance assessment (TSPA) for the license application (LA). This report has been developed in accordance with ''Technical Work Plan for: Near-Field Environment and Transport: Coupled Processes (Mountain-Scale TH/THC/THM, Drift-Scale THC Seepage, and Post-Processing Analysis for THC Seepage) Report Integration'' (BSC 2005 [DIRS 172761]). The technical work plan (TWP) describes planning information pertaining to the technical scope, content, and management of this report. The plan for validation of the models documented in this report is given in Section 2.2.2, ''Model Validation for the DS THC Seepage Model,'' of the TWP. The TWP (Section 3.2.2) identifies Acceptance Criteria 1 to 4 for ''Quantity and Chemistry of Water Contacting Engineered Barriers and Waste Forms'' (NRC 2003 [DIRS 163274]) as being applicable to this report; however, in variance to the TWP, Acceptance Criterion 5 has also been determined to be applicable, and is addressed, along with the other Acceptance Criteria, in Section 4.2 of this report. Also, three FEPS not listed in the TWP (2.2.10.01.0A, 2.2.10.06.0A, and 2.2.11.02.0A) are partially addressed in this report, and have been added to the list of excluded FEPS in Table 6.1-2. This report has been developed in accordance with LP-SIII.10Q-BSC, ''Models''. This report documents the THC seepage model and a derivative used for validation, the Drift Scale Test (DST) THC submodel. The THC seepage model is a drift-scale process model for predicting the composition of gas and water that could enter waste emplacement drifts and the effects of mineral

  4. Grid interaction of offshore wind farms. Part 1. Models for dynamic simulation

    Science.gov (United States)

    Morren, Johan; Pierik, Jan T. G.; de Haan, Sjoerd W. H.; Bozelie, Jan

    2005-07-01

    In this contribution, dynamic wind farm models suitable for fast simulation of power systems are presented. While deriving the models, special attention has been paid to increasing the computational speed of the simulation program. An important increase in speed is realized by the use of the well-known dq0 transformation (Park transformation) not only for the generator but also for all other electrical components. The use of the Park transformation is common practice in electrical machine models, but not in the modelling of other electrical components. For single turbines, simulations in the dq0 reference frame are 100 times faster than simulations in the abc reference frame. After a discussion of the Park transformation and its most important properties, it is explained how models in the dq0 reference frame can be obtained. The dq0 models of the most important electrical components are presented. The mechanical and aerodynamic models that are needed for dynamic simulation of wind turbines are discussed briefly. The models are applied in Part 2. Copyright

  5. Characterization and evaluation of agro-ecosystems on a farm scale, a case studies: Cotove Farming Center (Santa Fe de Antioquia, Colombia)

    International Nuclear Information System (INIS)

    De los Rios Cardona, Juan Camilo; Gallego Zapata, Andres Felipe; Velez Vargas, Leon Dario; Agudelo Otalvaro, Jose Ignacio; Toro Restrepo, Luis Jairo; Lema Tapias, Alvaro de Jesus; Acevedo Arango, Luis Ignacio

    2004-01-01

    The state, condition and tendencies of the agro-systems (AS) of the Cotove Farming Center of the Universidad Nacional de Colombia, sede Medellin was evaluated by means of a parameterization and analysis of the various receptivity technologies (RT) and intensity technologies (IT) based upon the proposed methodology of Velez and Gasto (1999) in terms of the diversity in AE and the uses, management, and technological state, techno-structural and hydro-structural endowment, potential productivity and benefits to local, regional and national society. Results showed that the majority of the area of the center (60%) has high RT that indicates the establishment of mechanized advanced agro-technological management systems (AMS), but only 15,72% of the area is managed with this SMA. fully 69,3% of the area of the center, mainly under pasture for raising cattle, is managed with traditional SMA. As a product of the interaction between RT and the SMA employed, nine AE were identified, of which five, that represent 27,1% of the area (33,6 ha.), are managed with technologies adequate for the biophysical conditions and the receptivity technology (adequate it), and the other four, which represent 69,4% of the area (86, l ha.) are managed with technologies that do not correspond to their RT conditions (extensive and inadequate its), that leads to a sub-utilization and/or deterioration of their biophysical and ecological conditions

  6. Scale Model Thruster Acoustic Measurement Results

    Science.gov (United States)

    Vargas, Magda; Kenny, R. Jeremy

    2013-01-01

    The Space Launch System (SLS) Scale Model Acoustic Test (SMAT) is a 5% scale representation of the SLS vehicle, mobile launcher, tower, and launch pad trench. The SLS launch propulsion system will be comprised of the Rocket Assisted Take-Off (RATO) motors representing the solid boosters and 4 Gas Hydrogen (GH2) thrusters representing the core engines. The GH2 thrusters were tested in a horizontal configuration in order to characterize their performance. In Phase 1, a single thruster was fired to determine the engine performance parameters necessary for scaling a single engine. A cluster configuration, consisting of the 4 thrusters, was tested in Phase 2 to integrate the system and determine their combined performance. Acoustic and overpressure data was collected during both test phases in order to characterize the system's acoustic performance. The results from the single thruster and 4- thuster system are discussed and compared.

  7. Energy balances of bioenergy crops (Miscanthus, maize, rapeseed) and their CO2-mitigation potential on a regional farm scale

    Science.gov (United States)

    Felten, D.; Emmerling, C.

    2012-04-01

    Increasing cultivation of energy crops in agriculture reveals the progressive substitution of fossil fuels, such as crude oil or brown coal. For the future development of renewable resources, the efficiency of different cropping systems will be crucial, as energy crops differ in terms of the energy needed for crop cultivation and refinement and the respective energy yield, e.g. per area. Here, balancing is certainly the most suitable method for the assessment of cropping system efficiency, contrasting energy inputs with energy outputs and the related CO2 emissions with potential CO2 credits due to substitution of fossil fuels, respectively. The aim of the present study was to calculate both energy and CO2 balances for rapeseed and maize, representing the recently most often cultivated energy crops in Germany, on a regional farm scale. Furthermore, special emphasis was made on perennial Miscanthus x giganteus, which is commonly used as a solid fuel for combustion. This C4-grass is of increasing interest due to its high yield potential accompanied by low requirements for soil tillage, weed control, and fertilization as well as long cultivation periods up to 25 years. In contrast to more general approaches, balances were calculated with local data from commercial farms. The site-specific consumption of diesel fuel was calculated using an online-based calculator, developed by the German Association for Technology and Structures in Agriculture (KTBL). By balancing each of the aforementioned cropping systems, our research focused on (i) the quantification of energy gains and CO2 savings due to fossil fuel substitution and (ii) the assessment of energy efficiency, expressed as the ratio of energy output to input. The energy input was highest for maize sites (33.8 GJ ha-1 yr-1), followed by rapeseed (18.2 GJ ha-1 yr-1), and Miscanthus (1.1 GJ ha-1 yr-1); corresponding energy yields were 129.5 GJ ha-1 yr-1 (maize), 83.6 GJ ha-1 yr-1 (rapeseed), and 259.7 GJ ha-1 yr-1

  8. Pore-Scale Model for Microbial Growth

    Science.gov (United States)

    Tartakovsky, G.; Tartakovsky, A. M.; Scheibe, T. D.

    2011-12-01

    A lagrangian particle model based on smoothed particle hydrodynamics (SPH) is used to simulate pore-scale flow, reactive transport and biomass growth which is controlled by the mixing of an electron donor and acceptor, in a microfluidic porous cell. The experimental results described in Ch. Zhang et al "Effects of pore-scale heterogeneity and transverse mixing on bacterial growth in porous media" were used for this study. The model represents the homogeneous pore structure of a uniform array of cylindrical posts with microbes uniformly distributed on the grain surfaces. Each one of the two solutes (electron donor and electron acceptor) enters the domain unmixed through separate inlets. In the model, pair-wise particle-particle interactions are used to simulate interactions within the biomass, and both biomass-fluid and biomass-soil grain interactions. The biomass growth rate is described by double Monod kinetics. For the set of parameters used in the simulations the model predicts that: 1) biomass grows in the shape of bridges connecting soil grains and oriented in the direction of flow so as to minimize resistance to the fluid flow; and 2) the biomass growth occurs only in the mixing zone. Using parameters available in the literature, the biomass growth model agrees qualitatively with the experimental results. In order to achieve quantitative agreement, model calibration is required.

  9. Improving efficiency assessments using additive data envelopment analysis models: an application to contrasting dairy farming systems

    Directory of Open Access Journals (Sweden)

    Andreas Diomedes Soteriades

    2015-10-01

    Full Text Available Applying holistic indicators to assess dairy farm efficiency is essential for sustainable milk production. Data Envelopment Analysis (DEA has been instrumental for the calculation of such indicators. However, ‘additive’ DEA models have been rarely used in dairy research. This study presented an additive model known as slacks-based measure (SBM of efficiency and its advantages over DEA models used in most past dairy studies. First, SBM incorporates undesirable outputs as actual outputs of the production process. Second, it identifies the main production factors causing inefficiency. Third, these factors can be ‘priced’ to estimate the cost of inefficiency. The value of SBM for efficiency analyses was demonstrated with a comparison of four contrasting dairy management systems in terms of technical and environmental efficiency. These systems were part of a multiple-year breeding and feeding systems experiment (two genetic lines: select vs. control; and two feeding strategies: high forage vs. low forage, where the latter involved a higher proportion of concentrated feeds where detailed data were collected to strict protocols. The select genetic herd was more technically and environmentally efficient than the control herd, regardless of feeding strategy. However, the efficiency performance of the select herd was more volatile from year to year than that of the control herd. Overall, technical and environmental efficiency were strongly and positively correlated, suggesting that when technically efficient, the four systems were also efficient in terms of undesirable output reduction. Detailed data such as those used in this study are increasingly becoming available for commercial herds through precision farming. Therefore, the methods presented in this study are growing in importance.

  10. Modelling the spread of farming in the Bantu-speaking regions of Africa: an archaeology-based phylogeography.

    Directory of Open Access Journals (Sweden)

    Thembi Russell

    Full Text Available We use archaeological data and spatial methods to reconstruct the dispersal of farming into areas of sub-Saharan Africa now occupied by Bantu language speakers, and introduce a new large-scale radiocarbon database and a new suite of spatial modelling techniques. We also introduce a method of estimating phylogeographic relationships from archaeologically-modelled dispersal maps, with results produced in a format that enables comparison with linguistic and genetic phylogenies. Several hypotheses are explored. The 'deep split' hypothesis suggests that an early-branching eastern Bantu stream spread around the northern boundary of the equatorial rainforest, but recent linguistic and genetic work tends not to support this. An alternative riverine/littoral hypothesis suggests that rivers and coastlines facilitated the migration of the first farmers/horticulturalists, with some extending this to include rivers through the rainforest as conduits to East Africa. More recently, research has shown that a grassland corridor opened through the rainforest at around 3000-2500 BP, and the possible effect of this on migrating populations is also explored. Our results indicate that rivers and coasts were important dispersal corridors, but do not resolve the debate about a 'Deep Split'. Future work should focus on improving the size, quality and geographical coverage of the archaeological (14C database; on augmenting the information base to establish descent relationships between archaeological sites and regions based on shared material cultural traits; and on refining the associated physical geographical reconstructions of changing land cover.

  11. Modelling the spread of farming in the Bantu-speaking regions of Africa: an archaeology-based phylogeography.

    Science.gov (United States)

    Russell, Thembi; Silva, Fabio; Steele, James

    2014-01-01

    We use archaeological data and spatial methods to reconstruct the dispersal of farming into areas of sub-Saharan Africa now occupied by Bantu language speakers, and introduce a new large-scale radiocarbon database and a new suite of spatial modelling techniques. We also introduce a method of estimating phylogeographic relationships from archaeologically-modelled dispersal maps, with results produced in a format that enables comparison with linguistic and genetic phylogenies. Several hypotheses are explored. The 'deep split' hypothesis suggests that an early-branching eastern Bantu stream spread around the northern boundary of the equatorial rainforest, but recent linguistic and genetic work tends not to support this. An alternative riverine/littoral hypothesis suggests that rivers and coastlines facilitated the migration of the first farmers/horticulturalists, with some extending this to include rivers through the rainforest as conduits to East Africa. More recently, research has shown that a grassland corridor opened through the rainforest at around 3000-2500 BP, and the possible effect of this on migrating populations is also explored. Our results indicate that rivers and coasts were important dispersal corridors, but do not resolve the debate about a 'Deep Split'. Future work should focus on improving the size, quality and geographical coverage of the archaeological (14)C database; on augmenting the information base to establish descent relationships between archaeological sites and regions based on shared material cultural traits; and on refining the associated physical geographical reconstructions of changing land cover.

  12. Farm production performance in Russian regions: farm panel data analysis

    NARCIS (Netherlands)

    Bezlepkina, I.

    2003-01-01

    The Russian agricultural sector has experienced many problems since the beginning of the 1990s that resulted in a fall in farm output. Employing a production function approach and, unlike other studies, farm-level data on more than 20,000 Russian large-scale farms for the period 1995-2000, this

  13. Genome scale metabolic modeling of cancer

    DEFF Research Database (Denmark)

    Nilsson, Avlant; Nielsen, Jens

    2017-01-01

    of metabolism which allows simulation and hypotheses testing of metabolic strategies. It has successfully been applied to many microorganisms and is now used to study cancer metabolism. Generic models of human metabolism have been reconstructed based on the existence of metabolic genes in the human genome......Cancer cells reprogram metabolism to support rapid proliferation and survival. Energy metabolism is particularly important for growth and genes encoding enzymes involved in energy metabolism are frequently altered in cancer cells. A genome scale metabolic model (GEM) is a mathematical formalization...

  14. Multi-agent modeling and simulation of farmland use change in the farming-pastoral zone: A case study of Qianjingou Town in Inner Mongolia, China

    Science.gov (United States)

    Yan, H.

    2015-12-01

    Farmland is the most basic material conditions for guaranteeing rural livelihoods and national food security, and exploring management strategies that take both of the sustainable rural livelihoods and sustainable farmland use into account has vital significance of theory and practice. Farmland is a complex and self-adaptive system that couples human and natural systems together, and natural factors and social factors that are related to its changing process need to be considered when modeling farmland changing process. This paper takes Qianjingou Town in Inner Mongolia farming-pastoral zone as study area. From the perspective of the relationship between households' livelihoods and farmland use, this study builds the process mechanism of farmland use change based on questionnaires data, and constructs multi-agent simulation model of farmland use change with the help of Eclipse and Repast toolbox. Through simulating the relationship between natural factors (with geographical location) and households' behaviors, this paper systematically simulates households' renting and abandoning farmland behaviors, and truly describes dynamic interactions between households' livelihoods and factors related to farmland use change. These factors include natural factors (net primary productivity, road accessibility, slope and relief amplitude) and social factors (households' family structures, economic development and government policies). In the end, this study scientifically predicts farmland use change trend in the future 30 years. The simulation results show that, the number of abandoned and sublet farmland plots has a gradually increasing trend, the number of non-farm households and pure-outwork households has a remarkable increasing trend, and the number of part-farm households and pure-farm households shows a decreasing trend. Households' livelihoods sustainability in the study area is confronted with increasing pressure, and households' nonfarm employment has an increasing

  15. Farm scale electrical power production from animal waste. Volume I. Final report, 30 June 1981-30 December 1983

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, P.A.

    1984-01-31

    A 1 1/2 (dry) tons per day biodigester cogeneration plant has been designed and constructed. This project is part of a federal program to promote energy conservation and the use of non-conventional energy resources. The main purpose of the project is to demonstrate that a dairy farm can generate its own power and supply excess power to a local utility. Such a facility can produce significant energy savings to livestock farms and small communities by allowing them to get energy from raw animal and human waste. Also, an odorless by-product is produced that is nearly pathogenically free and has the possibility of several end uses such as: fertilizer and soil conditioner, protein-rich animal refeed, livestock bedding material, and aquatic food for fish farming. 53 references, 18 figures, 4 tables.

  16. Fast All-Sky Radiation Model for Solar Applications (FARMS): A Brief Overview of Mechanisms, Performance, and Applications: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Yu; Sengupta, Manajit

    2016-06-01

    Solar radiation can be computed using radiative transfer models, such as the Rapid Radiation Transfer Model (RRTM) and its general circulation model applications, and used for various energy applications. Due to the complexity of computing radiation fields in aerosol and cloudy atmospheres, simulating solar radiation can be extremely time-consuming, but many approximations--e.g., the two-stream approach and the delta-M truncation scheme--can be utilized. To provide a new fast option for computing solar radiation, we developed the Fast All-sky Radiation Model for Solar applications (FARMS) by parameterizing the simulated diffuse horizontal irradiance and direct normal irradiance for cloudy conditions from the RRTM runs using a 16-stream discrete ordinates radiative transfer method. The solar irradiance at the surface was simulated by combining the cloud irradiance parameterizations with a fast clear-sky model, REST2. To understand the accuracy and efficiency of the newly developed fast model, we analyzed FARMS runs using cloud optical and microphysical properties retrieved using GOES data from 2009-2012. The global horizontal irradiance for cloudy conditions was simulated using FARMS and RRTM for global circulation modeling with a two-stream approximation and compared to measurements taken from the U.S. Department of Energy's Atmospheric Radiation Measurement Climate Research Facility Southern Great Plains site. Our results indicate that the accuracy of FARMS is comparable to or better than the two-stream approach; however, FARMS is approximately 400 times more efficient because it does not explicitly solve the radiative transfer equation for each individual cloud condition. Radiative transfer model runs are computationally expensive, but this model is promising for broad applications in solar resource assessment and forecasting. It is currently being used in the National Solar Radiation Database, which is publicly available from the National Renewable Energy

  17. Modelling and Control of VSC based DC Connection for Active Stall Wind Farms to Grid

    DEFF Research Database (Denmark)

    Iov, Florin; Sørensen, Poul; Hansen, Anca Daniela

    2006-01-01

    Currently, there is an increasing trend to connect large MW wind farms to the transmission system. Therefore the power system becomes more vulnerable and dependent on the wind energy production. At the same time requirements that focus on the influence of the farms on the grid stability and power...... quality, and on the control capabilities of wind farms have already been established. The main trends of modern wind turbines/farms are clearly the variable speed operation and a grid connection through a power electronic interface, especially using doubly-fed induction generators. Using power electronics...... the control capabilities of these wind turbines/farms are extended and thus the grid requirements are fulfilled.  However, the traditional squirrel-cage generators based wind turbines/wind farms directly connected to the grid does not have such control capabilities. They produce maximum possible power...

  18. Modeling and Control of VSC based DC Connection for Active Stall Wind Farms to Grid

    DEFF Research Database (Denmark)

    Iov, Florin; Sorensen, Poul; Hansen, Anca-Daniela

    2005-01-01

    Currently, there is an increasing trend to connect large MW wind farms to the transmission system. Therefore the power system becomes more vulnerable and dependent on the wind energy production. At the same time requirements that focus on the influence of the farms on the grid stability and power...... quality, and on the control capabilities of wind farms have already been established. The main trends of modem wind turbines/farms are clearly the variable speed operation and a grid connection through a power electronic interface, especially using doubly-fed induction generators. Using power electronics...... the control capabilities of these wind turbines/farms are extended and thus the grid requirements are fulfilled. However, the traditional squirrel-cage generators based wind turbines/wind farms directly connected to the grid does not have such control capabilities. They produce maximum possible power...

  19. Land surface evapotranspiration modelling at the regional scale

    Science.gov (United States)

    Raffelli, Giulia; Ferraris, Stefano; Canone, Davide; Previati, Maurizio; Gisolo, Davide; Provenzale, Antonello

    2017-04-01

    Climate change has relevant implications for the environment, water resources and human life in general. The observed increment of mean air temperature, in addition to a more frequent occurrence of extreme events such as droughts, may have a severe effect on the hydrological cycle. Besides climate change, land use changes are assumed to be another relevant component of global change in terms of impacts on terrestrial ecosystems: socio-economic changes have led to conversions between meadows and pastures and in most cases to a complete abandonment of grasslands. Water is subject to different physical processes among which evapotranspiration (ET) is one of the most significant. In fact, ET plays a key role in estimating crop growth, water demand and irrigation water management, so estimating values of ET can be crucial for water resource planning, irrigation requirement and agricultural production. Potential evapotranspiration (PET) is the amount of evaporation that occurs when a sufficient water source is available. It can be estimated just knowing temperatures (mean, maximum and minimum) and solar radiation. Actual evapotranspiration (AET) is instead the real quantity of water which is consumed by soil and vegetation; it is obtained as a fraction of PET. The aim of this work was to apply a simplified hydrological model to calculate AET for the province of Turin (Italy) in order to assess the water content and estimate the groundwater recharge at a regional scale. The soil is seen as a bucket (FAO56 model, Allen et al., 1998) made of different layers, which interact with water and vegetation. The water balance is given by precipitations (both rain and snow) and dew as positive inputs, while AET, runoff and drainage represent the rate of water escaping from soil. The difference between inputs and outputs is the water stock. Model data inputs are: soil characteristics (percentage of clay, silt, sand, rocks and organic matter); soil depth; the wilting point (i.e. the

  20. Large-scale multimedia modeling applications

    International Nuclear Information System (INIS)

    Droppo, J.G. Jr.; Buck, J.W.; Whelan, G.; Strenge, D.L.; Castleton, K.J.; Gelston, G.M.

    1995-08-01

    Over the past decade, the US Department of Energy (DOE) and other agencies have faced increasing scrutiny for a wide range of environmental issues related to past and current practices. A number of large-scale applications have been undertaken that required analysis of large numbers of potential environmental issues over a wide range of environmental conditions and contaminants. Several of these applications, referred to here as large-scale applications, have addressed long-term public health risks using a holistic approach for assessing impacts from potential waterborne and airborne transport pathways. Multimedia models such as the Multimedia Environmental Pollutant Assessment System (MEPAS) were designed for use in such applications. MEPAS integrates radioactive and hazardous contaminants impact computations for major exposure routes via air, surface water, ground water, and overland flow transport. A number of large-scale applications of MEPAS have been conducted to assess various endpoints for environmental and human health impacts. These applications are described in terms of lessons learned in the development of an effective approach for large-scale applications

  1. Efficiency of Estonian grain farms in 2000 2004

    Directory of Open Access Journals (Sweden)

    N. VASILIEV

    2008-12-01

    Full Text Available The aim of this study is to analyse the efficiency of Estonian grain farms after Estonia’s transition to a market economy and during the accession period to the European Union (EU. The non-parametric method Data Envelopment Analysis (DEA was used to estimate the total technical, pure technical and scale efficiency of Estonian grain farms in 2000–2004. Mean total technical efficiency varied from 0.70 to 0.78. Of the grain farms 62% are operating under increasing returns to scale. Solely based on the DEA model it is not possible to determine optimum farm scale and the range of Estonian farm sizes operating efficiently is extensive. The most pure technically efficient farms were the smallest and the largest but the productivity of small farms is low compared to larger farms because of their small scale. Therefore, they are the least competitive. Since pre-accession period to the EU, large input slacks of capital have replaced the former excessive use of labour and land. This raises the question about the effects on efficiency of the EU’s investment support schemes in new member states.;

  2. Dermal Exposure Assessment to Pesticides in Farming Systems in Developing Countries: Comparison of Models

    Directory of Open Access Journals (Sweden)

    Camilo Lesmes Fabian

    2015-04-01

    Full Text Available In the field of occupational hygiene, researchers have been working on developing appropriate methods to estimate human exposure to pesticides in order to assess the risk and therefore to take the due decisions to improve the pesticide management process and reduce the health risks. This paper evaluates dermal exposure models to find the most appropriate. Eight models (i.e., COSHH, DERM, DREAM, EASE, PHED, RISKOFDERM, STOFFENMANAGER and PFAM were evaluated according to a multi-criteria analysis and from these results five models (i.e., DERM, DREAM, PHED, RISKOFDERM and PFAM were selected for the assessment of dermal exposure in the case study of the potato farming system in the Andean highlands of Vereda La Hoya, Colombia. The results show that the models provide different dermal exposure estimations which are not comparable. However, because of the simplicity of the algorithm and the specificity of the determinants, the DERM, DREAM and PFAM models were found to be the most appropriate although their estimations might be more accurate if specific determinants are included for the case studies in developing countries.

  3. Weather Research and Forecasting model simulation of an onshore wind farm: assessment against LiDAR and SCADA data

    Science.gov (United States)

    Santoni, Christian; Garcia-Cartagena, Edgardo J.; Zhan, Lu; Iungo, Giacomo Valerio; Leonardi, Stefano

    2017-11-01

    The integration of wind farm parameterizations into numerical weather prediction models is essential to study power production under realistic conditions. Nevertheless, recent models are unable to capture turbine wake interactions and, consequently, the mean kinetic energy entrainment, which are essential for the development of power optimization models. To address the study of wind turbine wake interaction, one-way nested mesoscale to large-eddy simulation (LES) were performed using the Weather Research and Forecasting model (WRF). The simulation contains five nested domains modeling the mesoscale wind on the entire North Texas Panhandle region to the microscale wind fluctuations and turbine wakes of a wind farm located at Panhandle, Texas. The wind speed, direction and boundary layer profile obtained from WRF were compared against measurements obtained with a sonic anemometer and light detection and ranging system located within the wind farm. Additionally, the power production were assessed against measurements obtained from the supervisory control and data acquisition system located in each turbine. Furthermore, to incorporate the turbines into very coarse LES, a modification to the implementation of the wind farm parameterization by Fitch et al. (2012) is proposed. This work was supported by the NSF, Grants No. 1243482 (WINDINSPIRE) and IIP 1362033 (WindSTAR), and TACC.

  4. Amaranth farming

    DEFF Research Database (Denmark)

    Bjarklev, Araceli; Kjær, Tyge; Kjærgård, Bente

    2008-01-01

    farmers cultivating amaranth. This paper ddresses possibilities and limitations that Mexican small-scale farmers are facing to enhance sustainable livelihoods in the amaranth value chain. The study reveals that amaranth, as an alternative crop and livelihood, is perhaps one of the most complete endogenous......Though amaranth has been studied intensively for its exceptional nutritional properties, little has been reported about its capacity for fighting poverty, securing food supplies, turning migrations, or its impact on the environment and the prospect for mprovement of living conditions of those...... natural resources that small-scale farmers have to combat the abovementioned problems. The study identified several local and regional barriers for increasing the level of farming, production, processing and consumption. A striking and paradoxical limitation is the monopolization practices developed...

  5. Changes in fish communities on a small spatial scale, an effect of increased habitat complexity by an offshore wind farm

    NARCIS (Netherlands)

    Hal, van R.; Griffioen, A.B.; Keeken, van O.A.

    2017-01-01

    The number of offshore wind farms (OWF) is increasing to meet the demands for renewable energy. The piles and hard substrate surrounding these piles creates new habitat for species with preference to hard substrates. We studied the impact of this hard substrate on the fish community in a Dutch OWF

  6. Fostering business and software ecosystems for large-scale uptake of IoT in food and farming

    NARCIS (Netherlands)

    Verdouw, C.N.; Wolfert, J.; Beers, G.; Sundmaeker, Harald; Chatzikostas, Grigoris

    2017-01-01

    The Internet of Things (IoT) is expected to be a real game changer that will drastically improve productivity and sustainability in food and farming. However, current IoT applications in this domain are still fragmentary and mainly used by a small group of early adopters. The Internet of Food and

  7. The effects of contract farming on efficiency and productivity of small-scale sunflower farmers in Tanzania

    DEFF Research Database (Denmark)

    Henningsen, Arne; Mpeta, Daniel F.; Adem, Anwar S.

    -contract farmers that account for potential selection biases, and second, we create a meta-frontier. Using cross-sectional data from sunflower farmers in Tanzania, we find a significant selection bias. Contract farming significantly increases the yield potential but lowers the average group technical efficiency...

  8. Aerosol numerical modelling at local scale

    International Nuclear Information System (INIS)

    Albriet, Bastien

    2007-01-01

    At local scale and in urban areas, an important part of particulate pollution is due to traffic. It contributes largely to the high number concentrations observed. Two aerosol sources are mainly linked to traffic. Primary emission of soot particles and secondary nanoparticle formation by nucleation. The emissions and mechanisms leading to the formation of such bimodal distribution are still badly understood nowadays. In this thesis, we try to provide an answer to this problematic by numerical modelling. The Modal Aerosol Model MAM is used, coupled with two 3D-codes: a CFD (Mercure Saturne) and a CTM (Polair3D). A sensitivity analysis is performed, at the border of a road but also in the first meters of an exhaust plume, to identify the role of each process involved and the sensitivity of different parameters used in the modelling. (author) [fr

  9. Multi-scale atmospheric environment modelling for urban areas

    Directory of Open Access Journals (Sweden)

    A. A. Baklanov

    2009-04-01

    Full Text Available Modern supercomputers allow realising multi-scale systems for assessment and forecasting of urban meteorology, air pollution and emergency preparedness and considering nesting with obstacle-resolved models. A multi-scale modelling system with downscaling from regional to city-scale with the Environment – HIgh Resolution Limited Area Model (Enviro-HIRLAM and to micro-scale with the obstacle-resolved Micro-scale Model for Urban Environment (M2UE is suggested and demonstrated. The M2UE validation results versus the Mock Urban Setting Trial (MUST experiment indicate satisfactory quality of the model. Necessary conditions for the choice of nested models, building descriptions, areas and resolutions of nested models are analysed. Two-way nesting (up- and down-scaling, when scale effects both directions (from the meso-scale on the micro-scale and from the micro-scale on the meso-scale, is also discussed.

  10. Validation of Individual-Based Markov-Like Stochastic Process Model of Insect Behavior and a "Virtual Farm" Concept for Enhancement of Site-Specific IPM.

    Science.gov (United States)

    Lux, Slawomir A; Wnuk, Andrzej; Vogt, Heidrun; Belien, Tim; Spornberger, Andreas; Studnicki, Marcin

    2016-01-01

    The paper reports application of a Markov-like stochastic process agent-based model and a "virtual farm" concept for enhancement of site-specific Integrated Pest Management. Conceptually, the model represents a "bottom-up ethological" approach and emulates behavior of the "primary IPM actors"-large cohorts of individual insects-within seasonally changing mosaics of spatiotemporally complex faming landscape, under the challenge of the local IPM actions. Algorithms of the proprietary PESTonFARM model were adjusted to reflect behavior and ecology of R. cerasi. Model parametrization was based on compiled published information about R. cerasi and the results of auxiliary on-farm experiments. The experiments were conducted on sweet cherry farms located in Austria, Germany, and Belgium. For each farm, a customized model-module was prepared, reflecting its spatiotemporal features. Historical data about pest monitoring, IPM treatments and fruit infestation were used to specify the model assumptions and calibrate it further. Finally, for each of the farms, virtual IPM experiments were simulated and the model-generated results were compared with the results of the real experiments conducted on the same farms. Implications of the findings for broader applicability of the model and the "virtual farm" approach-were discussed.

  11. Optimal Active Power Control of A Wind Farm Equipped with Energy Storage System based on Distributed Model Predictive Control

    DEFF Research Database (Denmark)

    Zhao, Haoran; Wu, Qiuwei; Guo, Qinglai

    2016-01-01

    This paper presents the Distributed Model Predictive Control (D-MPC) of a wind farm equipped with fast and short-term Energy Storage System (ESS) for optimal active power control using the fast gradient method via dual decomposition. The primary objective of the D-MPC control of the wind farm...... is power reference tracking from system operators. Besides, by optimal distribution of the power references to individual wind turbines and the ESS unit, the wind turbine mechanical loads are alleviated. With the fast gradient method, the convergence rate of the DMPC is significantly improved which leads...... to a reduction of the iteration number. Accordingly, the communication burden is reduced. Case studies demonstrate that the additional ESS unit can lead to a larger wind turbine load reduction, compared to the conventional wind farm control without ESS. Moreover, the efficiency of the developed D-MPC algorithm...

  12. Land Use Change on Household Farms in the Ecuadorian Amazon: Design and Implementation of an Agent-Based Model.

    Science.gov (United States)

    Mena, Carlos F; Walsh, Stephen J; Frizzelle, Brian G; Xiaozheng, Yao; Malanson, George P

    2011-01-01

    This paper describes the design and implementation of an Agent-Based Model (ABM) used to simulate land use change on household farms in the Northern Ecuadorian Amazon (NEA). The ABM simulates decision-making processes at the household level that is examined through a longitudinal, socio-economic and demographic survey that was conducted in 1990 and 1999. Geographic Information Systems (GIS) are used to establish spatial relationships between farms and their environment, while classified Landsat Thematic Mapper (TM) imagery is used to set initial land use/land cover conditions for the spatial simulation, assess from-to land use/land cover change patterns, and describe trajectories of land use change at the farm and landscape levels. Results from prior studies in the NEA provide insights into the key social and ecological variables, describe human behavioral functions, and examine population-environment interactions that are linked to deforestation and agricultural extensification, population migration, and demographic change. Within the architecture of the model, agents are classified as active or passive. The model comprises four modules, i.e., initialization, demography, agriculture, and migration that operate individually, but are linked through key household processes. The main outputs of the model include a spatially-explicit representation of the land use/land cover on survey and non-survey farms and at the landscape level for each annual time-step, as well as simulated socio-economic and demographic characteristics of households and communities. The work describes the design and implementation of the model and how population-environment interactions can be addressed in a frontier setting. The paper contributes to land change science by examining important pattern-process relations, advocating a spatial modeling approach that is capable of synthesizing fundamental relationships at the farm level, and links people and environment in complex ways.

  13. Modeling farm nutrient flows in the North China Plain to reduce nutrient losses

    NARCIS (Netherlands)

    Zhao, Zhanqing; Bai, Zhaohai; Wei, Sha; Ma, Wenqi; Wang, Mengru; Kroeze, Carolien; Ma, Lin

    2017-01-01

    Years of poor nutrient management practices in the agriculture industry in the North China Plain have led to large losses of nutrients to the environment, causing severe ecological consequences. Analyzing farm nutrient flows is urgently needed in order to reduce nutrient losses. A farm-level

  14. Assessing regional differences in nitrogen losses from U.S. dairy farms using the integrated farm systems model

    Science.gov (United States)

    Nitrogen (N) enters and leaves a dairy production system through many pathways and in many forms: undergoing numerous transformations as it passes from feed to animal to milk or manure and back again. Due to the complexity of the dairy system, estimates of N flows and losses require the use of model...

  15. Wind Farm Power Forecasting for Less Than an Hour Using Multi Dimensional Models

    DEFF Research Database (Denmark)

    Knudsen, Torben; Bak, Thomas; Jensen, Tom Nørgaard

    2018-01-01

    The paper focus on prediction of wind farm power for horizons of 0-10 minutes and not more than one hour using statistical methods. These short term predictions are relevant for both transmission system operators, wind farm operators and traders. Previous research indicates that for short time...... horizons the persistence method performs as well as more complex methods. However, these results are based on accumulated power for an entire wind farm. The contribution in this paper is to develop multi-dimensional linear methods based on measurements of power or wind speed from individual wind turbine...... in a wind farm. These multi-dimensional methods are compared with the persistence method using real 1 minute average data from the Sheringham Shoal wind farm with 88 turbines. The results show that the use of measurements from individual turbines reduce the prediction errors 5-10% and also improves...

  16. Development of a farm-firm modelling system for evaluation of herbaceous energy crops

    Energy Technology Data Exchange (ETDEWEB)

    English, B.C.; Alexander, R.R.; Loewen, K.H.; Coady, S.A.; Cole, G.V.; Goodman, W.R. (Tennessee Univ., Knoxville, TN (United States). Dept. of Agricultural Economics and Rural Sociology)

    1992-01-01

    A complete analysis is performed to simulate biomass production incorporated into a realistic whole farm situation, including or replacing a typical crop mix. Representative farms are constructed to accommodate such simulation. Four management systems are simulated for each firm, with each simulation depicting a different crop mix and/or use of different farming technologies and production methods. The first simulation was a base farm plan in which the operator would maintain the historical crop mix for the area, participate in all price support programs, and not participate in either a conservative reserve or a biomass production program. In the second simulation, the operator would again maintain the historical crop mix, would not participate in a conservation reserve or biomass production program, and would be ineligible to participate in any price support system. The third simulation introduced the Conservation Reserve Program (CRP) and included participation in all price support programs. The fourth simulation introduced a biomass crop production enterprise (switchgrass) as an alternative to enrolling highly erodible cropland in the CRP and allowed participation in price support programs. Simulations were made for three farms, two in West Tennessee and on in South Georgia. Results indicate that erosion is likely to be reduced more by the diversion of cropland to permanent vegetative cover on farms similar to the more highly erodible West Tennessee farms than on the less erodible Tift County, Georgia farm. Equivalent reductions in erosion rates result from entering highly erodible cropland in the CRP and from production of switchgrass as a biomass energy crop. Both switchgrass and CRP farm plans result in decreased net returns from the base plan, although the biomass farm plans are, in general, more profitable than the CRP plans.

  17. Development of a farm-firm modelling system for evaluation of herbaceous energy crops

    International Nuclear Information System (INIS)

    English, B.C.; Alexander, R.R.; Loewen, K.H.; Coady, S.A.; Cole, G.V.; Goodman, W.R.

    1992-01-01

    A complete analysis is performed to simulate biomass production incorporated into a realistic whole farm situation, including or replacing a typical crop mix. Representative farms are constructed to accommodate such simulation. Four management systems are simulated for each firm, with each simulation depicting a different crop mix and/or use of different farming technologies and production methods. The first simulation was a base farm plan in which the operator would maintain the historical crop mix for the area, participate in all price support programs, and not participate in either a conservative reserve or a biomass production program. In the second simulation, the operator would again maintain the historical crop mix, would not participate in a conservation reserve or biomass production program, and would be ineligible to participate in any price support system. The third simulation introduced the Conservation Reserve Program (CRP) and included participation in all price support programs. The fourth simulation introduced a biomass crop production enterprise (switchgrass) as an alternative to enrolling highly erodible cropland in the CRP and allowed participation in price support programs. Simulations were made for three farms, two in West Tennessee and on in South Georgia. Results indicate that erosion is likely to be reduced more by the diversion of cropland to permanent vegetative cover on farms similar to the more highly erodible West Tennessee farms than on the less erodible Tift County, Georgia farm. Equivalent reductions in erosion rates result from entering highly erodible cropland in the CRP and from production of switchgrass as a biomass energy crop. Both switchgrass and CRP farm plans result in decreased net returns from the base plan, although the biomass farm plans are, in general, more profitable than the CRP plans

  18. Effect of physical activity on cardiac autonomic function of dairy cows on commercial dairy farms.

    Science.gov (United States)

    Kézér, Fruzsina Luca; Tőzsér, János; Bakony, Mikolt; Szenci, Ottó; Jurkovich, Viktor; Kovács, Levente

    2017-11-01

    Interbeat interval data were collected from 219 Holstein cows in 2 smaller-scale farms and 3 larger-scale farms to investigate the effects of posture (standing vs. lying), rumination (rumination vs. no rumination) and feeding on baseline values of heart rate (HR) and heart rate variability (HRV) parameters reflecting vagal and sympathetic activity. A General Linear Model was used for detecting factors (parity, milking technology, herd size) having possible effects on HRV calculated for undisturbed lying posture. Basal values of cardiac parameters were also compared between larger and smaller-scale farms. Neither parity nor milking technology affected HRV parameters. Sympathetic activity increased in the order of lying, ruminating when lying, standing, ruminating when standing and feeding on both sizes of farms. Vagal activity decreased in that order in both lower- and larger-scale farms. Rumination caused an increase in HR and a decrease in vagal tone in both lower- and larger-scale farms and an increase in sympathetic activity during lying in both farm sizes. Basal vagal activity was lower in larger-scale farms compared to smaller-scale farms, while greater sympathetic activity was found in cows housed on larger-scale farms. Our findings demonstrate that reference values of HRV parameters in lactating dairy cows cannot be generally defined for Holstein cattle as they are affected by physical activity and herd size. Higher HR and sympathetic activity at rest in larger-scale farms compared to farms with lower cow population might be associated with higher levels of social stress and therefore should be considered as a potential welfare concern.

  19. IEA-Task 31 WAKEBENCH: Towards a protocol for wind farm flow model evaluation. Part 1: Flow-over-terrain models

    DEFF Research Database (Denmark)

    Rodrigo, Javier Sanz; Gancarski, Pawel; Arroyo, Roberto Chavez

    2014-01-01

    The IEA Task 31 Wakebench is setting up a framework for the evaluation of wind farm flow models operating at microscale level. The framework consists on a model evaluation protocol integrated on a web-based portal for model benchmarking (www.windbench.net). This paper provides an overview of the ...

  20. Assessment of N and P status at the landscape scale using environmental models and measurements

    International Nuclear Information System (INIS)

    Sonneveld, M.P.W.; Vos, J.A. de; Kros, J.; Knotters, M.; Frumau, A.; Bleeker, A.; Vries, W. de

    2012-01-01

    We assessed the compliance of a Dutch landscape, dominated by dairy farming, with environmental quality standards using a combination of model calculations and measurements. The total ammonia emission of 2.4 kton NH 3 yr −1 does not exceed the environmental quality standard (2.6 kton NH 3 yr −1 ). Nevertheless, the total N deposition (on average 24.4 kg N ha −1 yr −1 ) is such that critical N loads are exceeded at 53% of the nature areas. The deposited N mainly results from non-agricultural sources and agricultural sources outside the area (72%). The calculated average NO 3 − concentration in the upper groundwater does not exceed the 50 mg l −1 threshold. Calculated annual average N-total and P-total concentrations in discharge water are relatively high but these cannot be directly compared with thresholds for surface water. The results suggest that compliance monitoring at the landscape scale needs to include source indicators and cannot be based on state indicators alone. - Highlights: ► There is scope for environmental monitoring programs at the landscape scale. ► Landscape assessment of state indicators for N and P require models and measurements. ► Monitoring at the landscape scale needs to consider farm management indicators. - The compliance of an agricultural landscape with quality standards is investigated using a combination of model calculations and measurements.

  1. Assays at laboratory scale for anaerobic treatment of piggery farm wastewater; Depuracion anaerobia de aguas residuales de granjas porcinas. Ensayos a escala de laboratorio

    Energy Technology Data Exchange (ETDEWEB)

    Duran Barrantes, M. M.; Alvarez Mateos, P.; Carta Escobar, F.; Romero Guzman, F. [Universidad de Sevilla (Spain); Fiestas Ros de Ursinos, J. A. [Instituto de la Grasa. Sevilla (Spain)

    2000-07-01

    The viability of an integrated biological treatment for the swine waste-water purification in a piggery farm, was studied. Previously, at a laboratory scale, the anaerobic biodegradability of this wastewater was analysed, using different clayey supports to immobilize the microorganisms in batch regime, at 35 degree centigree, with an organic load ranged from 0,2 to 2,2, g COD/I. The highest methane production was achieved at the first 24 hours. The mean highest efficiency (%COD removal) was obtained in reactors with sepiolite, natural sepiolite and treated sepiolite. (Author) 10 refs.

  2. Prevalence and Antimicrobial Resistance of Enterobacteriaceae in Shell Eggs from Small-Scale Poultry Farms and Farmers' Markets.

    Science.gov (United States)

    Kilonzo-Nthenge, A; Nahashon, S N; Godwin, S; Liu, S; Long, D

    2016-12-01

    Public health concerns over the emergence of antimicrobial resistant bacteria have increased recently. The purpose of this study was to investigate the prevalence of antimicrobial resistant Enterobacteriaceae in shell eggs purchased from small poultry farms and farmers' markets. A total of 504 eggs were pooled to make 252 composite samples, consisting of 2 eggs per composite. The microbial quality of shell eggs was determined by standard quantitative, biochemical, and PCR techniques. Susceptibility to 13 antimicrobial agents was determined by the Kirby-Bauer disk diffusion technique, and results were interpreted based on Clinical and Laboratory Standards Institute values. Shell eggs and egg contents were positive for Escherichia coli (11.9 and 5.2%, respectively), Enterobacter (9.1 and 7.9%), and Serratia (11.5 and 4.8%). Salmonella was isolated from 3.6% of egg shells but not from egg contents. Mean (±SD) Enterobacteriaceae levels (4.4 ± 2.0 log CFU per eggshell) on shell eggs from poultry farms was significantly higher (P ≤ 0.05) than that on shell eggs from farmers' markets (2.1 ± 1.3 log CFU per eggshell). Of the 134 isolates recovered, resistance among isolates from farm and market shell eggs to erythromycin was most common (48.5 and 32.8%, respectively) followed by ampicillin (44.8 and 17.2%), and tetracycline (29.9 and 17.2%). The multiple antibiotic resistance index value for E. coli and Pantoea was 0.62, and that for Salmonella and Klebsiella terrigena was 0.08, indicating that Enterobacteriaceae in shell eggs can be resistant to multiple antimicrobial agents. These data reveal that shell eggs from small poultry farms and farmers' markets can harbor antimicrobial resistant pathogenic and commensal bacteria. Thus, failure to properly handle shell eggs poses a potential health hazard to consumers.

  3. Farm to Work: Development of a Modified Community-Supported Agriculture Model at Worksites, 2007-2012.

    Science.gov (United States)

    Thi, Christina A; Horton, Karissa D; Loyo, Jennifer; Jowers, Esbelle M; Rodgers, Lindsay Faith; Smiley, Andrew W; Leversen, Eric; Hoelscher, Deanna M

    2015-10-22

    The Farm to Work program is a modified community-supported agriculture model at worksites in Texas. The objective of the Farm to Work program is to increase fruit and vegetable intake among employees and their households by decreasing cost, improving convenience, and increasing access while also creating a new market for local farmers at worksites. The objectives of this article were to describe the development, implementation, and outcome of a 5-year participation trend analysis and to describe the community relationships that were formed to enable the successful implementation of the program. The Farm to Work program began in November 2007 as a collaborative effort between the nonprofit Sustainable Food Center, the Texas Department of State Health Services, the Web development company WebChronic Consulting LLC, and Naegelin Farm. The program provides a weekly or biweekly opportunity for employees to order a basket of produce online to be delivered to the worksite by a local farmer. A 5-year participation trend analysis, including seasonal variation and sales trends, was conducted using sales data from November 2007 through December 2012. The total number of baskets delivered from November 2007 through December 2012 was 38,343; of these, 37,466 were sold and 877 were complimentary. The total value of sold and complimentary baskets was $851,035 and $21,925, respectively. Participation in the program increased over time and was highest in 2012. The Farm to Work program increased access to locally grown fruits and vegetables for employees and created a new market for farmers. Increased program participation indicates that Farm to Work can increase employees' fruit and vegetable consumption and thus help prevent chronic diseases in this population.

  4. Modelling landscape evolution at the flume scale

    Science.gov (United States)

    Cheraghi, Mohsen; Rinaldo, Andrea; Sander, Graham C.; Barry, D. Andrew

    2017-04-01

    The ability of a large-scale Landscape Evolution Model (LEM) to simulate the soil surface morphological evolution as observed in a laboratory flume (1-m × 2-m surface area) was investigated. The soil surface was initially smooth, and was subjected to heterogeneous rainfall in an experiment designed to avoid rill formation. Low-cohesive fine sand was placed in the flume while the slope and relief height were 5 % and 20 cm, respectively. Non-uniform rainfall with an average intensity of 85 mm h-1 and a standard deviation of 26 % was applied to the sediment surface for 16 h. We hypothesized that the complex overland water flow can be represented by a drainage discharge network, which was calculated via the micro-morphology and the rainfall distribution. Measurements included high resolution Digital Elevation Models that were captured at intervals during the experiment. The calibrated LEM captured the migration of the main flow path from the low precipitation area into the high precipitation area. Furthermore, both model and experiment showed a steep transition zone in soil elevation that moved upstream during the experiment. We conclude that the LEM is applicable under non-uniform rainfall and in the absence of surface incisions, thereby extending its applicability beyond that shown in previous applications. Keywords: Numerical simulation, Flume experiment, Particle Swarm Optimization, Sediment transport, River network evolution model.

  5. Abolition of set-aside schemes, associated impacts on habitat structure and modelling of potential effects of cross-farm regulation

    DEFF Research Database (Denmark)

    Levin, G.; Jepsen, Martin Rudbeck

    2010-01-01

    with the greatest benefit for habitat structure is retained as uncultivated, while set-aside land with the least effect is re-cultivated. The model is applied to individual farms and to farm agglomerations of increasing sizes, enabling us to explore potential effects of cross-farm regulation. The novelty of our...... reduces impacts. Effects increase with increasing size of farm agglomerations. However, marginal benefits become negligible at agglomeration sizes over 36 km(2). (C) 2010 Elsevier B.V. All rights reserved...

  6. Phasor model of full scale converter wind turbine for small-signal stability analysis

    OpenAIRE

    Gihga, Radu; Wu, Qiuwei; Nielsen, Arne Hejde

    2017-01-01

    The small-signal stability analysis of power system electromechanical oscillations is a well-established field in control and stability assessment of power systems. The impact of large wind farms on small-signal stability of power systems has been a topic of high interest in recent years. This study presents a phasor model of full scale converter wind turbines (WTs) implemented in MATLAB/SIMULINK for small-signal stability studies. The phasor method is typically used for dynamic studies of po...

  7. Integrated multi-scale modelling and simulation of nuclear fuels

    International Nuclear Information System (INIS)

    Valot, C.; Bertolus, M.; Masson, R.; Malerba, L.; Rachid, J.; Besmann, T.; Phillpot, S.; Stan, M.

    2015-01-01

    This chapter aims at discussing the objectives, implementation and integration of multi-scale modelling approaches applied to nuclear fuel materials. We will first show why the multi-scale modelling approach is required, due to the nature of the materials and by the phenomena involved under irradiation. We will then present the multiple facets of multi-scale modelling approach, while giving some recommendations with regard to its application. We will also show that multi-scale modelling must be coupled with appropriate multi-scale experiments and characterisation. Finally, we will demonstrate how multi-scale modelling can contribute to solving technology issues. (authors)

  8. Evaluating expansion strategies for startup European Union dairy farm businesses.

    Science.gov (United States)

    McDonald, R; Shalloo, L; Pierce, K M; Horan, B

    2013-06-01

    A stochastic whole-farm simulation model was used to examine alternative strategies for new entrant dairy farmers to grow and develop dairy farm businesses in the context of European Union (EU) milk quota abolition in 2015. Six alternative strategies were compared: remain static, natural growth expansion, waiting until after EU milk quota abolition to expand, a full-scale expansion strategy without milk quotas and not incurring super levy penalties, a full-scale expansion strategy with milk quotas and incurring super levy penalties, and once-a-day milking until EU milk quota abolition, followed by full-scale expansion. Each discrete whole farm investment strategy was evaluated over a 15-yr period (2013-2027) using multiple financial stability and risk indicators, including overall discounted farm business profitability, net worth change, return on investment, and financial risk. The results of this study indicate that, although associated with increased risk, dairy farm expansion will ensure the future profitability of the farm business. Within the context of EU milk quotas until 2015, the most attractive expansion strategy is to increase cow numbers while avoiding super levy fines using once-a-day milking techniques, increasing to the full capacity of the dairy farm once milk quotas are removed. In contrast, the results also indicate that dairy farms that remain static will experience a significant reduction in farm profitability in the coming year due to production cost inflation. Cash flow deficits were observed during the initial year of expansion and, therefore, rapidly expanding dairy farm businesses require a significant cash reserve to alleviate business risk during the initial year of expansion. The results of this analysis also indicate that dairy farm businesses that expand using lower cost capital investments and avoid milk quota super levy fines significantly reduce the financial risks associated with expansion. Copyright © 2013 American Dairy Science

  9. Capturing the externalities: National and watershed scale damages from release of reactive nitrogen beyond the farm, factory, tailpipe and table

    Science.gov (United States)

    Compton, J.; Sobota, D. J.; McCrackin, M. L.; Harrison, J.

    2014-12-01

    Human demand for food, fuel, and industrial products results in the release of 61% of the newly fixed anthropogenic N to the environment in the US each year. This 15.8 Tg N yr-1 input to air, land and water has important social, economic and environmental consequences, yet little research clearly links this N release to the full suite of effects. Here we connect the biogeochemical fluxes of N with existing data on N-associated damages in order to quantify the externalities of N release related to human health, ecosystems and climate regulation for the US at national and watershed scales. Release of N to the environment was estimated circa 2000 with models describing N inputs by source, nutrient uptake efficiency, leaching losses, and gaseous emissions at the scale of 8-digit US Geologic Survey Hydrologic Unit Codes (HUC8s). Potential damages or benefits of anthropogenic N leaked to the environment were calculated by scaling specific N fluxes with the costs associated with human health, agriculture, ecosystems, and the climate system. For the US, annual damage costs of anthropogenic N leaked to the environment in 2000 totaled 289 billion USD. Approximately 57% of the total damages were associated with fossil fuel combustion, driven by the human respiratory health impacts of NOx as a precursor of ozone and a component of particulates. Another 37% of the damage costs were associated with agricultural N. Damages associated with agriculture were 85.5 billion, largely through eutrophication and harmful effects on aquatic habitat. Through aggressive but tangible improvements in atmospheric emissions, agricultural N use and wastewater treatment, we could reduce N export to the coast by nearly 25% within 30 years. These improvements would reduce the externalities associated with the leakage of N beyond its intended uses in agriculture, transportation and energy with minimal impact to these sectors dependent on anthropogenic N fixation.

  10. Simulation of between-farm transmission of porcine reproductive and respiratory syndrome virus in Ontario, Canada using the North American Animal Disease Spread Model.

    Science.gov (United States)

    Thakur, Krishna K; Revie, Crawford W; Hurnik, Daniel; Poljak, Zvonimir; Sanchez, Javier

    2015-03-01

    Porcine reproductive and respiratory syndrome (PRRS), a viral disease of swine, has major economic impacts on the swine industry. The North American Animal Disease Spread Model (NAADSM) is a spatial, stochastic, farm level state-transition modeling framework originally developed to simulate highly contagious and foreign livestock diseases. The objectives of this study were to develop a model to simulate between-farm spread of a homologous strain of PRRS virus in Ontario swine farms via direct (animal movement) and indirect (sharing of trucks between farms) contacts using the NAADSM and to compare the patterns and extent of outbreak under different simulated conditions. A total of 2552 swine farms in Ontario province were allocated to each census division of Ontario and geo-locations of the farms were randomly generated within the agriculture land of each Census Division. Contact rates among different production types were obtained using pig movement information from four regions in Canada. A total of 24 scenarios were developed involving various direct (movement of infected animals) and indirect (pig transportation trucks) contact parameters in combination with alternating the production type of the farm in which the infection was seeded. Outbreaks were simulated for one year with 1000 replications. The median number of farms infected, proportion of farms with multiple outbreaks and time to reach the peak epidemic were used to compare the size, progression and extent of outbreaks. Scenarios involving spread only by direct contact between farms resulted in outbreaks where the median percentage of infected farms ranged from 31.5 to 37% of all farms. In scenarios with both direct and indirect contact, the median percentage of infected farms increased to a range from 41.6 to 48.6%. Furthermore, scenarios with both direct and indirect contact resulted in a 44% increase in median epidemic size when compared to the direct contact scenarios. Incorporation of both animal

  11. Modelling receiving water quality responses to brackishwater shrimp aquaculture farm effluents

    International Nuclear Information System (INIS)

    Roy Chaudhury, R.K.; Ramana Murty, V.; Ravindran, M.

    1999-01-01

    The objective was to perform a waste load allocation and determine the extent of aquaculture that the creeks can sustain, by meeting the water quality criteria for both the creek ecosystem and pond culture. Based on these results, similar assessments may be performed for other sites supporting large scale aquaculture activities. This paper introduces the sampling program and modelling methodology of the study

  12. Ways of farming and ways of thinking: do farmers' mental models of the landscape relate to their land management practices?

    Directory of Open Access Journals (Sweden)

    Carole Vuillot

    2016-03-01

    Full Text Available The efficiency of the European Union's Common Agricultural Policy in mitigating the negative effects of agricultural intensification on the landscape and biodiversity is increasingly being questioned. Enhancing a reciprocal understanding of various stakeholders' mental models of agro-social-ecosystems has been proposed to trigger changes in both policy design and farmers' behaviors. However, the relationship between farmers' mental models and practices is rarely considered. Here, we explore the relationship between farmers' individual mental models (IMMs of the agricultural landscape and their land management practices. To do so, we developed a theoretical and methodological framework grounded in cognitive psychology and farming system research for eliciting and comparing IMMs and land management practices. We applied this framework in the Coteaux de Gascogne territory, a hilly crop-livestock region in southern France. We identified groups of farmers according to their cropland and semi-natural habitat management practices. The results of our quantitative and qualitative comparisons of mental models between farmer groups showed that the way of farming partly relates to farmers' ways of thinking about the landscape and highlighted the heterogeneity of IMMs between and within farmer groups. We found evidence that path-dependent factors that constrain farmers' practices can modify their mental models, e.g., the role of agricultural machinery. Our study illustrates how an interdisciplinary framework coupling mental models and farming systems approaches provides an opportunity to enhance our understanding of the relationships between farmers' world views and their practices. Moreover, our results challenge current ways of thinking and designing biodiversity conservation policies in farmed landscapes.

  13. Development of Cattle farming as a Model For Sustainable Rural Development Goal using Spatial Approach (Case in Southern Parts of Merapi Volcano Slope Sleman Regency of Yogyakarta

    Directory of Open Access Journals (Sweden)

    Rini Widiati

    2017-07-01

    Full Text Available This study aims to build a model of beef cattle farming development using spatial approach in rural areas of the southern slopes of Merapi Volcano Sleman Regency of Yogyakarta after eruption 2010. Samples were taken Glagaharjo sub-district (Cangkringan district as impacted area and Wonokerto (Turi district as unimpacted areas. Survey method were used to land evaluation analysis and  Geographic Information System (GIS software for spatial analysis. Materials were used RBI map in 1:25 000 scale, map of land use, landform, slope, and IKONOS imagery (2015. Analysis potential of land capability  for forage cattle using the production unity in kg of TDN per AU. The research result showed that based on the land capability and suitability class maps, both villages had the potential of land carrying capacity of cattle feed of 2604.84 AU in Glagaharjo and 2162.26 AU in Wonokerto. However, further research to explore the potential of agricultural land use to develop smallholder model of beef cattle farming in both villages was still open to the researchers.

  14. Global-scale modeling of groundwater recharge

    Directory of Open Access Journals (Sweden)

    P. Döll

    2008-05-01

    Full Text Available Long-term average groundwater recharge, which is equivalent to renewable groundwater resources, is the major limiting factor for the sustainable use of groundwater. Compared to surface water resources, groundwater resources are more protected from pollution, and their use is less restricted by seasonal and inter-annual flow variations. To support water management in a globalized world, it is necessary to estimate groundwater recharge at the global scale. Here, we present a best estimate of global-scale long-term average diffuse groundwater recharge (i.e. renewable groundwater resources that has been calculated by the most recent version of the WaterGAP Global Hydrology Model WGHM (spatial resolution of 0.5° by 0.5°, daily time steps. The estimate was obtained using two state-of-the-art global data sets of gridded observed precipitation that we corrected for measurement errors, which also allowed to quantify the uncertainty due to these equally uncertain data sets. The standard WGHM groundwater recharge algorithm was modified for semi-arid and arid regions, based on independent estimates of diffuse groundwater recharge, which lead to an unbiased estimation of groundwater recharge in these regions. WGHM was tuned against observed long-term average river discharge at 1235 gauging stations by adjusting, individually for each basin, the partitioning of precipitation into evapotranspiration and total runoff. We estimate that global groundwater recharge was 12 666 km3/yr for the climate normal 1961–1990, i.e. 32% of total renewable water resources. In semi-arid and arid regions, mountainous regions, permafrost regions and in the Asian Monsoon region, groundwater recharge accounts for a lower fraction of total runoff, which makes these regions particularly vulnerable to seasonal and inter-annual precipitation variability and water pollution. Average per-capita renewable groundwater resources of countries vary between 8 m3

  15. Global-scale modeling of groundwater recharge

    Science.gov (United States)

    Döll, P.; Fiedler, K.

    2008-05-01

    Long-term average groundwater recharge, which is equivalent to renewable groundwater resources, is the major limiting factor for the sustainable use of groundwater. Compared to surface water resources, groundwater resources are more protected from pollution, and their use is less restricted by seasonal and inter-annual flow variations. To support water management in a globalized world, it is necessary to estimate groundwater recharge at the global scale. Here, we present a best estimate of global-scale long-term average diffuse groundwater recharge (i.e. renewable groundwater resources) that has been calculated by the most recent version of the WaterGAP Global Hydrology Model WGHM (spatial resolution of 0.5° by 0.5°, daily time steps). The estimate was obtained using two state-of-the-art global data sets of gridded observed precipitation that we corrected for measurement errors, which also allowed to quantify the uncertainty due to these equally uncertain data sets. The standard WGHM groundwater recharge algorithm was modified for semi-arid and arid regions, based on independent estimates of diffuse groundwater recharge, which lead to an unbiased estimation of groundwater recharge in these regions. WGHM was tuned against observed long-term average river discharge at 1235 gauging stations by adjusting, individually for each basin, the partitioning of precipitation into evapotranspiration and total runoff. We estimate that global groundwater recharge was 12 666 km3/yr for the climate normal 1961-1990, i.e. 32% of total renewable water resources. In semi-arid and arid regions, mountainous regions, permafrost regions and in the Asian Monsoon region, groundwater recharge accounts for a lower fraction of total runoff, which makes these regions particularly vulnerable to seasonal and inter-annual precipitation variability and water pollution. Average per-capita renewable groundwater resources of countries vary between 8 m3/(capita yr) for Egypt to more than 1 million m3

  16. Optimal Real-Time Scheduling for Hybrid Energy Storage Systems and Wind Farms Based on Model Predictive Control

    Directory of Open Access Journals (Sweden)

    Meng Xiong

    2015-08-01

    Full Text Available Energy storage devices are expected to be more frequently implemented in wind farms in near future. In this paper, both pumped hydro and fly wheel storage systems are used to assist a wind farm to smooth the power fluctuations. Due to the significant difference in the response speeds of the two storages types, the wind farm coordination with two types of energy storage is a problem. This paper presents two methods for the coordination problem: a two-level hierarchical model predictive control (MPC method and a single-level MPC method. In the single-level MPC method, only one MPC controller coordinates the wind farm and the two storage systems to follow the grid scheduling. Alternatively, in the two-level MPC method, two MPC controllers are used to coordinate the wind farm and the two storage systems. The structure of two level MPC consists of outer level and inner level MPC. They run alternatively to perform real-time scheduling and then stop, thus obtaining long-term scheduling results and sending some results to the inner level as input. The single-level MPC method performs both long- and short-term scheduling tasks in each interval. The simulation results show that the methods proposed can improve the utilization of wind power and reduce wind power spillage. In addition, the single-level MPC and the two-level MPC are not interchangeable. The single-level MPC has the advantage of following the grid schedule while the two-level MPC can reduce the optimization time by 60%.

  17. Construction and Application of an LP Farm Model with an Integrated Life Cycle Assessment for the Determination of Sustainable Milk Production Systems

    OpenAIRE

    Mohring, Anke; Zimmermann, Albert

    2005-01-01

    The increasingly stringent conditions underlying Swiss dairy production demand sustainable milk production systems that are economically optimized but also meet the ecological requirements of society. To determine such systems, a comparative-static LP model was constructed at farm level. Realistic production systems are reproduced in the model by means of binary variables. An Life Cycle Assessment (LCA) was integrated into the model to determine the environmental impacts of the farm. To this ...

  18. Design tool for offshore wind farm cluster planning

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Madsen, Peter Hauge; Giebel, Gregor

    2015-01-01

    In the framework of the FP7 project EERA DTOC: Design Tool for Offshore wind farm Cluster, a new software supporting the planning of offshore wind farms was developed, based on state-of-the-art approaches from large scale wind potential to economic benchmarking. The model portfolio includes WAsP,...... are useful for wind farm planning of the grid and necessary components and controls.......In the framework of the FP7 project EERA DTOC: Design Tool for Offshore wind farm Cluster, a new software supporting the planning of offshore wind farms was developed, based on state-of-the-art approaches from large scale wind potential to economic benchmarking. The model portfolio includes WAs......P, FUGA, WRF, Net-Op, LCoE model, CorWind, FarmFlow, EeFarm and grid code compliance calculations. The development is done by members from European Energy Research Alliance (EERA) and guided by several industrial partners. A commercial spin-off from the project is the tool ‘Wind & Economy’. The software...

  19. Migration and degradation of swine farm tetracyclines at the river catchment scale: Can the multi-pond system mitigate pollution risk to receiving rivers?

    Science.gov (United States)

    Chen, Qiuwen; Guo, Xiao; Hua, Guofen; Li, Guoliang; Feng, Ranran; Liu, Xiaoli

    2017-01-01

    The study investigated the degradation behaviors of swine farm tetracyclines (TCs) at a catchment scale and explored whether multi-pond systems could be beneficial to the interception of TCs so as to reduce the pollution risk to receiving rivers. The occurrence and migration of 12 kinds of tetracycline antibiotics, including their degradation products, were studied in four swine farms of the Meijiang River basin in China. The migration paths of the TCs were examined through sampling and analyzing the soil and/or sediment at different points along the swine wastewater outlet, which included sewer, sewage pond, mixed-canal (stream and sewage), farmland (paddy and upland soil) and finally the river. TC concentrations of all collected samples were obtained by solid phase extraction followed by measurement with high-performance liquid chromatography tandem mass spectrometry. The results showed that sediment TC concentrations varied greatly in different swine farms, from mg·kg -1 to μg·kg -1 levels. TCs had different decay patterns along different migration paths, such that TCs decayed exponentially in paddy soil, while linearly in sewer and mixed canal. The concentrations of TCs and their degradation products decreased in the order: sewer sediment > sewage pond sediment > mixed-canal sediment > paddy soil > upland soil, indicating that TCs tend to be more easily intercepted and accumulated in water-sediment systems such as ponds. Therefore, the multi-pond system could be an effective way to prevent TCs from migrating into rivers. These results provided essential information for contamination control of antibiotics in aquatic environments. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Modeling cancer metabolism on a genome scale

    Science.gov (United States)

    Yizhak, Keren; Chaneton, Barbara; Gottlieb, Eyal; Ruppin, Eytan

    2015-01-01

    Cancer cells have fundamentally altered cellular metabolism that is associated with their tumorigenicity and malignancy. In addition to the widely studied Warburg effect, several new key metabolic alterations in cancer have been established over the last decade, leading to the recognition that altered tumor metabolism is one of the hallmarks of cancer. Deciphering the full scope and functional implications of the dysregulated metabolism in cancer requires both the advancement of a variety of omics measurements and the advancement of computational approaches for the analysis and contextualization of the accumulated data. Encouragingly, while the metabolic network is highly interconnected and complex, it is at the same time probably the best characterized cellular network. Following, this review discusses the challenges that genome-scale modeling of cancer metabolism has been facing. We survey several recent studies demonstrating the first strides that have been done, testifying to the value of this approach in portraying a network-level view of the cancer metabolism and in identifying novel drug targets and biomarkers. Finally, we outline a few new steps that may further advance this field. PMID:26130389

  1. Modeling cancer metabolism on a genome scale.

    Science.gov (United States)

    Yizhak, Keren; Chaneton, Barbara; Gottlieb, Eyal; Ruppin, Eytan

    2015-06-30

    Cancer cells have fundamentally altered cellular metabolism that is associated with their tumorigenicity and malignancy. In addition to the widely studied Warburg effect, several new key metabolic alterations in cancer have been established over the last decade, leading to the recognition that altered tumor metabolism is one of the hallmarks of cancer. Deciphering the full scope and functional implications of the dysregulated metabolism in cancer requires both the advancement of a variety of omics measurements and the advancement of computational approaches for the analysis and contextualization of the accumulated data. Encouragingly, while the metabolic network is highly interconnected and complex, it is at the same time probably the best characterized cellular network. Following, this review discusses the challenges that genome-scale modeling of cancer metabolism has been facing. We survey several recent studies demonstrating the first strides that have been done, testifying to the value of this approach in portraying a network-level view of the cancer metabolism and in identifying novel drug targets and biomarkers. Finally, we outline a few new steps that may further advance this field. © 2015 The Authors. Published under the terms of the CC BY 4.0 license.

  2. Are large farms more efficient? Tenure security, farm size and farm efficiency: evidence from northeast China

    Science.gov (United States)

    Zhou, Yuepeng; Ma, Xianlei; Shi, Xiaoping

    2017-04-01

    How to increase production efficiency, guarantee grain security, and increase farmers' income using the limited farmland is a great challenge that China is facing. Although theory predicts that secure property rights and moderate scale management of farmland can increase land productivity, reduce farm-related costs, and raise farmer's income, empirical studies on the size and magnitude of these effects are scarce. A number of studies have examined the impacts of land tenure or farm size on productivity or efficiency, respectively. There are also a few studies linking farm size, land tenure and efficiency together. However, to our best knowledge, there are no studies considering tenure security and farm efficiency together for different farm scales in China. In addition, there is little study analyzing the profit frontier. In this study, we particularly focus on the impacts of land tenure security and farm size on farm profit efficiency, using farm level data collected from 23 villages, 811 households in Liaoning in 2015. 7 different farm scales have been identified to further represent small farms, median farms, moderate-scale farms, and large farms. Technical efficiency is analyzed with stochastic frontier production function. The profit efficiency is regressed on a set of explanatory variables which includes farm size dummies, land tenure security indexes, and household characteristics. We found that: 1) The technical efficiency scores for production efficiency (average score = 0.998) indicate that it is already very close to the production frontier, and thus there is little room to improve production efficiency. However, there is larger space to raise profit efficiency (average score = 0.768) by investing more on farm size expansion, seed, hired labor, pesticide, and irrigation. 2) Farms between 50-80 mu are most efficient from the viewpoint of profit efficiency. The so-called moderate-scale farms (100-150 mu) according to the governmental guideline show no

  3. Phasor model of full scale converter wind turbine for small-signal stability analysis

    DEFF Research Database (Denmark)

    Ghiga, Radu; Wu, Qiuwei; Nielsen, Arne Hejde

    2017-01-01

    The small-signal stability analysis of power system electromechanical oscillations is a well-established field in control and stability assessment of power systems. The impact of large wind farms on small-signal stability of power systems has been a topic of high interest in recent years....... This study presents a phasor model of full scale converter wind turbines (WTs) implemented in MATLAB/SIMULINK for small-signal stability studies. The phasor method is typically used for dynamic studies of power systems consisting of large electric machines. It can also be applied to any linear system....... This represents an advantage in small-signal stability studies, which are based on modal analysis of the linearised model and are usually complemented with dynamic simulations. The proposed model can represent a single WT or an aggregated wind power plant. The implemented model for small-signal stability analysis...

  4. SDG and qualitative trend based model multiple scale validation

    Science.gov (United States)

    Gao, Dong; Xu, Xin; Yin, Jianjin; Zhang, Hongyu; Zhang, Beike

    2017-09-01

    Verification, Validation and Accreditation (VV&A) is key technology of simulation and modelling. For the traditional model validation methods, the completeness is weak; it is carried out in one scale; it depends on human experience. The SDG (Signed Directed Graph) and qualitative trend based multiple scale validation is proposed. First the SDG model is built and qualitative trends are added to the model. And then complete testing scenarios are produced by positive inference. The multiple scale validation is carried out by comparing the testing scenarios with outputs of simulation model in different scales. Finally, the effectiveness is proved by carrying out validation for a reactor model.

  5. Potential market of wind farm in China

    Energy Technology Data Exchange (ETDEWEB)

    Pengfei Shi [Hydropower Planning General Inst., Beijing (China)

    1996-12-31

    Wind energy resources are abundant in China, in southeast coast area along with the rapid economic growth, electricity demand has been sharply increased, due to complex terrain detailed assessments are in urgent need. Advanced methodology and computer model should be developed. In this paper the existing wind farms, installed capacity, manufacturers share and projects in the near future are presented. For further development of wind farm in large scale, different ways of local manufacturing wind turbine generators (WTG) are going on. Current policy and barriers are analyzed. 4 refs., 2 figs., 4 tabs.

  6. Sustainable extensification as an alternative model for reducing GHG emissions from agriculture. The case of an extensively managed organic farm in Denmark

    DEFF Research Database (Denmark)

    Bluwstein, Jevgeniy; Braun, Martin; Henriksen, Christian Bugge

    2015-01-01

    GHG emissions of an extensively managed Danish organic farm were estimated upstream and on-farm. The results were compared to Danish national levels based on land area and output. Overall, the farm emitted 2.12 t CO2eq ha−1 yr−1. Excluding land use, land use change, and forestry (LULUCF) related...... emissions, the combined GHG emissions from energy- and agriculture-based activities at the case farm were 47% lower (per unit area) and 12% higher (per unit output), than GHG emissions from Danish agriculture. With current livestock density (0.64 LU ha−1) and crop production area, the case study farm would...... supply at average 1,466 kcal per inhabitant per day in Denmark, if the farm was scaled up to Danish national level. With a reduction of livestock density to 0.36 LU ha−1 and proportional cropland area expansion for food production (ceteris paribus), the case study farm could supply around 4,940 kcal...

  7. A model to estimate hydrological processes and water budget in an irrigation farm pond

    Science.gov (United States)

    Ying Ouyang; Joel O. Paz; Gary Feng; John J. Read; Ardeshir Adeli; Johnie N. Jenkins

    2017-01-01

    With increased interest to conserve groundwater resources without reducing crop yield potential, more on-farm water storage ponds have been constructed in recent years in USA and around the world. However, the hydrological processes, water budget, and environmental benefits and consequences of these ponds have not yet been fully quantified. This study developed a...

  8. A Hidden Markov Model Representing the Spatial and Temporal Correlation of Multiple Wind Farms

    DEFF Research Database (Denmark)

    Fang, Jiakun; Su, Chi; Hu, Weihao

    2015-01-01

    To accommodate the increasing wind energy with stochastic nature becomes a major issue on power system reliability. This paper proposes a methodology to characterize the spatiotemporal correlation of multiple wind farms. First, a hierarchical clustering method based on self-organizing maps...

  9. Wind Farm Group Efficiency - A Sensitivity Analysis with a Mesoscale Model

    DEFF Research Database (Denmark)

    Volker, Patrick; Badger, Jake; Hahmann, Andrea N.

    2014-01-01

    In the North Sea the total installed capacity was in 2012 5GW, and it estimated that it will grow to 40GW by 2020 (EWEA). This will lead to an increasing wind farm density in regions with the most favourable conditions. In this study, we investigate the sensitivity of power density losses to wind...

  10. Optimum Stock Control Model for Farm Tractor Spare Parts in Nigeria

    African Journals Online (AJOL)

    This paper examines the issue of developing an effective farm machinery maintenance management strategy in Nigeria. Investigative survey data on the inventory, type and condition of agricultural machinery in Nigeria were reviewed and additional information required was obtained from relevant establishments. Data on ...

  11. Combining economic and fluid dynamic models to determine the optimal spacing in very large wind farms

    NARCIS (Netherlands)

    Stevens, Richard J.A.M.; Hobbs, Benjamin F.; Ramos, Andrés; Meneveau, Charles

    2017-01-01

    Wind turbine spacing is an important design parameter for wind farms. Placing turbines too close together reduces their power extraction because of wake effects and increases maintenance costs because of unsteady loading. Conversely, placing them further apart increases land and cabling costs, as

  12. Enhanced Kalman filtering for a 2D CFD NS wind farm flow model

    NARCIS (Netherlands)

    Doekemeijer, B.M.; van Wingerden, J.W.; Boersma, S.; Pao, L.Y

    2016-01-01

    Wind turbines are often grouped together for financial reasons, but due to wake development this usually results in decreased turbine lifetimes and power capture, and thereby an increased levelized cost of energy (LCOE). Wind farm control aims to minimize this cost by operating turbines at their

  13. Potential benefits of commercial willow Short Rotation Coppice (SRC) for farm-scale plant and invertebrate communities in the agri-environment

    Energy Technology Data Exchange (ETDEWEB)

    Rowe, Rebecca L.; Hanley, Mick E.; Goulson, Dave; Clarke, Donna J.; Doncaster, C. Patrick; Taylor, Gail [University of Southampton, Faculty of Natural and Environmental Sciences, Life Sciences Building, Southampton, S017 1BJ (United Kingdom)

    2011-01-15

    The cultivation of bioenergy crops (BECs) represents a significant land-use change in agri-environments, but their deployment has raised important issues globally regarding possible impacts on biodiversity. Few studies however, have systematically examined the effect of commercial scale bioenergy plantations on biodiversity in agri-ecosystems. In this study we investigate how the abundance and diversity of two key components of farmland biodiversity (ground flora and winged invertebrates) varied between mature willow Short Rotation Coppice (SRC) and two alternative land-use options (arable crops and set-aside land). Although the abundance of winged invertebrates was similar across all land-uses, taxonomic composition varied markedly. Hymenoptera and large Hemiptera (>5 mm) were more abundant in willow SRC than in arable or set-aside. Similarly although plant species richness was greater in set-aside, our data show that willow SRC supports a different plant community to the other land-uses, being dominated by competitive perennial species such as Elytrigia repens and Urtica dioica. Our results suggest that under current management practices a mixed farming system incorporating willow SRC can benefit native farm-scale biodiversity. In particular the reduced disturbance in willow SRC allows the persistence of perennial plant species, potentially providing a stable refuge and food sources for invertebrates. In addition, increased Hymenoptera abundance in willow SRC could potentially have concomitant effects on ecosystem processes, as many members of this Order are important pollinators of crop plants or otherwise fulfil an important beneficial role as predators or parasites of crop pests. (author)

  14. Farm-scale testing of soybean peroxidase and calcium peroxide for surficial swine manure treatment and mitigation of odorous VOCs, ammonia and hydrogen sulfide emissions

    Science.gov (United States)

    Maurer, Devin L.; Koziel, Jacek A.; Bruning, Kelsey; Parker, David B.

    2017-10-01

    The swine industry, regulatory agencies, and the public are interested in farm-tested methods for controlling gaseous emissions from swine barns. In earlier lab- and pilot-scale studies, a renewable catalyst consisting of soybean peroxidase (SBP) mixed with calcium peroxide (CaO2) was found to be effective in mitigating gaseous emissions from swine manure. Thus, a farm-scale experiment was conducted at the university's 178-pig, shallow-pit, mechanically-ventilated swine barn to evaluate SBP/CaO2 as a surficial manure pit additive under field conditions. The SBP was applied once at the beginning of the 42-day experiment at an application rate of 2.28 kg m-2 with 4.2% CaO2 added by weight. Gas samples were collected from the primary barn exhaust fans. As compared to the control, significant reductions in gaseous emissions were observed for ammonia (NH3, 21.7%), hydrogen sulfide (H2S, 79.7%), n-butyric acid (37.2%), valeric acid (47.7%), isovaleric acid (39.3%), indole (31.2%), and skatole (43.5%). Emissions of dimethyl disulfide/methanethiol (DMDS/MT) increased by 30.6%. Emissions of p-cresol were reduced by 14.4% but were not statistically significant. There were no significant changes to the greenhouse gas (GHG) emissions of methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O). The total (material + labor) treatment cost was 2.62 per marketed pig, equivalent to 1.5% of the pig market price. The cost of CaO2 catalyst was ∼60% of materials cost. The cost of soybean hulls (SBP source) was 0.60 per marketed pig, i.e., only 40% of materials cost.

  15. Domestic Resources Cost Analysis of Small-Scale Beef Cattle Farming at Upstream Area of Benain-Noelmina Watershed, West Timor, East Nusa Tenggara

    Directory of Open Access Journals (Sweden)

    Nalle Agus Arnold

    2017-02-01

    Full Text Available The study aims to evaluate the Domestic Resources Cost (DRC of beef cattle raised either on grazing, or a tethering system of small-scale beef cattle farming. The study was done using a survey method. A total of 120 respondents were selected purposively to consist of 60 farmers applying the grazing system and another 60 farmers applying the tethering system. The parameters measured were socio-economic characteristic, Domestic Resources Cost Ratio (DRCR and Private Cost Ratio (PCR. Data were analyzed by applying a method of Policy Analysis Matrix (PAM. The result of the study indicated that 87% of those farmers involved in the grazing system and 85% of those involved in tethered beef cattle production, were within the productive age range. In the grazing system, the cattle farmers upstream of Benain-Noelmina watershed area gain the private and social profit levels which is IDR 406,284,-/AU/year and IDR 688,388,-/AU/year, respectively. Further, in the tethering system, the average of private and social profit gain is IDR 855,222,-/AU/year and IDR 1,385,712,-/AU/year, respectively. The small-scale beef cattle farming upstream of Benain-Noelmina watershed has competitive and comparative advantages, indicated by the value of PCR and DRCR which are less than 1. The PCR value was 0.41 in the grazing system and 0.71 on the tethering system; hence, the DRCR of the grazing system was 0.29 and 0.60 of the tethering system.

  16. Mercury Levels in Human Hair and Farmed Fish near Artisanal and Small-Scale Gold Mining Communities in the Madre de Dios River Basin, Peru

    Directory of Open Access Journals (Sweden)

    Aubrey L. Langeland

    2017-03-01

    Full Text Available Artisanal and small-scale gold mining (ASGM has been an important source of income for communities in the Madre de Dios River Basin in Peru for hundreds of years. However, in recent decades, the scale of ASGM activities in the region has increased dramatically, and exposures to a variety of occupational and environmental hazards related to ASGM, including mercury, are becoming more widespread. The aims of our study were to: (1 examine patterns in the total hair mercury level of human participants in several communities in the region and compare these results to the 2.2 µg/g total hair mercury level equivalent to the World Health Organization (WHO Expert Committee of Food Additives (JECFA’s Provisional Tolerable Weekly Intake (PTWI; and (2, to measure the mercury levels of paco (Piaractus brachypomus fish raised in local aquaculture ponds, in order to compare these levels to the EPA Fish Tissue Residue Criterion of 0.3 µg Hg/g fish (wet weight. We collected hair samples from 80 participants in four communities (one control and three where ASGM activities occurred in the region, and collected 111 samples from fish raised in 24 local aquaculture farms. We then analyzed the samples for total mercury. Total mercury levels in hair were statistically significantly higher in the mining communities than in the control community, and increased with increasing geodesic distance from the Madre de Dios headwaters, did not differ by sex, and frequently exceeded the reference level. Regression analyses indicated that higher hair mercury levels were associated with residence in ASGM communities. The analysis of paco fish samples found no samples that exceeded the EPA tissue residue criterion. Collectively, these results align with other recent studies showing that ASGM activities are associated with elevated human mercury exposure. The fish farmed through the relatively new process of aquaculture in ASGM areas appeared to have little potential to contribute

  17. Mercury Levels in Human Hair and Farmed Fish near Artisanal and Small-Scale Gold Mining Communities in the Madre de Dios River Basin, Peru.

    Science.gov (United States)

    Langeland, Aubrey L; Hardin, Rebecca D; Neitzel, Richard L

    2017-03-14

    Artisanal and small-scale gold mining (ASGM) has been an important source of income for communities in the Madre de Dios River Basin in Peru for hundreds of years. However, in recent decades, the scale of ASGM activities in the region has increased dramatically, and exposures to a variety of occupational and environmental hazards related to ASGM, including mercury, are becoming more widespread. The aims of our study were to: (1) examine patterns in the total hair mercury level of human participants in several communities in the region and compare these results to the 2.2 µg/g total hair mercury level equivalent to the World Health Organization (WHO) Expert Committee of Food Additives (JECFA)'s Provisional Tolerable Weekly Intake (PTWI); and (2), to measure the mercury levels of paco ( Piaractus brachypomus ) fish raised in local aquaculture ponds, in order to compare these levels to the EPA Fish Tissue Residue Criterion of 0.3 µg Hg/g fish (wet weight). We collected hair samples from 80 participants in four communities (one control and three where ASGM activities occurred) in the region, and collected 111 samples from fish raised in 24 local aquaculture farms. We then analyzed the samples for total mercury. Total mercury levels in hair were statistically significantly higher in the mining communities than in the control community, and increased with increasing geodesic distance from the Madre de Dios headwaters, did not differ by sex, and frequently exceeded the reference level. Regression analyses indicated that higher hair mercury levels were associated with residence in ASGM communities. The analysis of paco fish samples found no samples that exceeded the EPA tissue residue criterion. Collectively, these results align with other recent studies showing that ASGM activities are associated with elevated human mercury exposure. The fish farmed through the relatively new process of aquaculture in ASGM areas appeared to have little potential to contribute to human

  18. A novel spatial and stochastic model to evaluate the within and between farm transmission of classical swine fever virus: II validation of the model.

    Science.gov (United States)

    Martínez-López, B; Ivorra, B; Ngom, D; Ramos, A M; Sánchez-Vizcaíno, J M

    2012-02-24

    A new, recently published, stochastic and spatial model for the evaluation of classical swine fever virus (CSFV) spread into Spain has been validated by using several methods. Internal validity, sensitivity analysis, validation using historical data, comparison with other models and experiments on data validity were used to evaluate the overall reliability and consistency of the model. More than 100 modifications in input data and parameters were evaluated. Outputs were obtained after 1000 iterations for each new scenario of the model. As a result, the model was shown to be consistent, being the probability of infection by local spread, the time from infectious to clinical signs state, the probability of detection based on clinical signs at day t after detection of the index case outside the control and surveillance zones and the maximum number of farms to be depopulated at day t the parameters that have more influence (>10% of change) on the magnitude and duration of the epidemic. The combination of a within- and between-farm spread model was also shown to give significantly different results than using a purely between-farm spread model. Methods and results presented here were intended to be useful to better understand and apply the model, to identify key parameters for which it will be critical to have good estimates and to provide better support for prevention and control of future CSFV outbreaks. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. Sequential Convex Programming for Power Set-point Optimization in a Wind Farm using Black-box Models, Simple Turbine Interactions, and Integer Variables

    DEFF Research Database (Denmark)

    Hovgaard, Tobias Gybel; Larsen, Lars F. S.; Jørgensen, John Bagterp

    2012-01-01

    We consider the optimization of power set-points to a large number of wind turbines arranged within close vicinity of each other in a wind farm. The goal is to maximize the total electric power extracted from the wind, taking the wake effects that couple the individual turbines in the farm...... describing the turbulent wind fields’ propagation through the farm are included in a highly detailed black-box model, numerical results for any given values of the parameter sets can easily be evaluated. However, analytic expressions for model representation in the optimization algorithms might be hard...... convex approximation and compare with mixed-integer optimization tools. We demonstrate the method on a verified model and for various sizes and configurations of the wind farm. For all tested scenarios we observe a distribution of the power set-points which is at least as good as, and in many cases...

  20. Farm-scale costs and returns for second generation bioenergy cropping systems in the US Corn Belt

    International Nuclear Information System (INIS)

    Manatt, Robert K; Schulte, Lisa A; Hall, Richard B; Hallam, Arne; Heaton, Emily A; Gunther, Theo; Moore, Ken J

    2013-01-01

    While grain crops are meeting much of the initial need for biofuels in the US, cellulosic or second generation (2G) materials are mandated to provide a growing portion of biofuel feedstocks. We sought to inform development of a 2G crop portfolio by assessing the profitability of novel cropping systems that potentially mitigate the negative effects of grain-based biofuel crops on food supply and environmental quality. We analyzed farm-gate costs and returns of five systems from an ongoing experiment in central Iowa, USA. The continuous corn cropping system was most profitable under current market conditions, followed by a corn–soybean rotation that incorporated triticale as a 2G cover crop every third year, and a corn–switchgrass system. A novel triticale–hybrid aspen intercropping system had the highest yields over the long term, but could only surpass the profitability of the continuous corn system when biomass prices exceeded foreseeable market values. A triticale/sorghum double cropping system was deemed unviable. We perceive three ways 2G crops could become more cost competitive with grain crops: by (1) boosting yields through substantially greater investment in research and development, (2) increasing demand through substantially greater and sustained investment in new markets, and (3) developing new schemes to compensate farmers for environmental benefits associated with 2G crops. (letter)