WorldWideScience

Sample records for bio-economic farm model

  1. 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

  2. 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

  3. 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

  4. FISHRENT; Bio-economic simulation and optimisation model

    NARCIS (Netherlands)

    Salz, P.; Buisman, F.C.; Soma, K.; Frost, H.; Accadia, P.; Prellezo, R.

    2011-01-01

    Key findings: The FISHRENT model is a major step forward in bio-economic model-ling, combining features that have not been fully integrated in earlier models: 1- Incorporation of any number of species (or stock) and/or fleets 2- Integration of simulation and optimisation over a period of 25 years 3-

  5. Bio-economic household modelling for agricultural intensification

    NARCIS (Netherlands)

    Kruseman, G.

    2000-01-01

    This study contributes to the quest for sustainable agricultural intensification through the development of a quantitative bio-economic modelling framework that allows assessment of new technology and policy measures in terms of household welfare and sustainability indicators. The main aim

  6. Bio-economic modeling of water quality improvements using a dynamic applied general equilibrium approach

    NARCIS (Netherlands)

    Dellink, R.; Brouwer, R.; Linderhof, V.G.M.; Stone, K.

    2011-01-01

    An integrated bio-economic model is developed to assess the impacts of pollution reduction policies on water quality and the economy. Emission levels of economic activities to water are determined based on existing environmental accounts. These emission levels are built into a dynamic economic model

  7. Modeling and bio-economic analysis of broilers' performance in Benin

    DEFF Research Database (Denmark)

    Houndonougbo, Mankpondji Frederic; Chwalibog, André; Chrysostome, C.A.A.M.

    2009-01-01

    The objective of this paper was to model bio-economic variables in broilers feeding. During 7 weeks, 120 broilers Red Bro were fed with diets containing soybean meals from solvent (Ss) or expeller (Se) processing. At grower phase (d 22 to d 49) the diets were switched for half of broilers in each...

  8. A multi-disciplinary framework for bio-economic modeling in aquaculture: a welfare case study

    NARCIS (Netherlands)

    Noble, C.; Berrill, I.K.; Waller, B.; Schneider, O.; Kole, A.P.W.

    2012-01-01

    This article summarizes the framework that translated data from multiple disciplines into a bio-economic decision tool for modeling the costs and benefits of improving fish welfare in commercial aquaculture. This decision tool formed the basis of a recent EU research project, BENEFISH which was

  9. FLBEIA : A simulation model to conduct Bio-Economic evaluation of fisheries management strategies

    Directory of Open Access Journals (Sweden)

    Dorleta Garcia

    2017-01-01

    Here, we present FLBEIA, a flexible software to conduct bio-economic evaluation of fisheries management strategies. The model is multi-stock, multi-fleet, stochastic and seasonal. The fishery system is described as a sum of processes, which are internally assembled in a predetermined way. There are several functions available to describe the dynamic of each process and new functions can be added to satisfy specific requirements.

  10. A bio-economic model to improve profitability in a large national beef cattle population

    Directory of Open Access Journals (Sweden)

    Javier López-Paredes

    2017-12-01

    Full Text Available A bio-economic model was developed for estimating economic values for use in improving profitability in a large national beef cattle population from birth to slaughter. Results were divided into fattening costs, production costs and income. Economic values were derived for 17 traits for two regions, mature weight (-0.43 € and -0.38 €/+1 kg of live weight, age at first calving (-0.13 € and -0.11 €/+1d, calving interval (-1.06 € and -1.02 €/+1d, age at last calving (0.03 € and 0.03 €/+1d, mortality 0-48 h (-5.86 € and -5.63 €/1% calves per cow and year, pre-weaning mortality (-5.96 € and -5.73 €/+1% calves per cow and year, fattening mortality (-8.23 € and -7.88 €/+1% calves per cow and year, adult mortality (-8.92 € and -7.34 €/+1% adult cows per cow and year, pre-weaning average daily gain (2.56 € and 2.84 €/+10g/d, fattening young animals average daily gain (2.65 € and 3.00 €/+10g/d, culled cow in fattening average daily gain (0.25 € and 0.16 €/+10g/d, culled cow dressing carcass percentage (3.09 € and 2.42 €/+1%, culled cow price (4.59 € and 3.59 €/+0.06 €/kg, carcass conformation score (16.39 € and 15.3 €/+1 SEUROP class, dressing carcass rate of calf (18.22 € and 18.23 €/+1%, carcass growth (9.00 € and 10.09 €/+10g of carcass weight/d and age at slaughter (0.27 € and 0.44 €/+1d. Two sample herds were used to show the economic impact of calving interval and age at first calving shortening in the profit per slaughtered young animal, which was 178 € and 111 € for Herds A and B, respectively. The economic values of functional traits were reduced and production traits were enhanced when fertility traits were improved. The model could be applied in a Spanish national program.

  11. A Cow- and Herd-specific Bio-Economic Model of Intramammary Infections in Dairy Cows

    DEFF Research Database (Denmark)

    Kirkeby, Carsten Thure; Gussmann, Maya Katrin; Græsbøll, Kaare

    are Staphylococcus aureus, Streptococcus agalactiae and Streptococcus uberis. The contagious transmission is simulating transmission, e.g. via milk liners, and depends on the number of quarters with contagious pathogens in the herd. We chose to focus on these four pathogens because they are common in Danish dairy...... is often caused by more than one pathogen in the same herd, such a simulation model should also be pathogen-specific to account for different transmission characteristics and treatment effects. Moreover, as different strains of pathogens can have different transmission routes (i.e. environmental...... implemented two different transmission modes, namely environmental transmission based on a continuous reservoir of pathogens in the farm, and contagious IMI originating from other infected animals in the herd. Currently, the environmental pathogen included is Escherichia coli, and the contagious pathogens...

  12. Analyzing diversification possibilities on specialized tobacco farms in Argentina using a bio-economic farm model

    NARCIS (Netherlands)

    Chavez, M.D.; Berentsen, P.B.M.; Oude Lansink, A.G.J.M.

    2014-01-01

    Tobacco (Nicotiana tabacum L.) is the non-food crop with the largest acreage in the world. Tobacco is criticized because it causes health problems to its consumers and because production causes environmental damage such as soil degradation, deforestation and water pollution. Diversification has been

  13. A welfare study into capture fisheries in cirata reservoir: a bio-economic model

    Science.gov (United States)

    Anna, Z.; Hindayani, P.

    2018-04-01

    Capture fishery in inland such as reservoirs can be a source of food security and even the economy and public welfare of the surrounding community. This research was conducted on Cirata reservoir fishery in West Java, to see how far reservoir capture fishery can contribute economically in the form of resource rents. The method used is the bioeconomic model Copes, which can analyze the demand and supply functions to calculate the optimization of stakeholders’ welfare in various management regimes. The results showed that the management of capture fishery using Maximum Economic Yield regime (MEY) gave the most efficient result, where fewer inputs would produce maximum profit. In the MEY management, the producer surplus obtained is IDR 2,610.203.099, - per quarter and IDR 273.885.400,- of consumer surplus per quarter. Furthermore, researches showed that sustainable management regime policy MEY result in the government rent/surplus ofIDR 217.891,345, - per quarter with the average price of fish per kg being IDR 13.929. In open access fishery, it was shown that the producer surplus becomesIDR 0. Thus the implementation of the MEY-based instrument policy becomes a necessity for Cirata reservoir capture fishery.

  14. A bio-economic analysis of a shell fishery: The effects of recruitment and habitat in a meta population model

    NARCIS (Netherlands)

    Imeson, R.J.; van den Bergh, J.C.J.M.

    2004-01-01

    This paper presents a bioeconomic model where fishing effort exerted has multiple impacts on the recruitment process of a sedentary shellfish population. Recognizing that sedentary populations generally possess metapopulation characteristics at the recruitment stage, we show that fishing effort

  15. PIEteR : a field specific bio-economic production model for decision support in sugar beet growing

    NARCIS (Netherlands)

    Smit, A.B.

    1996-01-01


    To support decisions in sugar beet growing, a model, PIEteR, was developed. It simulates growth and production of the crop in a field specific way, making a tailor-made approach in decision taking possible.

    PIEteR is based on causal regression analysis of Dutch data of mostly

  16. SMART: a spatially explicit bio-economic model for assessing and managing demersal fisheries, with an application to italian trawlers in the strait of sicily.

    Directory of Open Access Journals (Sweden)

    Tommaso Russo

    Full Text Available Management of catches, effort and exploitation pattern are considered the most effective measures to control fishing mortality and ultimately ensure productivity and sustainability of fisheries. Despite the growing concerns about the spatial dimension of fisheries, the distribution of resources and fishing effort in space is seldom considered in assessment and management processes. Here we propose SMART (Spatial MAnagement of demersal Resources for Trawl fisheries, a tool for assessing bio-economic feedback in different management scenarios. SMART combines information from different tasks gathered within the European Data Collection Framework on fisheries and is composed of: 1 spatial models of fishing effort, environmental characteristics and distribution of demersal resources; 2 an Artificial Neural Network which captures the relationships among these aspects in a spatially explicit way and uses them to predict resources abundances; 3 a deterministic module which analyzes the size structure of catches and the associated revenues, according to different spatially-based management scenarios. SMART is applied to demersal fishery in the Strait of Sicily, one of the most productive fisheries of the Mediterranean Sea. Three of the main target species are used as proxies for the whole range exploited by trawlers. After training, SMART is used to evaluate different management scenarios, including spatial closures, using a simulation approach that mimics the recent exploitation patterns. Results evidence good model performance, with a noteworthy coherence and reliability of outputs for the different components. Among others, the main finding is that a partial improvement in resource conditions can be achieved by means of nursery closures, even if the overall fishing effort in the area remains stable. Accordingly, a series of strategically designed areas of trawling closures could significantly improve the resource conditions of demersal fisheries in

  17. SMART: a spatially explicit bio-economic model for assessing and managing demersal fisheries, with an application to italian trawlers in the strait of sicily.

    Science.gov (United States)

    Russo, Tommaso; Parisi, Antonio; Garofalo, Germana; Gristina, Michele; Cataudella, Stefano; Fiorentino, Fabio

    2014-01-01

    Management of catches, effort and exploitation pattern are considered the most effective measures to control fishing mortality and ultimately ensure productivity and sustainability of fisheries. Despite the growing concerns about the spatial dimension of fisheries, the distribution of resources and fishing effort in space is seldom considered in assessment and management processes. Here we propose SMART (Spatial MAnagement of demersal Resources for Trawl fisheries), a tool for assessing bio-economic feedback in different management scenarios. SMART combines information from different tasks gathered within the European Data Collection Framework on fisheries and is composed of: 1) spatial models of fishing effort, environmental characteristics and distribution of demersal resources; 2) an Artificial Neural Network which captures the relationships among these aspects in a spatially explicit way and uses them to predict resources abundances; 3) a deterministic module which analyzes the size structure of catches and the associated revenues, according to different spatially-based management scenarios. SMART is applied to demersal fishery in the Strait of Sicily, one of the most productive fisheries of the Mediterranean Sea. Three of the main target species are used as proxies for the whole range exploited by trawlers. After training, SMART is used to evaluate different management scenarios, including spatial closures, using a simulation approach that mimics the recent exploitation patterns. Results evidence good model performance, with a noteworthy coherence and reliability of outputs for the different components. Among others, the main finding is that a partial improvement in resource conditions can be achieved by means of nursery closures, even if the overall fishing effort in the area remains stable. Accordingly, a series of strategically designed areas of trawling closures could significantly improve the resource conditions of demersal fisheries in the Strait of

  18. Modeling fates and impacts for bio-economic analysis of hypothetical oil spill scenarios in San Francisco Bay

    International Nuclear Information System (INIS)

    French McCay, D.; Whittier, N.; Sankaranarayanan, S.; Jennings, J.; Etkin, D.S.

    2002-01-01

    The oil spill risks associated with four submerged rock pinnacles near Alcatraz Island in San Francisco Bay are being evaluated by the United States Army Corps of Engineers. Oil spill modeling has been conducted for a hypothetical oil spill to determine biological impacts, damages to natural resources and response costs. The scenarios are hypothetical vessel grounding on the pinnacles. The SIMAP modeling software by the Applied Science Associates was used to model 3 spill sizes (20, 50 and 95 percentile by volume) and 4 types of oil (gasoline, diesel, heavy fuel oil, and crude oil). The frequency distribution of oil fates and impacts was determined by first running each scenario in stochastic mode. The oil fates and biological effects of the spills were the focus of this paper. It was shown that diesel and crude oil spills would have greater impacts in the water column than heavy fuel or gasoline because gasoline is more volatile and less toxic and because heavy oil spills would be small in volume. It was determined that the major impacts and damage to birds would be low due to the high dilution potential of the bay. It was also noted that dispersants would be very effective in reducing impacts on wildlife and the shoreline. These results are being used to evaluate the cost-benefit analysis of removing the rocks versus the risk of an oil spill. The work demonstrates a statistically quantifiable method to estimate potential impacts that could be used in ecological risk assessment and cost-benefit analysis. 15 refs., 13 tabs., 11 figs

  19. 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...

  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. 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

  2. The role of spatial information in the preservation of the shrimp nursery function of mangroves: a spatially explicit bio-economic model for the assessment of land use trade-offs.

    Science.gov (United States)

    Zavalloni, Matteo; Groeneveld, Rolf A; van Zwieten, Paul A M

    2014-10-01

    Conversion to aquaculture affects the provision of important ecosystem services provided by mangrove ecosystems, and this effect depends strongly on the location of the conversion. We introduce in a bio-economic mathematical programming model relevant spatial elements that affect the provision of the nursery habitat service of mangroves: (1) direct or indirect connection of mangroves to watercourses; (2) the spatial allocation of aquaculture ponds; and (3) the presence of non-linear relations between mangrove extent and juvenile recruitment to wild shrimp populations. By tracing out the production possibilities frontier of wild and cultivated shrimp, the model assesses the role of spatial information in the trade-off between aquaculture and the nursery habitat function using spatial elements relevant to our model of a mangrove area in Ca Mau Province, Viet Nam. Results show that where mangrove forests have to coexist with shrimp aquaculture ponds, the inclusion of specific spatial information on ecosystem functions in considerations of land allocation can achieve aquaculture benefits while largely preserving the economic benefits generated by the nursery habitat function. However, if spatial criteria are ignored, ill-advised land allocation decisions can easily lead to a collapse of the mangrove's nursery function. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. IA of bio-economic projects in Region Zealand, Denmark

    DEFF Research Database (Denmark)

    Lybæk, Rikke; Kjær, Tyge; Palsberg, Aske

    Creating new pathways for sustainable ready-to-implement bio-economic projects within Region Zealand, Denmark, based on available biomass resources and existing and proven technology concepts.......Creating new pathways for sustainable ready-to-implement bio-economic projects within Region Zealand, Denmark, based on available biomass resources and existing and proven technology concepts....

  4. 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...

  5. 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 ...

  6. Integrated impact assessment of climate and socio-economic change on dairy farms in a watershed in the Netherlands

    NARCIS (Netherlands)

    Paas, Wim; Kanellopoulos, Argyris; Ven, van de Gerrie; Reidsma, Pytrik

    2016-01-01

    Climate and socio-economic change will affect the land use and the economic viability of Dutch dairy farms. Explorations of future scenarios, which include different drivers and impacts, are needed to perform ex-ante policy assessment. This study uses a bio-economic farm model to assess impacts

  7. Bio-economic modelling of the influence of family planning, land consolidation and soil erosion on farm production and food security in Rwanda

    NARCIS (Netherlands)

    Bidogeza, J.C.; Berentsen, P.B.M.; Graaff, de J.; Oude Lansink, A.G.J.M.

    2015-01-01

    Rwandan agriculture is not able to meet its population’s food needs from its own production, which results in food insecurity. Land degradation is a serious problem which contributes to a low and declining agricultural productivity and consequently to food insecurity. The objective of this paper is

  8. Epidemic corruption: a bio-economic homology

    OpenAIRE

    Hathroubi, Salem

    2013-01-01

    This paper aims to study corruption as an epidemic phenomenon using the epidemic diffusion model of Kermack and Mc-Kendrick (1927). We seek to determine the dynamics of corruption and its impact on the composition of the population at a given time. We determine a threshold epidemiological corruption based on the approximation of the honest population.

  9. 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.

  10. Evaluating water policy options in agriculture: a whole-farm study for the broye river basin (switzerland)†

    NARCIS (Netherlands)

    Lehmann, N.; Finger, R.

    2013-01-01

    In this study, we evaluate the impact of an increased volumetric water price and the implementation of a water quota on management decisions, income, income risk and utility of an arable farmer in the Broye River Basin, western Switzerland. We develop a bio-economic whole-farm model, which couples

  11. 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)…

  12. 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...

  13. Sustainable agricultural development in a rural area in the Netherlands? Assessing impacts of climate and socio-economic change at farm and landscape level

    NARCIS (Netherlands)

    Reidsma, P.; Bakker, M.M.; Kanellopoulos, A.; Alam, S.J.; Paas, W.H.; Kros, J.; Vries, de W.

    2015-01-01

    Changes in climate, technology, policy and prices affect agricultural and rural development. To evaluate whether this development is sustainable, impacts of these multiple drivers need to be assessed for multiple indicators. In a case study area in the Netherlands, a bio-economic farm model, an

  14. TEMAS: fleet-based bio-economic simulation software to evaluate management strategies accounting for fleet behaviour

    DEFF Research Database (Denmark)

    Ulrich, Clara; Andersen, Bo Sølgaard; Sparre, Per Johan

    2007-01-01

    TEMAS (technical management measures) is a fleet-based bio-economic software for evaluating management strategies accounting for technical measures and fleet behaviour. It focuses on mixed fisheries in which several fleets can choose among several fishing activities to target different stocks...... in one or several areas. The software combines a management strategy evaluation framework, using a forward-running operating model and a management procedure with a fleet behaviour module simulating both short-term (effort allocation) and long-term (entry/exit) fleet dynamics. The suite of models behind...... TEMAS can be thought of as an extension of the traditional ICES forecast model. Alternative management scenarios can be compared and evaluated for their bio-economic consequences and robustness to parameter uncertainty. The software is generic and user-friendly, and can be run at several space and time...

  15. 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.

  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. 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....

  18. Fuzzy Stochastic Optimal Guaranteed Cost Control of Bio-Economic Singular Markovian Jump Systems.

    Science.gov (United States)

    Li, Li; Zhang, Qingling; Zhu, Baoyan

    2015-11-01

    This paper establishes a bio-economic singular Markovian jump model by considering the price of the commodity as a Markov chain. The controller is designed for this system such that its biomass achieves the specified range with the least cost in a finite-time. Firstly, this system is described by Takagi-Sugeno fuzzy model. Secondly, a new design method of fuzzy state-feedback controllers is presented to ensure not only the regularity, nonimpulse, and stochastic singular finite-time boundedness of this kind of systems, but also an upper bound achieved for the cost function in the form of strict linear matrix inequalities. Finally, two examples including a practical example of eel seedling breeding are given to illustrate the merit and usability of the approach proposed in this paper.

  19. Bio-economic evaluation of implementing trawl fishing gear with different selectivity

    DEFF Research Database (Denmark)

    Grønbæk Kronbak, Lone; Nielsen, J. Rasmus; Jørgensen, Ole A.

    2009-01-01

    The paper develops a biological-economic evaluation tool to analyse the consequences for trawl fishers of implementing more selective fishing technologies. This is done by merging a dynamic biological population model and an economic cost-benefit evaluation framework to describe the consequences...... for the fish stocks, fishermen and society. The bio-economic evaluation is applied to the case of the Danish trawl fishery in Kattegat and Skagerrak, which experiences a high level of discards and byratches of several species. Four different kinds of selectivity scenarios are evaluated in comparison...... with a baseline. The results from the evaluation are indicators for the consequences on ecological and economic levels. The results show that implementation of different selective fishing gear in the Kattegat and Skagerrak mixed trawl fisheries generally implies a trade off over time between rebuilding the stocks...

  20. Bio-economic evaluation of implementing trawl fishing gear with different selectivity

    DEFF Research Database (Denmark)

    Kronbak, Lone Grønbæk; Nielsen, J. Rasmus; Jørgensen, Ole A.

    2009-01-01

    The paper develops a biological-economic evaluation tool to analyse the consequences for trawl fishers of implementing more selective fishing technologies. This is done by merging a dynamic biological population model and an economic cost-benefit evaluation framework to describe the consequences...... for the fish stocks, fishermen and society. The bio-economic evaluation is applied to the case of the Danish trawl fishery in Kattegat and Skagerrak, which experiences a high level of discards and bycatches of several species. Four different kinds of selectivity scenarios are evaluated in comparison...... with a baseline. The results from the evaluation are indicators for the consequences on ecological and economic levels. The results show that implementation of different selective fishing gear in the Kattegat and Skagerrak mixed trawl fisheries generally implies a trade off over time between rebuilding the stocks...

  1. 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)

  2. 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 ...

  3. 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...

  4. Quantifying the impact of weather extremes on global food security: A spatial bio-economic approach

    Directory of Open Access Journals (Sweden)

    Sika Gbegbelegbe

    2014-08-01

    Full Text Available This study uses a spatial bio-economic modelling framework to estimate the impact of the 2012 weather extreme in the USA on food security in the developing world. The study also quantifies the potential effects of a similar weather extreme occurring in 2050 under climate change. The study results indicate that weather extremes that affect maize productivity in key grain baskets can negatively affect food security in vulnerable countries. The 2012 weather extreme which occurred in the USA reduced US and global maize production by 29% compared to trend; maize consumption in the country decreased by 5% only and this resulted in less surplus maize for exports from the largest maize exporter in the world. Global maize production decreased by 6% compared to trend. The decrease in global maize production coupled with a reduction in the volume of global maize exports worsened food insecurity in eastern Africa, the Caribbean and Central America and India. The effects of the weather extreme on global food security would be worse, if the latter were to occur under climate change in 2050, assuming no climate change adaptation worldwide over the years. In addition, the hardest-hit regions would remain the same, whether the weather extreme occurs in 2012 instead of 2050: Sub-Saharan Africa (SSA, South Asia and the Latin America and Caribbean (LAC region. However, sustained growth in per capita income across world economies between 2000 and 2050 would allow few countries in SSA and the LAC region to virtually eliminate hunger within their borders. In these countries, per capita income would be high enough by 2050 to completely offset the negative effect of the weather extreme. The study results are also consistent with USDA׳s estimates on US and global maize production and consumption in 2012 after the weather extreme. Some discrepancy is found on the volume of global maize trade; this implies that the bio-economic model likely overestimates the effect of the

  5. A bio-economic analysis of harvest control rules for the Northeast Arctic cod fishery.

    Science.gov (United States)

    Eikeset, Anne Maria; Richter, Andries P; Dankel, Dorothy J; Dunlop, Erin S; Heino, Mikko; Dieckmann, Ulf; Stenseth, Nils Chr

    2013-05-01

    Harvest control rules (HCRs) have been implemented for many fisheries worldwide. However, in most instances, those HCRs are not based on the explicit feedbacks between stock properties and economic considerations. This paper develops a bio-economic model that evaluates the HCR adopted in 2004 by the Joint Norwegian-Russian Fishery Commission to manage the world's largest cod stock, Northeast Arctic cod (NEA). The model considered here is biologically and economically detailed, and is the first to compare the performance of the stock's current HCR with that of alternative HCRs derived with optimality criteria. In particular, HCRs are optimized for economic objectives including fleet profits, economic welfare, and total yield and the emerging properties are analyzed. The performance of these optimal HCRs was compared with the currently used HCR. This paper show that the current HCR does in fact comes very close to maximizing profits. Furthermore, the results reveal that the HCR that maximizes profits is the most precautionary one among the considered HCRs. Finally, the HCR that maximizes yield leads to un-precautionary low levels of biomass. In these ways, the implementation of the HCR for NEA cod can be viewed as a success story that may provide valuable lessons for other fisheries.

  6. 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.

  7. 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

  8. Management of Water and Fertilizer Consumption Using Bio-Economic Approach: A Case Study of Irrigation and Drainage Dorudzan

    International Nuclear Information System (INIS)

    Sheikhzeinoddin, A.; Esmaeili, A.; Zibaei, M.

    2016-01-01

    Today keep increasing the use of chemical fertilizer and water is an effort to improve yield, while overuse of fertilizer is making formerly arable land unusable but led to degrading the quality of water and serious problems for environmental. Hence, for accurate management, we require comprehensive and complete information on the economic and environmental impacts of different management methods. So, by using SWAT model were simulated the economic and environmental effects of each management strategies. Then, mathematical programming was used to determine the optimal cropping pattern subject to resources and environmental constraints in irrigation and Drainage Dorudzan. Based on the findings of this study, we can improve the economic and environmental benefits by moving from current status to economic or bio-economic pattern. Also, by moving from economic pattern to bio-economic pattern, 0.31 percent reduction of economic benefit is leading to improve nitrogen losses by 6.58 percent. In other words, we incur the cost equal to 64.5 thousand rials for reduction per kg nitrogen losses.

  9. 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, ...

  10. 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,

  11. 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

  12. 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...

  13. 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...

  14. 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.

  15. 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.

  16. Paths to Change: Bio-Economic Factors, Geographical Gradients and the Land-Use Structure of Italy.

    Science.gov (United States)

    Masini, Emanuela; Barbati, Anna; Bencardino, Massimiliano; Carlucci, Margherita; Corona, Piermaria; Salvati, Luca

    2018-01-01

    This study introduces a bio-economic approach to evaluate the influence of local socioeconomic contexts on complex processes of landscape transformation (urbanization, withdrawal of farming with woodland creation and loss in crop mosaics) in a sustainable development perspective. Land-use and socioeconomic indicators (including shares of agriculture, industry and services in total product, per-worker value added, productivity by economic sector, distance from central cities, latitude and elevation) at the local district scale in Italy have been considered together in an exploratory approach based on multivariate statistics. The combined use of land-use and socioeconomic indicators was preferred to more traditional approaches based on single-variable analysis and allows identifying latent factors of landscape transformation at the local scale. Our approach sheds light in the intimate relationship between regional economic structures and land-use change in districts with varying socio-environmental attributes across Italy. Urban-rural divides, coastal-inland dichotomy and the elevation gradient were relevant factors shaping urbanization-driven landscape transformations at the country scale. Indicators of economic structure (and especially industrial production and per-worker productivity of industry and services) were also documented to influence greatly entity and direction of change in the use of land. Discontinuous and dispersed urbanization has been demonstrated to be spatially-decoupled from consolidated (continuous and compact) urbanization, expanding into undeveloped rural areas progressively far away from central cities and being spatially associated with forest land.

  17. Paths to Change: Bio-Economic Factors, Geographical Gradients and the Land-Use Structure of Italy

    Science.gov (United States)

    Masini, Emanuela; Barbati, Anna; Bencardino, Massimiliano; Carlucci, Margherita; Corona, Piermaria; Salvati, Luca

    2018-01-01

    This study introduces a bio-economic approach to evaluate the influence of local socioeconomic contexts on complex processes of landscape transformation (urbanization, withdrawal of farming with woodland creation and loss in crop mosaics) in a sustainable development perspective. Land-use and socioeconomic indicators (including shares of agriculture, industry and services in total product, per-worker value added, productivity by economic sector, distance from central cities, latitude and elevation) at the local district scale in Italy have been considered together in an exploratory approach based on multivariate statistics. The combined use of land-use and socioeconomic indicators was preferred to more traditional approaches based on single-variable analysis and allows identifying latent factors of landscape transformation at the local scale. Our approach sheds light in the intimate relationship between regional economic structures and land-use change in districts with varying socio-environmental attributes across Italy. Urban-rural divides, coastal-inland dichotomy and the elevation gradient were relevant factors shaping urbanization-driven landscape transformations at the country scale. Indicators of economic structure (and especially industrial production and per-worker productivity of industry and services) were also documented to influence greatly entity and direction of change in the use of land. Discontinuous and dispersed urbanization has been demonstrated to be spatially-decoupled from consolidated (continuous and compact) urbanization, expanding into undeveloped rural areas progressively far away from central cities and being spatially associated with forest land.

  18. 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...

  19. 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...

  20. 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....

  1. 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.

  2. 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.

  3. 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...

  4. Modelo bioeconômico para cálculo de custos e receitas em sistemas de produção de gado de corte visando à obtenção de valores econômicos de características produtivas e reprodutivas Bio-economic model to calculate costs and revenues to obtain economic values for performance traits in beef cattle production systems

    Directory of Open Access Journals (Sweden)

    João Jorge Júnior

    2006-10-01

    Full Text Available Foi desenvolvido um modelo bioeconômico para o cálculo do desempenho, dos custos e das receitas para obtenção de valores econômicos de características de interesse econômico em sistemas de produção de gado de corte no Brasil. As informações de desempenho e de parâmetros biológicos e econômicos foram obtidas em uma propriedade de gado Nelore que realiza ciclo completo com venda de reprodutores. O modelo é determinístico e estático e foram usadas planilhas Excel para a realização dos cálculos. Com base nas informações originais, foram simulados dois sistemas de produção, um fazendo o ciclo completo com venda de reprodutores (CcoR e o outro, de cria (Cc. Foram calculados os custos e as receitas para esses dois sistemas e, a partir disto, foram obtidos seus lucros anuais. Para o cálculo dos valores econômicos foram escolhidas as características peso à desmama (PD, peso adulto da vaca (PAV, taxa de prenhez (TP e taxa de desmama (TD, que são de interesse nos dois sistemas de produção. Para avaliar o impacto das mudanças no desempenho das características sobre o lucro anual do sistema de produção, os valores iniciais das características foram aumentados em 1%. Esse aumento resultou em mudanças positivas no lucro, observando-se que a TD foi a característica que apresentou maior impacto nos dois sistemas. Para o CcoR, os valores econômicos para PD, PAV, TP e TD foram, respectivamente, R$ 0,40/kg, R$ 0,09/kg, R$ 3,20/1% e R$ 10,15/1%. Para Cc, estes valores foram, respectivamente, de R$ 1,31/kg, R$ 0,09/kg, R$ 2,41/1% e R$ 3,36/1%. O modelo foi capaz de reproduzir satisfatoriamente o sistema de produção de gado de corte estudado e pode ser adaptado para outras circunstâncias de produção.A bio-economic model was developed to calculate costs and revenues to obtain economic values (EV for performance traits of beef cattle in production systems in Brazil. Performance records, economic and biologic parameters were

  5. 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

  6. 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

  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. 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.

  9. 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.

  10. 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

  11. 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)

  12. 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...

  13. 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...

  14. 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...

  15. 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....

  16. 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

  17. 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.

  18. 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...

  19. 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

  20. 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...

  1. 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...

  2. 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...

  3. 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...

  4. 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

  5. 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.

  6. 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.

  7. 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...

  8. 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.

  9. 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...

  10. 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

  11. 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)

  12. 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...

  13. 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.

  14. 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...

  15. 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

  16. 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....

  17. 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...

  18. 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....

  19. 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...

  20. 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

  1. 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...

  2. 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....

  3. 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.

  4. Integrating agricultural research and policy analysis: analytical framework and policy applications for bio-economic modelling.

    NARCIS (Netherlands)

    Ruben, R.; Moll, H.; Kuyvenhoven, A.

    1998-01-01

    Interdisciplinary approaches to identify suitable incentives for enhancing sustainable natural resource use require an analytical framework that satisfies both practical purposes of policy support and disciplinary requirements regarding the specification of underlying technical and behavioural

  5. 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.

  6. 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.

  7. 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.

  8. 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...

  9. 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...

  10. 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....

  11. Assessing bio-economic impacts and climate adaptation potential in Flanders

    Science.gov (United States)

    Gobin, A.

    2009-04-01

    According to Global Circulation Model predictions, Belgium is situated on a wedge between a wetter and drier climatic regime. Observed changes show an increase of 1.3°C during the past decade, a higher frequency of warm summer days and a 6% increase in rainfall with a pronounced rise in winter precipitation of about 25% as compared to the normal (1961-1990). Since agriculture is particularly sensitive to climate variability and occupies more than 61% of the land surface in Flanders, the rural landscape will be confronted with profound changes. A combination of climate scenarios, production models and economic evaluation was used to assess climate impacts on agricultural goods & services, adaptation costs due to production losses and adaptation options. Agro-ecosystems offer a wide range of productive, supporting, regulating and cultural services to society. Productive services relate to crop, animal and energy production, but will alter with climate change. Supporting services such as biodiversity, soil and water quality will be negatively affected by a higher climate variability, increasing erosion and sediment transport, enhancing the breakdown of soil organic matter, lowering soil quality and increasing runoff or leaching of agri-chemicals. The effect of a warmer climate on regulating services is an intensification of most nutrient cycles with increased emissions, which may be compensated for by carbon storage in faster and longer growing crops. The need for flooding areas may result in a net-reduction of the agricultural area. A higher probability of dry weather during summer time and a longer growing season may enlarge the attraction of recreating in rural areas. Knowledge on the interaction of agro-ecosystem services and climate change is required to formulate sustainable adaptation measures. Heat stress and water shortages lead to reduced crop growth, whereas increased CO2-concentrations and a prolonged growing season have a positive effect on crop yields

  12. 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 ...

  13. 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)

  14. 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...

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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...

  4. 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

  5. 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.

  6. 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)

  7. 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...

  8. 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...

  9. 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.

  10. 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

  11. 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

  12. 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....

  13. 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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.

  18. 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.

  19. 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...

  20. 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,…

  1. 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

  2. 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...

  3. 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

  4. 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...

  5. 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....

  6. 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...

  7. 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.

  8. 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.

  9. 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)

  10. 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)

  11. 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.

  12. 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)

  13. 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.

  14. 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.

  15. 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

  16. 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...

  17. 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

  18. 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...

  19. 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...

  20. 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.

  1. 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...

  2. 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...

  3. 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

  4. 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...

  5. 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...

  6. 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)

  7. 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....

  8. Understanding bio-economics

    NARCIS (Netherlands)

    Patel, M.K.

    2008-01-01

    New plants for production of bio-based fuels, chemicals or plastics are being set up at an accelerating pace. However, this transition towards bio-based fuels, feedstocks and chemicals has not come without consequences. Increased demand has pushed up prices of key agricultural products such as maize

  9. 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.

  10. 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))

  11. 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.

  12. 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.

  13. 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

  14. 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).

  15. 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.

  16. 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

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

    Science.gov (United States)

    Chowdhury, Souma

    To meet the energy needs of the future, while seeking to decrease our carbon footprint, a greater penetration of sustainable energy resources such as wind energy is necessary. However, a consistent growth of wind energy (especially in the wake of unfortunate policy changes and reported under-performance of existing projects) calls for a paradigm shift in wind power generation technologies. This dissertation develops a comprehensive methodology to explore, analyze and define the interactions between the key elements of wind farm development, and establish the foundation for designing high-performing wind farms. The primary contribution of this research is the effective quantification of the complex combined influence of wind turbine features, turbine placement, farm-land configuration, nameplate capacity, and wind resource variations on the energy output of the wind farm. A new Particle Swarm Optimization (PSO) algorithm, uniquely capable of preserving population diversity while addressing discrete variables, is also developed to provide powerful solutions towards optimizing wind farm configurations. In conventional wind farm design, the major elements that influence the farm performance are often addressed individually. The failure to fully capture the critical interactions among these factors introduces important inaccuracies in the projected farm performance and leads to suboptimal wind farm planning. In this dissertation, we develop the Unrestricted Wind Farm Layout Optimization (UWFLO) methodology to model and optimize the performance of wind farms. The UWFLO method obviates traditional assumptions regarding (i) turbine placement, (ii) turbine-wind flow interactions, (iii) variation of wind conditions, and (iv) types of turbines (single/multiple) to be installed. The allowance of multiple turbines, which demands complex modeling, is rare in the existing literature. The UWFLO method also significantly advances the state of the art in wind farm optimization by

  18. Expanding risk consideration in integrated models - the role of downside risk aversion in irrigation decisions

    NARCIS (Netherlands)

    Finger, R.

    2013-01-01

    We present a bio-economic model that accounts for the effects of water and nitrogen use on the first three moments of profit margin distributions in Swiss maize production. We thus also account for downside risks in farmers’ decision making processes, which extents currently used bio-economic

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. 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)

  4. 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

  5. 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),

  6. 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...

  7. 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...

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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

  13. 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.

  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. 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

  17. 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...

  18. 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

  19. 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.

  20. 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)

  1. 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...

  2. 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)

  3. 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...

  4. 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...

  5. 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...

  6. 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....

  7. 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....

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. 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...

  13. 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.

  14. 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.

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. 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

  2. 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.

  3. 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.

  4. 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/).

  5. 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.

  6. 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.

  7. 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...

  8. 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

  9. 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.

  10. 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

  11. 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

  12. Deployment of a bio-economic 'hub' in rural Thailand by means of a Centralized biogas plant

    DEFF Research Database (Denmark)

    Lybæk, Rikke

    2017-01-01

    by cascading. The paper further reveals that large amount of appropriate and available feedstock for the suggested biogas plants are assessable within the community, and currently pose an environmental problem, or re-used inefficiently. The centralized biogas plant will thus provide a development ‘hub’ for bio...... of nitrogen, low milk yield and inappropriate cattle diets etc., can be improved in the cattle farms, by better housekeeping, as well as supply of manure to the local dairy. Here, fossil fuels use could be substituted by renewable energy from biogas, and the energy used at various temperature levels......-economic solutions to evolve, and constitute to a platform for new income and product outputs opportunities, as renewable energy production as well as various environmental benefits within rural Thailand....

  13. 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...

  14. 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

  15. 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

  16. 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.

  17. 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...

  18. 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.

  19. 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...

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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...

  9. 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

  10. 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...

  11. 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...

  12. 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.

  13. 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.

  14. 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.

  15. A bio-economic evaluation of the potential for establishing a commercial fishery on two newly developed stocks: The Ionian red shrimp fishery

    Directory of Open Access Journals (Sweden)

    Jordi Guillen

    2012-05-01

    Full Text Available It has recently been shown that two deep-water red shrimp species (Aristeus antennatus and Aristaeomorpha foliacea have the potential to support a viable fishery in the Greek Ionian Sea (eastern Mediterranean. In this article, we investigate (i the evolution that this newly developed trawl shrimp fishery may undergo when subjected to different management measures, and (ii the most suitable extraction rates considering the uncertainties about the resource. We further analyse the effects that potential future fuel price increases and changes in the market may have on the fishery. Forecasting the biological and economic consequences of management actions, as well as the effects of market changes on inputs and outputs before they are applied, may help managers select the most suitable management options. We approach the problem by means of bio-economic simulation analysis. The results of this study show that fishing effort can increase by 50-100%, increasing the fleet’s profitability without jeopardizing the sustainability of the fishery.

  16. 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...

  17. 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.

  18. 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...

  19. 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

  20. 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...

  1. 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....

  2. 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...

  3. 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.

  4. 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

  5. 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 ...

  6. 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.

  7. 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...

  8. 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.

  9. 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...

  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. 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

  12. 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

  13. 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.

  14. 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

  15. 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%.

  16. 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 ...

  17. 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...

  18. 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...

  19. 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...

  20. 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 ...

  1. 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

  2. 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

  3. Approaches to Bioeconomic Modelling in correlation with Consumer Model and Biodiversity Indicators

    Directory of Open Access Journals (Sweden)

    Ipate Iudith

    2015-04-01

    Full Text Available In this study we analysed the characteristics of bio-economic models in agricultural systems and agro-biodiversity indicators. The classical bioeconomic models are used to analyze the human consumption of ecosystems for production. The analysis focuses on changes in a limited set of agrobiodiversity indicators that matter to human beings. In existing bioeconomic models incorporate ecological complexities and dynamics is limited. Although bioeconomic model provides useful methods to integrate economic values into environmental analyses, improved the dynamic interrelationships between natural processes and socio-economic systems is needed to allow an integrated assessment of multiple values. The overview will enable a more informed decision about whether and how bio-economic models/modeling can contribute to the development of integrated environmental decision support tools. The bio economic modeling it is important for evaluating the costs and benefits associated with environmental resource use.

  4. 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.

  5. 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...

  6. Model Based Open-Loop Wind Farm Control Using Active Power for Power Increase and Load Reduction

    OpenAIRE

    Hyungyu Kim; Kwansu Kim; Insu Paek

    2017-01-01

    A new wind farm control algorithm that adjusts the power output of the most upstream wind turbine in a wind farm for power increase and load reduction was developed in this study. The algorithm finds power commands to individual wind turbines to maximize the total power output from the wind farm when the power command from the transmission system operator is larger than the total available power from the wind farm. To validate this wind farm control algorithm, a relatively high fidelity wind ...

  7. No Evidence for Connectivity between the Bushveld Igneous Complex and the Molopo Farms Complex from Forward Modeling of Receiver Functions

    Science.gov (United States)

    Skryzalin, P. A.; Ramirez, C.; Durrheim, R. J.; Raveloson, A.; Nyblade, A.; Feineman, M. D.

    2016-12-01

    The Bushveld Igneous Complex contains one of the most studied and economically important layered mafic intrusions in the world. The Rustenburg Layered Suite outcrops in northern South Africa over an area of 65,000 km2, and has a volume of up to 1,000,000 km3. Both the Bushveld Igneous Complex and the Molopo Farms Complex in Botswana intruded the crust at 2.05 Ga. Despite being extensively exploited by the mining industry, many questions still exist regarding the structure of the Bushveld Igneous Complex, specifically the total size and connectivity of the different outcrops. In this study, we used receiver function analysis, a technique for determining the seismic velocity structure of the crust and upper mantle, to search for evidence of the Bushveld at station LBTB, which lies in Botswana, between the Far Western Limb of the Bushveld and the Molopo Farms Complex. The goal of our study was to determine whether a fast, high-density mafic body can be seen in the crust beneath this region using receiver functions. Observation of a high density layer would argue in favor of connectivity of the Bushveld between The Far Western Limb and the Molopo Farms Complex. We forward modeled stacks of receiver functions as well as sub-stacks that were split into azimuthal groups which share similar characteristics. We found that there was no evidence for a high velocity zone in the crust, and that the Moho in this region is located at a depth of 38 ± 3 km, about 8-9 km shallower than Moho depths determined beneath the Bushveld Complex. These two lines of evidence give no reason to assume connectivity between the Bushveld Igneous Complex and the Molopo Farms Complex, and rather suggest two separate intrusive suites.

  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. 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

    In intensively farmed regions, habitat fragmentation represents a major pressure on biodiversity. Depending on its spatial setting, set-aside land can increase size and connectivity of habitats and thus counteract fragmentation. In 2008, the EU-wide set-aside obligation was suspended and a large...... proportion of set-aside land was re-cultivated. With Denmark as case we apply an indicator to measure the effect of set-aside land on spatial structure of semi-natural habitats in term of habitat size and connectivity. Furthermore, we model effects of a hypothetical spatial regulation, where set-aside land...... 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...

  10. Practical Solutions for Pesticide Safety: A Farm and Research Team Participatory Model.

    Science.gov (United States)

    Galvin, Kit; Krenz, Jen; Harrington, Marcy; Palmández, Pablo; Fenske, Richard A

    2016-01-01

    Development of the Practical Solutions for Pesticide Safety guide used participatory research strategies to identify and evaluate solutions that reduce pesticide exposures for workers and their families and to disseminate these solutions. Project principles were (1) workplace chemicals belong in the workplace, and (2) pesticide handlers and farm managers are experts, with direct knowledge of production practices. The project's participatory methods were grounded in self-determination theory. Practical solutions were identified and evaluated based on five criteria: practicality, adaptability, health and safety, novelty, and regulatory compliance. Research activities that had more personal contact provided better outcomes. The Expert Working Group, composed of farm managers and pesticide handlers, was key to the identification of solutions, as were farm site visits. Audience participation, hands-on testing, and orchard field trials were particularly effective in the evaluation of potential solutions. Small work groups in a Regional Advisory Committee provided the best direction and guidance for a "user-friendly" translational document that provided evidence-based practical solutions. The "farmer to farmer" format of the guide was endorsed by both the Expert Working Group and the Regional Advisory Committee. Managers and pesticide handlers wanted to share their solutions in order to "help others stay safe," and they appreciated attribution in the guide. The guide is now being used in educational programs across the region. The fundamental concept that farmers and farmworkers are innovators and experts in agricultural production was affirmed by this study. The success of this process demonstrates the value of participatory industrial hygiene in agriculture.

  11. Evaluating the effect of remote sensing image spatial resolution on soil exchangeable potassium prediction models in smallholder farm settings.

    Science.gov (United States)

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

    2017-09-15

    Major end users of Digital Soil Mapping (DSM) such as policy makers and agricultural extension workers are faced with choosing the appropriate remote sensing data. The objective of this research is to analyze the spatial resolution effects of different remote sensing images on soil prediction models in two smallholder farms in Southern India called Kothapally (Telangana State), and Masuti (Karnataka State), and provide empirical guidelines to choose the appropriate remote sensing images in DSM. Bayesian kriging (BK) was utilized to characterize the spatial pattern of exchangeable potassium (K ex ) in the topsoil (0-15 cm) at different spatial resolutions by incorporating spectral indices from Landsat 8 (30 m), RapidEye (5 m), and WorldView-2/GeoEye-1/Pleiades-1A images (2 m). Some spectral indices such as band reflectances, band ratios, Crust Index and Atmospherically Resistant Vegetation Index from multiple images showed relatively strong correlations with soil K ex in two study areas. The research also suggested that fine spatial resolution WorldView-2/GeoEye-1/Pleiades-1A-based and RapidEye-based soil prediction models would not necessarily have higher prediction performance than coarse spatial resolution Landsat 8-based soil prediction models. The end users of DSM in smallholder farm settings need select the appropriate spectral indices and consider different factors such as the spatial resolution, band width, spectral resolution, temporal frequency, cost, and processing time of different remote sensing images. Overall, remote sensing-based Digital Soil Mapping has potential to be promoted to smallholder farm settings all over the world and help smallholder farmers implement sustainable and field-specific soil nutrient management scheme. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Results of wake simulations at the Horns Rev I and Lillgrund wind farms using the modified Park model

    DEFF Research Database (Denmark)

    Peña, Alfredo; Réthoré, Pierre-Elouan; Hasager, Charlotte Bay

    This document reports on the results of the wake simulations performed at both the Horns Rev I and Lillgrund oshore wind farms using the modified Park model for the benchmark cases established under the project EERA-DTOC and the IEC Wind Task Wakebench. It also illustrates the comparison between...... are post-processed to partly take into account the wind direction uncertainty and when the wake decay coefficient is estimated either as function of the roughness, height, and atmospheric stability or turbulence intensity. For Lillgrund, the trends of the simulations and the observations are generally...

  13. Modeling wake effects in large wind farms in complex terrain: the problem, the methods and the issues

    DEFF Research Database (Denmark)

    Politis, E.S.; Prospathopoulos, J.; Cabezon, D.

    2012-01-01

    turbulence closures, are used. The wind turbines are modeled as momentum absorbers by means of their thrust coefficient through the actuator disk approach. Alternative methods for estimating the reference wind speed in the calculation of the thrust are tested. The work presented in this paper is part......Computational fluid dynamic (CFD) methods are used in this paper to predict the power production from entire wind farms in complex terrain and to shed some light into the wake flow patterns. Two full three-dimensional Navier–Stokes solvers for incompressible fluid flow, employing k - ε and k - ω...

  14. 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

  15. The Socioeconomic Basis of Farm Enterprise Diversification Decisions.

    Science.gov (United States)

    Anosike, Nnamdi; Coughenour, C. Milton

    1990-01-01

    Examines research relating farm size inversely to specialization and directly to farm-enterprise diversification. Develops model of farm management decision making. Tests model using survey examining land tenure, off-farm work, education, and environmental factors. Concludes diversification linked to farm size, human capital, and environmental…

  16. Farm Tourism

    DEFF Research Database (Denmark)

    Blichfeldt, Bodil Stilling; Nielsen, Niels Christian; Nissen, Kathrine Aae

    2011-01-01

    This paper draws on a study of one specific type of small tourism enterprises (i.e. farm tourism enterprises) and argues that these enterprises differ from other enterprises in relation to a series of issues other than merely size. The analysis shows that enterprises such as these are characterized......, our study suggests that it is problematic to threat farm tourism enterprises as if they have much in common with both larger corporations and other types of SMTEs. Farm tourism enterprises seem to differ significantly from other enterprises as the hosts are not in the tourism business because...

  17. CH4 Emission Model from Bos Primigenius Waste in Fish-Water: Implications for Integrated Livestock-Fish Farming Systems

    Directory of Open Access Journals (Sweden)

    Joshua O. Okeniyi

    2013-07-01

    Full Text Available This paper studies a methane (CH4 emission model from the waste of cattle (B. primigenius based on trends in integrated livestock-fish farming adoption by farmers in Nigeria. Dung of B. primigenius was employed as substrate in fish-water, obtained from a fish-rearing farm, as a matrix medium for simulating a low-oxygen wastewater environment of an agriculture-aquaculture system. A substrate to fish-water mass ratio of 1:3 was used, developed in a laboratory-size digesting reactor system. Volumetric readings, at ambient temperature conditions and with a retention time of thirty-two days, were then subjected to the logistic probability density function, and tested against correlation coefficient and Nash-Sutcliffe coefficient of efficiency criteria. The readings show that a volume of CH4-containing gas as high as 65.3 x 10−3 dm3 was produced on the 13th day from the B. primigenius substrate. Also, production of 234.59 x 10−3 dm3/kg CH4-containing gas, totaling 703.76 x 10−3 dm3, was observed through the studied retention time. The 60% CH4 constituent model of the measured gas generation showed a potency of 2.0664 kg emission per animal, which is equivalent to 43.3944 CO2eq of global warming potential (GWP annually per animal. This bears environmental and climate change implications, and therefore alternative sustainable practices for integrated livestock-fish farming adoption are suggested.

  18. Wakes in large offshore wind farms

    DEFF Research Database (Denmark)

    Berthelmie, Rebecca J.; Frandsen, Sten Tronæs; Rathmann, Ole

    2008-01-01

    Power losses due to wind turbine wakes are of the order of 10 and 20% of total power output in large wind farms. The focus of this research carried out within the EC funded UPWIND project is wind speed and turbulence modelling for large wind farms/wind turbines in complex terrain and offshore...... in order to optimise wind farm layouts to reduce wake losses and loads. For complex terrain, a set of three evaluations is underway. The first is a model comparison for a Gaussian Hill where CFD models and wind farm models are being compared for the case of one hilltop wind turbine. The next case...... is for five turbines in flat terrain. Finally a complex terrain wind farm will be modelled and compared with observations. For offshore wind farms, the focus is on cases at the Horns Rev wind farm which indicate wind farm models require modification to reduce under-prediction of wake losses while CFD models...

  19. 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...

  20. 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

  1. Murine depression model and its potential applications for discovering foods and farm products with antidepressant-like effects

    Directory of Open Access Journals (Sweden)

    Tatsuhiko eGoto

    2016-03-01

    Full Text Available Advanced societies face increased health problems related to various stresses. Chronic psychological stress is a major risk factor for psychiatric disorders such as depression. Although therapeutic agents reduce several symptoms of depression, most have side effects in a broad range of the population. Furthermore, some victims of depression do not show significant improvement with any drugs, so alternative approaches are needed. Good dietary habits may potentially reduce depressive symptoms, but there is little scientific evidence thus far. Murine depression models are useful to test nutritional approaches in vivo. Our model mice subjected to a subchronic mild social defeat stress (sCSDS paradigm show several alterations in physiological parameters and social behavior. These stress-induced symptoms in sCSDS mice can be used as cues to identify antidepressant-like natural resources including foods and farm products. We previously discovered that sCSDS mice show more vulnerability to social stress by changing dietary condition. In addition, we developed a more objective system for analyzing mouse behavior using a 3D depth-sensing camera to understand relationships between diet and behavior. The combination of sCSDS mice with 3D behavioral analysis is a powerful method for screening ingredients in foods and farm products for antidepressant-like effects.

  2. 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.

  3. Integration of membrane distillation into traditional salt farming method: Process development and modelling

    Science.gov (United States)

    Hizam, S.; Bilad, M. R.; Putra, Z. A.

    2017-10-01

    Farmers still practice the traditional salt farming in many regions, particularly in Indonesia. This archaic method not only produces low yield and poor salt quality, it is also laborious. Furthermore, the farming locations typically have poor access to fresh water and are far away from electricity grid, which restrict upgrade to a more advanced technology for salt production. This paper proposes a new concept of salt harvesting method that improves the salt yield and at the same time facilitates recovery of fresh water from seawater. The new concept integrates solar powered membrane distillation (MD) and photovoltaic cells to drive the pumping. We performed basic solar still experiments to quantify the heat flux received by a pond. The data were used as insight for designing the proposed concept, particularly on operational strategy and the most effective way to integrate MD. After the conceptual design had been developed, we formulated mass and energy balance to estimate the performance of the proposed concept. Based on our data and design, it is expected that the system would improve the yield and quality of the salt production, maximizing fresh water harvesting, and eventually provides economical gain for salt farmers hence improving their quality of life. The key performance can only be measured via experiment using gain output ratio as performance indicator, which will be done in a future study.

  4. Wind Farm Wake

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Karagali, Ioanna; Volker, Patrick

    2017-01-01

    together to investigate the atmospheric conditions at the time of the photos by analysing local meteorological observations and wind turbine information, satellite remote sensing and nearby radiosonde data. Two wake models and one mesoscale model were used to model the case and explain what was seen.......On 25 January 2016 at 12:45 UTC several photographs of the offshore wind farm Horns Rev 2 were taken by helicopter pilot Gitte Lundorff with an iPhone. A very shallow layer of fog covered the sea. The photos of the fog over the sea dramatically pictured the offshore wind farm wake. Researchers got...

  5. Summary of Data Farming

    Directory of Open Access Journals (Sweden)

    Gary Horne

    2016-03-01

    Full Text Available Data Farming is a process that has been developed to support decision-makers by answering questions that are not currently addressed. Data farming uses an inter-disciplinary approach that includes modeling and simulation, high performance computing, and statistical analysis to examine questions of interest with a large number of alternatives. Data farming allows for the examination of uncertain events with numerous possible outcomes and provides the capability of executing enough experiments so that both overall and unexpected results may be captured and examined for insights. Harnessing the power of data farming to apply it to our questions is essential to providing support not currently available to decision-makers. This support is critically needed in answering questions inherent in the scenarios we expect to confront in the future as the challenges our forces face become more complex and uncertain. This article was created on the basis of work conducted by Task Group MSG-088 “Data Farming in Support of NATO”, which is being applied in MSG-124 “Developing Actionable Data Farming Decision Support for NATO” of the Science and Technology Organization, North Atlantic Treaty Organization (STO NATO.

  6. Whole farm management to reduce nutrient losses from dairy farms: a simulation study

    NARCIS (Netherlands)

    Rotz, C.A.; Oenema, J.; Keulen, van H.

    2003-01-01

    Whole farm simulation provides a tool for evaluating the impact of nutrient conservation technologies and strategies on dairy farms. A farm simulation model was verified by simulating the production and nutrient flows of the De Marke experimental dairy farm in the Netherlands. Technology such as a

  7. Analysing the Effects of Forest Cover and Irrigation Farm Dams on Streamflows of Water-Scarce Catchments in South Australia through the SWAT Model

    Directory of Open Access Journals (Sweden)

    Hong Hanh Nguyen

    2017-01-01

    Full Text Available To assist water resource managers with future land use planning efforts, the eco-hydrological model Soil and Water Assessment Tool (SWAT was applied to three catchments in South Australia that experience extreme low flow conditions. Particular land uses and management issues of interest included forest covers, known to affect water yields, and farm dams, known to intercept and change the hydrological dynamics in a catchment. The study achieved a satisfactory daily calibration when irrigation farm dams were incorporated in the model. For the catchment dominated by extreme low flows, a better daily simulation across a range of qualitative and quantitative metrics was gained using the base-flow static threshold optimization technique. Scenario analysis on effects of forest cover indicated an increase of surface flow and a reduction of base-flow when native eucalyptus lands were replaced by pastures and vice versa. A decreasing trend was observed for the overall water yield of catchments with more forest plantation due to the higher evapotranspiration (ET rate and the decline in surface flow. With regards to effects of irrigation farm dams, assessment on a daily time step suggested that a significant volume of water is stored in these systems with the water loss rate highest in June and July. On an annual basis, the model indicated that approximately 13.1% to 22.0% of water has been captured by farm dams for irrigation. However, the scenario analysis revealed that the purposes of use of farm dams rather than their volumetric capacities in the catchment determined the magnitude of effects on streamflows. Water extracted from farm dams for irrigation of orchards and vineyards are more likely to diminish streamflows than other land uses. Outputs from this study suggest that the water use restrictions from farm dams during recent drought periods were an effective tool to minimize impacts on streamflows.

  8. Growth-Prediction Model for Blue Mussels (Mytilus edulis on Future Optimally Thinned Farm-Ropes in Great Belt (Denmark

    Directory of Open Access Journals (Sweden)

    Poul S. Larsen

    2016-07-01

    Full Text Available A recently developed BioEnergetic Growth (BEG model for blue mussels (Mytilus edulis, valid for juvenile mussels, has been further developed to an ‘extended model’ and an alternative ‘ad hoc BEG model’ valid for post-metamorphic mussels, where the latter accounts for changing ambient chl a concentration. It was used to predict the growth of M. edulis on optimally thinned farm-ropes in Great Belt (Denmark, from newly settled post-metamorphic mussels of an initial shell size of 0.8 mm to marketable juvenile 30–35 mm ‘mini-mussels’. Such mussels will presumably in the near future be introduced as a new Danish, smaller-sized consumer product. Field data for actual growth (from Day 0 = 14 June 2011 showed that size of ‘mini-mussel’ was reached on Day 109 (Oct 1 and length 38 mm on Day 178 (Dec 9 while the corresponding predictions using the extended model were Day 121 (Oct 13 and Day 159 (Nov 20. Similar results were obtained by use of the ad hoc BEG model which also demonstrated the sensitivity of growth prediction to levels of chl a concentration, but less to temperature. The results suggest that it is possible (when the conditions are optimal, i.e., no intraspecific competition ensured by sufficient thinning to produce ‘mini-mussels’ in Great Belt during one season, but not the usual marketable 45-mm mussels. We suggest that the prediction model may be used as a practical instrument to evaluate to what degree the actual growth of mussels on farm ropes due to intraspecific competition may deviate from the potential (optimal growth under specified chl a and temperature conditions, and this implies that the effect of thinning to optimize the individual growth by eliminating intraspecific competition can be rationally evaluated.

  9. Communicating safe sun practices to farm youth: a model and field test of a proposed curriculum

    International Nuclear Information System (INIS)

    Turk, D.R.; Parrott, R.; Martin, M.; Steiner, C.; Lewis, D.

    1997-01-01

    This project was designed to identify the barriers and motivators to farm youths' performance of skin cancer prevention and detection behavior in order to design curricula which could directly address both. The curriculum as developed was pilot tested in 1994 at the Georgia Healthy Farmers ''Farm Kids'' Safety Camp. The 82 participants, aged 8 to 15 years, were children of Georgia farmers. Eight Sun Safety classes were held over the course of two days. Participants were seated in a large conference room and were given a research questionnaire packet consisting of a skin cancer prevention/detection knowledge measure, three skin cancer related fact sheets, and a workbook to be used to rate various skin cancer prevention/detection materials and behaviors staged at centers around the room. A brief presentation about the dangers of sun exposure and skin cancer prevention behaviors was given after which subjects participated in three activities: a sun protection hat station, a sun block station, and skin self exam station. Student t- tests were conducted comparing the outcome expectancy scores for individuals who reported that they would wear the particular hat or sunscreen with the outcome expectancy scores for individuals who reported that they would not wear the particular hat or sunscreen. Participants who reported that they would wear the hat had significantly higher positive outcome expectancy scores than those who said that they would not wear those hats. For four out of five sun blocks, participants who reported that they would wear these blocks had significantly higher positive outcome expectancies than those reporting that they would not wear them. The authors conclude that health education curricula to promote sun safety to youth must focus on building positive outcome expectancies in relation to the most efficacious practices, and in drawing clear distinctions for youth among their options, so that they are able to make decisions for themselves. (author)

  10. From rainfall to farm incomes - transforming advice for managing climate risk in Australia. Part I: Development and testing of a bioeconomic modelling system

    NARCIS (Netherlands)

    Kokic, P.; Nelson, R.; Meinke, H.B.; Potgieter, A.; Carter, J.

    2007-01-01

    In this paper we report the development of a bioeconomic modelling system, AgFIRM, designed to help close a relevance gap between climate science and policy in Australia. We do this by making a simple econometric farm income model responsive to seasonal forecasts of crop and pasture growth for the

  11. On‐Farm and Off‐Farm Returns to Education among Farm Operators in Northern Ireland

    OpenAIRE

    Wallace, Michael T.; Jack, Claire G.

    2011-01-01

    This paper estimates returns to education for a sample of farm operators in Northern Ireland. The analysis examines the relationship between education and on-farm and off-farm labour incomes. Human capital earnings functions are estimated to identify the marginal return to education measured as years of schooling as well as the qualification level attained. Extending to a structural model, the methodology controls for the endogeneity of education in the earnings function and potential selecti...

  12. Fault Tolerant Wind Farm Control

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Stoustrup, Jakob

    2013-01-01

    In the recent years the wind turbine industry has focused on optimizing the cost of energy. One of the important factors in this is to increase reliability of the wind turbines. Advanced fault detection, isolation and accommodation are important tools in this process. Clearly most faults are dealt...... with best at a wind turbine control level. However, some faults are better dealt with at the wind farm control level, if the wind turbine is located in a wind farm. In this paper a benchmark model for fault detection and isolation, and fault tolerant control of wind turbines implemented at the wind farm...... control level is presented. The benchmark model includes a small wind farm of nine wind turbines, based on simple models of the wind turbines as well as the wind and interactions between wind turbines in the wind farm. The model includes wind and power references scenarios as well as three relevant fault...

  13. Techno-Economic Models for Optimised Utilisation of Jatropha curcas Linnaeus under an Out-Grower Farming Scheme in Ghana

    Directory of Open Access Journals (Sweden)

    Isaac Osei

    2016-11-01

    Full Text Available Techno-economic models for optimised utilisation of jatropha oil under an out-grower farming scheme were developed based on different considerations for oil and by-product utilisation. Model 1: Out-grower scheme where oil is exported and press cake utilised for compost. Model 2: Out-grower scheme with six scenarios considered for the utilisation of oil and by-products. Linear programming models were developed based on outcomes of the models to optimise the use of the oil through profit maximisation. The findings revealed that Model 1 was financially viable from the processors’ perspective but not for the farmer at seed price of $0.07/kg. All scenarios considered under Model 2 were financially viable from the processors perspective but not for the farmer at seed price of $0.07/kg; however, at seed price of $0.085/kg, financial viability was achieved for both parties. Optimising the utilisation of the oil resulted in an annual maximum profit of $123,300.

  14. A spatially distributed hydroeconomic model to assess the effects of drought on land use, farm profits, and agricultural employment

    Science.gov (United States)

    Maneta, M. P.; Torres, M. O.; Wallender, W. W.; Vosti, S.; Howitt, R.; Rodrigues, L.; Bassoi, L. H.; Panday, S.

    2009-11-01

    In this paper a high-resolution linked hydroeconomic model is demonstrated for drought conditions in a Brazilian river basin. The economic model of agriculture includes 13 decision variables that can be optimized to maximize farmers' yearly net revenues. The economic model uses a multi-input multioutput nonlinear constant elasticity of substitution (CES) production function simulating agricultural production. The hydrologic component is a detailed physics-based three-dimensional hydrodynamic model that simulates changes in the hydrologic system derived from agricultural activity while in turn providing biophysical constraints to the economic system. The linked models capture the effects of the interactions between the hydrologic and the economic systems at high spatial and temporal resolutions, ensuring that the model converges to an optimal economic scenario that takes into account the spatial and temporal distribution of the water resources. The operation and usefulness of the models are demonstrated in a rural catchment area of about 10 km2 within the São Francisco River Basin in Brazil. Two droughts of increasing intensity are simulated to investigate how farmers behave under rain shortfalls of different severity. The results show that farmers react to rainfall shortages to minimize their effects on farm profits, and that the impact on farmers depends, among other things, on their location in the watershed and on their access to groundwater.

  15. FARM OUTPUT, NON-FARM INCOME, AND COMMERCIALIZATION IN RURAL GEORGIA

    OpenAIRE

    Kan, Iddo; Kimhi, Ayal; Lerman, Zvi

    2006-01-01

    This article examines the decision of farmers to sell part of their farm output on the market, using data from the Republic of Georgia. A two-level empirical model is used, in which endowments and resource allocation decisions determine farm output and non-farm income, and these in turn determine market participation. We found, as expected, that farm output affects market participation positively, while non-farm income affects it negatively. Landholdings have an indirect positive effect on ma...

  16. Mathematical modeling of porcine epidemic diarrhea virus dynamics within a farrow-to-finish swine farm to investigate the effects of control measures.

    Science.gov (United States)

    Murai, Kiyokazu; Moriguchi, Sachiko; Hayama, Yoko; Kobayashi, Sota; Miyazaki, Ayako; Tsutsui, Toshiyuki; Yamamoto, Takehisa

    2018-01-01

    Porcine epidemic diarrhea (PED) is a highly contagious enteric disease in swine that can cause devastating economic damage to pig producers. Japan was severely affected by PED epidemics from 2013 through 2015, with over 1000 farms were affected during this period. Although many studies have unraveled pathological and molecular characteristics of PED virus (PEDV), the mechanism for within-farm spread is largely unknown. Here, we constructed a deterministic compartmental model to quantitatively describe the infection dynamics in a farm setting and to investigate effective control measures. The model consisted of three separate houses and four swine populations framed in a standard commercial farrow-to-finish swine operation in Japan, with a special focus on the role of indirect transmission via the on-farm environment contaminated by feces of infected pigs. Some model parameters were estimated using the Japanese empirical outbreak data. Model outputs over a 90-day period showed that the number of infected sows in a dry sow house peaked within a week after disease introduction, and PEDV was retained on the farm. In the farrowing house, the number of infected sows also peaked within a week followed by a tentative disappearance of infected pigs, whereas the number of infected piglets in the farrowing house spiked and the number of neonatal deaths increased rapidly until around Day 21 followed by a continued increase at a slower pace. In the fattening house, the number of infected pigs reached an equilibrium at around Day 25 and approximately 15% of pigs continued to be infected thereafter. Herd size was not found to have a significant influence on the overall trend in our model output. Among the control measures examined using our model, the application of effective vaccination was considered to be the most promising. Activities such as performing more thorough cleanings to remove residual virus or implementing stricter on-farm biosecurity to cease between-house virus

  17. Farm Animals

    Science.gov (United States)

    ... H7 infections among visitors to a dairy farm . New England Journal of Medicine . 2002; 347:555–560. Cryptosporidiosis Outbreak at a Summer Camp – North Carolina, 2009 . Morbidity and Mortality Weekly Report . 2011 ... in Humans – New York, Illinois, California, and Tennessee, 2004-2005 . Morbidity ...

  18. 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...

  19. Molecular farming

    NARCIS (Netherlands)

    Merck, K.B.; Vereijken, J.M.

    2006-01-01

    Molecular Farming is a new and emerging technology that promises relatively cheap and flexible production of large quantities of pharmaceuticals in genetically modified plants. Many stakeholders are involved in the production of pharmaceuticals in plants, which complicates the discussion on the

  20. Sensitivity analysis for models of greenhouse gas emissions at farm level. Case study of N2O emissions simulated by the CERES-EGC model

    International Nuclear Information System (INIS)

    Drouet, J.-L.; Capian, N.; Fiorelli, J.-L.; Blanfort, V.; Capitaine, M.; Duretz, S.; Gabrielle, B.; Martin, R.; Lardy, R.; Cellier, P.; Soussana, J.-F.

    2011-01-01

    Modelling complex systems such as farms often requires quantification of a large number of input factors. Sensitivity analyses are useful to reduce the number of input factors that are required to be measured or estimated accurately. Three methods of sensitivity analysis (the Morris method, the rank regression and correlation method and the Extended Fourier Amplitude Sensitivity Test method) were compared in the case of the CERES-EGC model applied to crops of a dairy farm. The qualitative Morris method provided a screening of the input factors. The two other quantitative methods were used to investigate more thoroughly the effects of input factors on output variables. Despite differences in terms of concepts and assumptions, the three methods provided similar results. Among the 44 factors under study, N 2 O emissions were mainly sensitive to the fraction of N 2 O emitted during denitrification, the maximum rate of nitrification, the soil bulk density and the cropland area. - Highlights: → Three methods of sensitivity analysis were compared in the case of a soil-crop model. → The qualitative Morris method provided a screening of the input factors. → The quantitative EFAST method provided a thorough analysis of the input factors. → The three methods provided similar results regarding sensitivity of N 2 O emissions. → N 2 O emissions were mainly sensitive to a few, especially four, input factors. - Three methods of sensitivity analysis were compared to analyse their efficiency in assessing the sensitivity of a complex soil-crop model to its input factors.

  1. 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.

  2. Offshore Wind Farms and HVDC Grids Modeling as a Feedback Control System for Stability Analysis

    DEFF Research Database (Denmark)

    Bidadfar, Ali; Saborío-Romano, Oscar; Altin, Müfit

    feedback control system (FCS) model is proposed to represent the dynamic characteristics of HVDC grids and their controllers. The FCS model can be used for different dynamic analyses in time and frequency domains. Moreover, using the FCS model the system stability is analyzed in both open- and closed...... OWPPs and two AC grids is used for simulations and verification of the proposed FCS model....

  3. The gross- and net-irrigation requirements of crops and model farms with different root zone capacities at ten locations in Denmark 1990-2015

    DEFF Research Database (Denmark)

    ten Damme, Loraine; Andersen, Mathias Neumann

    abstraction permits for irrigation. Here we present estimates of the gross and net irrigation water requirements for a range of agricultural crops and model farms in 10 locations across Denmark for the years 1990-2015. We generally found higher values for the irrigation requirement than previous studies...... conducted 40 years ago. The annual irrigation water requirement varied according to farm type (dairy, arable/pig and potatoes), location,soil type and especially year with more than 300%. Abstraction permits based on average values are deemed less suitable as they may restrict farmers’ production in one out...

  4. Net-energy analysis of integrated food and bioenergy systems exemplified by a model of a self-sufficinet system of dairy farms

    DEFF Research Database (Denmark)

    Markussen, Mads Ville; Pugesgaard, Siri; Oleskowicz-Popiel, Piotr

    2015-01-01

    of providing both food and surplus energy to the society as evalu - ated from a model study. We evaluated bioenergy technologies in a Danish dairy-farming context in four different scenarios: (1) vegetable oil based on oilseed rape, (2) biogas based on cattle manure and grass-clover lays, (3) bioethanol from...

  5. SWAT Model Application to Assess the Impact of Intensive Corn‐farming on Runoff, Sediments and Phosphorous loss from an Agricultural Watershed in Wisconsin

    Science.gov (United States)

    The potential future increase in corn-based biofuel may be expected to have a negative impact on water quality in streams and lakes of the Midwestern US due to increased agricultural chemicals usage. This study used the SWAT model to assess the impact of continuous-corn farming o...

  6. Transient Model Validation of Fixed-Speed Induction Generator Using Wind Farm Measurements

    DEFF Research Database (Denmark)

    Rogdakis, Georgios; Garcia-Valle, Rodrigo; Arana Aristi, Iván

    2012-01-01

    In this paper, an electromagnetic transient model for fixed-speed wind turbines equipped with induction generators is developed and implemented in PSCAD/EMTDC. The model is comprised by: an induction generator, aerodynamic rotor, and a two-mass representation of the shaft system. Model validation...

  7. A Combined Reliability Model of VSC-HVDC Connected Offshore Wind Farms Considering Wind Speed Correlation

    DEFF Research Database (Denmark)

    Guo, Yifei; Gao, Houlei; Wu, Qiuwei

    2017-01-01

    and WTGs outage. The wind speed correlation between different WFs is included in the two-dimensional multistate WF model by using an improved k-means clustering method. Then, the entire system with two WFs and a threeterminal VSC-HVDC system is modeled as a multi-state generation unit. The proposed model...

  8. Aggregated Modelling for Wind Farms for Power System Transient Stability Studies

    DEFF Research Database (Denmark)

    Liu, Hongzhi; Chen, Zhe

    2012-01-01

    to detailed modelling that models every wind turbines individually and the interconnections among them. In this paper, three aggregated modelling techniques, namely, multi-machine equivalent aggregation, full aggregation and semi-aggregation are presented for power system transient stability studies based...

  9. AIR AND RADON PATHWAY MODELING FOR THE F-AREA TANK FARM

    International Nuclear Information System (INIS)

    Dixon, K; Mark Phifer, M

    2007-01-01

    The F-Area Tank Farm (FTF) is located within F-Area in the General Separations Area (GSA) of the Savannah River Site (SRS) as seen in Figure 1. The GSA contains the F and H Area Separations Facilities, the S-Area Defense Waste Processing Facility, the Z-Area Saltstone Facility, and the E-Area Low-Level Waste Disposal Facilities. The FTF is a nearly rectangular shaped area and comprises approximately 20 acres, which is bounded by SRS coordinates N 76,604.5 to N 77,560.0 and E 52,435.0 to E 53,369.0. SRS is in the process of preparing a Performance Assessment (PA) to support FTF closure. As part of the PA process, an analysis was conducted to evaluate the potential magnitude of gaseous release of radionuclides from the FTF over the 100-year institutional control period and 10,000-year post-closure compliance period. Specifically, an air and radon pathways analysis has been conducted to estimate the flux of volatile radionuclides and radon at the ground surface due to residual waste remaining in the tanks following closure. This analysis was used as the basis to estimate the dose to the maximally exposed individual (MEI) for the air pathway per Curie (Ci) of each radionuclide remaining in the combined FTF waste tanks. For the air pathway analysis, several gaseous radionuclides were considered. These included carbon-14 (C-14), chlorine-36 (Cl-36), iodine-129 (I-129), selenium-79 (Se-79), antimony-125 (Sb-125), tin-126 (Sn-126), tritium (H-3), and technetium-99 (Tc-99). The dose to the MEI was estimated at the SRS Boundary during the 100 year institutional control period. For the 10,000 year post closure compliance period, the dose to the MEI was estimated at the 100 m compliance point. For the radon pathway analysis, five parent radionuclides and their progeny were analyzed. These parent radionuclides included uranium-238 (U-238), plutonium-238 (Pu-238), uranium-234 (U-234), thorium-230 (Th-230), and radium-226 (Ra-226). The peak flux of radon-222 due to each parent

  10. Simulating coastal effects on an offshore wind farm

    DEFF Research Database (Denmark)

    van der Laan, Paul; Pena Diaz, Alfredo; Volker, Patrick

    Wind turbine wakes can cause energy losses in wind farms1 and their effect needs to be modeled in order to design energy efficient wind farm layouts. Wake losses in offshore wind farms are often modeled by assuming offshore conditions for all wind directions; however, many offshore wind farms...

  11. Fault Detection and Load Distribution for the Wind Farm Challenge

    DEFF Research Database (Denmark)

    Borchersen, Anders Bech; Larsen, Jesper Abildgaard; Stoustrup, Jakob

    2014-01-01

    In this paper a fault detection system and a fault tolerant controller for a wind farm model is designed and tested. The wind farm model is taken from the wind farm challenge which is a public available challenge where a wind farm consisting of nine turbines is proposed. The goal of the challenge...

  12. Prediction models for wind speed at turbine locations in a wind farm

    DEFF Research Database (Denmark)

    Knudsen, Torben; Bak, Thomas; Soltani, Mohsen

    2011-01-01

    turbulence models. The esti- mator includes a nonlinear time varying wind speed model, which compared with literature results in an adaptive filter. Given the estimated effective wind speed, it is possible to establish wind speed prediction models by system identification. As the prediction models are based...... manifested through the wind field is hence required. This paper develops models for this relationship. The result is based on two new contributions: the first is related to the estimation of effective wind speeds, which serves as a basis for the second contribution to wind speed prediction models. Based...... on standard turbine measurements such as rotor speed and power produced, an effective wind speed, which represents the wind field averaged over the rotor disc, is derived. The effective wind speed estimator is based on a continuous–discrete extended Kalman filter that takes advantage of nonlinear time varying...

  13. Atmospheric Dispersion Modelling and Spatial Analysis to Evaluate Population Exposure to Pesticides from Farming Processes

    Directory of Open Access Journals (Sweden)

    Sofia Costanzini

    2018-01-01

    Full Text Available This work originates from an epidemiological study aimed to assess the correlation between population exposure to pesticides used in agriculture and adverse health effects. In support of the population exposure evaluation two models implemented by the authors were applied: a GIS-based proximity model and the CAREA atmospheric dispersion model. In this work, the results of the two models are presented and compared. Despite the proximity analysis is widely used for these kinds of studies, it was investigated how meteorology could affect the exposure assessment. Both models were applied to pesticides emitted by 1519 agricultural fields and considering 2584 receptors distributed over an area of 8430 km2. CAREA output shows a considerable enhancement in the percentage of exposed receptors, from the 4% of the proximity model to the 54% of the CAREA model. Moreover, the spatial analysis of the results on a specific test site showed that the effects of meteorology considered by CAREA led to an anisotropic exposure distribution that differs considerably from the symmetric distribution resulting by the proximity model. In addition, the results of a field campaign for the definition and planning of ground measurement of concentration for the validation of CAREA are presented. The preliminary results showed how, during treatments, pesticide concentrations distant from the fields are significantly higher than background values.

  14. Using Stochastically Downscaled Climate Models and Multiproxy Lake Sediment Data to Connect Climatic Variations Over the Past 1000 Years and the History of Prehistoric Maize Farming in Utah

    Science.gov (United States)

    Thomson, M. J.; MacDonald, G. M.

    2015-12-01

    We are investigating the relationship between climatic variations over the past 1000 years and the history of prehistoric maize farming expansion and decline in the American Southwest, with a focus on Utah. We are examining both the downscaled climate models and high resolution analyses of lake cores and dendrochronological data matched with occupation information. We are testing the specific utility of stochastically downscaled general circulation models (viz. ECHO-G) to reconstruct local conditions for sites with documented prehistoric dryland farming through the so-called Medieval Climate Anomaly (MCA) and transition to the Little Ice Age (LIA). We are testing our model-based reconstructions with proxies of temperature and aridity from three subalpine lake sediment cores transecting Utah. We compare the patterns of climate change from the downscaled models and the paleoclimate records to a database of 837 radiocarbon dates over 169 locations of archaeological Native American maize-farmer site occupations in Utah.

  15. THEORETICAL ASPECTS AND NUMERICAL MODELLING FOR LONG TERM PREDICTION OF ABL AND WIND DISTRIBUTION IN POWER FARM

    Directory of Open Access Journals (Sweden)

    RADULESCU V.

    2015-03-01

    Full Text Available The paper is structured in seven parts, the last for few conclusions and finally some references. It is based on concrete measurements and observation during around 2 years. First is presented an introduction of the actual situation. In part two are mentioned the methods and hypotheses in evaluation of wind velocity distribution in boundary layers for atmospheric air, taking into account the roughness of ground surfaces. It is mentioned a concrete area, south part of Moldova. In third part is presented a solution for the geodetic model and finally are selected the altimetry solution. In chapter four is determined the influence of air density, temperature and pressure on wind turbine functioning. In the next chapters are presented the numerical model with special boundary conditions, taking into account different value of roughness and finally the obtained results. It is also estimated velocity variation during day-night. Finally is presented the vertical distribution of horizontal wind velocity for a wind farm, obviously important due the power of turbine (around 3 MW each one. Some conclusions and references are also mentioned.

  16. 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.

  17. 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.

  18. Growth-Prediction Model for Blue Mussels (Mytilus edulis) on Future Optimally Thinned Farm-Ropes in Great Belt (Denmark)

    DEFF Research Database (Denmark)

    Larsen, Poul Scheel; Riisgård, Hans

    2016-01-01

    A recently developed BioEnergetic Growth (BEG) model for blue mussels (Mytilus edulis), valid for juvenile mussels, has been further developed to an ‘extended model’ and an alternative ‘ad hoc BEG model’ valid for post-metamorphic mussels, where the latter accounts for changing ambient chl...... a concentration. It was used to predict the growth of M. edulis on optimally thinned farm-ropes in Great Belt (Denmark), from newly settled post-metamorphic mussels of an initial shell size of 0.8 mm to marketable juvenile 30–35 mm ‘mini-mussels’. Such mussels will presumably in the near future be introduced...... as a new Danish, smaller-sized consumer product. Field data for actual growth (from Day 0 = 14 June 2011) showed that size of ‘mini-mussel’ was reached on Day 109 (Oct 1) and length 38 mm on Day 178 (Dec 9) while the corresponding predictions using the extended model were Day 121 (Oct 13) and Day 159 (Nov...

  19. Applying Bayesian network modelling to understand the links between on-farm biosecurity practice during the 2007 equine influenza outbreak and horse managers' perceptions of a subsequent outbreak.

    Science.gov (United States)

    Firestone, Simon M; Lewis, Fraser I; Schemann, Kathrin; Ward, Michael P; Toribio, Jenny-Ann L M L; Taylor, Melanie R; Dhand, Navneet K

    2014-10-01

    Australia experienced its first ever outbreak of equine influenza in August 2007. Horses on 9359 premises were infected over a period of 5 months before the disease was successfully eradicated through the combination of horse movement controls, on-farm biosecurity and vaccination. In a previous premises-level case-control study of the 2007 equine influenza outbreak in Australia, the protective effect of several variables representing on-farm biosecurity practices were identified. Separately, factors associated with horse managers' perceptions of the effectiveness of biosecurity measures have been identified. In this analysis we applied additive Bayesian network modelling to describe the complex web of associations linking variables representing on-farm human behaviours during the 2007 equine influenza outbreak (compliance or lack thereof with advised personal biosecurity measures) and horse managers' perceptions of the effectiveness of such measures in the event of a subsequent outbreak. Heuristic structure discovery enabled identification of a robust statistical model for 31 variables representing biosecurity practices and perceptions of the owners and managers of 148 premises. The Bayesian graphical network model we present statistically describes the associations linking horse managers' on-farm biosecurity practices during an at-risk period in the 2007 outbreak and their perceptions of whether such measures will be effective in a future outbreak. Practice of barrier infection control measures were associated with a heightened perception of preparedness, whereas horse managers that considered their on-farm biosecurity to be more stringent during the outbreak period than normal practices had a heightened perception of the effectiveness of other measures such as controlling access to the premises. Past performance in an outbreak setting may indeed be a reliable predictor of future perceptions, and should be considered when targeting infection control guidance to

  20. Modelling Fresh Strawberry Supply “From-Farm-to-Fork” as a Complex Adaptive Network

    OpenAIRE

    Engelseth, Per; Karlsen, Anniken; Verwaart, Tim

    2011-01-01

    The purpose of this study is to model and thereby enable simulation of the complete business entity of fresh food supply. A case narrative of fresh strawberry supply provides basis for this modelling. Lamming et al. (2000) point to the importance of discerning industry-specific product features (or particularities) regarding managing supply networks when discussing elements in “an initial classification of a supply network” while Fisher (1997) and Christopher et al. (2006, 2009) point to the ...

  1. Advanced Modeling System for Optimization of Wind Farm Layout and Wind Turbine Sizing Using a Multi-Level Extended Pattern Search Algorithm

    Energy Technology Data Exchange (ETDEWEB)

    DuPont, Bryony; Cagan, Jonathan; Moriarty, Patrick

    2016-07-01

    This paper presents a system of modeling advances that can be applied in the computational optimization of wind plants. These modeling advances include accurate cost and power modeling, partial wake interaction, and the effects of varying atmospheric stability. To validate the use of this advanced modeling system, it is employed within an Extended Pattern Search (EPS)-Multi-Agent System (MAS) optimization approach for multiple wind scenarios. The wind farm layout optimization problem involves optimizing the position and size of wind turbines such that the aerodynamic effects of upstream turbines are reduced, which increases the effective wind speed and resultant power at each turbine. The EPS-MAS optimization algorithm employs a profit objective, and an overarching search determines individual turbine positions, with a concurrent EPS-MAS determining the optimal hub height and rotor diameter for each turbine. Two wind cases are considered: (1) constant, unidirectional wind, and (2) three discrete wind speeds and varying wind directions, each of which have a probability of occurrence. Results show the advantages of applying the series of advanced models compared to previous application of an EPS with less advanced models to wind farm layout optimization, and imply best practices for computational optimization of wind farms with improved accuracy.

  2. Framework of Multi-objective Wind Farm Controller Applicable to Real Wind Farms

    DEFF Research Database (Denmark)

    Kazda, Jonas; Gögmen, Tuhfe; Giebel, Gregor

    2016-01-01

    Optimal wind farm control can mitigate adverse wake effects that can potentially cause up to 40% power loss and 80% increased fatigue loads in wind farms. The aim of this work is to outline a methodological framework of an optimal wind farm controller, which provides improved solutions to critical...... areas of optimal wind farm control research. The basis of this framework is a review of optimal wind farm control methodologies, which is presented first. It is observed that there is, at present, mainly a need for more advanced wind farm operation models. Thereafter the framework of a multi...... in the wind farm. The controller design provides improved solutions for the modelling of wind farm aerodynamics and turbine operation, that is the PossPOW algorithm and a HAWC2-based turbine model, respectively. Moreover, all components of the framework are designed as to enable the applicability...

  3. Development of an advanced noise propagation model for noise optimization in wind farm

    DEFF Research Database (Denmark)

    Barlas, Emre

    2017-01-01

    wind directions or time of the day). The latter causes turbines to be located at less resourceful sites in advance. Both of these scenarios increase the cost of energy. Hence there is a need for more accurate noise mapping tools. The thesis addresses this issue via development of a new tool based...... on combined source, propagation and flow models.The parabolic wave equation method is used for modelling the frequency dependent wave propagation. Different numerical techniques such as FFT’s or finite difference method are implemented to solve the equations. The wind speed and temperature distributions...

  4. Predictive modeling of Bacillus cereus spores in farm tank milk during grazing and housing periods

    NARCIS (Netherlands)

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

    2007-01-01

    The shelf life of pasteurized dairy products depends partly on the concentration of Bacillus cereus spores in raw milk. Based on a translation of contamination pathways into chains of unit-operations, 2 simulation models were developed to quantitatively identify factors that have the greatest effect

  5. Wind Farm Large-Eddy Simulations on Very Coarse Grid Resolutions using an Actuator Line Model

    NARCIS (Netherlands)

    Martinez, L.A.; Meneveau, C.; Stevens, Richard Johannes Antonius Maria

    2016-01-01

    In this work the accuracy of the Actuator Line Model (ALM) in Large Eddy Simula- tions of wind turbine flow is studied under the speci c conditions of very coarse spatial resolutions. For finely-resolved conditions, it is known that ALM provides better accuracy compared to the standard Actuator Disk

  6. Modeled Impacts of Farming Practices and Structural Agricultural Changes on Nitrogen Fluxes in the Netherlands

    NARCIS (Netherlands)

    Vries, de W.; Kros, J.; Oenema, O.

    2001-01-01

    In the Netherlands, nutrient emissions from intensive animal husbandry have contributed to decreased species diversity in (semi) natural terrestrial and aquatic ecosystems, pollution of groundwater, and possibly global warming due to N2O emissions. This paper presents the results of a modelling

  7. 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

  8. 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

  9. Bayesian Based Diagnostic Model for Condition Based Maintenance of Offshore Wind Farms

    Directory of Open Access Journals (Sweden)

    Masoud Asgarpour

    2018-01-01

    Full Text Available Operation and maintenance costs are a major contributor to the Levelized Cost of Energy for electricity produced by offshore wind and can be significantly reduced if existing corrective actions are performed as efficiently as possible and if future corrective actions are avoided by performing sufficient preventive actions. This paper presents an applied and generic diagnostic model for fault detection and condition based maintenance of offshore wind components. The diagnostic model is based on two probabilistic matrices; first, a confidence matrix, representing the probability of detection using each fault detection method, and second, a diagnosis matrix, representing the individual outcome of each fault detection method. Once the confidence and diagnosis matrices of a component are defined, the individual diagnoses of each fault detection method are combined into a final verdict on the fault state of that component. Furthermore, this paper introduces a Bayesian updating model based on observations collected by inspections to decrease the uncertainty of initial confidence matrix. The framework and implementation of the presented diagnostic model are further explained within a case study for a wind turbine component based on vibration, temperature, and oil particle fault detection methods. The last part of the paper will have a discussion of the case study results and present conclusions.

  10. Modelling drivers of mangrove propagule dispersal and restoration of abandoned shrimp farms

    Directory of Open Access Journals (Sweden)

    D. Di Nitto

    2013-07-01

    Full Text Available Propagule dispersal of four mangrove species Rhizophora mucronata, R. apiculata, Ceriops tagal and Avicennia officinalis in the Pambala–Chilaw Lagoon Complex (Sri Lanka was studied by combining a hydrodynamic model with species-specific knowledge on propagule dispersal behaviour. Propagule transport was simulated using a finite-volume advection-diffusion model to investigate the effect of dispersal vectors (tidal flow, freshwater discharge and wind, trapping agents (retention by vegetation and seed characteristics (buoyancy on propagule dispersal patterns. Sensitivity analysis showed that smaller propagules, like the oval-shaped propagules of Avicennia officinalis, dispersed over larger distances and were most sensitive to changing values of retention by mangrove vegetation compared to larger, torpedo-shaped propagules of Rhizophora spp. and C. tagal. Directional propagule dispersal in this semi-enclosed lagoon with a small tidal range was strongly concentrated towards the edges of the lagoon and channels. Short distance dispersal appeared to be the main dispersal strategy for all four studied species, with most of the propagules being retained within the vegetation. Only a small proportion (max. 5% of propagules left the lagoon through a channel connecting the lagoon with the open sea. Wind significantly influenced dispersal distance and direction once propagules entered the lagoon or adjacent channels. Implications of these findings for mangrove restoration were tested by simulating partial removal in the model of dikes around abandoned shrimp ponds to restore tidal hydrology and facilitate natural recolonisation by mangroves. The specific location of dike removal, (with respect to the vicinity of mangroves and independently suitable hydrodynamic flows, was found to significantly affect the resultant quantities and species of inflowing propagules and hence the potential effectiveness of natural regeneration. These results demonstrate the

  11. Modelling drivers of mangrove propagule dispersal and restoration of abandoned shrimp farms

    Science.gov (United States)

    Di Nitto, D.; Erftemeijer, P. L. A.; van Beek, J. K. L.; Dahdouh-Guebas, F.; Higazi, L.; Quisthoudt, K.; Jayatissa, L. P.; Koedam, N.

    2013-07-01

    Propagule dispersal of four mangrove species Rhizophora mucronata, R. apiculata, Ceriops tagal and Avicennia officinalis in the Pambala-Chilaw Lagoon Complex (Sri Lanka) was studied by combining a hydrodynamic model with species-specific knowledge on propagule dispersal behaviour. Propagule transport was simulated using a finite-volume advection-diffusion model to investigate the effect of dispersal vectors (tidal flow, freshwater discharge and wind), trapping agents (retention by vegetation) and seed characteristics (buoyancy) on propagule dispersal patterns. Sensitivity analysis showed that smaller propagules, like the oval-shaped propagules of Avicennia officinalis, dispersed over larger distances and were most sensitive to changing values of retention by mangrove vegetation compared to larger, torpedo-shaped propagules of Rhizophora spp. and C. tagal. Directional propagule dispersal in this semi-enclosed lagoon with a small tidal range was strongly concentrated towards the edges of the lagoon and channels. Short distance dispersal appeared to be the main dispersal strategy for all four studied species, with most of the propagules being retained within the vegetation. Only a small proportion (max. 5%) of propagules left the lagoon through a channel connecting the lagoon with the open sea. Wind significantly influenced dispersal distance and direction once propagules entered the lagoon or adjacent channels. Implications of these findings for mangrove restoration were tested by simulating partial removal in the model of dikes around abandoned shrimp ponds to restore tidal hydrology and facilitate natural recolonisation by mangroves. The specific location of dike removal, (with respect to the vicinity of mangroves and independently suitable hydrodynamic flows), was found to significantly affect the resultant quantities and species of inflowing propagules and hence the potential effectiveness of natural regeneration. These results demonstrate the value of propagule

  12. Improved decision-making on irrigation farming in arid zones using a system dynamics model

    Directory of Open Access Journals (Sweden)

    Martin de Wit

    2013-11-01

    Full Text Available The Sandveld region in the Western Cape is a low rainfall area dominated by agricultural production using groundwater resources. The rise in agricultural production in the Sandveld has led to questions regarding the region's ecological sustainability. We developed a system dynamics model for the Sandveld system which captures land-use change, agricultural production, and groundwater abstraction and recharge. Using this model, we find little evidence that pressures on livelihoods result, either currently or in the immediate future, from ecological feedback effects. The model does indicate that the highest risks are associated with the financial viability of agriculture, in its present form, in the region. With lower margins, a drive towards economies of scale in agricultural production is more likely in the future. This process has had severe implications in some sectors already, with a 39% decrease in the number of potato producers in the Sandveld region between 2003 and 2009. These results highlight that an integrated approach to agricultural, economic and environmental management and planning is needed to capture the economic and ecological complexity and dynamics of the Sandveld system.

  13. Off-Farm Employment and Economic Crisis: Evidence from Cyprus

    Directory of Open Access Journals (Sweden)

    Elias Giannakis

    2018-03-01

    Full Text Available Off-farm employment is an important strategy for complementing farm household income and maintaining rural livelihoods. A multilevel logistic regression model was applied to investigate the effect of farm-level and regional-level factors on off-farm employment in Cyprus during the recent economic crisis period. The performance of nonfarm sectors positively affects off-farm employment; a one-percent increase in the share of the secondary and tertiary sector employment increases the likelihood of off-farm work by 9.5 times. The importance of location was also identified. Farm households located in rural areas are 70% less likely to engage in off-farm work than households located in urban areas. The positive effect of educational attainment and the negative effect of farm training confirmed the importance of human capital characteristics on off-farm labour participation. Farm structural factors are also significant determinants of off-farm employment. A one-hectare increase in the farm size decreases the odds of off-farm labour participation by 50%. Operators of crop farming holdings are 4.2 times more likely to work off the farm than operators of livestock and mixed-farming holdings. The results reveal the importance of adopting a multilevel and integrated approach for the analysis of off-farm employment.

  14. Comparing wall modeled LES and prescribed boundary layer approach in infinite wind farm simulations

    DEFF Research Database (Denmark)

    Sarlak, Hamid; Mikkelsen, Robert; Sørensen, Jens Nørkær

    2015-01-01

    This paper aims at presenting a simple and computationally fast method for simulation of the Atmospheric Boundary Layer (ABL) and comparing the results with the commonly used wall-modelled Large Eddy Simulation (WMLES). The simple method, called Prescribed Mean Shear and Turbulence (PMST) hereafter...... inexpensive, is high flexibility meaning that the imposed boundary layer can be read from another CFD simulation, or from site measurements. For fundamental studies focusing on the wake structures rather than ABL for example, the grid can be refined in the rotor region and any desired shear layer can...

  15. Down on the farm: preventing farm accidents in children.

    Science.gov (United States)

    Conway, Alice E; McClune, Amy J; Nosel, Patricia

    2007-01-01

    Agriculture continues to rank as the most dangerous industry in the United States. The objectives of this pilot study were to identify the incidence of care provided to children involved in farm accidents, examine barriers to utilization of farm safety materiaJs by primary health care practitioners (PHCPs), and determine the percentage of PHCPs who provide anticipatory guidance related to farm safety. Pender's revised Health Promotion Model (2006) was used. A survey was developed and mailed to 110 PHCPs of all levels in North West Pennsylvania. The return rate was 20%. Types of injuries identified by the PHCPs included lacerations and musculosketal injuries caused by animals and farm equipment. Forty-five percent of the PHCPs reporting asked new patients/families if their children lived or worked on a farm. Eighteen percent specifically focused on farm-related injury prevention. Fourteen percent were aware of farm injury prevention materials and 73% were interested in receiving such materials. A larger study needs to be conducted to validate these findings.

  16. Farm Household Economic Model of The Integrated Crop Livestock System: Conceptual and Empirical Study

    Directory of Open Access Journals (Sweden)

    Atien Priyanti

    2007-06-01

    Full Text Available An integrated approach to enhance rice production in Indonesia is very prospectus throughout the implementation of adapted and liable integrated program. One of the challenges in rice crop sub sector is the stagnation of its production due to the limitation of organic matter availability. This provides an opportunity for livestock development to overcome the problems on land fertility through the use of manure as the source of organic fertilizer. Ministry of Agriculture had implemented a program on Increasing Integrated Rice Productivity with an Integrated Crop Livestock System as one of the potential components since 2002. Integrated crop livestock system program with special reference to rice field and beef cattle is an alternative to enhance the potential development of agriculture sector in Indonesia. The implementation on this integrated program is to enhance rice production and productivity through a system involving beef cattle with its goal on increasing farmers’ income. Household economic model can be used as one of the analysis to evaluate the success of the implemented crop livestock system program. The specificity of the farmers is that rationality behavior of the role as production and consumption decision making. In this case, farmers perform the production to meet home consumption based on the resources that used directly for its production. The economic analysis of farmers household can be described to anticipate policy options through this model. Factors influencing farmers’ decisions and direct interrelations to production and consumption aspects that have complex implications for the farmers’ welfare of the integrated crop livestock system program.

  17. National Farm Medicine Center

    Science.gov (United States)

    ... ROPS Rebate Skin Cancer Screening Zika Virus National Farm Medicine Center The National Farm Medicine Center was established in 1981 in response to occupational health problems seen in farm patients coming to Marshfield Clinic. The center continues ...

  18. Integrated water flow model and modflow-farm process: A comparison of theory, approaches, and features of two integrated hydrologic models

    Science.gov (United States)

    Dogrul, Emin C.; Schmid, Wolfgang; Hanson, Randall T.; Kadir, Tariq; Chung, Francis

    2016-01-01

    Effective modeling of conjunctive use of surface and subsurface water resources requires simulation of land use-based root zone and surface flow processes as well as groundwater flows, streamflows, and their interactions. Recently, two computer models developed for this purpose, the Integrated Water Flow Model (IWFM) from the California Department of Water Resources and the MODFLOW with Farm Process (MF-FMP) from the US Geological Survey, have been applied to complex basins such as the Central Valley of California. As both IWFM and MFFMP are publicly available for download and can be applied to other basins, there is a need to objectively compare the main approaches and features used in both models. This paper compares the concepts, as well as the method and simulation features of each hydrologic model pertaining to groundwater, surface water, and landscape processes. The comparison is focused on the integrated simulation of water demand and supply, water use, and the flow between coupled hydrologic processes. The differences in the capabilities and features of these two models could affect the outcome and types of water resource problems that can be simulated.

  19. 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...

  20. Off-farm Income and Risky Investments: What Happens to Farm and Nonfarm Assets?

    OpenAIRE

    Andersson, Hans; Ramaswami, Bharat; Moss, Charles B.; Erickson, Kenneth W.; Hallahan, Charles B.; Nehring, Richard F.

    2005-01-01

    Off-farm work improves and reduces the riskiness of household income. Theoretical analyses reveal that the level and riskiness of off-farm income affect demand for farm/nonfarm investments. A two-limit Tobit model is estimated using ARMS data for 1996-2003. The impact on investment behaviour is evaluated.

  1. Modeling the spatio-temporal dynamics of porcine reproductive & respiratory syndrome cases at farm level using geographical distance and pig trade network matrices.

    Science.gov (United States)

    Amirpour Haredasht, Sara; Polson, Dale; Main, Rodger; Lee, Kyuyoung; Holtkamp, Derald; Martínez-López, Beatriz

    2017-06-07

    Porcine reproductive and respiratory syndrome (PRRS) is one of the most economically devastating infectious diseases for the swine industry. A better understanding of the disease dynamics and the transmission pathways under diverse epidemiological scenarios is a key for the successful PRRS control and elimination in endemic settings. In this paper we used a two step parameter-driven (PD) Bayesian approach to model the spatio-temporal dynamics of PRRS and predict the PRRS status on farm in subsequent time periods in an endemic setting in the US. For such purpose we used information from a production system with 124 pig sites that reported 237 PRRS cases from 2012 to 2015 and from which the pig trade network and geographical location of farms (i.e., distance was used as a proxy of airborne transmission) was available. We estimated five PD models with different weights namely: (i) geographical distance weight which contains the inverse distance between each pair of farms in kilometers, (ii) pig trade weight (PT ji ) which contains the absolute number of pig movements between each pair of farms, (iii) the product between the distance weight and the standardized relative pig trade weight, (iv) the product between the standardized distance weight and the standardized relative pig trade weight, and (v) the product of the distance weight and the pig trade weight. The model that included the pig trade weight matrix provided the best fit to model the dynamics of PRRS cases on a 6-month basis from 2012 to 2015 and was able to predict PRRS outbreaks in the subsequent time period with an area under the ROC curve (AUC) of 0.88 and the accuracy of 85% (105/124). The result of this study reinforces the importance of pig trade in PRRS transmission in the US. Methods and results of this study may be easily adapted to any production system to characterize the PRRS dynamics under diverse epidemic settings to more timely support decision-making.

  2. Social-geographic approaches to application of economic-mathematical modeling in predicting the place of Ukrainian farming economies in food market commoditization

    Directory of Open Access Journals (Sweden)

    Valeriy Rudenko

    2017-11-01

    Full Text Available Social-geographic analysis of farmery with application of economic-mathematical modeling allowed for prediction of farming economies’ role in food market commoditization. The equation of potential demand was suggested. Actual consumption and its recommended rates with respect to meat and meat products, milk and milk products, eggs, fish and fish products, bread and cereal products, potatoes, vegetables, fruits and berries, etc, were compared. Cartographic model of Ukrainian domestic food market’s potential capacity (within good-money relations was developed. The low level of purchasing power, especially in rural population, makes a high percentage of foodstuffs be beyond the goods-money relations. In rural areas, they (inclusive of farmers produce and consume a significant portion of foodstuffs that escaped the goods-money relations, or such foodstuffs were given to them by the relatives. We regard that in the process of assessment of the capacity of domestic food market, this share of products should also be taken into account. The assessment also necessitates consideration of the number of urban and rural population in Ukrainian regions; manufacturing of certain types of agricultural production; needs in this or that type of product as prescribed by minimal and rational consumption rates. When predicting, with the use of economic-mathematical modeling, the places of farming economies in commoditization of food market, it is reasonable to apply the parameters of time series of the number of farming economies and the areas of lands used by them with consideration of the dynamics of population number and the level of its (population self-provision with agricultural production. Application of predictive linear models shows that the share of production manufactured by farming economies will be most essential before 2020 on the market of potatoes and vegetables (reaching 15 %. Despite the predicted double increase in animal production, its share

  3. Stochastic Prediction of Wind Generating Resources Using the Enhanced Ensemble Model for Jeju Island’s Wind Farms in South Korea

    OpenAIRE

    Deockho Kim; Jin Hur

    2017-01-01

    Due to the intermittency of wind power generation, it is very hard to manage its system operation and planning. In order to incorporate higher wind power penetrations into power systems that maintain secure and economic power system operation, an accurate and efficient estimation of wind power outputs is needed. In this paper, we propose the stochastic prediction of wind generating resources using an enhanced ensemble model for Jeju Island’s wind farms in South Korea. When selecting the poten...

  4. Mathematical modelling and simulation of solar-assisted drying of bulk farm products; Mathematische Modellierung und Simulation der solar unterstuetzten Trocknung landwirtschaftlicher Schuettgueter

    Energy Technology Data Exchange (ETDEWEB)

    Maltry, W.; Ziegler, T.; Richter, I.

    1997-04-01

    The report deals with problems associated with the harnessing of solar energy for drying bulk farm products: technical fundamentals, enthalpy diagrams, models for grain drying, experimental investigations, analysis of drying processes, benefits and applications of drying processes, advances. (HW) [Deutsch] Der Bericht behandelt die Probleme der Solarenergienutzung zur Trockung landwirtschaftlicher Massengueter: - Trocknungstechnische Grundlagen - Enthalpie-Diagramme - Modelle zur Koernertrocknung - experimentelle Untersuchungen - Analyse von Trocknungsprozesse - Nutzen und Verwertbarkeit der Trocknungsprozesse - Fortschritte. (HW)

  5. Modeling the effects of tile drain placement on the hydrologic function of farmed prairie wetlands

    Science.gov (United States)

    Werner, Brett; Tracy, John; Johnson, W. Carter; Voldseth, Richard A.; Guntenspergen, Glenn R.; Millett, Bruce

    2016-01-01

    The early 2000s saw large increases in agricultural tile drainage in the eastern Dakotas of North America. Agricultural practices that drain wetlands directly are sometimes limited by wetland protection programs. Little is known about the impacts of tile drainage beyond the delineated boundaries of wetlands in upland catchments that may be in agricultural production. A series of experiments were conducted using the well-published model WETLANDSCAPE that revealed the potential for wetlands to have significantly shortened surface water inundation periods and lower mean depths when tile is placed in certain locations beyond the wetland boundary. Under the soil conditions found in agricultural areas of South Dakota in North America, wetland hydroperiod was found to be more sensitive to the depth that drain tile is installed relative to the bottom of the wetland basin than to distance-based setbacks. Because tile drainage can change the hydrologic conditions of wetlands, even when deployed in upland catchments, tile drainage plans should be evaluated more closely for the potential impacts they might have on the ecological services that these wetlands currently provide. Future research should investigate further how drainage impacts are affected by climate variability and change.

  6. Factors affecting the level of farm indebtedness: the role of farming attitudes.

    OpenAIRE

    Peter Howley; Emma Dillon

    2012-01-01

    Using a nationally representative survey of farm operators in Ireland, this paper aims to provide a framework for better understanding the characteristics that influence the degree of indebtedness on farm businesses. This paper derives explanatory variables (based on a factor analysis of respondents mean ratings of 13 multiple value items) representing 3 different farming attitudes. An ordered logit model is then formulated to examine the effect of farming attitudes as well as personal charac...

  7. Wakes in very large wind farms and the effect of neighbouring wind farms

    International Nuclear Information System (INIS)

    Nygaard, Nicolai Gayle

    2014-01-01

    We present the first analysis of wake losses in some of the largest offshore wind farms built to date. In addition, we give an example of the external wake losses that can be imposed by a neighbouring wind farm. Both situations lend insights to the wake phenomena in large offshore wind farm clusters. A simple wake model is compared to the data to assess the need for a more detailed physical description of large wind farm wakes

  8. Disease spread models to estimate highly uncertain emerging diseases losses for animal agriculture insurance policies: an application to the U.S. farm-raised catfish industry.

    Science.gov (United States)

    Zagmutt, Francisco J; Sempier, Stephen H; Hanson, Terril R

    2013-10-01

    Emerging diseases (ED) can have devastating effects on agriculture. Consequently, agricultural insurance for ED can develop if basic insurability criteria are met, including the capability to estimate the severity of ED outbreaks with associated uncertainty. The U.S. farm-raised channel catfish (Ictalurus punctatus) industry was used to evaluate the feasibility of using a disease spread simulation modeling framework to estimate the potential losses from new ED for agricultural insurance purposes. Two stochastic models were used to simulate the spread of ED between and within channel catfish ponds in Mississippi (MS) under high, medium, and low disease impact scenarios. The mean (95% prediction interval (PI)) proportion of ponds infected within disease-impacted farms was 7.6% (3.8%, 22.8%), 24.5% (3.8%, 72.0%), and 45.6% (4.0%, 92.3%), and the mean (95% PI) proportion of fish mortalities in ponds affected by the disease was 9.8% (1.4%, 26.7%), 49.2% (4.7%, 60.7%), and 88.3% (85.9%, 90.5%) for the low, medium, and high impact scenarios, respectively. The farm-level mortality losses from an ED were up to 40.3% of the total farm inventory and can be used for insurance premium rate development. Disease spread modeling provides a systematic way to organize the current knowledge on the ED perils and, ultimately, use this information to help develop actuarially sound agricultural insurance policies and premiums. However, the estimates obtained will include a large amount of uncertainty driven by the stochastic nature of disease outbreaks, by the uncertainty in the frequency of future ED occurrences, and by the often sparse data available from past outbreaks. © 2013 Society for Risk Analysis.

  9. 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

  10. Wind Farm Control Survey

    DEFF Research Database (Denmark)

    Knudsen, Torben; Bak, Thomas; Svenstrup, Mikael

    2013-01-01

    This document is a delivery in the project NORCOWE. It is part of work package WP3.2.2. The main goal is to establish the present state-of-the-art for wind farm control for both research and practice. The main approach will be to study the literature. This will of cause be much more efficient...... for the research part than for the practice part. It is however not the intention to do company interviews or similar. This report is structured into a section for each WF control objective. These sections then includes the important control project issues: choice of input and output, control method, and modelling...... turbine farm based on a dynamic programming type of method....

  11. Monitoring and Modeling the Fate and Transport of Nitrate in the Vadose Zone beneath a Suwannee River Basin Vegetable Farm

    Science.gov (United States)

    Albert, M. A.; Graham, W. D.; Graetz, D.

    2002-05-01

    The Suwannee River basin has received much attention in recent years due to increased nitrogen levels in the groundwater-fed rivers of the basin that could seriously affect the welfare of this ecosystem. Nitrogen levels have increased from 0.1mg/l NO3-N to more than 5 mg/L NO3-N in many springs in the Suwannee Basin over the past 40 years. Nitrate concentrations in the Suwannee River itself have been increasing at the rate of .02 mg/L per year over the past 20 years. Suwannee River nitrate loads increase from 2300 kg/day to 6000 kg/day over a 33 mile stretch of the river between Dowling Park and Branford, Florida. Within this stretch of river, 89% of the nitrate loading appeared to come from the lower two-thirds, where agriculture is the dominant land use. The objective of this research is to monitor and model the impacts of alternative nutrient and water management practices on soil water quality, groundwater quality and crop yield at a commercial vegetable farm in the Suwannee River Basin. Groundwater monitoring wells, suction lysimeters, soil cores and TDR probes are used to monitor water and nitrogen transport at the site. Periodic plant biomass sampling is conducted to determine nitrogen uptake by the plants and to estimate crop yield. Field data show that two-thirds of the nitrogen applied to the spring 2001 potato crop leached to groundwater due to excessive irrigation and poor nitrogen uptake efficiency by the potatoes. The DSSAT35-Potato Crop model and the LEACHM vadose-zone model were calibrated for the spring 2001 potato crop and used to predict nitrogen leaching and crop yield for alternative management practices. Simulation results show that by reducing the duration of irrigation, reducing the fertilizer application rate, and improving the timing of fertilizer applications, nitrogen leaching can be reduced by approximately 50% while maintaining acceptable crop yields. Results of this project will ultimately be used to develop best management practices

  12. Determination of the phenomena involved when de-energing transformers for wind-farms. Modelling, residual fluxes calculation and validation by on site tests

    Energy Technology Data Exchange (ETDEWEB)

    Rioual, Michel [Societe Electricite de France (EDF) (France). Themis Dept.; Reveret, Jean-Christophe [Ecole Speciale de Mecanique et d' Electricite, Ivry-sur-Seine (France)

    2009-07-01

    The energization of the main transformers for wind-farms is an important issue, as it has a major impact on the voltage dips at the Delivery Point and consequently on the power delivery. One of the main point is the determination of the phenomena at the transformer energizing prior its energization, which are described in the paper, and mainly the residual fluxes circulating in the iron core. The residual fluxes have been determined in the case of the de-energization of the main transformers for wind-farms, with a detailed modelling of the equipment under the phenomena involved. A methodology is presented to obtain those fluxes; the values obtained have then be considered as initial conditions for the transformers energization, the inrush currents and overvoltages determined by the EMTP-RV program, and finally validated by on site tests. (orig.)

  13. 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....

  14. Challenges in wind farm optimization

    DEFF Research Database (Denmark)

    Larsen, Gunner Chr.

    for the wind turbine modeling, where aeroelastic models are required, and for the wind farm flow field description, where in-stationary flow field modeling is needed to capture the complicated mixture of atmospheric boundary layer (ABL) flows and upstream emitted meandering wind turbine wakes, which together...... dictates the fatigue loading of the individual wind turbines. Within an optimization context, the basic challenge in describing the in-stationary wind farm flow field is computational speed. The Dynamic Wake Meandering (DWM) model includes the basic features of a CFD Large Eddy Simulation approach...

  15. 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

  16. 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 ...

  17. ARIZONA FARM LABOR REPORT.

    Science.gov (United States)

    SALTER, RICHARD H.

    THE ORGANIZATION OF THE FARM PLACEMENT PROGRAM IS DESCRIBED. INCLUDED ARE THE ADMINISTRATIVE ORGANIZATIONS, THE LOCAL LEVELS, THE STATE FARM LABOR ADVISORY COMMITTEE, AND THE PLANNING AND OPERATING METHODS USED BY FARM PLACEMENT PERSONNEL IN MEETING FARM LABOR NEEDS. MAJOR CROP ACTIVITIES ARE RELATED TO COTTON AND VEGETABLES. THE LABOR FORCE IS…

  18. Mountain Pesticide Education and Safety Outreach program: a model for community collaboration to enhance on-farm safety and health.

    Science.gov (United States)

    Hamilton, Jim; Sidebottom, Jill

    2011-01-01

    This article showcases the outcomes of the Mountain Pesticide Education and Safety Outreach program, a collaborative effort between Christmas tree growers, cooperative extension, farmworkers, farmworker health outreach staff, and others to reduce pesticide exposure and on-farm injuries. Lessons learned during the project that can be adopted by other communities will also be shared.

  19. Modelling farmers' action: decision rules capture methodology and formalisation structure: a case of biomass flow operations in dairy farms of a tropical island.

    Science.gov (United States)

    Vayssières, J; Lecomte, P; Guerrin, F; Nidumolu, U B

    2007-06-01

    Studies on decision-making processes are generally aimed at identifying farmers' needs and predicting farmers' reactions to technical innovations. In the present paper we study these decision-making processes, with reference to dairy farms, to build a whole-farm computer model (WFM) which simulates farmers' actions. In this study, (i) a multi-tool and multi-step methodology is proposed, which can also be qualified as an iterative and interactive methodology to reveal decision rules and (ii) a generic structure to formalise how action is conducted, termed 'structure for action modelling' (SAM). In the case of forage crop-dairy cattle systems, we have tested the current methodology to capture the decision rules and the SAM to represent action concerning farm management. An 'immersion' approach, inspired by the ethnographic approach has been adapted to access operational technical decisions (taken on a daily basis). This study helped in understanding how detailed and large approaches can be complementary and can facilitate identification of what can be generalised in a conceptual model. To define the generic structure (SAM), a set of descriptive variables concerning technical operations has been selected. The conceptual model generated is composed of decision rules reconstructed by researchers with farmers' committed participation. The validation method is based on participatory approaches and on comparing of actions simulated by the model with practices on the ground. Not contesting the fact that farmers plan their action, this study also revealed the importance of adjustments in action. For example, 20 to 55% of the time the planned food ration is not distributed to the milking cows because of forage unavailability. We also discuss how this structure can facilitate integration of decision mechanisms in biophysical models and how such an integration of adjustment decision rules can produce more realistic simulations of technical actions. Error of biotechnical

  20. Organic Farming in Austria

    OpenAIRE

    Vogl, C. R.; Heß, J.

    1999-01-01

    During the present decade, Austria has experienced a dramatic increase in organic farming among those countries that comprise the European Union (EU). For example, in 1992, approximately 2,000 farms were practicing organic, ecological, or biodynamic farming methodes. By 1997 the number of certified organic farms plus those in transition from conventional farming had increased 10-fold to some 20,000 farms. This represents almost 9% of the total farms in Austria and an area of 345,375 ha, or 10...

  1. 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

  2. IS NON-FARM INCOME RELAXING FARM INVESTMENT LIQUIDITYCONSTRAINTS FOR MARGINAL FARMS? AN INSTRUMENTALVARIABLE APPROACH

    Directory of Open Access Journals (Sweden)

    Kidanemariam Gebregziabher

    2012-01-01

    Full Text Available This papertests thehypothesis that off-farm income relaxes the liquidityconstraints of farm households usingsurvey data derived from 734 householdsfrom eight villages, drawn from the three agro-climatic zones of northernEthiopia.The results of the econometric models show that off-farm incomepositively affects agricultural input expenditure but negatively affects livestockinvestment. This may be explained by the higher per capita land holdings ofhouseholds who invest in improved agricultural inputs compared to those whoinvest in livestock. Our results show the complementarities between off-farmactivities and productivity enhancing investment for agricultural inputs. However,off-farm activities may be competing for labor resources for landless and nearlandless households (those who invest in livestock.

  3. 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

  4. Report on the use of stability parameters and mesoscale modelling in short-term prediction[Wind speed at wind farm sites

    Energy Technology Data Exchange (ETDEWEB)

    Badger, J.; Giebel, G.; Guo Larsen, X.; Skov Nielsen, T.; Aalborg Nielsen, H.; Madsen, Henrik; Toefting, J.

    2007-06-15

    In this report investigations using atmospheric stability measures to improve wind speed predictions at wind farm sites are described. Various stability measures have been calculated based on numerical weather prediction model output. Their ability to improve the wind speed predictions is assessed at three locations. One of the locations is in complex terrain. Mesoscale modelling has been carried out using KAMM at this location. The characteristics of the measured winds are captured well by the mesoscale modelling. It can be seen that the atmospheric stability plays an important role in determining how the flow is influence by the terrain. A prediction system employing a look-up table approach based on wind class simulations is presented. The mesoscale modelling results produced by KAMM were validated using an alternative mesoscale model called WRF. A good agreement in the results of KAMM and WRF was found. It is shown that including a stability parameter in physical and/or statistical modelling can improve the wind speed predictions at a wind farm site. A concept for the inclusion of a stability measure in the WPPT prediction system is presented, and the testing of the concept is outlined. (au)

  5. Adoption of Organic Farming as an Opportunity for Syrian Farmers of Fresh Fruit and Vegetables: An Application of the Theory of Planned Behaviour and Structural Equation Modelling

    Directory of Open Access Journals (Sweden)

    Irwa Issa

    2017-11-01

    Full Text Available Exporting organic fresh fruit and vegetables (FFV to the European Union could represent a great opportunity for Syrian farmers and exporters. Yet, the organic sector in Syria is comparatively young and only a very small area of FFV is organically managed. To date, little is known about Syrian farmers’ attitudes towards organic FFV production. Therefore, the aim of this study was to explore the intentions and attitudes of Syrian farmers of FFV towards organic farming and how likely they are to convert their farms to organic production within the next five years. Using a two-stage cluster sampling procedure, 266 conventional farmers of FFV in 75 villages located in different districts of Syria’s coastal region were selected for this survey. Data was collected through face-to-face interviews by a project partner in Syria (Citrus Fruit Board in Tartous from December 2012 until mid-May 2013. We used the Theory of Planned Behaviour as theoretical framework and Partial Least Squares Path Modelling as the main tool for data analysis. The results show that most farmers used at least one of the practices that are also part of certified organic production (throughout this article, the term organic agriculture, farming, and/or production always refer to certified organic agricultural production, and hold strong positive attitudes and intentions to adopt organic production within the next five years.

  6. 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.

  7. 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.

  8. Investigating Navy Officer Retention Using Data Farming

    Science.gov (United States)

    2015-09-01

    OFFICER RETENTION USING DATA FARMING by Aurel N. DeHollan September 2015 Thesis Advisor: Samuel E. Buttrey Second Reader: Thomas W...COVERED Master’s thesis 4. TITLE AND SUBTITLE INVESTIGATING NAVY OFFICER RETENTION USING DATA FARMING 5. FUNDING NUMBERS 6. AUTHOR(S) DeHollan...historical loss rates. The application of data farming to this model allows for investigation of different scenarios that can provide insight into both

  9. Data Farming and Defense Applications

    Science.gov (United States)

    Horne, Gary; Meyer, Ted

    2011-01-01

    .Data farm,ing uses simulation modeling, high performance computing, experimental design and analysis to examine questions of interest with large possibility spaces. This methodology allows for the examination of whole landscapes of potential outcomes and provides the capability of executing enough experiments so that outliers might be captured and examined for insights. It can be used to conduct sensitivity studies, to support validation and verification of models, to iteratively optimize outputs using heuristic search and discovery, and as an aid to decision-makers in understanding complex relationships of factors. In this paper we describe efforts at the Naval Postgraduate School in developing these new and emerging tools. We also discuss data farming in the context of application to questions inherent in military decision-making. The particular application we illustrate here is social network modeling to support the countering of improvised explosive devices.

  10. The Effect of Off-Farm Employment on Forestland Transfers in China: A Simultaneous-Equation Tobit Model Estimation

    Directory of Open Access Journals (Sweden)

    Han Zhang

    2017-09-01

    Full Text Available China’s new round tenure reform has devolved collective forests to individuals on an egalitarian basis. To balance the equity–efficiency dilemma, forestland transfers are highly advocated by policymakers. However, the forestland rental market is still inactive after the reform. To examine the role of off-farm employment in forestland transfers, a simultaneous Tobit system of equations was employed to account for the endogeneity, interdependency, and censoring issues. Accordingly, the Nelson–Olson two-stage procedure, embedded with a multivariate Tobit estimator, was applied to a nationally representative dataset. The estimation results showed that off-farm employment plays a significantly negative role in forestland rent-in, at the 5% risk level. However, off-farm activities had no significant effect on forestland rent-out. Considering China’s specific situation, a reasonable explanation is that households hold forestland as a crucial means of social security against the risk of unemployment. In both rent-in and rent-out equations, high transaction costs are one of the main obstacles impeding forestland transfer. A remarkable finding was that forestland transactions occurred with a statistically significant factor equalization effect, which would be helpful to adjust the mismatched labor–land ratio and improve the land-use efficiency.

  11. Environmental Bio Economic Impact in Nicaragua

    OpenAIRE

    Blanco Orozco, Napoleón Vicente; Zuniga Gonzalez, Carlos Alberto

    2013-01-01

    In this article the Bio economy of power plants connected to the national interconnected system of Nicaragua is analyzed, through the study of environmental effects of greenhouse gases emissions from the use of solid biomass from sugarcane bagasse and oil to generate electricity. In addition, an analysis of Cost - Benefit of investments to the electricity generation using fossil fuel and bagasse is done. The Methodology EX-Ante Carbon-balance Tool (EX-ACT) was used; this methodology was propo...

  12. AN EVOLUTIONARY STUDY ON CROP PRODUCTION IN SMALL FARM SYSTEMS IN THE MID-WEST REGION OF BRAZIL BASED ON A LINEAR PROGRAMMING MODEL

    Directory of Open Access Journals (Sweden)

    Maria Amelia Biagio

    2014-05-01

    Full Text Available Based on an agro-technical study for the mid-west region of Brazil, and considering financial conditions like monthly expenses and long-term investments, a mixed integer and dynamic linear model has been proposed for representing crop production systems. This model establishes a monthly dynamic treatment of production and financial activities over a long-term planning horizon for small and medium farm systems. In this paper, by considering more recent government financial policies for the Brazilian agricultural sector related to the Pronaf and Proger credit lines, a mathematical model is updated for distinct situations derived from the use of short and long-term loans which were defined for small and medium farmers. In this way, new versions of the original model are obtained by separately implementing into the production systems economic and financial conditions of credit lines for the years 2006 and 2009. Computational tests are performed and the results obtained are presented in several scenarios. Also, an evolutionary analysis on the socio-economic and financial feasibility of the agricultural farm system is drawn over the last decade by comparing the results obtained to one known from the year 2002.

  13. Offshore Wind Farms

    DEFF Research Database (Denmark)

    Lundtang Petersen, Erik; Hasager, Charlotte Bay; Courtney, Michael

    2015-01-01

    The technology behind constructing wind farms offshore began to develop in 1991 when the Vindeby wind farm was installed off the Danish coast (11 Bonus 450 kW turbines). Resource assessment, grid connection, and wind farm operation are significant challenges for offshore wind power just...... concern are the problems associated with locating the turbines close together in a wind farm and the problems of placing several large wind farms in a confined area. The environmental impacts of offshore wind farms are also treated, but not the supply chain, that is, the harbors, the installation vessels...

  14. Estimation of flock/herd-level true Mycobacterium avium subspecies paratuberculosis prevalence on sheep, beef cattle and deer farms in New Zealand using a novel Bayesian model.

    Science.gov (United States)

    Verdugo, Cristobal; Jones, Geoff; Johnson, Wes; Wilson, Peter; Stringer, Lesley; Heuer, Cord

    2014-12-01

    The study aimed to estimate the national- and island-level flock/herd true prevalence (HTP) of Mycobacterium avium subsp. paratuberculosis (MAP) infection in pastoral farmed sheep, beef cattle and deer in New Zealand. A random sample of 238 single- or multi-species farms was selected from a postal surveyed population of 1940 farms. The sample included 162 sheep flocks, 116 beef cattle and 99 deer herds from seven of 16 geographical regions. Twenty animals from each species present on farm were randomly selected for blood and faecal sampling. Pooled faecal culture testing was conducted using a single pool (sheep flocks) or two pools (beef cattle/deer herds) of 20 and 10 samples per pool, respectively. To increase flock/herd-level sensitivity, sera from all 20 animals from culture negative flocks/herds were individually tested by Pourquier(®) ELISA (sheep and cattle) or Paralisa™ (deer). Results were adjusted for sensitivity and specificity of diagnostic tests using a novel Bayesian latent class model. Outcomes were adjusted by their sampling fractions to obtain HTP estimates at national level. For each species, the posterior probability (POPR) of HTP differences between New Zealand North (NI) and South (SI) Islands was obtained. Across all species, 69% of farms had at least one species test positive. Sheep flocks had the highest HTP estimate (76%, posterior probability interval (PPI) 70-81%), followed by deer (46%, PPI 38-55%) and beef herds (42%, PPI 35-50%). Differences were observed between the two main islands of New Zealand, with higher HTP in sheep and beef cattle flocks/herds in the NI. Sheep flock HTP was 80% in the NI compared with 70% (POPR=0.96) in the SI, while the HTP for beef cattle was 44% in the NI and 38% in the SI (POPR=0.80). Conversely, deer HTP was higher in the SI (54%) than the NI (33%, POPR=0.99). Infection with MAP is endemic at high prevalence in sheep, beef cattle and deer flocks/herds across New Zealand. Copyright © 2014 Elsevier B

  15. Effect of dairy farming system, herd, season, parity, and days in milk on modeling of the coagulation, curd firming, and syneresis of bovine milk.

    Science.gov (United States)

    Bittante, G; Cipolat-Gotet, C; Malchiodi, F; Sturaro, E; Tagliapietra, F; Schiavon, S; Cecchinato, A

    2015-04-01

    The objectives of this study were to characterize the variation in curd firmness model parameters obtained from coagulating bovine milk samples, and to investigate the effects of the dairy system, season, individual farm, and factors related to individual cows (days in milk and parity). Individual milk samples (n = 1,264) were collected during the evening milking of 85 farms representing different environments and farming systems in the northeastern Italian Alps. The dairy herds were classified into 4 farming system categories: traditional system with tied animals (29 herds), modern dairy systems with traditional feeding based on hay and compound feed (30 herds), modern dairy system with total mixed ration (TMR) that included silage as a large proportion of the diet (9 herds), and modern dairy system with silage-free TMR (17 herds). Milk samples were analyzed for milk composition and coagulation properties, and parameters were modeled using curd firmness measures (CFt) collected every 15 s from a lacto-dynamographic analysis of 90 min. When compared with traditional milk coagulation properties (MCP), the curd firming measures showed greater variability and yielded a more accurate description of the milk coagulation process: the model converged for 93.1% of the milk samples, allowing estimation of 4 CFt parameters and 2 derived traits [maximum CF (CF(max)) and time from rennet addition to CF(max) (t(max))] for each sample. The milk samples whose CFt equations did not converge showed longer rennet coagulation times obtained from the model (RCT(eq)) and higher somatic cell score, and came from less-productive cows. Among the sources of variation tested for the CFt parameters, dairy herd system yielded the greatest differences for the contrast between the traditional farm and the 3 modern farms, with the latter showing earlier coagulation and greater instant syneresis rate constant (k(SR)). The use of TMR yielded a greater tmax because of a higher instant curd

  16. Modeling and Simulation of Transient Fault Response at Lillgrund Wind Farm when Subjected to Faults in the Connecting 130 kV Grid

    Energy Technology Data Exchange (ETDEWEB)

    Eliasson, Anders; Isabegovic, Emir

    2009-07-01

    The purpose of this thesis was to investigate what type of faults in the connecting grid should be dimensioning for future wind farms. An investigation of over and under voltages at the main transformer and the turbines inside Lillgrund wind farm was the main goal. The results will be used in the planning stage of future wind farms when performing insulation coordination and determining the protection settings. A model of the Lillgrund wind farm and a part of the connecting 130 kV grid were built in PSCAD/EMTDC. The farm consists of 48 Siemens SWT-2.3-93 2.3 MW wind turbines with full power converters. The turbines were modeled as controllable current sources providing a constant active power output up to the current limit of 1.4 pu. The transmission lines and cables were modeled as frequency dependent (phase) models. The load flows and bus voltages were verified towards a PSS/E model and the transient response was verified towards measuring data from two faults, a line to line fault in the vicinity of Barsebaeck (BBK) and a single line-to-ground fault close to Bunkeflo (BFO) substation. For the simulation, three phase to ground, single line to ground and line to line faults were applied at different locations in the connecting grid and the phase to ground voltages at different buses in the connecting grid and at turbines were studied. These faults were applied for different configurations of the farm. For single line to ground faults, the highest over voltage on a turbine was 1.22 pu (32.87 kV) due to clearing of a fault at BFO (the PCC). For line to line faults, the highest over voltage on a turbine was 1.59 pu (42.83 kV) at the beginning of a fault at KGE one bus away from BFO. Both these cases were when all radials were connected and the turbines ran at full power. The highest over voltage observed at Lillgrund was 1.65 pu (44.45 kV). This over voltage was caused by a three phase to ground fault applied at KGE and occurred at the beginning of the fault and when

  17. A simulation of the SDC on-line processing farm

    International Nuclear Information System (INIS)

    Wang, C.; Chen, Y.; Dorenbosch, J.; Lee, J.; Sayle, R.

    1993-10-01

    In the Solenoidal Detector Collaboration (SDC) data acquisition system (DAQ), an enormous amount of data flows into a processor farm for extraction of interesting physics events. To design an efficient on-line filter, the operations in the farm must be carefully modeled. The authors present a simulation model developed at the Superconducting Super Collider Laboratory which efficiently allocates physics events to the farm

  18. Harmonic Aspects of Offshore Wind Farms

    DEFF Research Database (Denmark)

    Kocewiak, Lukasz Hubert; Bak, Claus Leth; Hjerrild, Jesper

    2010-01-01

    This paper presents the aim, the work and the findings of a PhD project entitled "Harmonics in Large Offshore Wind Farms". It focuses on the importance of harmonic analysis in order to obtain a better performance of future wind farms. The topic is investigated by the PhD project at Aalborg...... University (AAU) and DONG Energy. The objective of the project is to improve and understand the nature of harmonic emission and propagation in wind farms (WFs), based on available information, measurement data and simulation tools. The aim of the project is to obtain validated models and analysis methods...... of offshore wind farm (OWF) systems....

  19. Formulating Rural Development Programmes to Aid Low-Income Farm Families

    OpenAIRE

    Findeis, Jill L.; Reddy, Venkateshwar K.

    1989-01-01

    Rural development programmes may facilitate the off-farm employment of low-income farm families and provide additional public suppon beyond traditional US farm income and price support programmes. To examine the implications of alternative rural development strategies for low-income farmers, joint off-farm labour participation models are developed for farm operators and spouses. Univariate and bivariate probit models are estimated. based on 1985 Current Population Survey farm household data. ...

  20. An MCDA and GIS coupling conceptual model to be used in a circular decision process by stakeholders involved in large wind farm projects

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez, M. [Quebec Univ., Rimouski, PQ (Canada). Laboratoire de Recherche en Energie Eolienne; Quebec Univ., Montreal, PQ (Canada). GEIGER; Waaub, J.P. [Quebec Univ., Montreal, PQ (Canada). GEIGER; Ilinca, A. [Quebec Univ., Rimouski, PQ (Canada). Laboratoire de Recherche en Energie Eolienne

    2010-07-01

    This poster presentation described an MCDA and geographic information system (GIS) coupling conceptual model designed for use in stakeholder decision-making processes for large wind farm projects. The model was comprised of 4 modules and 4 stakeholder categories that considered the environment and communities involved in the project. The integrated modelling approach was designed to ensure a transparent decision-making process. The modules included: (1) an MCDA module, (2) a local expertise and scientific knowledge module, (3) a stakeholder involvement module, and (4) a participatory GIS module. The model can be used to structure issues during consultation procedures, as well as to conduct preference analyses and to identify indicators. Examples of stakeholder weighting were included. tabs., figs.

  1. TOPFARM wind farm optimization tool

    Energy Technology Data Exchange (ETDEWEB)

    Rethore, P.-E.; Fuglsang, P.; Larsen, Torben J.; Buhl, T.; Larsen, Gunner C.

    2011-02-15

    A wind farm optimization framework is presented in detail and demonstrated on two test cases: 1) Middelgrunden and 2) Stags Holt/Coldham. A detailed flow model describing the instationary flow within a wind farm is used together with an aeroelastic model to determine production and fatigue loading of wind farm wind turbines. Based on generic load cases, the wind farm production and fatigue evaluations are subsequently condensed in a large pre-calculated database for rapid calculation of lifetime equivalent loads and energy production in the optimization loop. The objective function defining the optimization problem includes elements as energy production, turbine degradation, operation and maintenance costs, electrical grid costs and foundation costs. The objective function is optimized using a dedicated multi fidelity approach with the locations of individual turbines in the wind farm spanning the design space. The results are over all satisfying and are giving some interesting insights on the pros and cons of the design choices. They show in particular that the inclusion of the fatigue loads costs give rise to some additional details in comparison with pure power based optimization. The Middelgrunden test case resulted in an improvement of the financial balance of 2.1 M Euro originating from a very large increase in the energy production value of 9.3 M Euro mainly counterbalanced by increased electrical grid costs. The Stags Holt/Coldham test case resulted in an improvement of the financial balance of 3.1 M Euro. (Author)

  2. The Circumstances and Subjects of "Eco-Farming" through the Collaboration among Cultivation and Livestock Farming : The Analysis of Cases based on "The Nonprofit Making Business Model of Social Entrepreneur"

    OpenAIRE

    Honda, Hikaru

    2009-01-01

    This research investigated the cases of "Eco-Farming" through the construction system combination of crop cultivation and livestock farming, for the purpose of preserving the natural ecosystem and responding to the needs of consumers who look for safety and reliability in agricultural products. The research further presented conditions in which to realize such agriculture. The conditions are as follows: (1) A leader exists, in which s/he develops the ideas of sales operation as well as collab...

  3. Wind turbine wakes; power deficit in clusters and wind farms

    DEFF Research Database (Denmark)

    Hansen, Kurt Schaldemose; Barthelmie, Rebecca

    2012-01-01

    The purpose of this presentation is to present recent power deficit analysis based on wind farm measurements. The power deficit is used to validate wind farm prediction models for different inflow conditions......The purpose of this presentation is to present recent power deficit analysis based on wind farm measurements. The power deficit is used to validate wind farm prediction models for different inflow conditions...

  4. Organic farming at the farm level

    DEFF Research Database (Denmark)

    Jacobsen, Brian H.; Madsen, Niels; Ørum, Jens Erik

    The purpose of this report is to present possible impacts of new technology and changes in legislation on the profitability of different types of organic farms. The aim is also to look at both the current and future trends in the organic area in Denmark. The farm level analyses are carried out...... as part of a larger project entitled “Economic analyses of the future development of organic farming – effects at the field, farm, sector and macroeconomic level”. The project links effects at the field-level with analyses at the farm level. These effects are then used in sector and macroeconomic analyses......, which are described in other reports from Food and Resource Economic Institute (Jacobsen, 2005 and Andersen et al., 2005). This gives coherent results from the field to the macroeconomic level regarding changes in technology and legislation....

  5. The farm apprentice: agricultural college students recollections of learning to farm "safely".

    Science.gov (United States)

    Sanderson, L L; Dukeshire, S R; Rangel, C; Garbes, R

    2010-10-01

    A consistent message in the farm safety literature is the need to develop effective interventions to manage the unacceptably high rate of injury and death among farm children. To better understand the influence of childhood farm experiences on safety beliefs, attitudes, and practices, semi-structured interviews were conducted with 24 farm youth attending the Nova Scotia Agricultural College. The interviews were designed to elicit information pertaining to participants' earliest memories of involvement in farm activities, the decision-making processes that led them to assume work-related responsibilities, and the roles that their parents played in their safety training. A common theme of experiencing childhood as a "farm apprentice" emerged across all narratives whereby farm activities were learned primarily through observational learning and modeling of parents and then mastered through repetition. As "farm apprentices," the youths' involvement in dangerous activities such as tractor driving and livestock handling began at early ages, with very little formal training and supervision. Although participants clearly described themselves as being exposed to dangerous activities, they believed that they had the capacity to control the risks and farm safely. Based on our findings, the concept of the "farm apprentice" appears to be integral to the social context of the farming community and should be considered in the design of interventions to reduce child injury and death.

  6. Modeling of Mycobacterium avium subsp. paratuberculosis in farm bulk tank milk

    DEFF Research Database (Denmark)

    Okura, Hisako; Nielsen, Søren Saxmose; Toft, Nils

    2012-01-01

    positive. Furthermore, direct MAP contamination of milk was related to infection stages while indirect contamination was associated to within-herd prevalence and distribution of infection stages. Control options implemented included discarding of milk based on diagnostic test results. Median MAP load...... in farm bulk tank milk at within-herd infection prevalences from 7.5 to 60% were estimated to 0.74-6.81 cfu/ml, of which the contribution of direct contamination was less than 1%. Maximum concentration at the prevalence of 60% could be 1186 cfu/ml caused by shedding of high amounts of MAP in feces from...

  7. Values in Organic Farming

    DEFF Research Database (Denmark)

    Kjærgård, Bente; Pedersen, Kirsten Bransholm; Land, Birgit

    The study focuses on the recent debate about what is, or what constitutes, organic farming and what is the right path for organic farming in the future. The study is based on a critical discourse analysis of the controversy about suspending the private standard for organic farming adopted by the ...

  8. Forest farming practices

    Science.gov (United States)

    J.L. Chamberlain; D. Mitchell; T. Brigham; T. Hobby; L. Zabek; J. Davis

    2009-01-01

    Forest farming in North America is becoming popular as a way for landowners to diversify income opportunities, improve management of forest resources, and increase biological diversity. People have been informally "farming the forests" for generations. However, in recent years, attention has been directed at formalizing forest farming and improving it...

  9. 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.

  10. Evaluation of Two Models of Non-Penetrating Captive Bolt Devices for On-Farm Euthanasia of Turkeys

    Directory of Open Access Journals (Sweden)

    Caitlin R. Woolcott

    2018-03-01

    Full Text Available On-farm euthanasia is a critical welfare issue in the poultry industry and can be particularly difficult to perform on mature turkeys due to their size. We evaluated the efficacy of two commercially available non-penetrating captive bolt devices, the Zephyr-EXL and the Turkey Euthanasia Device (TED, on 253 turkeys at three stages of production: 4–5, 10, and 15–20 weeks of age. Effectiveness of each device was measured using both ante- and post-mortem measures. Application of the Zephyr-EXL resulted in a greater success rate (immediate abolishment of brainstem reflexes compared to the TED (97.6% vs. 89.3%, p = 0.0145. Times to last movement (p = 0.102 and cardiac arrest (p = 0.164 did not differ between devices. Ante- and post-mortem measures of trauma and hemorrhage were highly correlated. Skull fractures and gross subdural hemorrhage (SDH were present in 100% of birds euthanized with both the Zephyr-EXL and TED devices. Gross SDH scores were greater in birds killed with the Zephyr-EXL than the TED (p < 0.001. Microscopic SDH scores indicated moderate to severe hemorrhage in 92% of turkeys for the Zephyr-EXL and 96% of turkeys for the TED, with no difference between devices (p = 0.844. Overall, both devices were highly effective inducing immediate insensibility through traumatic brain injury and are reliable, single-step methods for on-farm euthanasia of turkeys.

  11. Net-energy analysis of integrated food and bioenergy systems exemplified by a model of a self-sufficient system of dairy farms

    Directory of Open Access Journals (Sweden)

    Mads Ville Markussen

    2015-11-01

    Full Text Available Agriculture is expected to contribute in substituting of fossil fuels in the future. This constitutes a paradox as agriculture depends heavily on fossil energy for providing fuel, fodder, nutrients and machinery. The aim of this paper is to investigate whether organic agriculture is capable of providing both food and surplus energy to the society as evaluated from a model study. We evaluated bioenergy technologies in a Danish dairy farming context in four different scenarios: 1 vegetable oil based on oilseed rape, 2 biogas based on cattle manure and grass-clover lays, 3 bioethanol from rye grain and whey, and 4 a combination of 1 and 2. When assessing the energetic net-contribution to society from bioenergy systems, two types of problems arise: How to aggregate non-equivalent types of energy services, and how to account for non-equivalent types of inputs and co-products from the farming? To avoid the first type, the net output of liquid fuels, electricity, useful heat and food were calculated separately. Further, to avoid the second type, all scenarios were designed to provide self-sufficiency with fodder and fertilizer and to utilize co-products within the system. This approach resulted in a transparent assessment of the net-contribution to society, which is easy to interpret. We conclude that if 20% of land is used for energy crops, farm-gate energy self-sufficiency can be achieved at the cost of 17% reduction in amount of food produced. These results demonstrate the strong limitations for (organic agriculture in providing both food and surplus energy.

  12. Net-Energy Analysis of Integrated Food and Bioenergy Systems Exemplified by a Model of a Self-Sufficient System of Dairy Farms

    International Nuclear Information System (INIS)

    Markussen, Mads Ville; Pugesgaard, Siri; Oleskowicz-Popiel, Piotr; Schmidt, Jens Ejbye; Østergård, Hanne

    2015-01-01

    Agriculture is expected to contribute in substituting of fossil fuels in the future. This constitutes a paradox as agriculture depends heavily on fossil energy for providing fuel, fodder, nutrients, and machinery. The aim of this paper is to investigate whether organic agriculture is capable of providing both food and surplus energy to the society as evaluated from a model study. We evaluated bioenergy technologies in a Danish dairy-farming context in four different scenarios: (1) vegetable oil based on oilseed rape, (2) biogas based on cattle manure and grass-clover lays, (3) bioethanol from rye grain and whey, and (4) a combination of (1) and (2). When assessing the energetic net-contribution to society from bioenergy systems, two types of problems arise: how to aggregate non-equivalent types of energy services and how to account for non-equivalent types of inputs and coproducts from the farming? To avoid the first type, the net output of liquid fuels, electricity, useful heat, and food were calculated separately. Furthermore, to avoid the second type, all scenarios were designed to provide self-sufficiency with fodder and fertilizer and to utilize coproducts within the system. This approach resulted in a transparent assessment of the net-contribution to society, which is easy to interpret. We conclude that if 20% of land is used for energy crops, farm-gate energy self-sufficiency can be achieved at the cost of 17% reduction in amount of food produced. These results demonstrate the strong limitations for (organic) agriculture in providing both food and surplus energy.

  13. Server farms with setup costs

    NARCIS (Netherlands)

    Gandhi, A.; Harchol-Balter, M.; Adan, I.

    2010-01-01

    In this paper we consider server farms with a setup cost. This model is common in manufacturing systems and data centers, where there is a cost to turn servers on. Setup costs always take the form of a time delay, and sometimes there is additionally a power penalty, as in the case of data centers.

  14. Power fluctuations from large wind farms - Final report

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, Poul; Pinson, P.; Cutululis, N.A.; Madsen, Henrik; Jensen, Leo Enrico; Hjerrild, J.; Heyman Donovan, M.; Vigueras-ROdriguez, A.

    2009-08-15

    Experience from power system operation with the first large offshore wind farm in Denmark: Horns Rev shows that the power from the wind farm is fluctuating significantly at certain times, and that this fluctuation is seen directly on the power exchange between Denmark and Germany. This report describes different models for simulation and prediction of wind power fluctuations from large wind farms, and data acquired at the two large offshore wind farms in Denmark are applied to validate the models. Finally, the simulation model is further developed to enable simulations of power fluctuations from several wind farms simultaneously in a larger geographical area, corresponding to a power system control area. (au)

  15. Alley Farming in Thailand

    Directory of Open Access Journals (Sweden)

    Teerapol Silakul

    2010-08-01

    Full Text Available Poverty alleviation and environmental preservation are very important issues to many governments. Alley farming is beneficial to the environment because it conserves soil and sustains yields over time. Specifically, alley farming reduces soil erosion, which is a major problem in Thailand. Alley farming was conducted on a farmer’s field at Khaokwan Thong, a village in Uthaithani Province, Northern Thailand. We did a two-by-two factorial with and without alley farming, and with and without fertilizer. From this study, we observed that the two species used, Leucaena leucocephala and Acacia auriculiformis, grow well in Thailand, and that alley farming is suitable for Thailand. Few Thai farmers have heard about alley farming. However, it is nevertheless useful to know that there is potential for alley farming in Thailand using the two species. These plants, based upon the diameter and height measurements provided, grew well.

  16. Whole farm assessment of alternative cropping and feeding strategies

    Science.gov (United States)

    A change in cropping and feeding practices can affect the performance, economics and environmental impacts of a dairy farm. A whole farm assessment of all major effects can only be done through process level simulation of the production system. The Integrated Farm System Model provides a research an...

  17. Offshore Wind Farm Clusters - Towards new integrated Design Tool

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Réthoré, Pierre-Elouan; Peña, Alfredo

    In EERA DTOC testing of existing wind farm wake models against four validation data test sets from large offshore wind farms is carried out. This includes Horns Rev-1 in the North Sea, Lillgrund in the Baltic Sea, Roedsand-2 in the Baltic Sea and from 10 large offshore wind farms in Northern Euro...

  18. Evidence for Experiential Learning in Undergraduate Teaching Farm Courses

    Science.gov (United States)

    Mazurkewicz, Melissa; Harder, Amy; Roberts, T. Grady

    2012-01-01

    Higher education institutions are attempting to use teaching farms to provide hands-on learning experiences to students, but there is a lack of research on the degree of cognitive engagement at teaching farms. Kolb's model provided the theoretical framework for assessing evidence of experiential learning in courses using teaching farms.…

  19. Environmental variables affecting the success of conservation farming in Zambia

    OpenAIRE

    Gatere, Lydiah; Delve, R.; Hobbs, P.; DeGloria, S.; Lehmann, J.

    2008-01-01

    This presentation discusses conservation farming methods in Zambia. The research highlights how conservation farming methods may help to negate environmental variables that hinder crop production, such as lack of rainfall and poor soil quality. The study compares conservation farming practices with variable amendments, including cow manure, gliricidia leaves, biochar, and fertilizer applications. LTRA-2 (An Agricultural Markets Model for Biodiversity Conservation)

  20. impacts of alternative farm policies on rural communities

    Science.gov (United States)

    J. Michael Bowker; James W. Richardson

    1989-01-01

    The purpose of this study was to describe an LP/IO model for evaluating the economic impacts of alternative farm policies on rural communities and demonstrate its capabilities by analyzing the impacts of three farm policies on a rural community in Texas. Results indicate that in the noncrop sector, two groups of industries are most affected by farm policy. The first...

  1. Behaviour of model particles of local precipitations of surface nuclear explosion in food chain and digestive tract of farm animals

    International Nuclear Information System (INIS)

    Koz'min, G.V.; Epimakhov, V.G.; Sanzharova, N.I.

    2016-01-01

    The behaviour regularities of radioactive particles - simulators of nuclear surface explosion local fall outs in food chain and gastrointestinal tract (GIT) of farm animals are analyzed. The results show that there is a large difference in transport regularities of radioactive silicate particles and radioactive solutions in GIT. At intake of young fission products high concentrations of radionuclides in GIT content deal with sorption and concentrating of radionuclides on food particles and observe in third stomach, blind gut, terminals of middle and bung guts. Transport regularities of fused radioactive particles depend on digestive apparatus mobility, content consistency and morphological peculiarities of mucosa, which work towards transport slowing and storage of such particles in the part of sheep GIT with minimal dry substance content - abomasum [ru

  2. Why Don’t More Farmers Go Organic? Using A Stakeholder-Informed Exploratory Agent-Based Model to Represent the Dynamics of Farming Practices in the Philippines

    Directory of Open Access Journals (Sweden)

    Laura Schmitt Olabisi

    2015-10-01

    Full Text Available In spite of a growing interest in organic agriculture; there has been relatively little research on why farmers might choose to adopt organic methods, particularly in the developing world. To address this shortcoming, we developed an exploratory agent-based model depicting Philippine smallholder farmer decisions to implement organic techniques in rice paddy systems. Our modeling exercise was novel in its combination of three characteristics: first, agent rules were based on focus group data collected in the system of study. Second, a social network structure was built into the model. Third, we utilized variance-based sensitivity analysis to quantify model outcome variability, identify influential drivers, and suggest ways in which further modeling efforts could be focused and simplified. The model results indicated an upper limit on the number of farmers adopting organic methods. The speed of information spread through the social network; crop yields; and the size of a farmer’s plot were highly influential in determining agents’ adoption rates. The results of this stylized model indicate that rates of organic farming adoption are highly sensitive to the yield drop after switchover to organic techniques, and to the speed of information spread through existing social networks. Further research and model development should focus on these system characteristics.

  3. Implementing contour bank farming practices into the J2000 model to improve hydrological and erosion modelling in semi-arid Western Cape Province of South Africa

    CSIR Research Space (South Africa)

    Steudel, T

    2013-01-01

    Full Text Available Contour bank farming is a well-known agricultural management technique in areas which are characterised by intensive and erosive rainfalls. Contour banks are designed to reduce the flow velocity of overland flow and to intercept water before...

  4. Lessons Learned Developing an Extension-Based Training Program for Farm Labor Supervisors

    Science.gov (United States)

    Roka, Fritz M.; Thissen, Carlene A.; Monaghan, Paul F.; Morera, Maria C.; Galindo-Gonzalez, Sebastian; Tovar-Aguilar, Jose Antonio

    2017-01-01

    This article outlines a four-step model for developing a training program for farm labor supervisors. The model draws on key lessons learned during the development of the University of Florida Institute of Food and Agricultural Sciences Farm Labor Supervisor Training program. The program is designed to educate farm supervisors on farm labor laws…

  5. A model record of technologies for use in a compatible projects for environmental licensing of wind farms; Um modelo de registro das tecnologias para uso na compatibilizacao de projetos para licenciamento ambiental de parques eolicos

    Energy Technology Data Exchange (ETDEWEB)

    Tavares Junior, Wandemberg; Oliveira, Lucia Maria Barbosa [Universidade de Fortaleza (UNIFOR), CE (Brazil)

    2008-07-01

    This article presents the development of a model for survey and registration of technologies that can be inserted in the process of reconciliation of the subjects of the project for environmental licensing of wind farms. It was used a basis for the theoretical model of the Simultaneous Engineering and Failure Mode and Effect Analysis - FMEA. Given the importance that the wind has for the pursuit of sustainable development, this work had as its main objective to contribute to the reduction of negative indices, proposing improvements to the process of project for environmental licensing of wind farms. (author)

  6. Organic farming benefits local plant diversity in vineyard farms located in intensive agricultural landscapes.

    Science.gov (United States)

    Nascimbene, Juri; Marini, Lorenzo; Paoletti, Maurizio G

    2012-05-01

    The majority of research on organic farming has considered arable and grassland farming systems in Central and Northern Europe, whilst only a few studies have been carried out in Mediterranean agro-systems, such as vineyards, despite their economic importance. The main aim of the study was to test whether organic farming enhances local plant species richness in both crop and non-crop areas of vineyard farms located in intensive conventional landscapes. Nine conventional and nine organic farms were selected in an intensively cultivated region (i.e. no gradient in landscape composition) in northern Italy. In each farm, vascular plants were sampled in one vineyard and in two non-crop linear habitats, grass strips and hedgerows, adjacent to vineyards and therefore potentially influenced by farming. We used linear mixed models to test the effect of farming, and species longevity (annual vs. perennial) separately for the three habitat types. In our intensive agricultural landscapes organic farming promoted local plant species richness in vineyard fields, and grassland strips while we found no effect for linear hedgerows. Differences in species richness were not associated to differences in species composition, indicating that similar plant communities were hosted in vineyard farms independently of the management type. This negative effect of conventional farming was probably due to the use of herbicides, while mechanical operations and mowing regime did not differ between organic and conventional farms. In grassland strips, and only marginally in vineyards, we found that the positive effect of organic farming was more pronounced for perennial than annual species.

  7. Organic Farming Benefits Local Plant Diversity in Vineyard Farms Located in Intensive Agricultural Landscapes

    Science.gov (United States)

    Nascimbene, Juri; Marini, Lorenzo; Paoletti, Maurizio G.

    2012-05-01

    The majority of research on organic farming has considered arable and grassland farming systems in Central and Northern Europe, whilst only a few studies have been carried out in Mediterranean agro-systems, such as vineyards, despite their economic importance. The main aim of the study was to test whether organic farming enhances local plant species richness in both crop and non-crop areas of vineyard farms located in intensive conventional landscapes. Nine conventional and nine organic farms were selected in an intensively cultivated region (i.e. no gradient in landscape composition) in northern Italy. In each farm, vascular plants were sampled in one vineyard and in two non-crop linear habitats, grass strips and hedgerows, adjacent to vineyards and therefore potentially influenced by farming. We used linear mixed models to test the effect of farming, and species longevity (annual vs. perennial) separately for the three habitat types. In our intensive agricultural landscapes organic farming promoted local plant species richness in vineyard fields, and grassland strips while we found no effect for linear hedgerows. Differences in species richness were not associated to differences in species composition, indicating that similar plant communities were hosted in vineyard farms independently of the management type. This negative effect of conventional farming was probably due to the use of herbicides, while mechanical operations and mowing regime did not differ between organic and conventional farms. In grassland strips, and only marginally in vineyards, we found that the positive effect of organic farming was more pronounced for perennial than annual species.

  8. Modeling the migration of fallout radionuclides to quantify the contemporary transfer of fine particles in Luvisol profiles under different land uses and farming practices

    International Nuclear Information System (INIS)

    Jagercikova, M.; Balesdent, J.; Cornu, S.; Evrard, O.; Lefevre, I.

    2014-01-01

    Soil mixing and the downward movement of solid matter in soils are dynamic pedological processes that strongly affect the vertical distribution of all soil properties across the soil profile. These processes are affected by land use and the implementation of various farming practices, but their kinetics have rarely been quantified. Our objective was to investigate the vertical transfer of matter in Luvisols at long-term experimental sites under different land uses (cropland, grassland and forest) and different farming practices (conventional tillage, reduced tillage and no tillage). To investigate these processes, the vertical radionuclide distributions of 137 Cs and 210 Pb (xs) were analyzed in 9 soil profiles. The mass balance calculations showed that as much as 91± 9% of the 137 Cs was linked to the fine particles (2 mm). To assess the kinetics of radionuclide redistribution in soil, we modeled their depth profiles using a convection-diffusion equation. The diffusion coefficient represented the rate of bioturbation, and the convection velocity provided a proxy for fine particle leaching. Both parameters were modeled as either constant or variable with depth. The tillage was simulated using an empirical formula that considered the tillage depth and a variable mixing ratio depending on the type of tillage used. A loss of isotopes due to soil erosion was introduced into the model to account for the total radionuclide inventory. All of these parameters were optimized based on the 137 Cs data and were then subsequently applied to the 210 Pb (xs) data. Our results show that the 137 Cs isotopes migrate deeper under grasslands than under forests or croplands. Additionally, our results suggest that the diffusion coefficient decreased with depth and that it remained negligible below the tillage depth at the cropland sites, below 20 cm in the forest sites, and below 80 cm in the grassland sites. (authors)

  9. Evaluation of wind farm efficiency and wind turbine wakes at the Nysted offshore wind farm

    DEFF Research Database (Denmark)

    Barthelmie, Rebecca Jane; Jensen, L.E.

    2010-01-01

    be quantified, albeit with relatively large uncertainty due to stochastic effects in the data. There is evidence of the ‘deep array effect’ in that wake losses in the centre of the wind farm are under-estimated by the wind farm model WAsP, although overall efficiency of the wind farm is well predicted due......Here, we quantify relationships between wind farm efficiency and wind speed, direction, turbulence and atmospheric stability using power output from the large offshore wind farm at Nysted in Denmark. Wake losses are, as expected, most strongly related to wind speed variations through the turbine...... thrust coefficient; with direction, atmospheric stability and turbulence as important second order effects. While the wind farm efficiency is highly dependent on the distribution of wind speeds and wind direction, it is shown that the impact of turbine spacing on wake losses and turbine efficiency can...

  10. CREDIT LEVEL INFLUENCING FACTORS AT HUNGARIAN FARMS

    Directory of Open Access Journals (Sweden)

    Toth Jozsef

    2012-12-01

    Full Text Available In this paper we estimate the impact of different factors on creditability of agricultural farms. According to the literature the collateral (tangible assets, the farm size, productivity, and subsidies should have significant effects on farm loans. We use data from the Hungarian Farm Accountancy Data Network to test our two hypotheses and theoretical assumptions for the period 2001-2010. Because of using panel data, we do our estimations using fixed effects econometrics model to test our assumptions. The results indicate that the chosen factors have significant influence on total liabilities and short- and long-term loans as well. With specially interest of subsidies the growing level of supports decrease the need of other financial tools. At output factors (inclusive farm size have significant and positive effect, same as collateral (tangible assets.

  11. Exploring the multifunctional role of farming systems

    DEFF Research Database (Denmark)

    Hermansen, John Erik; Noe, Egon; Halberg, Niels

    2006-01-01

    Public expectations of farming practices are changing from a demand for environmentally "sustainable farming practices" to farming making an "enhanced contribution to the development of the rural areas", the so-called multifunctionality. Based on our research model of including farmers...... in the development of eco-friendly farming systems, we propose that the achievement of these changed expectations could be facilitated through an appropriate research and development initiative in several European regions. Key elements in such a project sould include: (i) the establishment of platforms for dialogue...... makers and administrators, grassroots movements and research staff. It is expected that such a coordinated research initiative can revitalize the contribution of farming to rural development and yield important insight to be used by the individual farmer in coping with future challenges....

  12. Is Farm Management Skill Persistent?

    OpenAIRE

    Li, Xin; Paulson, Nicholas

    2014-01-01

    Farm management skills can affect farm managers' performance. In this article, farm management performance is analyzed based on yearly Illinois Farm Business Farm Management (FBFM) panel data across 6,760 farms from 1996 through 2011. Two out-of-sample measures of skill are used to analyze the ability of farm managers that consistently perform well over yearly and longer time horizons. Persistence tests show management skills are consistent and predictable. Results also suggest that the most ...

  13. Optimizing transmission from distant wind farms

    International Nuclear Information System (INIS)

    Pattanariyankool, Sompop; Lave, Lester B.

    2010-01-01

    We explore the optimal size of the transmission line from distant wind farms, modeling the tradeoff between transmission cost and benefit from delivered wind power. We also examine the benefit of connecting a second wind farm, requiring additional transmission, in order to increase output smoothness. Since a wind farm has a low capacity factor, the transmission line would not be heavily loaded, on average; depending on the time profile of generation, for wind farms with capacity factor of 29-34%, profit is maximized for a line that is about 3/4 of the nameplate capacity of the wind farm. Although wind generation is inexpensive at a good site, transmitting wind power over 1600 km (about the distance from Wyoming to Los Angeles) doubles the delivered cost of power. As the price for power rises, the optimal capacity of transmission increases. Connecting wind farms lowers delivered cost when the wind farms are close, despite the high correlation of output over time. Imposing a penalty for failing to deliver minimum contracted supply leads to connecting more distant wind farms.

  14. Farm Health and Safety

    Science.gov (United States)

    ... jobs in the United States. Farms have many health and safety hazards, including Chemicals and pesticides Machinery, ... equipment can also reduce accidents. Occupational Safety and Health Administration

  15. Evaluation of Two Models of Non-Penetrating Captive Bolt Devices for On-Farm Euthanasia of Turkeys.

    Science.gov (United States)

    Woolcott, Caitlin R; Torrey, Stephanie; Turner, Patricia V; Serpa, Lilia; Schwean-Lardner, Karen; Widowski, Tina M

    2018-03-20

    On-farm euthanasia is a critical welfare issue in the poultry industry and can be particularly difficult to perform on mature turkeys due to their size. We evaluated the efficacy of two commercially available non-penetrating captive bolt devices, the Zephyr-EXL and the Turkey Euthanasia Device (TED), on 253 turkeys at three stages of production: 4-5, 10, and 15-20 weeks of age. Effectiveness of each device was measured using both ante- and post-mortem measures. Application of the Zephyr-EXL resulted in a greater success rate (immediate abolishment of brainstem reflexes) compared to the TED (97.6% vs. 89.3%, p = 0.0145). Times to last movement ( p = 0.102) and cardiac arrest ( p = 0.164) did not differ between devices. Ante- and post-mortem measures of trauma and hemorrhage were highly correlated. Skull fractures and gross subdural hemorrhage (SDH) were present in 100% of birds euthanized with both the Zephyr-EXL and TED devices. Gross SDH scores were greater in birds killed with the Zephyr-EXL than the TED ( p euthanasia of turkeys.

  16. Stress among Finnish farm entrepreneurs.

    Science.gov (United States)

    Kallioniemi, Marja Kristiina; Simola, Ahti Jarkko Kalervo; Kymäläinen, Hanna-Riitta; Vesala, Hannu Tapio; Louhelainen, Jarmo Kyösti

    2008-01-01

    The aims were to examine the prevalence of stress among Finnish full-time farm entrepreneurs in 2004 (n = 1,182) and to compare the results with those for the general working population in 2003. The second aim was to analyze which factors were associated with the prevalence of stress. A stratified random sample of farm entrepreneurs gathered from the farm register was surveyed using computer-assisted telephone interviews. A binary logistic regression model was used to analyze the association with background factors. One third (34 %) of the examined farmers had experienced stress. This amount was lower than among the general working population (44 %). The most common factors associated with farmers' stress were problems in social family relationships and mental support. Physical factors such as the strenuousness of agricultural work, illness and a low estimation of their own working ability, were also related to stress. Increased stress was also associated with economic problems. Health and extension services should pay special attention to encouraging farm entrepreneurs to maintain their social relationships. The relatively low level of stress observed may indicate that those who have continued within the agricultural sector have the psychological capacity to deal with stressful situations.

  17. Impact of assimilating met-tower, turbine nacelle anemometer and other intensified wind farm observation systems on 0 - 12h wind energy prediction using the NCAR WRF-RTFDDA model

    Science.gov (United States)

    Liu, Y.; Cheng, W.; Liu, Y. W.; Wiener, G.; Frehlich, R.; Mahoney, W.; Warner, T.; Himelic, J.; Parks, K.; Early, S.

    2010-09-01

    In collaboration with Xcel Energy and Vasaila Inc., the National Center for Atmospheric Research (NCAR) conducts modeling study to evaluate the existing and the enhanced intensive observation systems for wind power nowcasting and short-range forecasting at a northern Colorado wind farm. The NCAR WRF (Weather Research and Forecasting model) based Real-Time Four-Dimensional Data Assimilation (RTFDDA) and forecasting system, which has been employed to support Xcel Energy operational wind forecast, was used in this study. The observational data include ten met-towers, a 915Hz wind profiler, a sodar and a Windcube Doppler lidar, besides the in-farm met-towers and wind speed and power reports from more than 300 of wind turbines. The WRF-RTFDDA 4-dimensioanl data assimilation algorithm allows to spread and propagate observation information in the WRF model space (x, y, z and time) with weighting functions built according to the observation location and time. The WRF-RTFDDA was set up to run with four nested domains with grid increments of 30, 10, 3.333 and 1.111km respectively. The standard and diverse non-conventional observations are assimilated on coarse grid domains along with the special wind farm observations. In this study, we investigate a) spread of surface observations in PBL according to PBL depth and regimes, b) optimization of horizontal influence radii and steep-terrain adjustment, and c) impact of different observation platforms and data types on 0 - 12 h wind prediction . It is found that PBL mixing and thermodynamic structures are greatly influenced by the PBL parameterization formulation. The range of the data assimilation effect on forecasts relies on weather and PBL regimes. In most cases, assimilation of in-farm and near-farm observations improves up to 12-hour wind power prediction and assimilation of in-farm data can significantly improves 0 - 6 hour forecasts.

  18. Evaluation of the wind farm parameterization in the Weather Research and Forecasting model (version 3.8.1) with meteorological and turbine power data

    Science.gov (United States)

    Lee, Joseph C. Y.; Lundquist, Julie K.

    2017-11-01

    Forecasts of wind-power production are necessary to facilitate the integration of wind energy into power grids, and these forecasts should incorporate the impact of wind-turbine wakes. This paper focuses on a case study of four diurnal cycles with significant power production, and assesses the skill of the wind farm parameterization (WFP) distributed with the Weather Research and Forecasting (WRF) model version 3.8.1, as well as its sensitivity to model configuration. After validating the simulated ambient flow with observations, we quantify the value of the WFP as it accounts for wake impacts on power production of downwind turbines. We also illustrate with statistical significance that a vertical grid with approximately 12 m vertical resolution is necessary for reproducing the observed power production. Further, the WFP overestimates wake effects and hence underestimates downwind power production during high wind speed, highly stable, and low turbulence conditions. We also find the WFP performance is independent of the number of wind turbines per model grid cell and the upwind-downwind position of turbines. Rather, the ability of the WFP to predict power production is most dependent on the skill of the WRF model in simulating the ambient wind speed.

  19. Evaluation of the wind farm parameterization in the Weather Research and Forecasting model (version 3.8.1 with meteorological and turbine power data

    Directory of Open Access Journals (Sweden)

    J. C. Y. Lee

    2017-11-01

    Full Text Available Forecasts of wind-power production are necessary to facilitate the integration of wind energy into power grids, and these forecasts should incorporate the impact of wind-turbine wakes. This paper focuses on a case study of four diurnal cycles with significant power production, and assesses the skill of the wind farm parameterization (WFP distributed with the Weather Research and Forecasting (WRF model version 3.8.1, as well as its sensitivity to model configuration. After validating the simulated ambient flow with observations, we quantify the value of the WFP as it accounts for wake impacts on power production of downwind turbines. We also illustrate with statistical significance that a vertical grid with approximately 12 m vertical resolution is necessary for reproducing the observed power production. Further, the WFP overestimates wake effects and hence underestimates downwind power production during high wind speed, highly stable, and low turbulence conditions. We also find the WFP performance is independent of the number of wind turbines per model grid cell and the upwind–downwind position of turbines. Rather, the ability of the WFP to predict power production is most dependent on the skill of the WRF model in simulating the ambient wind speed.

  20. Grid Integration of Wind Farms

    Science.gov (United States)

    Giæver Tande, John Olav

    2003-07-01

    This article gives an overview of grid integration of wind farms with respect to impact on voltage quality and power system stability. The recommended procedure for assessing the impact of wind turbines on voltage quality in distribution grids is presented. The procedure uses the power quality characteristic data of wind turbines to determine the impact on slow voltage variations, flicker, voltage dips and harmonics. The detailed assessment allows for substantially more wind power in distribution grids compared with previously used rule-of-thumb guidelines. Power system stability is a concern in conjunction with large wind farms or very weak grids. Assessment requires the use of power system simulation tools, and wind farm models for inclusion in such tools are presently being developed. A fixed-speed wind turbine model is described. The model may be considered a good starting point for development of more advanced models, hereunder the concept of variable-speed wind turbines with a doubly fed induction generator is briefly explained. The use of dynamic wind farm models as part of power system simulation tools allows for detailed studies and development of innovative grid integration techniques. It is demonstrated that the use of reactive compensation may relax the short-term voltage stability limit and allow integration of significantly more wind power, and that application of automatic generation control technology may be an efficient means to circumvent thermal transmission capacity constraints. The continuous development of analysis tools and technology for cost-effective and secure grid integration is an important aid to ensure the increasing use of wind energy. A key factor for success, however, is the communication of results and gained experience, and in this regard it is hoped that this article may contribute.

  1. Wind Farm Structures’ Impact on Harmonic Emission and Grid Interaction

    DEFF Research Database (Denmark)

    Kocewiak, Lukasz Hubert; Hjerrild, Jesper; Bak, Claus Leth

    The impact of a wind farm’s internal structures on harmonic emission at the point of common coupling and on the whole system frequency characteristic is investigated in this paper. The largest wind farms in the world, Horns Rev 2 Offshore Wind Farm and Polish Karnice Onshore Wind Farm......, are thoroughly analyzed. Different wind farm configurations are taken into consideration in order to entirely describe phenomena associated with harmonics. Some aspects of wind farm modelling for harmonic studies are also presented in this paper. The simulation results are compared with measurement data in order...

  2. 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.

  3. Time series analysis based on two-part models for excessive zero count data to detect farm-level outbreaks of swine echinococcosis during meat inspections.

    Science.gov (United States)

    Adachi, Yasumoto; Makita, Kohei

    2017-12-01

    Echinococcus multilocularis is a parasite that causes highly pathogenic zoonoses and is maintained in foxes and rodents on Hokkaido Island, Japan. Detection of E. multilocularis infections in swine is epidemiologically important. In Hokkaido, administrative information is provided to swine producers based on the results of meat inspections. However, as the current criteria for providing administrative information often results in delays in providing information to producers, novel criteria are needed. Time series models were developed to monitor autocorrelations between data and lags using data collected from 84 producers at the Higashi-Mokoto Meat Inspection Center between April 2003 and November 2015. The two criteria were quantitatively compared using the sign test for the ability to rapidly detect farm-level outbreaks. Overall, the time series models based on an autoexponentially regressed zero-inflated negative binomial distribution with 60th percentile cumulative distribution function of the model detected outbreaks earlier more frequently than the current criteria (90.5%, 276/305, pdisadvantages of the current criteria to provide an earlier indication of increases in the rate of echinococcosis. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. INTEGRATION OF PEPPER AND LIVESTOCK (Alternative Eco-Friendly Farm Model During Post-Mining of Tin in Bangka Belitung Islands

    Directory of Open Access Journals (Sweden)

    Achmad A. Rivaie *

    2014-01-01

    Full Text Available Commodity of white pepper from the Bangka Island is one of spice crop comodities having a high economic value and can be expected to be the supporting crop for the strength of household economy in a pepper-cow-based agroforestry (LASA during post-mining of tin. In this farm model, pepper (Piper nigrum is integrated with livestocks (cows and the crops of cattle feed grown as a hedge crop or as intercrop in alley cropping. The increase of global demand for pepper along with the price gives a great oppotunity to the development of this integrated model to revive farmers’s motivation in the Province of Bangka Belitung to manage their crops in a eco-friendly manner, which is in turn can also increase the region's economy. Needs analysis shows that it is necessary to do studies on innovations, technologies, and institutions that can be applied from upstream to downstream, as well as policies to support the development of agribusiness model of LASA.

  5. Year rather than farming system influences protein utilization and energy value of vegetables when measured in a rat model.

    Science.gov (United States)

    Jørgensen, Henry; Brandt, Kirsten; Lauridsen, Charlotte

    2008-12-01

    The aim of the study was to measure protein utilization and energy value of dried apple, carrot, kale, pea, and potato prepared for human consumption and grown in 2 consecutive years with 3 different farming systems: (1) low input of fertilizer without pesticides (LIminusP), (2) low input of fertilizers and high input of pesticides (LIplusP), (3) and high input of fertilizers and high input of pesticides (HIplusP). In addition, the study goal was to verify the nutritional values, taking into consideration the physiologic state. In experiment 1, the nutritive values, including protein digestibility-corrected amino acid score, were determined in single ingredients in trials with young rats (3-4 weeks) as recommended by the Food and Agriculture Organization of the United Nations/World Health Organization for all age groups. A second experiment was carried out with adult rats to assess the usefulness of digestibility values to predict the digestibility and nutritive value of mixed diets and study the age aspect. Each plant material was included in the diet with protein-free basal mixtures or casein to contain 10% dietary protein. The results showed that variations in protein utilization and energy value determined on single ingredients between cultivation strategies were inconsistent and smaller than between harvest years. Overall, dietary crude fiber was negatively correlated with energy digestibility. The energy value of apple, kale, and pea was lower than expected from literature values. A mixture of plant ingredients fed to adult rats showed lower protein digestibility and higher energy digestibility than predicted. The protein digestibility data obtained using young rats in the calculation of protein digestibility-corrected amino acid score overestimates protein digestibility and quality and underestimates energy value for mature rats. The present study provides new data on protein utilization and energy digestibility of some typical plant foods that may

  6. Turbine Control Strategies for Wind Farm Power Optimization

    DEFF Research Database (Denmark)

    Mirzaei, Mahmood; Göçmen Bozkurt, Tuhfe; Giebel, Gregor

    2015-01-01

    and wind farms. One way of achieving these goals is to optimize the power generated by a wind farm. One optimization method is to choose appropriate operating points for the individual wind turbines in the farm. We have made three models of a wind farm based on three difference control strategies...... are different. This means that choosing an appropriate control strategy for the individual wind turbines will result in an increased power production of the wind farm........ Basically, the control strategies determine the steady state operating points of the wind turbines. Except the control strategies of the individual wind turbines, the wind farm models are similar. Each model consists of a row of 5MW reference wind turbines. In the models we are able to optimize...

  7. 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...

  8. A decision support system for strategic planning on pig farms

    OpenAIRE

    Backus, Ge B.C.; Timmer, G. Th.; Dijkhuizen, A.A.; Eidman, V.R.; Vos, F.

    1995-01-01

    This paper reported on a decision support system (DSS) for strategic planning on pig farms. The DSS was based . on a stochastic simulation model of investment decisions (ISM). ISM described a farm with one loan and one building using 23 variables. The simulation model calculated the results of a strategic plan for an individual pig farm over a time horizon of a maximum of 20 years for a given scenario. For six distinct replacement strategies, regression metamodels were specified to describe t...

  9. People on the Farm: Corn and Hog Farming.

    Science.gov (United States)

    Department of Agriculture, Washington, DC. Office of Governmental and Public Affairs.

    This booklet provides information on corn and hog farming on a small farm through a profile of a farm family. According to the profile, John and Mary Miller and their three children are a comfortable family operating a corn and hog farm in Iowa. John, the principal farmer, uses a variety of skills in management, veterinary science, soil science,…

  10. 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....

  11. Energy consumption across European Union farms: Efficiency in terms of farming output and utilized agricultural area

    International Nuclear Information System (INIS)

    Martinho, Vítor João Pereira Domingues

    2016-01-01

    Energy consumption is a global concern, namely due to the limited availability of energy sources and the consequences in terms of gas emissions, with its implications upon greenhouse gas emissions. In the agricultural sector this question bears an additional concern, considering that it is an economic activity which is sensitive to the dimension of the costs associated with production factors. In this way, the objective of the study presented here is to analyze, the efficiency of energy consumption, for the twelve former European Union countries, at farm level, in terms of farming output and utilized agricultural area, over the period 1989–2009 and for the years 2004–2012, with data available in the Farm Accountancy Data Network. On the other hand, the implications of energy consumption in farms' economic performance were analyzed, through econometric techniques (time series, panel data and generalized method of moments) and models based on the Kaldor developments. As a main conclusion, to stress the decrease in efficiency related with energy consumption by farms in the twelve former European Union countries. - Highlights: • It was analyzed the efficiency of energy consumption. • It was considered data for the twelve former European Union states at farm level. • They were evaluated the implications of energy consumption in farms performance. • The conclusions stress the decrease in efficiency of the farms energy consumption.

  12. Farm Consumption Behavior in the Presence of Uncertainty and Restrictions on Credit

    OpenAIRE

    Euan Phimister

    1995-01-01

    Farm consumption behavior has an important indirect role in determining the ability of farms to invest and grow. In this paper I examine the effect on farm consumption behavior of the presence of quantitative restrictions on farm borrowing. Using a form of the life cycle model which allows for both consumption and production by the household, the effect of borrowing restrictions on consumption behavior is tested econometrically for a sample of Dutch farm households. The results suggest that t...

  13. Agriculture: Organic Farming

    Science.gov (United States)

    Organic Farming - Organically grown food is food grown and processed using no synthetic fertilizers or pesticides. Pesticides derived from natural sources (such as biological pesticides) may be used in producing organically grown food.

  14. Farm-made aquafeeds

    National Research Council Canada - National Science Library

    New, Michael B; Tacon, Albert G. J; Csavas, I

    1995-01-01

    .... Five other working papers are on economics, the selection of equipment, feed ingredients, formulation and on-farm management and supplementary feeding in semi-intensive aquaculture, all directed...

  15. The Farm in American History.

    Science.gov (United States)

    Shideler, James H.

    1991-01-01

    Explores the family farm as an economic institution and cultural symbol in U.S. history. Explains how farms worked as economic units. Contrasts the idyllic family farm against realities of business failures and family problems. Examines the family farm's role in shaping the U.S. character and asks what its essential demise will mean. (CH)

  16. Escrevendo por sobre a terra: as fazendas-modelo em Minas Gerais (1906-1915 - Writing upon the land: model farms in Minas Gerais (1906-1915

    Directory of Open Access Journals (Sweden)

    Irlen Antônio Gonçalves

    2015-05-01

    Full Text Available As fazendas-modelo, instituições de ensino agrícola de caráter prático, foram implantadas pelo Brasil e,em Minas Gerais, na capital e em algumas cidades do interior. Elas foram instituídas como parte de uma política pública nacional nos anos iniciais do século 20.Em Minas Geraisforam criadas entre os anos de 1906 e 1915. Neste texto nos propomos compreender como as fazendas-modelo surgiram como instituições de ensino, sua materialidade e os sujeitos da aprendizagem e conhecimentos. Assim, será realizado um diálogo e uma problematização das fontes históricas de diversas origens, tais como a legislação, os anais do Congresso Legislativo, os relatórios anuais e expedientes da diretoria de Agricultura e os relatórios anuais da Secretaria da Agricultura.Palavras-chave: fazendas-modelo, ensino agrícola, campos de demonstração.WRITING UPON THE LAND: MODEL FARMS IN MINAS GERAIS (1906-1915 AbstractModel farms, institutions for practical agricultural education, were spread all over Brazil and, in Minas Gerais, in the capital and other country towns. They were instituted as part as a national public policy in the first years of the 20th century. In Minas Gerais, were created between the years 1906 and1915. Inthis text we propose to understand how the model farms came to be education institutions, in the aspects of her materiality and the subject of learning and knowledge. Then, there will be a dialogue and a questioning of the historical sources of many roots, such as legislation, the proceedings of the Congress Legislature, annual reports and records of the Board of Agriculture and the annual reports of the Secretary of Agriculture.Key-words: model farms, agricultural education, demonstration fields.ESCREVENDO POR SOBRE A TERRA: LAS HACIENDAS MODELO EN MINAS GERAIS (1906-1915 Resumen Las haciendas modelo, instituciones de enseñanza agrícola práctica, se han implantado en todo el Brasil y en Minas Gerais, en la capital, y en

  17. Ashes for organic farming

    OpenAIRE

    Kousa, T.; Heinonen, M.; Suoniitty, T.; Peltonen, K.

    2013-01-01

    Nowadays only eight percent of the cultivated field area is used for organic farming. The Ministry of Agriculture and Forestry has published the guidelines for the program of organic farming to diversify the supply and the consumption of organic food. The aim is to increase organically arable land to 20% by the year 2020.The demand of organic fertilizer products is strongly increasing. Interest in forestry by-products (ash, bark, zero fiber, etc.) for use in organic production has recently be...

  18. Farming the seaweed Kappaphycus

    OpenAIRE

    Hurtado, Anicia

    2003-01-01

    Seaweed farming is the top foreign exchange earner for the Philippines. Kappaphycus constitutes 80% of the Philippine seaweed export. It is sold in both fresh and dried forms; although dried seaweed has a greater demand, fresh seaweed is highly prices in restaurants. The 3 main seaweed products marketed are agar, alginate and carrageenan. A brief outline is given of farming operations and investment costs and returns.

  19. Wind farms and planning

    International Nuclear Information System (INIS)

    Arkesteijn, L.; Havinga, R.; Benner, J.H.B.

    1992-01-01

    The siting of wind farms is becoming an increasingly important issue in the Netherlands. This paper gives an overview of the current situation concerning the planning of wind farms. We will pay attention to: Wind energy in official Dutch planning policy. To select the optimal sites, the government has made an administrative agreement with the 7 windy provinces. Nevertheless, wind energy is still fighting for a rightful position in physical planning policy. Some examples will illustrate this. Studies on siting and siting problems in the Netherlands. In order to gain more insight into aspects of wind farming several studies have been executed. In this paper special attention will be paid to the results of a study on the potential impact of large windturbine clusters on an existing agricutural area. Experiences with siting of wind farms in the Netherlands. Based on experiences with the planning and realization of farms, this paper gives the main problems. In the final part of the paper we present some general conclusions. Generally speaking, the knowledge is available for selecting optimal sites in the Netherlands. The basic problems for wind farming nowadays seem to be the visual impact and actually obtaining the ground. Nevertheless, there do seem to be enough sites for realizing the goals in the Netherlands. (au)

  20. Exploring options for sustainable farming systems development for vegetable family farmers in Uruguay using a modeling toolkit

    NARCIS (Netherlands)

    Casagrande, M.; Dogliotti, S.; Groot, J.C.J.; Aguerre, V.; Abbas, A.; Albin, A.; Claassen, G.D.H.; Chilibroste, P.; Rossing, W.A.H.

    2010-01-01

    Economic and environmental sustainability of family-based vegetable production systems in south Uruguay are seriously compromised after two decades of net decreasing prices and strategies based on specialization and intensification. This paper presents a model-based exploration of alternative

  1. Effective Tutorial Ontology Modeling on Organic Rice Farming for Non-Science & Technology Educated Farmers Using Knowledge Engineering

    Science.gov (United States)

    Yanchinda, Jirawit; Chakpitak, Nopasit; Yodmongkol, Pitipong

    2015-01-01

    Knowledge of the appropriate technologies for sustainable development projects has encouraged grass roots development, which has in turn promoted sustainable and successful community development, which a requirement is to share and reuse this knowledge effectively. This research aims to propose a tutorial ontology effectiveness modeling on organic…

  2. Classification of real farm conditions Iberian pigs according to the feeding regime with multivariate models developed by using fatty acids composition or NIR spectral data

    Directory of Open Access Journals (Sweden)

    De Pedro, Emiliano

    2009-07-01

    Full Text Available Multivariate Classification models to classify real farm conditions Iberian pigs, according to the feeding regime were developed by using fatty acids composition or NIR spectral data of liquid fat samples. A total of 121 subcutaneous fat samples were taken from Iberian pigs carcasses belonging to 5 batches reared under different feeding systems. Once the liquid sample was extracted from each subcutaneous fat sample, it was determined the percentage of 11 fatty acids (C14:0, C16:0, C16:1, C17:0, C17:1, C18:0, C18:1, C18:2, C18:3, C20:0 and C20:1. At the same time, Near Infrared (NIR spectrum of each liquid sample was obtained. Linear Discriminant Analysis (LDA was considered as pattern recognition method to develop the multivariate models. Classification errors of the LDA models generated by using NIR spectral data were 0.0% and 1.7% for the model generated by using fatty acids composition. Results confirm the possibility to discriminate Iberian pig liquid samples from animals reared under different feeding regimes on real farm conditions by using NIR spectral data or fatty acids composition. Classification error obtained using models generated from NIR spectral data were lower than those obtained in models based on fatty acids composition.Se han desarrollado modelos multivariantes, generados a partir de la composición en ácidos grasos o datos espectrales NIR, para clasificar según el régimen alimenticio cerdos Ibéricos producidos bajo condiciones no experimentales. Se han empleado 121 muestras de grasa líquida procedentes de grasa subcutánea de canales de cerdos Ibéricos pertenecientes a 5 partidas con regímenes alimenticios diferentes. A dichas muestras líquidas se les determinó el contenido en 11 ácidos grasos (C14:0, C16:0, C16:1, C17:0, C17:1, C18:0, C18:1, C18:2, C18:3, C20:0 and C20:1 y se obtuvo su espectro NIR. Los modelos de clasificación multivariantes se desarrollaron mediante Análisis Discriminante Lineal. Dichos

  3. Influence of Permissive Parenting on Youth Farm Risk Behaviors.

    Science.gov (United States)

    Jinnah, Hamida A; Stoneman, Zolinda

    2016-01-01

    Farm youth continue to experience high rates of injuries and premature deaths as a result of agricultural activities. Increased parental permissiveness is positively associated with many different types of high-risk behaviors in youth. This study explored whether permissive parenting (fathering and mothering) predicts youth unsafe behaviors on the farm. Data were analyzed for 67 youth and their parents. Families were recruited from a statewide farm publication, through youth organizations (i.e., FFA [Future Farmers of America]), local newspapers, farmer referrals, and through the Cooperative Extension Network. Hierarchical multiple regression was completed. Results revealed that fathers and mothers who practiced lax-inconsistent disciplining were more likely to have youth who indulged in unsafe farm behaviors. Key hypotheses confirmed that permissive parenting (lax-inconsistent disciplining) by parents continued to predict youth unsafe farm behaviors, even after youth age, youth gender, youth personality factor of risk-taking, and father's unsafe behaviors (a measure associated with modeling) were all taken into account. A key implication is that parents may play an important role in influencing youth farm safety behaviors. Parents (especially fathers) need to devote time to discuss farm safety with their youth. Farm safety interventions need to involve parents as well as address and respect the culture and values of families. Interventions need to focus not only on safe farm practices, but also promote positive parenting practices, including increased parent-youth communication about safety, consistent disciplining strategies, and increased monitoring and modeling of safe farm behaviors by parents.

  4. Stability analysis of offshore wind farm and marine current farm

    Science.gov (United States)

    Shawon, Mohammad Hasanuzzaman

    -trend for large electric energy production using offshore wind generators and marine current generators, respectively. Thus DFIG based offshore wind farm can be an economic solution to stabilize squirrel cage induction generator based marine current farm without installing any addition FACTS devices. This thesis first focuses on the stabilization of fixed speed IG based marine current farm using SDBR. Also stabilization of DFIG based variable speed wind farm utilizing SDBR is studied in this work. Finally a co-operative control strategy is proposed where DFIG is controlled in such a way that it can even provide necessary reactive power demand of induction generator, so that additional cost of FACTS devices can be avoided. In that way, the DFIGs of the offshore wind farm (OWF) will actively compensate the reactive power demand of adjacent IGs of the marine current farm (MCF) during grid fault. Detailed modeling and control scheme for the proposed system are demonstrated considering some realistic scenarios. The power system small signal stability analysis is also carried out by eigenvalue analysis for marine current generator topology, wind turbine generator topology and integrated topology. The relation between the modes and state variables are discussed in light of modal and sensitivity analyses. The results of theoretical analyses are verified by MATLAB/SIMULINK and laboratory standard power system simulator PSCAD/EMTDC.

  5. Organic Sheep and Goat Farming

    OpenAIRE

    Rahmann, Gerold

    2007-01-01

    Organic sheep and goat farming is on the rise in Germany and the EU. Many consumers see organic farms as an example of the "intact world" of farming and rural living. Agrienvironmental schemes support conversion from conventional towards organic farming. Only few know how difficult organic sheep and goat farming is from animal welfare, ecological and economic perspective. Newcomers particularly overestimate the production and marketing potential of the field, and underestimate the associated ...

  6. Brazilian Soybean Yields and Yield Gaps Vary with Farm Size

    Science.gov (United States)

    Jeffries, G. R.; Cohn, A.; Griffin, T. S.; Bragança, A.

    2017-12-01

    Understanding the farm size-specific characteristics of crop yields and yield gaps may help to improve yields by enabling better targeting of technical assistance and agricultural development programs. Linking remote sensing-based yield estimates with property boundaries provides a novel view of the relationship between farm size and yield structure (yield magnitude, gaps, and stability over time). A growing literature documents variations in yield gaps, but largely ignores the role of farm size as a factor shaping yield structure. Research on the inverse farm size-productivity relationship (IR) theory - that small farms are more productive than large ones all else equal - has documented that yield magnitude may vary by farm size, but has not considered other yield structure characteristics. We examined farm size - yield structure relationships for soybeans in Brazil for years 2001-2015. Using out-of-sample soybean yield predictions from a statistical model, we documented 1) gaps between the 95th percentile of attained yields and mean yields within counties and individual fields, and 2) yield stability defined as the standard deviation of time-detrended yields at given locations. We found a direct relationship between soy yields and farm size at the national level, while the strength and the sign of the relationship varied by region. Soybean yield gaps were found to be inversely related to farm size metrics, even when yields were only compared to farms of similar size. The relationship between farm size and yield stability was nonlinear, with mid-sized farms having the most stable yields. The work suggests that farm size is an important factor in understanding yield structure and that opportunities for improving soy yields in Brazil are greatest among smaller farms.

  7. A DECISION MAKING MODEL FOR SELECTION OF WIND ENERGY PRODUCTION FARMS BASED ON FUZZY ANALYTIC HIERARCHY PROCESS

    OpenAIRE

    SAGBAS, Aysun; MAZMANOGLU, Adnan; ALP, Reyhan

    2013-01-01

    The purpose of this paper is to present an evaluation model for the prioritization of wind energy production sites, namely, Mersin, Silifke and Anamur, located in Mediterranean Sea region of Turkey. For this purpose, a fuzzy analytical hierarchy decision making approach based on multi-criteria decision making framework including economic, technical, and environmental criteria was performed. It is found that the results obtained from fuzzy analytical hierarchy process (FAHP) approach, Anamur d...

  8. Farmed deer: A veterinary model for chronic mycobacterial diseases that is accessible, appropriate and cost-effective

    Directory of Open Access Journals (Sweden)

    Frank Griffin

    2014-01-01

    Full Text Available Although most studies in immunology have used inbred mice as the experimental model to study fundamental immune mechanisms they have been proven to be limited in their ability to chart complex functional immune pathways, such as are seen in outbred populations of humans or animals. Translation of the findings from inbred mouse studies into practical solutions in therapeutics or the clinic has been remarkably unproductive compared with many other areas of clinical practice in human and veterinary medicine. Access to an unlimited array of mouse strains and an increasing number of genetically modified strains continues to sustain their paramount position in immunology research. Since the mouse studies have provided little more than the dictionary and glossary of immunology, another approach will be required to write the classic exposition of functional immunity. Domestic animals such as ruminants and swine present worthwhile alternatives as models for immunological research into infectious diseases, which may be more informative and cost effective. The original constraint on large animal research through a lack of reagents has been superseded by new molecular technologies and robotics that allow research to progress from gene discovery to systems biology, seamlessly. The current review attempts to highlight how exotic animals such as deer can leverage off the knowledge of ruminant genomics to provide cost-effective models for research into complex, chronic infections. The unique opportunity they provide relates to their diversity and polymorphic genotypes and the integrity of their phenotype for a range of infectious diseases.

  9. Investment appraisal of technology innovations on dairy farm electricity consumption

    NARCIS (Netherlands)

    Upton, J.; Murphy, M.; Boer, de I.J.M.; Groot Koerkamp, P.W.G.; Berentsen, P.B.M.; Shalloo, L.

    2015-01-01

    The aim of this study was to conduct an investment appraisal for milk-cooling, water-heating, and milk-harvesting technologies on a range of farm sizes in 2 different electricity-pricing environments. This was achieved by using a model for electricity consumption on dairy farms. The model simulated

  10. Switching transients in large offshore wind farms

    Energy Technology Data Exchange (ETDEWEB)

    King, Rose; Jenkins, Nick [Cardiff Univ., Wales (United Kingdom). Centre for Integrated Renewable Energy, Generation and Supply

    2008-07-01

    The energisation of a wind farm is studied in EMTP-RV. Two different types of array collection networks are studied, one with redundancy and the other with tapered cabling. A wideband frequency-dependent model is used to represent the cables and a circuit breaker model which includes pre-strike and re-strike characteristics is used. The response of the circuit to switching at the offshore substation is shown. The cable lengths between the turbines are varied to show the impact this has on the wave propagation of the transient over-voltage. The difficulties associated with modelling the offshore wind farm for high frequency transient studies are highlighted. (orig.)

  11. Optimization of Wind Farm Layout in Complex Terrain

    DEFF Research Database (Denmark)

    Xu, Chang; Yang, Jianchuan; Li, Chenqi

    2013-01-01

    Microscopic site selection for wind farms in complex terrain is a technological difficulty in the development of onshore wind farms. This paper presented a method for optimizing wind farm layout in complex terrain. This method employed Lissaman and Jensen wake models, took wind velocity distribut......Microscopic site selection for wind farms in complex terrain is a technological difficulty in the development of onshore wind farms. This paper presented a method for optimizing wind farm layout in complex terrain. This method employed Lissaman and Jensen wake models, took wind velocity...... are subject to boundary conditions and minimum distance conditions. The improved genetic algorithm (GA) for real number coding was used to search the optimal result. Then the optimized result was compared to the result from the experienced layout method. Results show the advantages of the present method...

  12. Evaluating the cost-effectiveness of brown-rot control strategies : development of a bio-economic model of brown-rot prevalence in the Dutch potato production chain

    NARCIS (Netherlands)

    Breukers, M.L.H.; Mourits, M.C.M.; Werf, van der W.; Kettenis, D.L.; Oude Lansink, A.G.J.M.

    2007-01-01

    Quarantine diseases comprise a distinct class of plant diseases. In contrast to other plant diseases, direct losses through crop damage are often limited. Yet, quarantine diseases may have serious economic consequences for a country as they threaten the country¿s export of affected crops. In

  13. Farm Models and Eco-Health of Poultry Production Clusters (PPCs following Avian Influenza Epidemics in Thailand

    Directory of Open Access Journals (Sweden)

    Worapol Aengwanich

    2014-04-01

    Full Text Available Thailand is located in Southeast Asia and is a country that was affected by highly pathogenic avian influenza (HPAI epidemics during 2003–2004. Nevertheless, the Thai government’s issuance policy of strict control and prevention of the disease has resulted in efficient disease control of avian influenza (AI. Poultry farmers have been both positively and negatively affected by this policy. There are three poultry cluster models worthy of attention in Thailand: (1 egg chicken poultry clusters over ponds; (2 egg chicken poultry clusters in coops raised from the ground and managed by a cooperative; and (3 poultry clusters in closed coops under contract with the private sector. Following the AI epidemics, additional poultry husbandry and biosecurity systems were developed, thereby generating income and improving the quality of life for poultry farmers. Nevertheless, raising large clusters of poultry in the same area results in disadvantages, particularly problems with both air and water pollution, depending upon the environments of each poultry model. Furthermore, the government’s policy for controlling AI during epidemics has had a negative effect on the relationship between officials and farmers, due to poultry destruction measures.

  14. User guide for the farm process (FMP1) for the U.S. Geological Survey's modular three-dimensional finite-difference ground-water flow model, MODFLOW-2000

    Science.gov (United States)

    Schmid, Wolfgang; Hanson, R.T.; Maddock, Thomas; Leake, S.A.

    2006-01-01

    There is a need to estimate dynamically integrated supply-and-demand components of irrigated agriculture as part of the simulation of surface-water and ground-water flow. To meet this need, a computer program called the Farm Process (FMP1) was developed for the U.S. Geological Survey three-dimensional finite-difference modular ground-water flow model, MODFLOW- 2000 (MF2K). The FMP1 allows MF2K users to simulate conjunctive use of surface- and ground water for irrigated agriculture for historical and future simulations, water-rights issues and operational decisions, nondrought and drought scenarios. By dynamically integrating farm delivery requirement, surface- and ground-water delivery, as well as irrigation-return flow, the FMP1 allows for the estimation of supplemental well pumpage. While farm delivery requirement and irrigation return flow are simulated by the FMP1, the surface-water delivery to the farm can be simulated optionally by coupling the FMP1 with the Streamflow Routing Package (SFR1) and the farm well pumping can be simulated optionally by coupling the FMP1 to the Multi-Node Well (MNW) Package. In addition, semi-routed deliveries can be specified that are associated with points of diversion in the SFR1 stream network. Nonrouted surface-water deliveries can be specified independently of any stream network. The FMP1 maintains a dual mass balance of a farm budget and as part of the ground-water budget. Irrigation demand, supply, and return flow are in part subject to head-dependent sources and sinks such as evapotranspiration from ground water and leakage between the conveyance system and the aquifer. Farm well discharge and farm net recharge are source/sink terms in the FMP1, which depend on transpiration uptake from ground water and other head dependent consumptive use components. For heads rising above the bottom of the root zone, the actual transpiration is taken to vary proportionally with the depth of the active root zone, which can be restricted

  15. Regenerative agriculture: merging farming and natural resource conservation profitably

    OpenAIRE

    Claire E. LaCanne; Jonathan G. Lundgren

    2018-01-01

    Most cropland in the United States is characterized by large monocultures, whose productivity is maintained through a strong reliance on costly tillage, external fertilizers, and pesticides (Schipanski et al., 2016). Despite this, farmers have developed a regenerative model of farm production that promotes soil health and biodiversity, while producing nutrient-dense farm products profitably. Little work has focused on the relative costs and benefits of novel regenerative farming operations, w...

  16. Improving risk models for avian influenza: the role of intensive poultry farming and flooded land during the 2004 Thailand epidemic.

    Directory of Open Access Journals (Sweden)

    Thomas P Van Boeckel

    Full Text Available Since 1996 when Highly Pathogenic Avian Influenza type H5N1 first emerged in southern China, numerous studies sought risk factors and produced risk maps based on environmental and anthropogenic predictors. However little attention has been paid to the link between the level of intensification of poultry production and the risk of outbreak. This study revised H5N1 risk mapping in Central and Western Thailand during the second wave of the 2004 epidemic. Production structure was quantified using a disaggregation methodology based on the number of poultry per holding. Population densities of extensively- and intensively-raised ducks and chickens were derived both at the sub-district and at the village levels. LandSat images were used to derive another previously neglected potential predictor of HPAI H5N1 risk: the proportion of water in the landscape resulting from floods. We used Monte Carlo simulation of Boosted Regression Trees models of predictor variables to characterize the risk of HPAI H5N1. Maps of mean risk and uncertainty were derived both at the sub-district and the village levels. The overall accuracy of Boosted Regression Trees models was comparable to that of logistic regression approaches. The proportion of area flooded made the highest contribution to predicting the risk of outbreak, followed by the densities of intensively-raised ducks, extensively-raised ducks and human population. Our results showed that as little as 15% of flooded land in villages is sufficient to reach the maximum level of risk associated with this variable. The spatial pattern of predicted risk is similar to previous work: areas at risk are mainly located along the flood plain of the Chao Phraya river and to the south-east of Bangkok. Using high-resolution village-level poultry census data, rather than sub-district data, the spatial accuracy of predictions was enhanced to highlight local variations in risk. Such maps provide useful information to guide

  17. Classification of Specialized Farms Applying Multivariate Statistical Methods

    Directory of Open Access Journals (Sweden)

    Zuzana Hloušková

    2017-01-01

    Full Text Available Classification of specialized farms applying multivariate statistical methods The paper is aimed at application of advanced multivariate statistical methods when classifying cattle breeding farming enterprises by their economic size. Advantage of the model is its ability to use a few selected indicators compared to the complex methodology of current classification model that requires knowledge of detailed structure of the herd turnover and structure of cultivated crops. Output of the paper is intended to be applied within farm structure research focused on future development of Czech agriculture. As data source, the farming enterprises database for 2014 has been used, from the FADN CZ system. The predictive model proposed exploits knowledge of actual size classes of the farms tested. Outcomes of the linear discriminatory analysis multifactor classification method have supported the chance of filing farming enterprises in the group of Small farms (98 % filed correctly, and the Large and Very Large enterprises (100 % filed correctly. The Medium Size farms have been correctly filed at 58.11 % only. Partial shortages of the process presented have been found when discriminating Medium and Small farms.

  18. The Impact of Farm Consolidation on Productive Efficiency in Korean Agriculture: Analysis of Farm-Level Panel Data

    OpenAIRE

    Hye-Jung Kang

    2005-01-01

    This paper examines the impact of farm consolidation on productive efficiency, using farm-level panel data from 1998 to 2002. For representation of efficiency and its determinants, this paper uses a model that estimates the deviations of farms from a translog distance function and the determinants of these deviations. Especially, this paper estimates a stochastic multi-output distance function to accommodate multiple outputs and inputs within the frontier framework. The empirical evidence fin...

  19. A modelling framework to predict bat activity patterns on wind farms: An outline of possible applications on mountain ridges of North Portugal.

    Science.gov (United States)

    Silva, Carmen; Cabral, João Alexandre; Hughes, Samantha Jane; Santos, Mário

    2017-03-01

    Worldwide ecological impact assessments of wind farms have gathered relevant information on bat activity patterns. Since conventional bat study methods require intensive field work, the prediction of bat activity might prove useful by anticipating activity patterns and estimating attractiveness concomitant with the wind farm location. A novel framework was developed, based on the stochastic dynamic methodology (StDM) principles, to predict bat activity on mountain ridges with wind farms. We illustrate the framework application using regional data from North Portugal by merging information from several environmental monitoring programmes associated with diverse wind energy facilities that enable integrating the multifactorial influences of meteorological conditions, land cover and geographical variables on bat activity patterns. Output from this innovative methodology can anticipate episodes of exceptional bat activity, which, if correlated with collision probability, can be used to guide wind farm management strategy such as halting wind turbines during hazardous periods. If properly calibrated with regional gradients of environmental variables from mountain ridges with windfarms, the proposed methodology can be used as a complementary tool in environmental impact assessments and ecological monitoring, using predicted bat activity to assist decision making concerning the future location of wind farms and the implementation of effective mitigation measures. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. America's Diverse Family Farms 2007 Edition

    OpenAIRE

    Hoppe, Robert A.; Banker, David E.; Korb, Penelope J.; O'Donoghue, Erik J.; MacDonald, James M.

    2007-01-01

    American farms encompass a wide range of sizes, ownership structures, and business types, but most farms are still family farms. Family farms account for 98 percent of farms and 85 percent of production. Although most farms are small and own most of the farmland, production has shifted to very large farms. Farms with sales of $1 million or more make up less than 2 percent of all farms, but they account for 48 percent of farm product sales. Most of these million-dollar farms are family farms. ...

  1. Observing farming systems

    DEFF Research Database (Denmark)

    Noe, Egon; Alrøe, Hugo Fjelsted

    2012-01-01

    of analysis from individual farmers to communication and social relations. This is where Luhmann’s social systems theory can offer new insights. Firstly, it can help observe and understand the operational closure and system logic of a farming system and how this closure is produced and reproduced. Secondly......, it provides a theory of functional differentiation and structural couplings that opens up for a new approach to look at sustainability by way of decoupling, recoupling and new forms of coupling.......In Denmark, agriculture is becoming increasingly specialised, and more and more actors are becoming involved in farm decision making. These trends are more or less pronounced in other European countries as well. We therefore find that to understand modern farming systems, we have to shift the focus...

  2. Smart Farming Technologies

    DEFF Research Database (Denmark)

    Balafoutis, Athanasios T.; Beck, Bert; Tsiropoulos, Zisis

    2017-01-01

    Precision Agriculture is a cyclic optimization process where data have to be collected from the field, analysed and evaluated and finally used for decision making for site-specific management of the field. Smart farming technologies (SFT ) cover all these aspects of precision agriculture and can...... comprise the delineation of management zones, decision support systems and farm management information system s. Finally, precision application technologies embrace variable-rate application technologies, precision irrigation and weeding and machine guidance. In this chapter, the reader can find...... a technical description of the technologies included in each category accompanied by a taxonomy of all SFT in terms of farming system type, cropping system, availability, level of investment and farmers’ motives to adopt them. Finally, the economic impact that each SFT has compared to conventional...

  3. Data Farming Process and Initial Network Analysis Capabilities

    Directory of Open Access Journals (Sweden)

    Gary Horne

    2016-01-01

    Full Text Available Data Farming, network applications and approaches to integrate network analysis and processes to the data farming paradigm are presented as approaches to address complex system questions. Data Farming is a quantified approach that examines questions in large possibility spaces using modeling and simulation. It evaluates whole landscapes of outcomes to draw insights from outcome distributions and outliers. Social network analysis and graph theory are widely used techniques for the evaluation of social systems. Incorporation of these techniques into the data farming process provides analysts examining complex systems with a powerful new suite of tools for more fully exploring and understanding the effect of interactions in complex systems. The integration of network analysis with data farming techniques provides modelers with the capability to gain insight into the effect of network attributes, whether the network is explicitly defined or emergent, on the breadth of the model outcome space and the effect of model inputs on the resultant network statistics.

  4. Organic food and farming

    DEFF Research Database (Denmark)

    Kledal, Paul Rye

    The paper is based on research conducted for DARCOF II (Danish Research Centre for Organic Farming, www.darcof.dk). The aim of the research project is to analyze the future development of the Danish organic food sector through focusing on two agro-commodities: vegetables and pork. Emphasis...... is placed on identification of economic forces within the supply chains. The main conclusions of the paper – being the results from the organic vegetable chain – are that the rules and regulations, and the development of alternative transaction processes in organic food and farming have so far been founded...

  5. Wind farm policy 1995

    International Nuclear Information System (INIS)

    Anon.

    1995-03-01

    Argyll and Bute District Council, having received a number of planning applications for the erection of wind farms, seeks, in this document, to set out its environmental policy on these installations in line with national government guidelines and those from Strathclyde Regional Council. District Council policy on thirteen environmental issues connected with wind farm construction is set out, covering issues such as environmental impacts on wild-life, noise pollution, access for construction, maintenance and decommissioning vehicles as well as planning consent issues. Recommendations are made to four interested bodies, Strathclyde Regional Council, the Forestry Authority and Scottish Natural Heritage and the Royal Society for the Protection of Birds. (UK)

  6. 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

  7. Urban Farm Business Plan Handbook

    Science.gov (United States)

    The Urban Farm Business Plan Handbook (this document) provides guidance for developing a business plan for the startup and operation of an urban farm. It focuses on food and non-food related cultivated agriculture.

  8. Measurement of farm level efficiency of home gardens in Uyo ...

    African Journals Online (AJOL)

    To investigate the farm level efficiency of home vegetable gardens in Uyo, a stochastic production function which incorporates a model for the technical inefficiency effects was used. Using farm-level data from 80 home gardeners obtained through structured questionnaire, the parameters were estimated simultaneously with ...

  9. Wind Farm Dispatch Control for Demand Tracking and Minimized Fatigue

    DEFF Research Database (Denmark)

    Juelsgaard, Morten; Schiøler, Henrik; Leth, John-Josef

    2012-01-01

    This work presents a strategy for dispatching production references to the individual turbines in a wind farm, such that an overall production demand for the farm is obeyed, while the fatigue experienced by the turbines is minimized. Using a turbine fatigue model for simulating the aging across t...

  10. 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

  11. The profitability of automatic milking on Dutch dariy farms

    NARCIS (Netherlands)

    Bijl, R.; Kooistra, S.R.; Hogeveen, H.

    2007-01-01

    Several studies have reported on the profitability of automatic milking based on different simulation models, but a data-based study using actual farm data has been lacking. The objective of this study was to analyze the profitability of dairy farms having an automatic milking system (AMS) compared

  12. Improving women's lives in Cambodia through fish on farms

    International Development Research Centre (IDRC) Digital Library (Canada)

    improving food security and nutrition? To find out, HKI and UBC conducted a randomized control trial involving 900 women farmers, whose farming practice was one of three types: the original HFP model; HFP plus fishponds; and a group of normal, unassisted farming practice. (control). By Zaman Talukder, Hou Kroeun and ...

  13. A farm to fork approach to nutritious school meals: Tackling ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2016-04-26

    Apr 26, 2016 ... In St Kitts-Nevis and Trinidad and Tobago, partnerships between the agriculture, health, and education sectors have united in a "Farm to Fork" effort to tackle childhood obesity. The Farm to Fork model is built on three pillars: increased fruit and vegetables in school lunches; procurement from local farmers; ...

  14. Farm household risk balancing: empirical evidence from Switzerland

    NARCIS (Netherlands)

    Mey, de Yann; Wauters, E.; Schmid, D.; Passel, van S.; Vancauteren, Mark; Lips, M.

    2016-01-01

    This paper presents the first empirical evidence on household risk balancing behavior, i.e., strategic off-farm decisions in response to changes in expected business risk. Using Swiss FADN data, we estimate a fixed effects seemingly unrelated regression model to analyze how farm households jointly

  15. NORCOWE Reference Wind Farm

    DEFF Research Database (Denmark)

    Bak, Thomas; Graham, Angus

    2015-01-01

    Offshore wind farms are complex systems, influenced by both the environment (e.g. wind, waves, current and seabed) and the design characteristics of the equipment available for installation (e.g. turbine type, foundations, cabling and distance to shore). These aspects govern the capital and opera...

  16. Terraces and contour farming

    Science.gov (United States)

    Terraces are earthen embankments constructed across the prevailing field land slope. They have been used in differing forms for thousands of years in an attempt to protect steep land slopes from runoff induced erosion. Contour farming, where tillage and planting create ridges and furrows at nearly...

  17. Stochastic dynamic simulation modeling including multitrait genetics to estimate genetic, technical, and financial consequences of dairy farm reproduction and selection strategies.

    Science.gov (United States)

    Kaniyamattam, K; Elzo, M A; Cole, J B; De Vries, A

    2016-10-01

    cows in the herd was $263 greater in yr 15 in a scenario that combined sexed semen use in heifers and culling of surplus heifers with the lowest EBV of NM$, compared with a scenario that used only conventional semen and surplus heifers were culled randomly. The average TBV of daughter pregnancy rate of all cows in the herd was 1.25 percentage points greater in yr 15 in a scenario that combined using sexed semen in heifers as well as culling of surplus heifers ranked by EBV of NM$, compared with a scenario using conventional semen only as well as culling surplus heifers ranked by EBV of milk. In conclusion, the multitrait genetics model resulted in improved estimates of genetic, technical, and financial effects and appears useful to evaluate consequences of various reproduction and selection strategies within a dairy farm. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  18. Ten qualities of family farming

    NARCIS (Netherlands)

    Ploeg, van der J.D.

    2013-01-01

    Even in the International Year of Family Farming there is confusion about family farming. What is it, and what distinguishes it from entrepreneurial farming or family agribusiness? The confusion tends to be highest in places where the modernisation of agriculture has led society further away from

  19. Influence of farm resource endowment on possibilities for sustainable development: a case study for vegetable farms in South Uruguay

    NARCIS (Netherlands)

    Dogliotti, S.; Ittersum, van M.K.; Rossing, W.A.H.

    2006-01-01

    In different parts of the world, there is an urgent need for redesigning and innovating farming systems. Such a process may be supported by model-based explorations that enable ex-ante evaluation of a broad range of alternatives. Since a variety of viable patterns of farm development exists related

  20. CPS and the Fermilab farms

    Energy Technology Data Exchange (ETDEWEB)

    Fausey, M.R.

    1992-06-01

    Cooperative Processes Software (CPS) is a parallel programming toolkit developed at the Fermi National Accelerator Laboratory. It is the most recent product in an evolution of systems aimed at finding a cost-effective solution to the enormous computing requirements in experimental high energy physics. Parallel programs written with CPS are large-grained, which means that the parallelism occurs at the subroutine level, rather than at the traditional single line of code level. This fits the requirements of high energy physics applications, such as event reconstruction, or detector simulations, quite well. It also satisfies the requirements of applications in many other fields. One example is in the pharmaceutical industry. In the field of computational chemistry, the process of drug design may be accelerated with this approach. CPS programs run as a collection of processes distributed over many computers. CPS currently supports a mixture of heterogeneous UNIX-based workstations which communicate over networks with TCP/IR CPS is most suited for jobs with relatively low I/O requirements compared to CPU. The CPS toolkit supports message passing remote subroutine calls, process synchronization, bulk data transfers, and a mechanism called process queues, by which one process can find another which has reached a particular state. The CPS software supports both batch processing and computer center operations. The system is currently running in production mode on two farms of processors at Fermilab. One farm consists of approximately 90 IBM RS/6000 model 320 workstations, and the other has 85 Silicon Graphics 4D/35 workstations. This paper first briefly describes the history of parallel processing at Fermilab which lead to the development of CPS. Then the CPS software and the CPS Batch queueing system are described. Finally, the experiences of using CPS in production on the Fermilab processor farms are described.