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1
Dunaway, Tarrah M. "Farm Financial Performance of Kentucky Farms". UKnowledge, 2013. http://uknowledge.uky.edu/agecon_etds/13.
Testo completoAbstract (sommario):
This study examines farm financial performance of Kentucky farms using Kentucky Farm Business Management data from 1998-2010. Logit models are used to estimate the likelihood of farm characteristics affecting whether financial ratios fall into critical zones or not. The results show that large farms in terms of total gross returns and total assets are less likely to experience repayment capacity problems. Total gross returns significantly affect all five financial measures. These findings will help farmers and lenders understand what factors influence farm financial performance. Profitability migration is tested to see if the migration probabilities differ across business cycles. Migration drift is also tested to determine if the Markov property of independence is violated. Results show substantial retention in return on equity (ROE) performance over time, and a tendency for trend-reversal if ROE changes occur. Results are compared to previous literature using ARMS data and Illinois FBFM.
2
Xu, Qing Yun. "The competitiveness of Ontario dairy farms : a farm level analysis". Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=116061.
Testo completoAbstract (sommario):
The Canadian supply managed dairy sector is likely to face more competitive pressure from challenges through the World Trade Organization (WTO) and the changing global trade environment. Therefore, it is highly prudent for Canadian dairy producers to focus their concern on their level of competitiveness and how to improve it. This study investigated the competitiveness of Ontario dairy sector based on a sample of farm level data with a Box-Cox transformed econometric cost model. The data were gathered by the Ontario Dairy Farm Accounting Project, for the years 2005, 2006, and 2007. The impacts of output, yield per cow and several farm-specific characteristics on the average cost of milk production were examined. Results support the presence of significant size economies and yield economies within Ontario milk production. Minimum costs were achieved for farms with approximately 125 cows. The results also indicated that some farm-specific characteristics, breed and region, also had significant impacts on the cost of Ontario milk production. However, it appears that Ontario farms may find it difficult to survive if they are forced to face international competition. Even at their minimum, average costs were above an indicator international dairy price.
3
BELLINGERI, ANDREA. "WHOLE FARM DECISION MAKING AND TOOLS FOR DAIRY FARMS PROFITABILITY". Doctoral thesis, Università Cattolica del Sacro Cuore, 2020. http://hdl.handle.net/10280/72496.
Testo completoAbstract (sommario):
Nel tentativo di rispondere alle richieste della società per lo sviluppo sostenibile, i sistemi agricoli di tutto il mondo devono affrontare sfide ambientali, tecniche ed economiche. I raccolti irregolari, i prezzi fluttuanti delle materie prime e l'impatto delle attività agricole sull'ambiente sono preoccupazioni crescenti. Le tendenze demografiche effettive e i maggiori costi energetici potrebbero complicare ulteriormente lo scenario nel prossimo futuro. La ricerca sta affrontando queste sfide lavorando su sistemi di allevamento e zootecnia più sostenibili e rispettosi dell'ambiente in grado di fornire sia alti livelli di produttività che sostenibilità economica per gli agricoltori. Per ottenere un effetto, le innovazioni derivate dalla ricerca devono essere implementate a livello di azienda agricola. Tuttavia, a causa delle relazioni tra i vari elementi del bestiame nel sistema di produzione lattiero-casearia, la diversità delle aziende agricole anche in una piccola area rende complessa la piena attuazione di tali raccomandazioni. Abbiamo scoperto che pochissimi studi tentano di affrontare i tre componenti principali dei sistemi di produzione di caseifici (bestiame, terreni coltivati, mercato e materie prime) all'interno di un unico quadro di ricerca. Abbiamo quindi sviluppato un quadro collegando le caratteristiche e le esigenze del bestiame, le caratteristiche dei terreni coltivati e le opportunità di mercato per sostenere il piano di coltivazione e la gestione nutrizionale a livello aziendale al fine di massimizzare i profitti e ridurre i costi di produzione del latte.
Abbiamo scoperto che il costo reale di produzione in loco dei principali foraggi coltivati presenta un'elevata variabilità tra le aziende agricole e che una strategia decisionale dedicata al piano colturale è un modo adatto per migliorare le IOFC (reddito sul costo dell'alimentazione) a livello di azienda agricola.In trying to respond to the society demands for sustainable development, environmental, technical and economic challenges are faced by farming systems worldwide. Irregular crop yields, fluctuating commodities prices, and the impact of agricultural activities on the environment are growing concerns. Actual demographic trends and higher energy costs are likely to further complicate the scenario in the near future. Research is facing these challenges by working on more sustainable and environmental friendly cropping and livestock systems able to provide both high productivity levels and economical sustainability for farmers. To obtain an effect, innovations derived from the research, has to implemented at the farm level. However, due to the relationships between the various elements of the cropping-livestock in the dairy production system, the farms diversity even in a small area, make the fully implementation of such recommendations complex. We found that very few studies attempt to address the three main components of the dairy farm production systems (livestock, crop land, market and commodities) within a single research framework. We therefore developed a framework by connecting livestock characteristics and requirement, crop land characteristics and market opportunities to support cropping plan and nutritional management at the farm level in order to maximize profit and reducing milk costs of production. We found that home-grown real cost of production of the main forages cultivated has a high variability among farms and that a dedicated crop plan decision making strategy is a suitable way to improve IOFC (Income Over Feed Cost) at the farm level.
4
Mai, Chi Le Phuong Hartarska Valentina M. "Farm investment and off-farm income h [electronic resource] : a study of farms in Alabama /". Auburn, Ala., 2006. http://repo.lib.auburn.edu/Send%206-15-07/MAI_CHI_44.pdf.
Testo completo
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Vaddella, Venkata Kumar. "Ammonia emissions management and modeling from storages of dairy manure". Pullman, Wash. : Washington State University, 2010. http://www.dissertations.wsu.edu/Dissertations/Spring2010/V_Vaddella_1030810.pdf.
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6
Heenan, Deirdre Anne. "The role and contribution of farm wives on farms in Northern Ireland". Thesis, University of Ulster, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242144.
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Bannon, Brian. "Engaging existing conditions with new conditions a farm equipment museum amidst an abandoned dairy farm /". This title; PDF viewer required Home page for entire collection, 2008. http://archives.udmercy.edu:8080/dspace/handle/10429/9.
Testo completo
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Chaplin, Hannah Elizabeth. "Non-agricultural diversification of corporate farms and and farm households in Central Europe". Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416117.
Testo completo
9
Holland, Cody. "Labor standards and efficiency estimation of farms in the Kansas Farm Management Association". Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/13607.
Testo completoAbstract (sommario):
Master of ScienceDepartment of Agricultural Economics
Michael Langemeier
The objectives of this thesis are to examine the labor requirements of Kansas crop and livestock enterprises and farms and the connection between labor efficiency and productivity, and other important farm characteristics including farm size and type. The derived labor requirements are compared to current KFMA labor requirements. Enterprise summary reports and a five year whole-farm panel data set from 1,016 Kansas Farm Management Association (KFMA) farms are used in the analysis. Whole-farm labor requirements are computed with and without an adjustment for managerial and overhead cost. Individual regressions will be estimated to determine the effects that farm size, type, region and profit margin have on labor requirements. The estimation results suggest that many of the current labor requirements still in use are accurate. However, there are enterprises with labor requirements that need updating. When the newly estimated requirements are compared to the previous KFMA requirements, 14 enterprises have lower labor requirements. Irrigated alfalfa showed the greatest decrease in labor required when compared to the previous standard, decreasing from 3.85 hrs/acre to 1.70 hrs/acre. Regression estimation results indicated that whole farm labor standards that were corrected for un-allocated overhead and managerial costs appear to be a more accurate representation of farm labor requirements.
10
O'Leary, Niall. "Farmer attributes associated with farm profitability : a study of dairy farms in Great Britain". Thesis, University of Reading, 2017. http://centaur.reading.ac.uk/75745/.
Testo completoAbstract (sommario):
How farmer attributes influence farm businesses performance and profitability is poorly understood. This thesis sets out to ascertain the farmer attributes that are associated with farm performance and profitability. For the first time from a farm management perspective, the management and job performance literature is reviewed comprehensively. A broad exploratory study focusing on farmer attitudes is reported along with a focused study on farmer personality attributes. Participants in both studies were dairy farmers in Great Britain. Linear models are presented in both studies. Just six and three variables were included in each model in the respective attitudes and personality studies. Models in both studies predict more than 40% of the variation in profitability. Cumulatively, more than half the profitability variation can be predicted by the GCA, Detail Conscientious competence, Leadership competence, temperament, attitudes and beliefs of farmers. These findings underline the major significance farm manager attributes are likely to have in driving farm profitability. The qualification ‘likely’ is used as causality has yet to be clearly established in agriculture (unlike in other sectors). The findings reported here relating to dairy farms are consistent with findings in other sectors. They thus appear to be broadly applicable and so likely to be of similar relevance to farms in sectors other than dairy. The effect sizes and the proportion of variation explained are large and may be surprising but are also similar to those found in other sectors. Strategic development and management of the highlighted farmer attributes is advised to facilitate potentially large improvements in farm profitability and financial viability. For farm management research, these may be pivotal findings offering several promising avenues for future research.
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Shubert, Natalie E. "No Farm, No Food: Organizing Appalachian Family Farms around the Politics of 'Good Food'". Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1272911792.
Testo completo
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Li, Simeng. "WIND ARRAY PERFORMANCE EVALUATION MODEL FOR LARGE WIND FARMS AND WIND FARM LAYOUT OPTIMIZATION". Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1405080318.
Testo completo
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Lutton, Susan J. "Aquatic biodiversity and the ecological value of on-farm water storages on irrigation farms". Thesis, Griffith University, 2010. http://hdl.handle.net/10072/367656.
Testo completoAbstract (sommario):
Globally, natural wetlands are under threat from water resource development
reflecting the need to support a growing population. In the Border Rivers Catchment
in Queensland, Australia, a large irrigation industry coupled with a highly variable
flow regime has necessitated the building of large on-farm water storages and often
associated destruction or isolation of their natural counterparts. With the decline in
abundance of natural wetlands, the presence of these storages on the floodplain has
raised the question of their suitability as alternative aquatic habitat. This project
aimed to investigate the diversity of storages and the structure and function of the
aquatic assemblages they support compared with nearby natural wetlands. These
results were then used to recommend best management practice for optimising both
diversity and ecosystem function in storages.
Initially the physical variety of water storages in the Border Rivers Catchment was
described and their morphology and hydrology compared to that of natural wetlands.
Storages and natural wetlands formed two distinct groups based on morphology.
Storages tended to be large, deep structures with a more regular shape, while natural
wetlands were irregular and shallow with large perimeters. Although there was a
degree of variability amongst storage sites, most fell into one group and were
considered to be a ‘typical’ storage in this region.
After classifying the storages based on hydrology and morphology, the spatial and
temporal biodiversity of the different storage groups was compared with natural
wetlands. Spatial patterns (between waterbody types) in fish and macroinvertebrate
assemblages composition were explored between August and October 2005 in three
waterbody types; natural wetlands, typical storages and a group of storages with
similar morphology to typical storages but lacking tailwater (‘no tailwater’ storages).
In total nine fish species were collected comprising seven natives and two exotic
species. Only one species, the eel-tailed catfish, Tandanus tandanus, was specific to
natural wetlands. Although fish species diversity was similar between the two storage
types and natural wetlands, there was significant spatial variation in total abundances,
with typical storages having ten times the average catch size of that found in natural
wetlands. In both storage types catches were dominated by bony bream, Nematalosa
erebi, while in natural wetlands there was a more even distribution of species. The
percentage of exotic species was much lower in both storage types (< 8%) compared
with natural wetlands (> 40%).
There were also significant spatial differences in macroinvertebrate assemblages; 24
samples from natural wetlands were represented by more than 14,500 individuals
across 84 different taxa. In comparison, only 34 taxa from 2,142 individuals and 34
taxa from 7,611 individuals were collected in 15 samples from typical storage sites
and 12 samples from ‘no tailwater’ sites respectively. Seventeen taxa were common
to all three waterbody types while 45 taxa were specific to natural wetlands. None of
the measured environmental variables explained the observed variation in
macroinvertebrate assemblages between waterbody types. Temporal patterns in
macroinvertebrate and zooplankton assemblages were also investigated comparing
natural wetlands and typical storages during the 05/06 and 06/07 cotton seasons.
Specifically, macroinvertebrate and zooplankton assemblages from typical storages
were less diverse than those found in natural wetlands. Temporal variation in aquatic
assemblages was also apparent with macroinvertebrate and zooplankton assemblages
of both waterbody types following a similar pattern through time. However, there
were no strong associations between the environmental data collected and the
observed assemblage composition.
To further investigate the spatial variation observed in aquatic assemblages, two
sources of colonisation of storages were examined, namely the aquatic assemblages
found in extracted river water and those hatching from the egg bank. Eight different
fish species including three exotics were collected during sampling of pumped river
water. As was observed in storages, the catch was dominated by N. erebi and the
contribution of exotic species to the total catch was extremely low (< 1%). Fish with
a standard length of over 200 mm survived the extraction process. The eight samples
of pumped river water were represented by 22 macroinvertebrate taxa and 332
individuals. This was a reduced diversity than collected from typical storages (34
taxa). In comparison, zooplankton assemblages had similar diversity to those
observed in the typical storages, 25 taxa compared with 22 taxa. Sediment samples
collected from the floodplain had a more diverse but less abundant egg bank (46,463
individuals from 20 taxa) than those collected from dry typical storages (70,600
individuals from 16 taxa).
The observed spatial differences in morphological and hydrological features and
aquatic assemblages suggested that there may also have been variations in aquatic
processes between waterbody types. Stable isotope analyses were used to investigate
the major sources of energy fuelling the aquatic food webs of natural wetlands and
typical storages. In general all components of the food web in typical storages were
13C and 15N-enriched in comparison with natural wetlands. The importance of source
carbon to consumers varied greatly between species, sites, and waterbody types.
Algae, in the form of biofilm and floating algae, along with zooplankton were the
major sources of organic carbon to aquatic food webs, contributing 50% of organic
carbon across natural wetlands and 54% across typical storages.
Storages primarily function as water supplies and their associated management makes
them mostly unsuitable as ‘replacement’ wetlands. However, given the large numbers
of storages across the catchment, if managed effectively, they may provide an
additional source of aquatic habitat and help maintain regional biodiversity. To
maximise the biodiversity of storages it will be essential to reduce the morphological
homogeneity of storages across the landscape and increase habitat diversity within
storages. In the future, improved design of new storages and alterations to existing
storages and their management could help overcome this problem of low diversity of
habitat.
As a group, storages in the Border Rivers Catchment are still fundamentally different
to natural waterbodies, with storages being a mostly homogeneous group. If we are to
sustain the aquatic biodiversity in the Border Rivers Catchment and other similar
irrigation regions it will be necessary to preserve the spatial and temporal variation in
habitat evident in natural wetlands.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
Full Text
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Makhura, Moraka Thomas. "Overcoming transaction costs barriers to market participation of smallholder farmers in the Northern Province of South Africa". Pretoria : [s.n.], 2001. http://upetd.up.ac.za/thesis/available/etd-09012001-131116/.
Testo completo
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Flo, Randi Aardal. "Configuration of large offshore wind farms". Thesis, Norwegian University of Science and Technology, Department of Electrical Power Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9957.
Testo completoAbstract (sommario):
This master thesis is written at the Department of Electric Power Engineering at the Norwegian University of Science and Technology. The work has been carried out at NTNU in Trondheim. The thesis deals with configuration of large offshore wind farms and transmission systems, and is a continuation of the project written during the autumn 2008. Today several plans on 1000 MW offshore wind farms exists. The size of the wind farms has led to a challenge of how to find an efficient and secure design of the overall system. The system has to be cost-effective in order to compete with other forms of power generation. In this study, costs is not considered. The purpose of this thesis was to study different transmission systems and configuration of an 1000 MW wind farm located 75 km from shore. The optimal distance between the turbines is a compromise between wake effect, wind farm are and cable lengths. To perform a detailed study of wake effects and optimal spacing, computer programs like WindSim would be necessary. Three common wind farm configurations is radial, star and ring layout. The selection of layout depends on costs, wind data and the wind farm area. Various wind turbine systems have been developed and different wind generators have been built. According to the survey of different wind generator system and considering the grid connection requirements on wind turbines, the developing trends of wind turbine generator systems shows that variable speed is very attractive and concepts with full-scale power converters will become more attractive. In this thesis two wind farm configurations with different transmission system were further studied. AC/AC, AC/DC and DC/DC are possible transmission systems. In this thesis AC/AC and AC/DC were compared. The selected layout of the wind farm was the radial layout. Number of strings was 35, with eight turbines in each string. Each wind turbine could produce 3.6 MW, which gives a total generation of 1008 MW. The two configurations were modeled in PSS/E. Siemens has made a model called WT3 that was developed to simulate performance of a wind turbine employing a doubly fed induction generator (DFIG). The model was developed in close cooperation with the GE Energy modeling team. This model was used in this thesis. For the dc transmission the HVDC Light from ABB was used. Two different disturbances were applied. One at the connection point at shore, and one at the connection point for all the radials. The load flow results shows that the losses are 5.8$%$ higher in the AC/DC system. The dynamical result shows that both of the systems were stable, and fulfill the grid code requirements. The results indicates that the short-circuit MVA is higher in the ac system than in the dc system. After a fault the voltage recovery was more smoother in the dc system, and the voltage recovery time were shorter.
16
Khatab, Abdul Mouez. "Performance Analysis of Operating Wind Farms". Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-331783.
Testo completoAbstract (sommario):
This work proposes a methodology to evaluate the performance of operating wind farms via the use of Supervisory Control and Data Acquisition System (SCADA) and modeled data. The potential annual energy is calculated per individual turbine considering underperforming/loss events to have their power output in accordance with a representative derived operational power curve. Losses/underperformance events are calculated and categorized into several groups aiming at identifying and quantify their causes. The methodology requires both anemometry data from SCADA system as well as modeled data. The discrepancy of the data representing the valid points of the power curve is taken into consideration as well when assessing the performance, i.e. wind speed vs power output of events that are not loss/underperformance. Production loss and relative standard deviation of power output of what is defined as “valid sample” in this work (per each turbine) are the main results obtained in this work. Finally, a number of optimization measures are suggested in order to enhance the performance, which can lead to a boost in the financial output of a wind farm. Aiming at judging the reliability of the proposed methodology, a case study is conducted and evaluated. The investigated case study shows that the methodology is capable of determining potential energy and associated losses/underperformance events. Several questions were raised during the assessment and are discussed in this report, recommendation for optimization measures are presented at the end of the study. Also, a discussion on the limitations and uncertainties associated to the presented methodology and the case study.
17
Bezerra, Rufino Ferreira Paiva Eduardo. "Wind Velocity Estimation for Wind Farms". Electronic Thesis or Diss., Université Paris sciences et lettres, 2023. http://www.theses.fr/2023UPSLM046.
Testo completoAbstract (sommario):
Cette thèse propose des algorithmes pour estimer la vitesse et la direction du vent pour des éoliennes et des parcs éoliens.Tout d'abord, nous proposons des méthodes basées sur les données pour estimer la vitesse effective du rotor (REWS) sans nécessiter la connaissance de certains paramètres physiques de l'éolienne, qui pourraient être inconnus de l'opérateur. Nous fournissons deux méthodes basées sur les données, l'une basée sur la régression par processus gaussien et l'autre combinant la régression par processus gaussien avec un observateur grand gain.Ensuite, en nous basant sur cette estimation locale de la REWS, au niveau d'une éolinenne, nous abordons la question de l'estimation du vent en écoulement libre au niveau du parc éolien.Nous commençons par nous concentrer sur l'estimation de la vitesse du vent, pour une direction du vent connue. Pour un parc éolien de géométrie simple, nous démontrons qu'une mesure locale de la vitesse perturbée par la présence des éoliennes peut être utilisée pour estimer la vitesse du vent en écoulement libre. Nous fondons notre méthodologie d'estimation sur une modélisation simplifiée de l'effet de sillage qui consiste en des équations aux dérivées partielles hyperboliques du premier ordre en cascade, et dont la vitesse de transport est la vitesse du vent en écoulement libre. Nous proposons d'utiliser une solution analytique de ces équations, impliquant des retards de transport, pour effectuer une estimation de la mesure locale et mettre à jour l'estimation de la vitesse du vent en écoulement libre. Nous démontrons formellement la convergence de cette estimation et illustrons numériquement l'efficacité de cette méthode.Enfin, nous passons à une configuration plus générale où à la fois la vitesse et la direction du vent en écoulement libre sont inconnues. Nous proposons d'utiliser une modélisation bidimensionelle du sillage et de nous appuyer sur une méthode basée sur l'optimisation. Le problème d'identification que nous formulons se révèle être particulièrement difficile en raison de l'apparition de retards de transport, mais nous montrons comment contourner cette difficulté en considérant une valeur moyenne de l'historique de la vitesse du vent en écoulement libre. Des résultats de simulation obtenus avec le simulateur FAST.Farm illustrent l'intérêt de la méthode proposéeThis thesis designs algorithms to estimate the wind speed and direction for wind turbines and wind farms.First, we propose data-based methods to estimate the Rotor Effective Wind Speed (REWS) for a single turbine without prior knowledge of certain physical parameters of the turbine that might be unknown to an operator.We provide two data-based methods, based respectively on Gaussian Process Regression (GPR) and on an combination of GPR with high-gain observers.Second, grounding on this REWS estimation at the local level of one turbine, we address the question of estimating the free-flow wind at the level of a wind farm.We start by focusing on wind speed estimation, for a given known wind direction. For a wind farm with a simple geometry, we prove that a local speed measurement disturbed by the presence of the turbines can be used to estimate the free-flow wind speed. We ground our estimation methodology on a simplified wake model, which consists of first-order hyperbolic partial differential equations, the transport speed of which is the free-flow wind speed. We propose to use an analytical solution of these equations, involving transport delays, to perform an estimate of the local measurement and to update the free-flow wind speed estimate. We formally prove the convergence of this estimate and numerically illustrate the efficiency of this method.Finally, we move to a more general setup where both the free-flow wind speed and direction are unknown. We propose to use a two-dimensional wake model and to rely on an optimization-based method. This identification problem reveals to be particularly challenging due to the appearance of transport delays, but we illustrate how to circumvent this issue by considering an average value of the free flow wind speed history. Simulation results obtained with the simulator FAST.Farm illustrate the interest of the proposed method
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Demir, Ibrahim. "The firm size, farm size, and transaction costs the case of hazelnut farms in Turkey /". Connect to this title online, 2007. http://etd.lib.clemson.edu/documents/1202498616/.
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Amornvivat, Sutapa 1974. "Impact of on-farm water storage for increasing agricultural productivity of rice farms in Thailand". Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/84308.
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Can, Edna Maria de Andrade Vieira. "Welfare assessment in Portuguese dairy goat farms : on-farm overall feasibility of an international prototype". Master's thesis, Universidade de Lisboa. Faculdade de Medicina Veterinária, 2015. http://hdl.handle.net/10400.5/8862.
Testo completoAbstract (sommario):
Dissertação de Mestrado Integrado em Medicina VeterináriaThis study describes and assesses the application of the on-farm welfare assessment prototype for dairy goats (Capra hircus) developed by the AWIN project. Thirty Portuguese dairy goat farms were assessed from January to March 2014. Pen-level observations were carried out on 2715 animals and detailed individual observations were performed on 1172 of these animals. The main areas of concern were associated with claw overgrowth, queuing at feeding, overweight animals, poor hair coat condition and improper disbudding. The results obtained show that these welfare issues are related to farm sizes, with larger farms heading higher concerns. Furthermore, the reliability and feasibility of the animal-based indicators were tested. Overall, moderate to high levels of agreement between observers were identified, with the exception of Qualitative Behaviour Assessment (QBA). From all stages of the prototype ‘Queuing’ and ‘Clinical scoring’ were the most time consuming, with the mean time required to apply the prototype being longer in large farms. In conclusion, the protocol has shown the potential not only for legislative and regulatory purposes, but also as a certification, advisory/management and research tool, probably following a two-step approach.
RESUMO - Avaliação de Bem-Estar Animal em Explorações Portuguesas de Caprinos de Leite: exequibilidade de um protótipo internacional de avaliação de bem-estar - Este estudo tem como objectivo descrever e avaliar a aplicação do protótipo de avaliação de bem-estar animal, desenvolvido pelo projecto AWIN em explorações de caprinos de leite em regime intensivo. Trinta explorações portuguesas foram avaliadas de Janeiro a Março de 2014, tendo sido efectuadas avaliações no parque de 2715 caprinos de leite e observações individuais a 1172 desses animais. Os principais problemas identificados nas explorações encontram-se associados a um crescimento excessivo das unhas, filas na manjedoura, animais com condição corporal elevada, com má condição do pêlo e alvo de uma má descorna. Os resultados obtidos indicam que estes problemas de bem-estar animal encontram-se relacionados com a dimensão das explorações, em que as de maior dimensão demonstram prevalências mais elevadas. A repetibilidade e exequibilidade dos indicadores que compõem o protótipo foram também testadas. De uma forma global, os níveis de repetibilidade entre os observadores, são moderados a elevados, com excepção da Avaliação Qualitativa do Comportamento (AQC). Das várias etapas que constituem o protótipo, as que envolvem mais tempo são a 'Presença de filas' e a 'Avaliação clínica', com o tempo médio necessário para a sua aplicação atingindo valores mais elevados em explorações maiores. A realização deste estudo permite concluir que o protocolo final de avaliação de bem-estar animal em caprinos de leite terá potencial não só como uma base legislativa e regulamentar, mas igualmente como uma ferramenta de certificação, consultoria/gestão e de pesquisa, seguindo uma estratégia baseada em dois níveis de avaliação.
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Stewart, Brittany Allison. "The Impact of Feed Management Software on Whole-Farm Nutrient Balance on Virginia Dairy Farms". Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/42718.
Testo completoAbstract (sommario):
Agricultural runoff is the largest source of nitrogen and phosphorus pollution entering the Chesapeake Bay, contributing 38% of nitrogen and 45% of phosphorus (USEPA, 2010). Since agricultural runoff is the number one contributing source of nitrogen and phosphorus entering the Chesapeake Bay, action needs to be taken to reduce nitrogen and phosphorus on agriculture production facilities, such as dairy farms. The impact of feed management software on whole-farm nutrient balance was studied on 18 dairy farms located in Virginia from 2006 to 2010. Nine farms began using the TMR Tracker feed management software in 2006 and were compared to 9 control farms not using feed management software. Each of the treatment farms were visited on a monthly basis to collect ration and feed ingredient samples and feed management data. Whole-farm nutrient balance was calculated using University of Nebraska software. Herd sizes and crop hectares averaged 314 and 366 for treatment and 298 and 261 for control farms. Milk production averaged 3,226 and 2,650 tonnes per year respectively. Measures of surplus (input-output) and use efficiency (input/output) for nitrogen and phosphorus were analyzed over a four year time span and did not differ between treatment and control farms whether expressed on a per farms, cow or hectare basis. Due to the large variation in feeding accuracy within farms, the use of feed management software did not influence whole-farm nutrient balance. Sources of variation that contributed to loading errors were investigated within the feed management data. Percent load deviation increased over time from 2007 to 2009 from 0.94 ± 0.53 to 2.37 ± 0.50 percent of the actual load weight. Effects of month, day of the week and time of day on percent load deviation were not significant. There was no effect of percent load deviation on milk production. No relationship was observed between percent load deviation and whole-farm nutrient balance.Master of Science
22
Wasserfall, Michiel Nicolaas. "Rain events based hillslope hydrological processes at the Langgewens Experimental Farm, Western Cape, South Africa". Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80045.
Testo completoAbstract (sommario):
Thesis (MScAgric)--Stellenbosch University, 2013.ENGLISH ABSTRACT: Hillslope hydrology represents a complex system with several interacting processes influencing the movement of water through the landscape. The Western Cape area of South Africa is expected to be impacted on by a change in climate and the importance of water management that will increase in the future. Climate, especially precipitation, is the driving factor behind the hydrological system and there are currently no predictions as to what the impact will be on the hydrological conditions. The main objective of the study is to understand the hydrological responses along a hillslope and secondly to determine the effect of climate change on the hydrology by using hydrological models. The studied system is situated on the Langgewens Experimental Farm, north of Malmesbury in the Swartland region of the Western Cape. Six sites in a range of vegetation, land use and expected soil types along a toposequence were investigated. All sites are rain fed areas with natural vegetation, seasonal or long-term shrubs. Through monitoring different components of the hydrological cycle, including rainfall, overland flow, infiltration, soil water content, base flow and water table depth at the different sites, the movement of water through the landscape can be defined. Hillslope hydrological processes at different positions on the hillslope were investigated. The baseline data obtained during this process was used in hydrological modelling for the different positions on the hillslope to determine the accuracy of model predictions. Expected future climatic conditions were emulated in this model to determine the possible effect of a change in climate on the hydrological system. The research confirmed the complex interaction between different processes within the hydrological system. At each point along the toposequence different components of the hydrological cycle contributed on a different scale to the hydrological system. Soil properties were the most significant factor influencing water movement through the landscape, directly impacting infiltration, overland flow, lateral water flow and deep percolation. This resulted in water table fluctuations through the seasons as the contribution of different components towards the hydrological cycle changed. By comparing soil water content measurements through the season with modelled water content levels, accurate hydrological models were created for different measuring points in the landscape. By using forecasted climate data of two different weather generators, accurate estimations of expected soil water content were possible. This indicated that droughts will occur on a regular basis in the future. This research made it possible to understand water movement through the landscape at hillslope level and contributed towards future water management plans by estimating future soil water content levels based on current predictions.
AFRIKAANSE OPSOMMING: Heuwelhang hidrologie omskryf die proses van water beweging deur die landskap en dit word deur verskeie prosesse beinvloed. Onder huidige toestande word verwag dat die Weskaap provinsie van Suid-Afrika warmer en droëer sal word in die toekoms as gevolg van klimaatsverandering. Dit sal die noodsaaklikheid van effektiewe waterbestuur verhoog in die toekoms. Klimaat, en in besonder reënval, is die dryfkrag agter die hidrologiese sisteem en huidiglik is daar geen aanduiding van wat die effek van klimaatsverandering op die hidrologiese sisteem gaan wees nie. Die eerste doel van die studie is om die heuwelhang se hidrologiese sisteem te ontleed en tweedens om die impak van klimaatsverandering op die hidrologiese sisteem te bepaal deur gebruik te maak van hidrologiese modelle. Die studie area is geleë op die Langgewens Proefplaas, noord van Malmesbury in die Swartland distrik van die Weskaap. Ses verskillende posisies is op die heuwelhang geselekteer op grond van posisie in die landskap, plantegroei, landgebruik en verwagte grondvorms. Al die studiepunte ontvang slegs water deur reën en die landgebruik wissel ten opsigte van natuurlike plantegroei, en eenjarige- of meerjarige gewasse wat gevestig is. Deur verskillende komponente van die hidrologiese sisteem te monitor, insluitend reënval, oppervlak afloop, infiltrasie, grond water inhoud, laterale water vloei en die diepte van die watertafel, kan die beweging van water deur die landskap gedefinieër word. Die data wat versamel is gedurende die proses word gebruik om die akkuraatheid van die hidrologiese modelle se resultate te bepaal. Tesame met vooruitgeskatte klimaatdata kan die modelle gebruik word om die impak van klimaatsverandering op grondwater toestande vas te stel. Die navorsing toon die komplekse interaksie tussen verskillende prosesse in die hidrologiese sisteem. By elke punt in die landskap dra verskillende komponente op verskillende skale by tot die hidrologiese sisteem. Grondeienskappe het die meeste invloed op die verskillende komponente van die hidrologiese sisteem en beïnvloed die infiltrasie, oppervlak afloop, laterale water vloei en diep dreinering. Soos die verskillende komponente se bydrae tot die hidrologiese sisteem verander, vind daar fluktuasies in die diepte van die water tafel plaas. Deur die vergelyking van gemete grondwaterinhoud teen hidrologiese model voorspelde grondwaterinhoude, is akkurate hidrologiese modelle opgestel vir verskillende punte in die landskap. Deur gebruik te maak van twee moontlike verwagte klimaat toestande, is gevind dat droogtes op ‘n roetine basis in die toekoms sal voorkom. Die navorsing maak dit moontlik om die beweging van water deur die landskap te verstaan en dra by tot die opstelling van toekomstige waterbestuur planne. Dit word moontlik gemaak deur die vooruitskatting van grondwater inhoude gebasseer op verwagte klimaatsveranderinge en huidige grondwater toestande.
Water Research Commission
23
Dickerson, J. Ryan. "Modified drastic model for siting confined animal feeding operations (CAFOs) in Williams County, Ohio". Bowling Green, Ohio : Bowling Green State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1178903565.
Testo completo
24
MacVicker, Helen J. "The ecotoxicology of rodenticide use on farms". Thesis, University of Leicester, 1998. http://hdl.handle.net/2381/29783.
Testo completoAbstract (sommario):
The major findings of the study were as follows: 1. Rats ate significantly more coumatetralyl than brodifacoum, and rats in an area of physiological resistance (central southern England) ate greater quantities of rodenticide than rats in the east midlands. Coumatetralyl failed to achieve rat control on farms in central southern England. 2. Physiological resistance was suspected on two farms in the east midlands (near Lincoln) where rats ate excessive quantities of coumatetralyl and the control programme was unexpectedly extended. 3. GCMS analyses performed on extracts of 169 whole rodents revealed that some rats had eaten levels of coumatetralyl that far exceeded a lethal dose for susceptible animals. Excessive bait consumption occurred mostly in the area of physiological resistance, but also on the two sites in the east midlands where resistance was suspected. Brodifacoum consumption by some rats was also high, but complete control was usually achieved with brodifacoum and there was no evidence of any resistance to brodifacoum. 4. HPLC analyses carried out on 10 rats from coumatetralyl sites (five from each region), revealed that trapped, physiologically-resistant animals are capable of carrying 50 times the LD50 of coumatetralyl without any obvious ill effect. Rats from the east midlands carried a significantly lower load of coumatetralyl. 5. Video observations gave no evidence to support a bait point monopoly theory. Interactions at feeding sites were common. 6. This study has revealed that the potential exposure of non-target predators and scavengers to rodenticides is considerably higher in areas where rats show physiological resistance. This fact is discussed with reference to the regulation and monitoring of pesticides in the UK.
25
Moeller, Sabina. "Novel farms, textual memory and spatial imagination". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0007/MQ36061.pdf.
Testo completo
26
Shanmugam, Ramaradj. "Efficiency and productivity of Quebec dairy farms". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0007/MQ44104.pdf.
Testo completo
27
Grant, Heather-Anne Ruth. "The cost competitiveness of Alberta dairy farms". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ60433.pdf.
Testo completo
28
Nord, Erika. "Cost estimation of wind farms' internal grids". Thesis, KTH, Elektriska energisystem, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-47831.
Testo completoAbstract (sommario):
When establishing new wind farms there are a lot of different stakeholders that have different demands and ambitions.The local grid in a wind farm constitutes of about 10% of the total investment cost and therefore it is of importance that it is optimized both regarding losses and costs. In a wind farm project a system analysis is ordered thatsummarizes information such as cable layout, electric data and losses. A drawback is that this analysis is given in a later part of the project, when most decisions already have been made due to permits. If the analysis shows that there are unnecessarily high losses in the system it can be too late to make changes.The aim of this Master’s thesis project is to develop a method that makes the essential calculations so that an estimation of losses and its costs together with the investment costs can be made at an early stage. The first part of the thesis consisted of developing a program using this method with the requests above to, in the next stage, compare the results the method acquires with a reference system analysis of an existing wind farm. From this comparison conclusions were made whether the method is usable and in which ways it resembles and differs from the more advanced method used in a program today.The results show that the method makes a good estimation of losses. Deviations between the developed method and the reference analysis are due to that different approaches are made when calculating certain losses and also the depth of the calculations. Furthermore there is no description of how precise the calculations in the reference report were made so approximations can be a source of error.The conclusion is that this method can be used to get an early estimation of the losses and the corresponding costs of the local grid.
29
Stulpinienė, Vaida. "Financial distress prediction model of family farms". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2013~D_20140123_133545-56537.
Testo completoAbstract (sommario):
Designed financial distress prediction model is intended directly for the farmer (decision-maker) in order to diagnose the farm’s financial condition and predict the likelihood of financial distress, by using financial information of his farm. There are identified family farm characteristics in which family farms have higher risks to run in financial distress and are guidelines for the family farms that intend to more carefully monitor and control their financial condition. The aim of the research: after analysing the conception of financial distress and identifying the factors determining the financial condition as well as related indicators and prediction models, to methodologically justify and design financial distress prediction model of family farms.Parengtas finansinio išsekimo prognozavimo modelis tiesiogiai skirtas ūkininkui, kuris panaudodamas savo ūkio finansinę informaciją, galėtų diagnozuoti ūkio finansinę būklę ir iš anksto numatyti finansinio išsekimo grėsmę. Disertacijoje nustatytos ir įvardintos ūkininkų ūkių charakteristikos, kurioms esant ūkiai turi didesnes grėsmes finansiškai išsekti, yra gairės ūkininkų ūkiams, kurie ketina atidžiau stebėti savo veiklą ir kontroliuoti finansinę būklę. Tyrimo tikslas – ištyrus finansinio išsekimo sampratą, identifikavus finansinę būklę sąlygojančius veiksnius, indikatorius ir prognozavimo modelius, metodologiškai pagrįsti ir parengti ūkininkų ūkių finansinio išsekimo prognozavimo modelį.
30
Shanmugam, Ramaradj. "Efficiency and productivity of Quebec dairy farms". Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=20234.
Testo completoAbstract (sommario):
The analysis of cost and profit efficiencies of a sample of 588 Quebec dairy farms shows significant potential to reduce costs and increase profits. In general, the small farms were more cost efficient while large farms were more profit efficient. Increased use of farm grown feed was associated with higher efficiency while increased use of concentrates was associated with lower efficiency.The productivity of individual dairy farms were estimated using data envelopment analysis. The average annual growth rate of productivity was 0.70% with a standard deviation of 2.44% for the 1987--93 period. The Spearman's rank correlation coefficient did not show any significant relationship between farm size and growth rate.
The Artificial Neural Networks (ANN) approach, used for the first time to estimate technical efficiency, performed equally as good as the regression models in modeling the technology especially at the higher levels of output. The efficiency values estimated using ANN were higher than that estimated by ordinary least squares method. The results indicate the existence of significant potential for improving the efficiency of resources on Quebec dairy farms.
31
Li, Pei 1981. "Controlling hour-long power of wind farms". Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112574.
Testo completoAbstract (sommario):
In attempting to control the power output of a wind farm, it is first necessary to smooth the power fluctuations due to wind turbulence. This is accomplished by spatial smoothing, whereby the high frequency power components of a single wind turbine generator (WTG) is reduced by a factor of N-1/2, where N is the number of WTGs in the farm. For this reason the first part of the thesis is concerned with developing a model of smoothing in a wind farm and justifying it mathematically.After spatial smoothing, the wind farm output still contains low frequency fluctuations. The second part of the thesis makes use of a combination of: (i) pitch angle control of the turbine blades, (ii) power electronic control of the generators, (iii) spatial filtering and (iv) negative feedback control to remove the low frequency fluctuations. The wind farm output then has the quality to be sold as regulated power which fetches a better economic return than when sold as energy. This, of course, presumes that 1-hour ahead prediction of wind velocity at 1-hour long low variance is available.
The thesis also considers the case when the conditions for regulated power are not predicted. In this situation, the wind farm may opt to use the tracking mode which tracks the slowly time varying non-turbulent wind power. The thesis examines the possibility of diverting some of the wind farm power to implement dynamic performance enhancement strategies, for system damping for example.
The controllability of the wind farm is demonstrated by simulations of a wind farm made up of 24 wind turbine-generators (WTGs) using 1-hour long wind velocity data.
32
Hawkins, Elizabeth Anne. "Changing technologies : negotiating autonomy on Cheshire farms". Thesis, London South Bank University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281127.
Testo completo
33
Eriksson, Ola. "Numerical Computations of Wakes Behind Wind Farms". Licentiate thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-255859.
Testo completoAbstract (sommario):
More and larger wind farms are planned offshore. As the most suitable build sites are limited wind farms will be constructed near to each other in so called wind farm clusters. Behind the wind turbines in these farms there is a disrupted flow of air called a wake that is characterized by reduced wind speed and increased turbulence. These individual turbine wakes combine to form a farm wake that can travel a long distance. In wind farm clusters farm to farm interaction will occur, i.e. the long distance wake from one wind farm will impact the wind conditions for other farms in the surrounding area. The thesis contains numerical studies of these long distance wakes. In this study Large Eddy Simulations (LES) using an Actuator Disc method (ACD) are used. A prescribed boundary layer is used where the wind shear is introduced using body forces. The turbulence, based on the Mann model, is introduced as fluctuating body forces upstream of the farm. A neutral atmosphere is assumed. The applied method has earlier been used for studies of wake effects inside farms but not for the longer distances needed for farm to farm interaction. Numerical studies are performed to get better knowledge about the use of this model for long distance wakes. The first study compares the simulation results with measurements behind an existing farm. Three parameter studies are thereafter setup to analyze how to best use the model. The first parameter study examines numerical and physical parameters in the model. The second one looks at the extension of the domain and turbulence as well as the characteristics of the flow far downstream. The third one gathers information on the downstream development of turbulence with different combinations of wind shear and turbulence level. The impact of placing the turbines at different distances from the turbulence plane is also studied. Finally a second study of an existing wind farm is performed and compared with a mesoscale model. The model is shown to be relevant also for studies of long distance wakes. Combining LES with a mesoscale model can be of interest.
34
Bravaccini, Giovanni. "Frequency regulation provision by wind power farms". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022.
Cerca il testo completoAbstract (sommario):
La tesi tratta il contributo alla regolazione della frequenza della generazione di energia elettrica da fonte eolica, che tipicamente avviene tramite parchi eolici connessi alla rete di alta tensione. Lo studio è motivato dal recente regolamento europeo sui generatori che prevede che a tali servizi di rete contribuiscano anche le fonti rinnovabili. Il contributo della generazione nei transitori di sottofrequenza richiede la presenza di una riserva di potenza, che nel caso delle fonti rinnovabili può essere realizzata attraverso sistemi di accumulo di energia oppure attraverso le due tecniche che sono affrontate nella tesi, ossia sistemi di controllo che non inseguono il punto di massima potenza (deloading) oppure l’utilizzo dell'energia cinetica delle masse rotanti. Sono stati messi a punto e implementati due modelli dinamici di turbina eolica in ambiente Matlab-Simulink. Entrambi i modelli si riferiscono a turbine eoliche a velocità variabile interfacciate con la rete tramite convertitore (type 4). I due modelli rappresentano il sistema di controllo del convertitore in grado di fornire inerzia sintetica ed il contributo alla regolazione della frequenza primaria. Il primo modello trascura la risposta in velocità della turbina mentre il secondo modello implementa anche un modello meccanico. I modelli sono stati utilizzati per calcolare la risposta in frequenza di una rete in isola in seguito ad un grande squilibrio di potenza.
35
Pearce, Austin Willis. "Moving Virginia Dairy Farms Toward Phosphorus Balance". Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/99836.
Testo completoAbstract (sommario):
Sustainability for Virginia dairy farms requires balancing phosphorus (P) imports and exports at the farm-gate level. Balancing P helps prevent further accumulation of P in farm soils through routine applications of manure, which over time contributes to surface water quality issues. The objectives of this research centered on guiding dairy farms in Virginia toward lower, more sustainable P balance, and without adversely impacting profitability. First, the state of P balance had to be determined for a sample of dairy farms, including risk factors for excessively high P balance. Second, a repeated assessment of P balance on those dairy farms sought to determine any key factors of change in P balance between years. Lastly, a small Virginia dairy farm was used as a case farm to evaluate whether or not it could reduce its P balance while maintaining or improving farm profitability. An initial assessment of 58 dairy farms in Virginia showed that 75% of farms could operate with a P balance less than 18.7 kg ha-1. The two risk factors that led to excessively high P surpluses were the use of poultry litter and excessive P imported with purchased feed. The repeated assessment included 30 of the 58 original dairy farms. Increases of 1.0 kg P ha-1 of total P imports and exports were respectively correlated to a mean P balance increase of 0.76 kg ha-1 and a mean P balance decrease of 0.43 kg ha-1, suggesting that changes in P imports affect changes in P balance more than changes in P exports. Reduced poultry litter use was highly correlated to reduced P balance, and increasing cow manure exports also reduced P balance for the farms with the opportunity. As a significant portion of the farms assessed were small (less than 200 milking cows), a case farm of 105 cows on 100 acres was used to explore how farm profitability could be affected as P balance was reduced through additional acres, increased crop production, and with a grazing-based farming strategy. Results from partial budget analysis showed that after expanding the land base from 100 to 150 acres for crop production, the change in potential net return ranged from $-0.90 to $1.26/cwt of milk, with accompanying changes in P balance ranging from -9.0 to -14.7 lbs/ac. The analysis also showed that changes in potential net returns after converting to a grazing-based system ranged from $-2.14 to $1.39/cwt, with greater change in P balance ranging from -9.7 to -17.8 lbs/ac. The most profitable strategy, generally, for this farm seemed to be expanding the land base and growing a cash crop. Phosphorus balance on Virginia dairy farms can be reduced, potentially without negative impacts on farm net return, though challenges remain for farms with limited land or areas with high density of animal agriculture.Doctor of Philosophy
Phosphorus (P) is a vital nutrient for crops and livestock, but too much of it in soils leads to surface water quality problems. Sustainability for Virginia dairy farms requires balancing P imports and exports at the farm level. This research centered on guiding dairy farms in Virginia toward lower, more sustainable P balance. An initial assessment of 58 dairy farms in Virginia helped establish a zone of operation, a feasible target toward which the 25% of farms with high P balance could aim. Avoiding poultry litter as a fertilizer choice and limiting P imported with purchased feed were both ways in which some of these farms could lower their P balance. A repeated assessment in a second year showed that reductions in P imported were more likely to reduce P balance than were increasing P exports. In this, reducing the use of poultry litter as a fertilizer was again an effective way of lowering P balance. As a significant portion of the farms assessed were small (less than 200 milking cows), a case farm of 105 cows on 100 acres was used to explore how farm profitability could be affected as P balance was reduced through various management changes. Results showed that after expanding the land base by at least 50 acres for additional crop production, P balance could be significantly reduced while maintaining or increasing the potential net return to the farmer, especially if the farmer can ensure a high milk yield grazing-based operation or if they grow a cash crop like corn or soybeans. Overall, the research suggests that P balance on Virginia dairy farms can be reduced, and that these farms can operate more sustainably, though challenges remain for farms with limited land or areas with high density of animal agriculture.
36
Zwart, Maria Catharina. "Disturbance effects of wind farms on birds". Thesis, University of Newcastle upon Tyne, 2014. http://hdl.handle.net/10443/2737.
Testo completoAbstract (sommario):
Wind energy, like all renewable energy production, is a sustainable resource with a far lower carbon footprint than the burning of fossil fuels and consequently plays a role in mitigating climate change. There has been a rapid rise in its use over the last 15 years. However, there are concerns regarding the potential effects of wind turbines on wildlife, especially birds and bats. Potential effects include disturbance through direct or indirect habitat loss, or fatality through collision with turbine blades. First, I investigated the potential of using existing bird monitoring data collected by Environmental Impact Assessments (EIAs) and post-construction monitoring for developing an evidence base for the impacts of wind turbines on bird populations. As EIAs are required for wind farms to predict and mitigate potential negative effects, vast amounts of data are gathered by wind farm companies but subsequently not used to assess the effects, due to the associated logistical issues of obtaining these data (despite being officially available in the public domain). Using data from seven wind farm sites, I found that lekking black grouse (Tetrao tetrix) that were initially close to the wind turbines (up to 500m) moved locally after wind farm construction but their abundance at the wind farm sites did not change. I conclude that data from EIAs and post-construction monitoring can be used to assess potential effects of wind farms on biodiversity and should be widely available for scientists and policy-makers, ideally via a central data repository. Second, I investigated whether noise from wind farms might affect birds as bird song could be potentially masked. It is widely known that anthropogenic noise such as traffic and urban noise affects communication in birds. To investigate whether birds are affected by wind turbine noise, I modelled how song from iii birds propagates in a hypothetical environment with and without wind turbine noise. I found that songs from species where most of the energy lies in the lower frequencies are masked by wind turbine noise. As this model can predict potential disturbance effects for specific species, it could be used as a tool during EIAs by identifying which species will be affected by wind turbine noise. Third, as bird communication is masked by wind turbine noise, male-male, male-female and parent-offspring communication could be affected. I investigated if male-male interaction in European robins (Erithacus rubecula) is affected by wind turbine noise. Males responded less aggressively during simulated territorial intrusion with background wind turbine noise. This could lead to reduced breeding success as males might not be able to effectively defend their respective territories. Finally, I explored whether bioaoustic recorders could be used as a replacement for human wildlife surveys. Using the European nightjar (Caprimulgus europaeus) as an example, I found that survey methods using bioacoustic recorders are much more accurate and cheaper than surveys by humans. This could aid EIAs as they require wildlife surveys to determine which species might be affected by the development.
37
Mir, Ghafourian Seyed Mohammad sadegh. "Switching transients in large offshore wind farms". Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/switching-transients-in-large-offshore-wind-farms(00ac9266-599e-4282-a497-b0e7dc9c1f78).html.
Testo completoAbstract (sommario):
This thesis deals with the analysis of switching transients in large offshore wind farms. Switching transient is of great importance in electrical power systems in general, not least in offshore wind farms. The large area required for an offshore wind farm along with its offshore location results in extensive cable systems with a large number of radial feeders and medium voltage transformers. These transmission systems are very different from traditional onshore networks. Hence, accurate transient analysis is important, as travelling wave reflections can become critical in some reflection points; where aggregate overvoltage may exceed the voltage withstand level of the system components. The rate of rise of overvoltage is a crucial issue to be considered for transformer inter-turn resonances, which leads to high frequency over-voltages. The closing operation of a vacuum circuit breaker during energisation of wind farm networks can cause switching transients which might damage the insulation structure of cables, transformers and turbine generators. The repetitive impact on the systems without remedialaction may cause premature ageing of the above mentioned components, so to minimize the failure risk, the accurate model is essential. One of the contributions of this thesis is in refining a new modelling of the VCB and in the implementation of the new VCB model in the assessment of a specific switching transient event (VCB closing operation in an offshore wind farm). Experimental verification of transient overvoltage phenomena modeling in submarine cable networks is another contribution of this work. Correlation calculation shows that simulations of the high frequency transients with this novel refined model are in a very good agreement of better than 94% in comparison with the measurements taken in an offshore wind farm.
38
Pennells, Jonathan Stephen. "Atmospheric boundary layer impacts on wind farms". Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/19660/.
Testo completoAbstract (sommario):
Increasing demand for renewable energy sources has meant that wind power is becoming a more crucial source of energy, leading to larger wind farms. It is currently unknown whether wind farms impact the boundary layer. This thesis aims to improve our understanding of the impact from wind farms. To do this, numerical simulations are carried out in BLASIUS and WRF with an existing Wind Farm Parametrisation (WFP) being implemented in BLASIUS. Neutral boundary layer simulations are carried out in BLASIUS, with different velocities, height and capping inversion strengths. It is found that decreases in boundary layer height increase the impact from the wind farm, where the height is between 715 m and 992 m for turbines with a hub height of 95 m. Increases in velocity increase the vertical advection of horizontal momentum upstream of the turbines and greater deceleration of momentum in the wind farm. Non-dimensional analysis found jumps in the inversion layer above the wind farm for Fr < 1, and increases in the pressure perturbations for low Z flows. Comparisons are made between BLASIUS and a linear model for wind farms in neutral boundary layers. The drag term in the linear model is overestimated and should be modified to account for the logarithmic velocity profile near the surface. The assumptions made in the linear model do not inhibit its representation of the velocity and pressure perturbations within the boundary layer. The impact of a wind farm on a sea breeze is investigated using WRF simulations. It is found that a wind farm at the coast does not impact the propagation of the sea breeze but does impact the land breeze. This is due to the turbulent boundary layer which the wake is in, causing a fast decay of the wake. The land breeze propagates through the wind farms and is directly impacted.
39
Marchiori, Elisa. "Sustainability of dairy farms in mountainous areas". Doctoral thesis, Università degli studi di Padova, 2013. http://hdl.handle.net/11577/3423119.
Testo completoAbstract (sommario):
The general aim of this thesis was to analyze the sustainability of dairy cattle farms in mountainous areas. The studies were conducted in the Eastern Italian Alps, a study area representative of the evolution of livestock systems in mountainous areas.L'obiettivo generale è di questa tesi di dottorato è lo studio della sostenibilità delle aziende di bovini da latte in ambito montano. I lavori presentati sono stati condotti nelle Alpi italiane orientali, che rappresentano un modello dell’evoluzione dei sistemi di allevamento nelle aree montane.
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Mayson, David. "The Rural Foundation, management and change on fruit farms : a case study of selected farms in the Elgin area". Master's thesis, University of Cape Town, 1990. http://hdl.handle.net/11427/17265.
Testo completoAbstract (sommario):
Includes bibliography.This is an exploratory study which investigates changes introduced by management on farms in Elgin and explores the perceptions of some of those involved in the changes. The initiatives and activities of the Rural Foundation for Community Development (Rural Foundation) and its involvement in these changes forms a crucial part of the exploration. Three questions direct the study. 1. What are the changes that have been introduced? 2. Why were they introduced? 3. What is the social meaning of the changes? The study is based on a case study of four farms. Documentary material was collected from a variety of sources including the Rural Foundation, the South African Government, as well as other agencies operating in the field. Interviews with various actors were conducted, including management and a selection of workers on each of the four farms, Rural Foundation officials as well as other actors connected to the developments on the farms. The study is informed by historical materialist theory and draws from certain labour process theories. Important for the study was the discussion raised in these theories around the effect that workers' motivation has on their productivity. The study is located in the context of the national historical development of capitalist agriculture since the Second World War. More specifically it is situated locally in terms of changes that occurred on Elgin farms more generally prior to the 1980's as well as the present general circumstances in the area. Three fields of change are identified on the four farms: (i) training of workers, (ii) new incentives and pay structures, and (iii) community development. It is asserted that these changes are measures introduced by management in an attempt to, firstly, decrease production costs by employing greater numbers of women and migrant workers and paying them less. Secondly, they are aimed at increasing the productivity of workers through measures designed to improve the 'quality' and stability of workers and to develop a new authority structure on the farms. Four trends are thus identified as occurring on the farms: 1. Increasing use of women and migrant workers. 2. An improvement in workers' living conditions and standards. 3. An increasing emphasis on improving workers' productivity. 4. A shift in the emphasis on control towards developing workers' consent.
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Becot, Florence Anne Stephanie. "Linking farm households’ social needs, social policy, and farm persistence to better understand and support family farms in the 21st century". The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1576518795181479.
Testo completo
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Baker, Laurence Bruce Bell. "Studies of lease-buy decisions and models for forecasting land prices". Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41526.
Testo completoAbstract (sommario):
The choice between purchasing land or entering into a long-term lease is analyzed using a deterministic cash analysis both from the tenant's and landlord's perspective. It is less financially stressful to start farming through a lease agreement than by purchasing the assets. The lease period of landlord indifference between these choices is determined for each combination of input variables.Land value and income forecasting models are developed and presented. These models are based on two similar but conceptually different statistical tests. Each test results in different forecasting models which has implications for the use of such models in the future.
Consumption-based asset pricing models are tested using agricultural rental income. These models, although appealing both intuitively and theoretically are found wanting in terms of their formulation as the model results are highly sensitive to the data employed. This concern increases with the level of data aggregation.
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Saffert, Andrew Thomas. "An economic analysis of adjusted gross Revenue-Lite insurance on farm income variability for southeast Kansas farms". Thesis, Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/308.
Testo completo
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Falletisch, Leila Ann. "Understanding the legacy of dependency and powerlessness by farm workers on wine farms in the Western Cape /". Thesis, Link to the online version, 2008. http://hdl.handle.net/10019/836.
Testo completo
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Shim, Sangyun. "Coupled dynamic analysis of floating offshore wind farms". [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-2564.
Testo completo
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Biggers, Earl D. Jr. "Considerations for direct tanker loading on dairy farms". Thesis, Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/3873.
Testo completo
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Nordvarg, Lennart. "Predictive Models and Eutrophication Effects of Fish Farms". Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2001. http://publications.uu.se/theses/91-554-4932-8/.
Testo completo
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Lopez, Andreu Monica. "Studies on the economic efficiency of Kansas farms". Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/952.
Testo completo
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King, Rosemary Louise. "Electrical transmission systems for large offshore wind farms". Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/54217/.
Testo completoAbstract (sommario):
Simulations of switching transients were carried out in EMTP-RV. Overvoltages in offshore wind farms ranged from temporary over voltages to very fast front transients. Transient Recovery Voltages of the offshore circuit breakers exceeded IEC 62271 requirements in some situations. The disconnection of an array produced the most severe overvoltages, exceeding IEC 60071 requirements.
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Plew, David Russell. "The Hydrodynamic Effects of Long-line Mussel Farms". Thesis, University of Canterbury. Civil Engineering, 2005. http://hdl.handle.net/10092/1069.
Testo completoAbstract (sommario):
The hydrodynamic effects of long-line mussel farms are studied through a two-pronged approach. Large-scale hydrodynamic effects are investigated through the use of field measurements, primarily at a large mussel farm in Golden Bay, New Zealand (230 long-lines, covering an area of 2.45 km by 0.65 km). The research focuses on three areas: the effect of the farm on currents, mixing and stratification, and the dissipation of wave energy. Measurements are also made of the forces on long-line anchor ropes, and a limited investigation is made of phytoplankton depletion. The second approach is the use of laboratory drag measurements and Particle Tracking Velocimetry (PTV) to study the effect of mussel dropper (vertical lengths of mussel-encrusted crop rope) roughness and spacing on flow at small scales. These experiments provide data on very rough cylinders, and on cylinder arrays. The field measurements show that the local effects of mussel farms on currents are significant, but that magnitudes of the effects depend on dropper density, mussel sizes, orientation of the long-lines to the flow, and other parameters that are necessary to characterise the complex interactions between a farm and the flow. The drag on the submerged structures reduces water velocities within the Golden Bay farm by between 47% and 67%. Mussel farms present a porous obstacle to the flow, and flow that does not pass through the farm must be directed around or beneath it. The field measurements indicate that at the study site, most of the flow is diverted around the farm despite its large horizontal dimensions. The droppers at the study site extend over most of the water column (average dropper length ~ 8 m, average water depth ~ 11 m), providing a restriction to the flow beneath the farm. The strength of the density stratification may also favour a horizontal diversion. The flow around the farm is essentially two-dimensional. This suggests that two-dimensional numerical models should be sufficient to obtain reasonable predictions of the velocity drop within, and the diversion around, mussel farms. A simple two-dimensional pipe-network model gives reasonable estimates of the velocity within the farm, demonstrating that the drag of the farm may be adequately parameterised through local increases of bed friction. A wake in the form of reduced velocities extends downstream of the farm, and a mixing layer analogy suggests that this wake spreads slowly. The downstream extent of the wake cannot be determined, although it is likely to be limited by the tidal excursion. The degree of vertical mixing caused by the flow through a mussel farm cannot be quantified, although there are clear interactions between the stratification and the farm. Two mixing mechanisms are considered. A shear layer is generated beneath the farm due to the difference in velocities between the retarded flow within the farm and the flow beneath. Shear layers beneath mussel farms are likely to be weak unless the ambient currents are strong. It will be necessary for stratification to be weak or non-existent for this mechanism to generate significant mixing. The second mechanism is smaller-scale turbulence generated by the mussel droppers. Although the efficiency of this form of mixing is likely to be low, the large number of mussel droppers suggests that there will be some enhancement of vertical mixing. Frequency-dependent wave attenuation is recorded, and is predicted with some success by an analytical model. Both the model and the field data show that wave dissipation increases as the wave period decreases. Wave energy dissipation at the study site averages approximately 10%, although the measurements are made during a period of low wave heights (Hs < 0.25 m). Measurements of long-line anchor rope tension at two study sites indicate that the loadings are induced by the tide, currents, and waves. Dynamic wave loadings may be significant, and higher wave forces are measured at the offshore end of a long-line. The issue of seston or phytoplankton depletion is considered briefly through the examination of fluorescence, turbidity, and acoustic backscatter data. Although the results are consistent with a reduction of seston within the farm, differences between the inside and outside of the farm are not statistically significant. Mussel droppers resemble extremely rough circular cylinders, with the mussel shells forming the surface roughness elements. Drag measurements and PTV flow visualisation are used to investigate the importance of the large surface roughness, and the influence of dropper spacing and long-line orientation on flow. Drag measurements conducted with smooth and rough cylinders show that high surface roughness (ks/D ~ 0.092) has little effect on the drag coefficient of single cylinders in the range 4,000 < Re < 13,000, yet increases the drag coefficient of a row of cylinders normal to the flow. High surface roughness on single cylinders has the effect of shortening the near-wake region, increasing the peak turbulent kinetic energy (TKE) behind the cylinder, and decreasing the Strouhal number (St = 0.21, 0.19, 0.17 for ks/D = 0, 0.048, and 0.094 respectively). Arrays of rough cylinders (ks/D = 0.094) demonstrate similar flow characteristics to those of smooth cylinders. At cylinder spacings of S/D < 2.2, the surface roughness acts to favour the formation of a particular metastable wake pattern, whereas different metastable wake patterns are formed each run behind the smooth cylinders. The experiments show that the drag on single row arrays of cylinders are related to the cylinder spacing (increasing drag with decreasing spacing), and the drag also varies with the sine of the angle to the flow, except where the array is at low angles to the flow. The PTV measurements provide new data regarding the two-dimensional distributions of velocity, TKE, and turbulence statistics behind the cylinder arrays.