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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
251

A CHARACTERIZATION OF CEREAL RYE COVER CROP PERFORMANCE, NITROGEN CYCLING, AND ASSOCIATED ECONOMIC RISK WITHIN REGENERATIVE CROPPING SYSTEMS

Richard T Roth (11206164) 30 July 2021 (has links)
<p>Cereal rye (<i>Secale cereale</i>, L., CR) is the most commonly utilized cover crop species within the United States. Yet, the total land area planted to CR on an annual basis remains relatively low despite its numerous proven environmental benefits. The relatively low rates of CR adoption could be due to a dearth of knowledge surrounding certain agronomic and economic components of CR adoption. Currently, there exists knowledge gaps within the scientific literature regarding CR performance, N cycling, and associated economic risk. <a>Thus, to address the above-mentioned knowledge gaps, three individual studies were developed to: i) investigate the fate of scavenged CR nitrogen (N) amongst soil N pools, ii) assess the suitability of visible-spectrum vegetation indices (VIs) to predict CR biomass and nutrient accumulation (BiNA), and iii) characterize the economic risk of CR adoption at a regional scale over time.</a></p> <p>In the first study, <sup>15</sup>N, a stable isotope of N, was used in an aerobic incubation to track the fate of CR root and shoot N among the soil microbial biomass, inorganic, and organic N pools, as well as explore CR N bioavailability over a simulated corn growing season. In this study, the C:N ratio of the shoot residues was 16:1 and the roots was 31:1 and differences in residue quality affected the dynamics of CR N release from each residue type. On average, 14% of whole plant CR N was recovered in the soil inorganic N pool at the final sample date. Correspondingly, at the final sampling date 53%, 33%, and less than 1% of whole plant CR N was recovered as soil organic N, undecomposed residue, and as microbial biomass N, respectively. Most CR N remained unavailable to plants during the first cash crop growing season subsequent to termination. This knowledge could support the advancement of N fertilizer management strategies for cropping systems containing cereal rye.</p> <p>In the second study, a commercially available unmanned aerial vehicle (UAV) outfitted with a standard RGB sensor was used to collect aerial imagery of growing CR from which visible-spectrum VIs were computed. Computed VIs were then coupled with weather and geographic data using linear multiple regression to produce prediction models for CR biomass, carbon (C), N, phosphorus (P), potassium (K), and sulfur (S). Five visible-spectrum VIs (Visible Atmospherically Resistant Index (VARI), Green Leaf Index (GLI), Modified Green Red Vegetation Index (MGRVI), Red Green Blue Vegetation Index (RGBVI), and Excess of Green (ExG)) were evaluated and the results determined that MGRVI was the best predictor for CR biomass, C, K, and S and that RGBVI was the best predictor for CR N and P. Furthermore, the final prediction models for the VIs selected as the best predictors developed in this study performed satisfactorily in the prediction of CR biomass, C, N, P, K, and S producing adjusted R<sup>2</sup> values of 0.79, 0.79, 0.75, 0.81, 0.81, and 0.78, respectively. The results of this study have the potential to aid producers in making informed decisions regarding CR and fertility management. </p> <p>In the final study, agronomic data for corn and soybean cropping systems with and without CR was collected from six states (Illinois, Indiana, Iowa, Minnesota, Missouri, and Wisconsin) and used within a Monte-Carlo stochastic simulation to characterize the economic risk of adopting CR at a regional scale over time. The results of this study indicate that average net returns to CR are always negative regardless of CR tenure primarily due to added costs and increased variability in cash crop grain yields associated with CR adoption. Further, the results demonstrate that the additional risk assumed by adopting CR is not adequately compensated for with current CR adoption incentive programs and that the risk premium necessary can be 1.7 to 15 times greater than existing incentive payments. Knowledge gained from this study could be used to reimagine current incentive programs to further promote adoption of CR.</p>
252

SOYBEAN PLANT POPULATIONS AND DIGITAL ASSESSMENTS

Richard M Smith (14279081), Shaun N. Casteel (10972050), Jason Ackerson (9749436), Keith Cherkauer (7890221), Melba Crawford (14279296) 20 December 2022 (has links)
<p> Soybean seed cost has dramatically increased in recent decades which has led to producer interest in lowering input cost through reductions in seeding rate. Fifty-eight seeding rate trials of soybean were conducted at field-scale in Indiana from 2010 to 2021 to update recommendations of seeding rates and plant population. The objectives were to determine the agronomic optimal seeding rate (AOSR) and plant population (AOPP) based on planting equipment, tillage practices, and planting date. Economic optimal seeding rate (EOSR) was also determined based on these field scenarios. Harvest AOPP was not influenced by planting equipment (~212,000 plants ha-1) or tillage (~239,000 plants ha-1), but AOSR varied. Soybean seeded with a row-crop planter optimized grain yield with 352,600 seeds ha-1; whereas, the grain drill required 75,200 more seeds ha-1. Soybean seeded into conventional tillage maximized grain yield at 380,400 seeds ha-1; whereas, under no-till conditions 41,400 more seeds ha-1 were required. Timely planting required 417,300 seeds ha-1 to optimize grain yield, which resulted in harvest AOPP of 216,700 plants ha-1. Conversely, late plantings required 102,800 fewer seeds ha-1 but 36,200 more plants ha-1 than timely planting. Depending on seed cost and soybean market price, seeding rates could be reduced 13,700 to 92,800 seeds ha-1 below AOSR to maximize profit.</p> <p>Secondly, digital imagery with high spatial resolution was collected with an unmanned aerial vehicle (UAV) to develop a simple and practical method to segment soybean from non-plant pixels. The best vegetation indices were selected to segment young soybean plants (VC to V6). Two field-scale trials of soybean were planted in 2020 with the agronomic trial design of two varieties x five seeding rates with three replications. The imagery was collected during this period as it coincides with the time for determining whether a soybean stand should be replanted. Five relative vegetative indices based on the red, green, and blue (RGB) imagery were evaluated: excess greenness index (ExG), excess redness index (ExR), green leaf index (GLI), normalized green-red difference index (NGRDI) and visible atmospheric resistance index (VARI). Both GLI and ExG were superior in overall accuracy compared to all other vegetative indices with very small soybean plants (VC to V1 growth stages). VARI and NGRDI had relatively poor overall accuracy at VC and V1, but had similar overall accuracy to GLI as soybean plants grew larger (V2 to V6 growth stages). Across all growth stages and locations, ExR performed the poorest. Moreover, GLI had consistent performance across the range of growth stages, suggesting its suitability for early soybean stand assessment methods.</p> <p>Six field-scale trials were established in 2020 and 2021 in Indiana with two varieties seeded from 123,000 to 618,000 seeds ha-1. Canopy cover was calculated using GLI to create binary segmentation of plant pixels and non-plant pixels. UAV-derived canopy cover measurements were correlated with plant population of soybean from VC to V4 and growing degree days (GDD) after planting. Yield potential (75, 80, 85, 90, 95, 100%) was correlated with canopy cover from VC to V4 and GDD after planting. Canopy cover of 2.1, 5.0, 8.9 and 13.8% by 150, 250, 350, and 450 GDD°C after planting, respectively, would maximize yield. Canopy cover for 75% yield potential was one-fourth as much as the 100% yield potential. Recommended threshold for replant decisions should be based on canopy cover to attain 95% yield potential. Field observations below a canopy cover of 1.8, 4.2, 7.4, and 11.5% canopy cover by 150, 250, 350, and 450 GDD°C after planting respectively, would consider replanting. </p>
253

Operational performance driven production system design process

Islam, Md Hasibul January 2022 (has links)
The design process of a production system referred to as the production system design process (PSDP) impacts on the operational performancethroughout the lifecycle of the production system, especially on the rampupand operation phases. Despite the impact of activities of PSDP on the operational performance, how to manage the PSDP is still a challenge for manufacturing companies. Earlier research urged to develop a systematic PSDP concerning its impact on the operational performance. This thesis aims to contribute with knowledge of how manufacturingcompanies can manage the PSDP by investigating 1) the enablers in thePSDP that impact on operational performance in ramp-up and operation phases, and 2) how the lean production concept could be adopted tomanage the activities during the PSDP. A case study was conducted in aprocess type manufacturing company, where empirical data were collectedfrom three new production line launching projects by qualitative means. This thesis identifies a set of enablers in the PSDP that potentiallyimpact the operational performance after launching the productionsystem. Empirical findings demonstrate that ensuring proper actions onthe identified enablers in the PSDP could lead to higher operationalperformance of the designed production system. These enablers rangefrom the company´s internal boundary to external vendors, requiring asystematic way to manage these diverse aspects. Adopting the lean production concept in the PSDP context, this thesis proposes a model of Lean Production System Design Process, containing 13 principles andrelevant practices. The proposed model of lean PSDP could be used as a systematic processto manage the activities in the PSDP that would ensure proper actions related to the identified enablers. Empirical findings indicate that adoptionof lean in the PSDP could result in reducing lead time of launching a new production system, and achieving fast ramp-up and desired operational performance considering sustainability aspects. Finally, this thesis demonstrates how the lean PSDP could be a means to achieve a sustainable competitive advantage based on the resource based view theoretical perspective. / Utformningsprocessen av ett produktionssystem, i denna avhandlingkallad produktionssystemets utformningsprocess (PSUP), påverkar denoperativa prestandan under hela produktionssystemets livscykel, särskilt iupprampnings- och driftsfasen. Traditionellt sett ligger fokus underutformningsprocessen på att lansera det nya produktionssystemet vidplanerad tidpunkt och enligt budget. Trots att de aktiviteter somgenomförs i utformningsprocessen påverkar den operativa prestandan idriftsfasen, ägnas ofta mindre uppmärksamhet åt designfasen än vad somvore önskvärt. Tidigare forskning har argumenterat för att utveckla ensystematisk designprocess för framtagning av produktionssystem medsyfte att nå en positiv påverkan på den operativa prestandan. Forskningen i denna avhandling bidrar till att öka kunskapen om hurPSUP kan hanteras och förbättras genom att identifiera: 1) möjliggörare i PSUP som påverkar den operativa prestandan i upprampnings- ochdriftfasen, och 2) hur lean konceptet skulle kunna användas för att hanteraaktiviteterna under PSUP. Resultatet är identifieringen av ett antal faktorer/möjliggörare iproduktionssystemets utformningsprocess (PSUP) som potentiellt kanpåverka den operativa prestandan efter lansering av produktionssystemetoch produktionsstart. Dessa möjliggörare handlar om alltifrån frånföretagets interna gränser till externa leverantörer och kräver ensystematisk procedur för att dra nytta av faktorernas potential. Genom attanvända lean även i PSUP-sammanhanget, föreslås här konceptet Lean PSUP (produktionssystemsutformningsprocess), som innehåller 13 principer och relevanta praxis. Den föreslagna modellen för lean PSUP skulle kunna användas och gestruktur till hanteringen av aktiviteterna i utformningsprocessen.Forskningen indikerar att lean inte bara kan användas i driftsfasen utanäven i utformningen av ett produktionssystem, vilket skulle kunnaresultera i bättre integration mellan olika funktioner, minska ledtiden förutformning och lansering av ett nytt produktionssystem, och uppnå snabbupprampning och önskad operativ prestanda, både avseende produktionoch hållbarhet. Slutligen visar denna avhandling hur lean PSUP kan varaett sätt att uppnå konkurrensfördelar ur ett resursbaserat teoretiskt perspektiv.
254

Управление модернизацией производственной системы предприятия в концепции бережливого производства : магистерская диссертация / Management of modernization of the production system of enterprises in the concept of the cooking production

Рудаков, М. А., Rudakov, M. A. January 2018 (has links)
The aim of the thesis was to develop an integration approach based on benchmarking and the Lean Manufacturing concept for the modernization of the production system of the defense industry enterprise, as well as a method for reducing risks when introducing the BP concept at Russian enterprises. This work contains 8 goals that were achieved in the performance of the work. This work contains 3 positions of scientific novelty. Approbation of scientific novelty is contained in 6 sub-clauses of the work. With the help of the lean manufacturing project, the company will be able to reach the target figures that have been planned. / Целью диссертации заключалась в разработке интеграционный подход, основанный на бенчмаркинге и концепции Бережливого производства для модернизации производственной системы предприятия ОПК, так же был разработан метод снижения рисков при внедрения концепции БП на предприятиях РФ. Данная работа содержит 8 целей, которые были достигнуты при выполнении работы. Данная работа содержит 3 позиции научной новизны. Апробация научной новизны содержится в 6 подпунктах работы. С помощью проекта по внедрению Бережливого производства, предприятие сможет выйти на целевые показатели, которые были запланированы.
255

INTENSIVE VERTICAL URBAN AGRICULTURE: Rethinking our Cities’ Food Supply. Moving Towards Sustainable Urban Development

VUATTOUX, Romain January 2013 (has links)
Our modern “traditional” agricultural system is not sustainable. This system is highly dependent on limited resources such as land, oil and water. It also has numerous negative impacts, including the depletion of resources leading to higher prices, pollutions leading to health risks, global warming, deforestation and biodiversity loss. These dependencies and consequences are combined with a growing and ever more affluent global population which requires greater amount of resources to support its growth and which increases the negative impacts on the environment. All indicates that our system is reaching its limits and that there is a need for new solutions. This research introduces the general context (problem and existing research) and explores an alternative, namely: Intensive Vertical Urban Agriculture (I.V.U.A.). This method seems to offer two particularly interesting promises beneficial for Sustainable Urban Development: the reduction of transportation, and the integration of food production in the urban nutrient and energy cycles. However, to achieve these potential benefits the technology (in a broad sense) has to meet several challenges and there is a need for further experimentation. This study explores challenges of I.V.U.A. and key factors enabling or hindering experimentation in this field. This investigation identified key barriers to further development of I.V.U.A. through the use of a case study. The Plantagon International ABis a unique project which will be built in 2013, in Linkoping, Sweden. It will be the first vertical greenhouse of a considerable scale in the world with a research and commercial aim. Barriers to I.V.U.A. were identified as: - Lack of awareness about the problems with our modern food supply, and hence missed opportunities for S.U.D. - Attitudes that are working against I.V.U.A. and competition for recognition with other forms of agriculture as alternative to the problem of food production - Lack of technical abilities, knowledge and skills in I.V.U.A. - Funding/supporting infrastructures (physical or informational) - Blockages that are the result of administrations and policies which are largely based around “traditional” agriculture. Finally, a set of recommendations was drawn from the interviews of the case study and the literature review, to help planners and decision-makers lift these barriers and enable experimenting. These four implications to consider and explore are: - Gaining understanding of the complexity of S.U.D.problems and the need for a wide range of solutions which include I.V.U.A.; - Including a greater amount of stakeholders, and considering contexts - Improving access to land but also to resources and infrastructures - Building support to enable I.V.U.A. to thrive on its own
256

Valoración socioeconómica del impacto de la expansión del cultivo de Quinua (Chenopodium quinoa W.) sobre la competitividad y sostenibilidad de la diversidad en las explotaciones tradicionales del Perú

Huillca Quispe, Jhon 04 March 2022 (has links)
[ES] Aunque la quinua (Chenopodium quinoa W.) se venía cultivando por los pueblos andinos desde la época preincaica, durante la segunda mitad del siglo XX, por diversas razones, fue postergado, siendo abandonado y casi olvidado en los lugares en los que se domesticó originalmente, originando así una serie de consecuencias sobre los sistemas productivos y comportamiento sociocultural de los pobladores andinos. Sin embargo, las cualidades intrínsecas de su grano como alimento, unido a cambios en los hábitos de consumo en países desarrollados, provocaron un interés creciente por su cultivo, pasando de ser un producto de autoconsumo, en un ámbito geográfico y cultural muy limitado, a ser un producto estrella de exportación; el rápido incremento de la demanda ha provocado un ajuste en los modelos productivos de la región y generando así impactos multidimensionales. En la presente investigación se ha analizado el impacto generado por el boom de quinua en los sistemas productivos agrarios de las zonas en las que su cultivo se había mantenido de forma tradicional. De acuerdo con los objetivos planteados, se ha realizado, en primer lugar, un diagnóstico y desarrollo de la importancia del cultivo sobre la población andina peruana y el papel desempeñado en los sistemas agrarios tradicionales del ande peruano. En segundo lugar, se ha realizado un análisis de la evolución de las variables que determinan la producción y distribución del grano en los últimos 70 años; se han identificado periodos de subutilización, recuperación y expansión en el contexto nacional y a nivel de los departamentos productores; hemos centrado nuestro análisis en dos escenarios extremos de superficie. Con las variables de comercialización se ha determinado la importancia económica de las zonas productoras, la penetración en nuevo mercados y su contribución sobre la economía nacional y, algunos cambios estructurales, para lo que hemos realizado un estudio de caso en las comunidades andinas de Cusco; los resultados de la encuesta nos han permitido observar la situación actual de los agricultores en el contexto del auge de quinua desde la dimensión social, tecnológica y económica; mostrando un panorama limitado y precario por las condiciones geográficas y medios productivos para el mantenimiento del cultivo en las condiciones que garanticen la sostenibilidad y el mantenimiento de la diversidad propia de los sistemas agrarios tradicionales de la zona andina del Perú. Así mismo, el indicador de sustentabilidad ambiental y social son similares y superiores al umbral, mientras que el económico es inferior, influyendo sobre el índice general de sustentabilidad. El análisis de los resultados económicos en términos absolutos de las distintas alternativas de tecnología productiva en diversos escenarios económicos muestra que, antes del boom de quinua, los agricultores prácticamente carecían de alicientes para introducir transformaciones tecnológicas importantes en sus procesos productivos tradicionales, conservando la tecnología productiva que permitía la sostenibilidad del cultivo, mientras que hoy en día los retornos de un sistema productivo basado en la productividad de variedades mejoradas genéticamente e insumos externos de las explotaciones son muy elevados y suponen un aliciente importante para el abandono de los sistemas productivos tradicionales, más o menos evolucionados, que corren el riesgo de ser abandonados, perdiéndose parte de la capacidad de estos sistemas tradicionales de ser sostenibles y adaptarse a los retos del cambio climático. El análisis de simulación efectuado sobre los resultados monetarios en diversos escenarios económicos y tecnológicos nos permite disponer de una base cuantitativa sobre la que estimar un modelo de compensación equilibrada que permita el mantenimiento de los sistemas tradicionales de producción con su demostrada capacidad para adaptarse a diversos escenarios agroclimáticos. / [CA] Encara que la quinoa (Chenopodium quinoa W.) s'havia cultivat pels pobles andins des de l'època preincaica, durant la segona meitat del segle XX, per diverses raons va ser postergat, sent abandonat i quasi oblidat als llocs en els quals es va domesticar originàriament, causant així una sèrie de conseqüències sobre els sistemes productius i comportament sociocultural dels pobladors andins. No obstant això, les qualitats intrínseques del seu gra com a aliment, unit a canvis en els hàbits de consum en països desenvolupats van provocar un interés creixent pel seu cultiu, passant de ser un producte d'autoconsum, en un àmbit geogràfic i cultural molt limitat, a ser un producte estrela d'exportació; el ràpid increment de la demanda ha provocat un ajust en els models productius de la regió i generant així impactes multidimensionals. En la present investigació s'ha analitzat l'impacte generat pel boom de quinoa en els sistemes productius agraris de les zones en les quals el seu cultiu s'havia mantingut de manera tradicional. D'acord els objectius plantejats, s'ha realitzat, en primer lloc, un diagnòstic i desenvolupament de la importància del cultiu sobre la població andina peruana i el paper exercit en els sistemes agraris tradicionals de la serralada dels Andes del Perú. En segon lloc s'ha elaborat una anàlisi de l'evolució de les variables que determinen la producció i distribució del gra en els últims 70 anys; s'han identificat períodes de subutilizació, recuperació i expansió en el context nacional i a escala dels departaments productors; hem centrat la nostra anàlisi en dos escenaris extrems de superfície. Amb les variables de comercialització s'ha determinat la importància econòmica de les zones productores, la penetració en nou mercats i la seua contribució sobre l'economia nacional i, alguns canvis estructurals, per al que hem realitzat un estudi de cas en les comunitats andines de Cusco; els resultats de l'enquesta ens han permés observar la situació actual dels agricultors en el context de l'auge de quinoa des de la dimensió social, tecnològica i econòmica; mostrant un panorama limitat i precari per les condicions geogràfiques i mitjans productius per al manteniment del cultiu en les condicions que garantisquen la sostenibilitat i el manteniment de la diversitat pròpia dels sistemes agraris tradicionals de la zona andina del Perú. Així mateix, l'indicador de sustentabilitat ambiental i social són similars i superiors al llindar, mentre que el d'econòmic és inferior, influint sobre l'índex general de sostenibilitat. L'anàlisi dels resultats econòmics en termes absoluts de les diferents alternatives de tecnologia productiva en diversos escenaris econòmics mostra que, abans del boom de quinoa, els agricultors pràcticament mancaven d'al·licients per a introduir transformacions tecnològiques importants en els seus processos productius tradicionals, conservant la tecnologia productiva que permetia la sostenibilitat del cultiu, mentre que hui dia els retorns d'un sistema productiu basat en la productivitat de varietats millorades genèticament i inputs externs de les explotacions són molt elevats i suposen un al·licient important per a l'abandó dels sistemes productius tradicionals, més o menys evolucionats, que corren el risc de ser abandonats, perdent-se part de la capacitat d'aquests sistemes tradicionals ser sostenibles i adaptar-se als reptes del canvi climàtic. L'anàlisi de simulació efectuada sobre els resultats monetaris en diversos escenaris econòmics i tecnològics ens permet disposar d'una base quantitativa sobre la qual estimar un model de compensació equilibrada que permeta el manteniment dels sistemes tradicionals de producció amb la seua demostrada capacitat per a adaptar-se a diversos escenaris agroclimàtics. / [EN] Although quinoa (Chenopodium quinoa W.) had been cultivated by the Andean Peoples since pre-Inca times, its farming was postponed during the second half of the 20th century for various reasons. In fact, it was abandoned and almost forgotten in the places where it was originally domesticated what has caused a series of consequences on the productive systems and sociocultural behaviour of the Andean inhabitants. Nevertheless, the intrinsic qualities of its grain as a food supply, together with changes in consumption habits in developed countries, has provoked a growing interest in its cultivation. From being a product of self-consumption in a very limited geographical and cultural scope to becoming a star product to export. The quick increase in its demand has caused an adjustment in the productive models of the region and that has generated multidimensional impacts. In the present research, the impact generated by the quinoa's boom on the agricultural production system of the traditionally-maintained cultivation areas has been analysed. According to the objectives considered on this work, a diagnosis and development of the importance of the crop on the Peruvian population has firstly been made, same with the role played in the traditional agrarian systems of the Peruvian Andes. Secondly, an analysis of the evolution of the variables that determine the production and distribution of the grain in the last 70 years has been carried out. The periods of underutilization, recovery and expansion have been also identified in both the national context and at the level of the producing departments. We have focused our analysis on two extreme surface scenarios. With the commercial variables, the economic importance of the producing areas has been determined, same with the penetration of new markets and their contribution to the national economy and some structural changes, for which we have conducted a case study in the Andean communities of Cusco. The results of the conducted survey have allowed us to observe the current farmers' situation in the context of the quinoa's boom. This has showed a limited and precarious panorama due to geographical conditions and productive means which keep the crop in the conditions that guarantee sustainability and maintenance of the diversity of the traditional agrarian systems of the Andes in Peru. Moreover, the environmental and social sustainability indicators are similar at the same time they both exceed the threshold whereas the economic indicator is lower influencing on the overall sustainability index. The analysis of the economic results in absolute terms of the different alternatives of productive technology in various economic scenarios shows that, before the quinoa's boom, farmers had virtually no incentive to introduce major technological transformations into their traditional production processes preserving the productive technology that allowed the sustainability of the crop whereas nowadays, the returns of a production system based on the productivity of genetically-improved varieties and external inputs from farms are really higher. They represent an important incentive for abandoning traditional production systems, more or less evolved, which run the risk of being abandoned what provokes a loss of some of the capacity of these traditional systems to be sustainable and to be adapted to the climate change. The simulation analysis carried out on the monetary results in various economic and technological scenarios allows us to have a quantitative basis on which estimate a balanced compensation model allowing the maintenance of traditional production systems with its proven ability to be adapted to various agroclimatic scenarios. / Huillca Quispe, J. (2022). Valoración socioeconómica del impacto de la expansión del cultivo de Quinua (Chenopodium quinoa W.) sobre la competitividad y sostenibilidad de la diversidad en las explotaciones tradicionales del Perú [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/181509
257

Prise en compte de la fatigue des opérateurs dans la modélisation et la simulation des systèmes de production / Taking workers' fatigue into account in modelling and simulation of manufacturing systems

Ferjani, Aicha 22 February 2019 (has links)
Le développement rapide des technologies de l’information dans l’usine du futur nécessite de repenser l’organisation des systèmes de production. Si l’importance des opérateurs est bien reconnue dans l’industrie 4.0, les facteurs humains restent cependant insuffisamment pris en considération dans les méthodes d’organisation. La simulation est parmi les méthodes largement utilisées pour étudier les systèmes de production et évaluer leurs performances. Toutefois, les approches de simulation existantes et les logiciels disponibles sont centrés sur les dimensions techniques de ces systèmes (machines, transport, règles de priorité, etc.). Malheureusement, les facteurs humains, particulièrement la fatigue des opérateurs, semble être très insuffisamment pris en compte dans les modèles de simulation. Dans ce contexte, la présente thèse vise à étudier dans quelle mesure la fatigue pourrait être intégrée dans les modèles de simulation des ateliers de production. Un cadre conceptuel combinant différents paradigmes de modélisation est ainsi proposé pour aider à concevoir de tels modèles. Le paradigme de simulation à événements discrets est utilisé pour décrire la dynamique de fonctionnement des ateliers. Le paradigme d’agent intelligent est utilisé pour modéliser les opérateurs et intégrer leur comportement de fatigue que nous avons modélisé en utilisant la simulation continue. Nous avons également utilisé la logique floue pour caractériser les facteurs de pénibilité, connus de façon imprécise, et leur impact sur l’évolution de la fatigue. Nous avons montré comment le cadre conceptuel proposé peut être mis en œuvre de façon assez générique avec le logiciel Anylogic. L’approche proposée a ensuite été utilisée pour aborder deux différents problèmes de production: le premier concerne l’affectation dynamique des opérateurs sur les machines et le deuxième est relatif à l’agencement de machines lors de la phase de conception des ateliers. Ceci nous a permis d’illustrer l’utilité de l’approche propose et montrer sa pertinence. L’analyse des résultats de simulation permet d’apporter des connaissances à la fois sur les performances des systèmes et sur les tendances d’évolution de la fatigue des opérateurs durant le travail. De tels résultats aident à réfléchir sur la façon dont laquelle nous pourrions améliorer les méthodes d’organisation et de gestion des ateliers pour contribuer à l’amélioration de leurs performances et au bien-être de leurs opérateurs. / The quick development of information technology in the factory of the future requires rethinking about the organization of production systems. Although the importance of the workers in the industry 4.0, human factors are still insufficiently taken into consideration in the organizational methods. Simulation is among the methods widely used to study production systems and evaluate their performances. However, the existing simulation approaches and the available softwares mainly focus on technical dimensions of these systems (machines, transport, priority rules, etc.). Unfortunately, human factors, particularly workers’ fatigue, seem to be very insufficiently taken into account in the simulation models. In this context, this thesis aims to study how the workers’ fatigue could be integrated into the simulation models of workshops. A framework combining different modelling paradigms is proposed to help in designing such models. Discrete event simulation is used to describe the dynamic of the working process in workshops. The paradigm of intelligent agent is used to model operators and integrate their behavior of fatigue, which has been modeled using continuous simulation paradigms. We have also used fuzzy logic in order to characterize the arduousness’s factors, known imprecisely, and impacts on the evolution of the workers’ fatigue. We have shown how the proposed framework can be implemented can be implemented generically enough with the software ANYLOGIC. The proposed approach has been then used to address two different production problems: the first one concerns the dynamic assignment of workers to machines and the second is related to the machines layout in the design stage of the system. This illustrated the utility of the proposed approach and showed its relevance. The analysis of the simulation results yields some knowledge on both the performance of the systems and on trends of the evolution the operators’ fatigue during the work. Such results help to thank on how to improve the methods of organization and management of the workshops so to contribute to the improvement of their performances and the well-being of their operators.
258

Livestock futures in a changing world

Weindl, Isabelle 10 November 2017 (has links)
Die Nutzung von Biomasse als Nahrungs- und Futtermittel sowie als Rohstoff geht mit einem erheblichen Eingriff in biochemische Kreisläufe einher. Die Nutztierhaltung beansprucht dabei den Großteil der ökonomisch genutzten Phytomasse und dominiert Stoffströme in der Landwirtschaft. Während bereits der gegenwärtige ökologische Fußabdruck von tierischen Erzeugnissen Anlass zur Sorge bietet, wird die globale Nachfrage nach Fleisch, Milch und Eiern im Zuge von Bevölkerungswachstum und steigenden Einkommen voraussichtlich weiter zunehmen. Die vorliegende Arbeit untersucht die wechselseitigen Zusammenhänge zwischen Tierhaltung und Umwelt im Kontext globaler Wandlungsprozesse und adressiert Unsicherheiten auch in Bezug auf gegenwärtige Umweltauswirkungen. Im Rahmen der Dissertation wurde das räumlich explizite ökonomische Landnutzungsmodell MAgPIE (Model of Agricultural Production and its Impact on the Environment) um eine detaillierte Darstellung des Nutztiersektors erweitert. Die Modellsimulationen unterstreichen das Potenzial, sowohl durch eine Änderung der Ernährungsgewohnheiten als auch der Produktionsweise von tierischen Erzeugnissen landwirtschaftliche Stoffströme und Landnutzung deutlich zu beeinflussen sowie Stickstoffverluste und Emissionen von klimaschädlichen Gasen zu verändern. Moderate Produktivitätssteigerungen können Waldökosysteme bewahren und Kohlenstoffemissionen vermeiden, führen allerdings auch zu Zielkonflikten zwischen dem Schutz aquatischer und terrestrischer Ökosysteme sowie zwischen Stickstoff- und Kohlenstoffverlusten. Zudem ziehen ehrgeizige Produktivitätssteigerungen großflächige Umwandlungen von Weide- zu Ackerland und damit eine Verringerung von Bodenkohlenstoffbeständen auf landwirtschaftlichen Flächen nach sich. Ein reduzierter Konsum tierischer Produkte in wohlhabenden Regionen trägt maßgeblich zum Erhalt der Wälder, der Vermeidung von Treibhausgasemissionen und der Verringerung des landwirtschaftlichen Wasserverbrauchs bei. / Human appropriation of biomass as food, feed and raw material interferes with key biochemical cycles. Livestock is at the epicentre of agricultural material flows and resource use, utilising the majority of the economically used plant biomass, substantially amplifying the agricultural nitrogen cycle, contributing to greenhouse gas emissions and water use, and dominating human use of land. While already today’s environmental footprint of livestock gives cause for concern, demand for meat, milk and eggs is expected to continue growing, driven by population growth, increasing incomes, and urbanization. Between the poles of current environmental externalities and the magnitude of the expected growth of the livestock sector, this thesis explores interactions between animal agriculture and the environment in the context of broad-scale developments such as globalization, technological innovation, rising food demand, and climate change and addresses gaps in our knowledge about current environmental impacts of livestock. For this aim, the spatially explicit economic land use model MAgPIE (Model of Agricultural Production and its Impact on the Environment) was extended by a detailed representation of animal agriculture. Model simulations demonstrate the large demand- and supply-side potential inherent in livestock production to transform biomass flows in agriculture and alter environmental externalities of food production. While moderate productivity gains in the livestock sector can reduce deforestation and emissions from land use change, trade-offs emerge between aquatic and terrestrial ecosystems, and between nitrogen and carbon losses. Moreover, ambitious productivity increases trigger large-scale pasture-to-cropland conversion that involves depletion of soil carbon stocks on agricultural land. A reduced consumption of livestock products in affluent regions considerably mitigates deforestation, carbon emissions and agricultural water consumption.
259

Design of an Assembly System at AERCRETE INDUSTRIES

Hansson Tengberg, Henrik, Adlerborn, Andreas January 2009 (has links)
The forming of an assembly system is a complex task, which should be considered as never ending. In order to successfully plan and implement an assembly system it is of vital importance that the obstacles and preconditions that have an impact on the system are identified and evaluated. This together with the necessary support activities and the attributes of the product to be assembled constitutes the starting point for the forming of the assembly system. The aim of this thesis is to link the theoretical findings with the issues stated above, and through this explain a best practice approach when forming the assembly system. The theoretical work aims at describing the nature and activities within assembly and manufacturing systems and explains these in three different levels of strategies divided into Manufacturing strategies, Layout, material flow and design strategies and finally Logistic, material handling and quality strategies. Then the obstacles and preconditions found are discussed and evaluated which set the basis for the forming of the assembly system and by linking these with the relevant theory, conceptual design proposals for the assembly system and the Logistic support system are formed. These are then evaluated and finally a proposal for the detailed layout of the assembly system is given. This proposal is then to be used as a guideline for the company Aercrete when forming their assembly system.
260

Design of an Assembly System at AERCRETE INDUSTRIES

Hansson Tengberg, Henrik, Adlerborn, Andreas January 2009 (has links)
<p>The forming of an assembly system is a complex task, which should be considered as never ending. In order to successfully plan and implement an assembly system it is of vital importance that the obstacles and preconditions that have an impact on the system are identified and evaluated. This together with the necessary support activities and the attributes of the product to be assembled constitutes the starting point for the forming of the assembly system.</p><p>The aim of this thesis is to link the theoretical findings with the issues stated above, and through this explain a best practice approach when forming the assembly system. The theoretical work aims at describing the nature and activities within assembly and manufacturing systems and explains these in three different levels of strategies divided into Manufacturing strategies, Layout, material flow and design strategies and finally Logistic, material handling and quality strategies. Then the obstacles and preconditions found are discussed and evaluated which set the basis for the forming of the assembly system and by linking these with the relevant theory, conceptual design proposals for the assembly system and the Logistic support system are formed.</p><p>These are then evaluated and finally a proposal for the detailed layout of the assembly system is given. This proposal is then to be used as a guideline for the company Aercrete when forming their assembly system.</p>

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