At the Swedish forest owner association Mellanskog pre-harvest planning prior to thinning is traditionally performed by company foresters. In the past three years, Mellanskog has in one business area, instead outsourced pre-harvest planning to thinning contractors. The purpose of this study was to investigate how the outsourcing of pre-harvest planning is perceived by the company foresters and contractors and how it affects the working environment and costs. The study showed positive experiences from foresters and contractors, though there were some responsibility issues and economic concerns. Outsourcing improves the contractor’s working environment, but deteriorates that of the foresters. Having foresters performing the pre-harvest planning is more expensive than having contractors performing it, especially on small harvesting worksites.

A preocupação com a sustentabilidade nos empreendimentos florestais, em relação aos aspectos ambientais, sociais e econômicos, tem se evidenciado como uma realidade crescente. Para representar essa preocupação na elaboração nos planos de manejo florestal, buscou-se atribuir maior grau de detalhamento nas análises e compreensão da interação desses aspectos para prevenir possíveis impactos futuros e avaliar soluções a serem adotadas. Entretanto, esse detalhamento, representado pelo planejamento em níveis tático e operacional, muitas vezes é elaborado através de métodos que podem apresentar alto grau de risco relacionado à ocorrência de soluções não realistas, prejudicando o processo de tomada de decisão. Nesse contexto, este estudo teve como objetivo aprimorar as técnicas de planejamento operacional de colheita, através da elaboração de um modelo de programação linear padrão, avaliar esse modelo em diferentes cenários sujeitos a restrições ambientais e de abastecimento de uma empresa usada como estudo de caso, e realizar a comparação entre os resultados obtidos nesses cenários com os resultados efetivamente verificados pela empresa durante os períodos de avaliação. O estudo de caso considerou as áreas de produção de uma empresa florestal produtora de celulose no Uruguai a partir de plantações de eucalipto, onde foram selecionadas áreas para colheita em três anos consecutivos. A partir dessas áreas e parâmetros de produção dos povoamentos florestais, e das características da operação de colheita e expectativas do setor industrial, foi elaborado um modelo de programação linear inteira mista com minimização de desvios de metas. Através desse modelo foram avaliadas a ampliação da capacidade operacional, restrições ambientais e de abastecimento. A restrição ambiental exigiu a classificação das áreas de corte quanto à probabilidade de ocorrência de danos ao meio ambiente durante a operação de colheita em determinadas épocas do ano. A restrição de abastecimento considerou a regulação da densidade média da madeira entregue na indústria em cada período de análise, de acordo com um intervalo máximo de variação de 5% em relação á média geral. Já, a ampliação da capacidade operacional envolveu a análise de contratação de equipes terceirizadas para dar suporte à operação de colheita em determinados períodos. Além disso, o modelo matemático permitiu a incorporação de limites de deslocamento espacial da frente de colheita ao longo dos períodos de avaliação. Como resultado, foi selecionado um conjunto de indicadores de desempenho para a avaliação dos itens considerados no modelo, bem como suas interações, além da comparação dos cenários com os resultados realizados para cada um desses indicadores. O estudo mostra que é possível elaborar um modelo de programação linear capaz de representar o planejamento operacional de colheita, além de incorporar aspectos produtivos, ambientais e de abastecimento. A comparação dos resultados gerados pelo modelo nos diferentes cenários com os resultados obtidos pela empresa no período de análise mostrou a possibilidade de melhora na qualidade das soluções ao fazer uso das técnicas de programação linear e a vantagem da utilização de técnicas de planejamento mais holísticas. / Sustainability concerns in forest-based industries, as related to environmental, social and economic aspects, have been highlighted with crescent realism. Therefore, forest management plans must consider a greater level of details when analyzing and understanding the interaction among these aspects to prevent possible future impacts. At the tactical and operational planning levels, methods based on generic assumptions usually provide non-realistic solutions, impairing the decision making process. This study is aimed to improve current operational harvesting planning techniques, through the development of a standard linear programming model that allows for the evaluation of different scenarios, subject to environmental and supply constraints, and that provides the basic framework for comparisons with the results observed in the study case during the period of assessment. The study case comprised eucalyptus plantations harvested by a pulp mill in Uruguay over three consecutive years. Forest plantation parameters, like area, growth, harvesting conditions etc., and industrial requirements were mathematically represented in a linear mixed integer goal programming model. The model considered the increase on operational capacity and was constrained by environmental and supply limits. The environmental constraint required the classification of harvesting areas according to impacts due to environmental damages incurred during harvest operations. The supply constraint considered the need for regulating the average wood density and imposed a maximum range of variation of 5% on overall average. The possibility of increasing operational capacity was allowed by hiring outsourced crews to support harvest operations in certain periods. Furthermore, the spatial consequences of dispatching harvest crews to certain distances over the evaluation period were also considered. As a result, a set of performance indicators was selected to evaluate all optimal solutions provided to different possible scenarios and combinations of these scenarios, and to compare these outcomes with the real results observed by the mill in the study case area. Results showed that it is possible to elaborate a linear programming model that represents adequately harvesting limitations, production aspects, and environmental and supply constraints. The comparison involving the evaluated scenarios and the real observed results showed the advantage of using more holistic approaches and that it is possible to improve the quality of the planning recommendations using linear programming techniques.

Thesis (MScFor (Dept. of Forest and Wood Science)--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: This study aims to quantify the benefits of implementing an operational harvesting plan in forest harvesting operations. This is to be achieved by comparing productivity and costs from unplanned and planned harvesting operations. The study was conducted on a Pinus radiata plantation owned by Mountain to Ocean Forestry Company (Pty) Ltd (MTO) located near the town of Grabouw in the Western Cape Province of South Africa. MTO conducts harvesting operations using semi-mechanised tree-length harvesting systems. A wheeled H67 Clark Ranger cable skidder is used to extract tree-lengths from infield to the landing. Data was obtained both manually (work study) and from GPS tracking. Choking and dechoking data was obtained through time and method studies. GPS tracking was used to measure travel loaded and travel empty times, as well as travel distances and travel speeds. The aim of using both manual techniques and GPS tracking was to obtain detailed and spatially accurate information about the operation. The operating costs were estimated using South African Harvesting and Transport Costing Model. Productivity of the newly introduced tagline system (45.97 m³/pmh) exceeded that of mainline system (37.85 m³/pmhh) by 26%. The unit production cost of using tagline system (R20.21/m³) was 10% lower than the unit production cost of using mainline system (R22.54/³3). There were no benefits to be gained from improving the level of skid trail construction by removal of logging residue or cutting down stumps to as near the ground level as possible. A combination of manual (time and method studies) data collection and GPS tracking provided more detailed and accurate information on the semi-mechanised harvesting system. / AFRKAANSE OPSOMMING: Hierdie studie beoog om die voordele van die uitvoering van 'n operasionele inoestingsplan te kwantifiseer. Dit word bereik deur produktiwiteit en kostes van beplande en onbeplande inoestingswerksaamhede te vergelyk. Die studie is gedoen in Pinus radiata opstande van Mountain to Ocean Forestry Company (Pty) Ltd (MTO) naby Grabouw in die Wes-Kaap provinsie van Suid Afrika. MTO gebruik semi-gemeganiseerde boomlengte inoestingstelsels in hul inoestingswerksaamhede. . H67 Clark Ranger wielsleeptrekker met kabel en wenas is gebruik om boomlengtes van die veld na die pad te sleep. Data is versamel deur van beide hand (werkstudie) en GPS-opsporing gebruik te maak. Afhaak en aanhaak data is verkry deur van tyd- en metodestudies gebruik te maak. Gelaaide en ongelaaide tyd, spoed en afstande is met behulp van die GPS gemeet. Deur van beide hand en GPS versamelingsmetodes gebruik te maak, kon omvattende sowel as ruimtelik akkurate inligting oor die werksaamhede verkry word. Die bedryfskostes is verkry van die South African Harvesting and Transport Costing Model. Produktiwiteit van die nuut ingestelde verbindingslynstelsel (45.97 m³/pmh) het die hooflynstelsel (37.85 m³/pmh) met 26% oorskry. Die eenheidsproduksiekoste van die verbindingslynstelsel (R20.21/m³) was 10% laer as die eenheidsproduksiekoste van die hooflynstelsel (R22.54/m³). Daar was geen voordeel in die verbetering van die sleeppad konstruksie deur afval te verwyder of stompe nader aan die grondvlak af te sny nie. 'n Kombinasie van hand (tyd- en metodestudies) dataversameling en GPS-opsporing het meer akkurate en omvattende inligting oor die semi-gemeganiseerde inoestingstelsel verskaf.

A preocupação com a sustentabilidade nos empreendimentos florestais, em relação aos aspectos ambientais, sociais e econômicos, tem se evidenciado como uma realidade crescente. Para representar essa preocupação na elaboração nos planos de manejo florestal, buscou-se atribuir maior grau de detalhamento nas análises e compreensão da interação desses aspectos para prevenir possíveis impactos futuros e avaliar soluções a serem adotadas. Entretanto, esse detalhamento, representado pelo planejamento em níveis tático e operacional, muitas vezes é elaborado através de métodos que podem apresentar alto grau de risco relacionado à ocorrência de soluções não realistas, prejudicando o processo de tomada de decisão. Nesse contexto, este estudo teve como objetivo aprimorar as técnicas de planejamento operacional de colheita, através da elaboração de um modelo de programação linear padrão, avaliar esse modelo em diferentes cenários sujeitos a restrições ambientais e de abastecimento de uma empresa usada como estudo de caso, e realizar a comparação entre os resultados obtidos nesses cenários com os resultados efetivamente verificados pela empresa durante os períodos de avaliação. O estudo de caso considerou as áreas de produção de uma empresa florestal produtora de celulose no Uruguai a partir de plantações de eucalipto, onde foram selecionadas áreas para colheita em três anos consecutivos. A partir dessas áreas e parâmetros de produção dos povoamentos florestais, e das características da operação de colheita e expectativas do setor industrial, foi elaborado um modelo de programação linear inteira mista com minimização de desvios de metas. Através desse modelo foram avaliadas a ampliação da capacidade operacional, restrições ambientais e de abastecimento. A restrição ambiental exigiu a classificação das áreas de corte quanto à probabilidade de ocorrência de danos ao meio ambiente durante a operação de colheita em determinadas épocas do ano. A restrição de abastecimento considerou a regulação da densidade média da madeira entregue na indústria em cada período de análise, de acordo com um intervalo máximo de variação de 5% em relação á média geral. Já, a ampliação da capacidade operacional envolveu a análise de contratação de equipes terceirizadas para dar suporte à operação de colheita em determinados períodos. Além disso, o modelo matemático permitiu a incorporação de limites de deslocamento espacial da frente de colheita ao longo dos períodos de avaliação. Como resultado, foi selecionado um conjunto de indicadores de desempenho para a avaliação dos itens considerados no modelo, bem como suas interações, além da comparação dos cenários com os resultados realizados para cada um desses indicadores. O estudo mostra que é possível elaborar um modelo de programação linear capaz de representar o planejamento operacional de colheita, além de incorporar aspectos produtivos, ambientais e de abastecimento. A comparação dos resultados gerados pelo modelo nos diferentes cenários com os resultados obtidos pela empresa no período de análise mostrou a possibilidade de melhora na qualidade das soluções ao fazer uso das técnicas de programação linear e a vantagem da utilização de técnicas de planejamento mais holísticas. / Sustainability concerns in forest-based industries, as related to environmental, social and economic aspects, have been highlighted with crescent realism. Therefore, forest management plans must consider a greater level of details when analyzing and understanding the interaction among these aspects to prevent possible future impacts. At the tactical and operational planning levels, methods based on generic assumptions usually provide non-realistic solutions, impairing the decision making process. This study is aimed to improve current operational harvesting planning techniques, through the development of a standard linear programming model that allows for the evaluation of different scenarios, subject to environmental and supply constraints, and that provides the basic framework for comparisons with the results observed in the study case during the period of assessment. The study case comprised eucalyptus plantations harvested by a pulp mill in Uruguay over three consecutive years. Forest plantation parameters, like area, growth, harvesting conditions etc., and industrial requirements were mathematically represented in a linear mixed integer goal programming model. The model considered the increase on operational capacity and was constrained by environmental and supply limits. The environmental constraint required the classification of harvesting areas according to impacts due to environmental damages incurred during harvest operations. The supply constraint considered the need for regulating the average wood density and imposed a maximum range of variation of 5% on overall average. The possibility of increasing operational capacity was allowed by hiring outsourced crews to support harvest operations in certain periods. Furthermore, the spatial consequences of dispatching harvest crews to certain distances over the evaluation period were also considered. As a result, a set of performance indicators was selected to evaluate all optimal solutions provided to different possible scenarios and combinations of these scenarios, and to compare these outcomes with the real results observed by the mill in the study case area. Results showed that it is possible to elaborate a linear programming model that represents adequately harvesting limitations, production aspects, and environmental and supply constraints. The comparison involving the evaluated scenarios and the real observed results showed the advantage of using more holistic approaches and that it is possible to improve the quality of the planning recommendations using linear programming techniques.

Ce projet de recherche a été réalisé avec la collaboration de FPInnovations. Une part des travaux concernant le problème de récolte chilien a été effectuée à l'Instituto Sistemas Complejos de Ingeniería (ISCI) à Santiago (Chili). / La planification de la récolte forestière comporte différents niveaux de planification selon l'horizon de temps du problème et la nature des décisions à prendre. Dans un premier temps, nous nous intéressons à un problème de planification annuelle de la récolte, à mi-chemin entre la planification tactique et opérationnelle. Ce problème appliqué à l'exploitation forestière au Québec, naît d'un besoin de l'industrie québécoise d'un outil pour la planification annuelle intégrée qui fournit aux équipes de récolte leur calendrier. L'intégration consiste à déterminer les affectations des équipes aux blocs en fonction des besoins des usines, et qui respectent les contraintes de transport, de gestion des stocks, et bien entendu les conditions d'exploitation en forêt. Plusieurs modèles de types MIP ont été formulés, des approches de résolution adaptées à la structure de chacun des modèles ont été développées. L'approche par horizon roulant est celle dont les résultats surpassent les deux autres et surtout, améliorent de façon significative les plans usuellement suivis, notamment en réduisant les volumes non livrés aux usines de moitié, ou encore en divisant entre 2 et 6 fois les volumes en stock quand la demande diminue. De plus, le développement d'une interface pour systématiser le processus de résolution et élargir le nombre d'utilisateurs, est la seconde contribution de la thèse. Cette étape du projet correspond à un transfert de technologie de l'université vers l'industrie. Le second problème de planification se situe au Chili, est une planification tactique de la récolte dirigée par les prix et demandes en produits finis, ces derniers étant considérés comme des paramètres aléatoires. Le problème stochastique formulé est résolu suivant une méthode de décomposition par scénarios dont le nombre varie entre 10 et 100. Pour chaque scénario, la solution déterministe, lorsqu'elle est réalisable, est comparée avec celle issue de la résolution du problème stochastique. La solution déterministe n'est réalisable que pour une dizaine de scénarios parmi 100, et les pertes encourues sont en moyenne de 9%. / Harvest planning has different levels according to the time horizon of the problem and the nature of the decisions to be taken. Initially, we are interested in an annual harvest scheduling problem, halfway between tactical and operational planning. This problem applied in Qu\'ebec, is motivated by a need from the industry for an integrated tool that provides annual schedules to harvest teams. The integration is to determine demand driven assignments of teams to cutblocks and to manage transportation and inventory accordingly. Several MIP models have been formulated, and three solution approaches have been developed according to the structure of each model. The rolling horizon approach performs better than the other two, by improving significantly from the traditional harvest plan, especially by reducing by half non delivered volumes or by dividing between 2 and 6 times volumes in storage when demands decrease. Another contribution of the thesis is the creation of an interface to systematize solution process and to allow other users. This is the object of a transfer project between academics and industry. The second problem is a Chilean tactical harvest planning. Harvesting decisions are driven by stochastic demands and prices of final products. The stochastic problem is solved using a heuristic based on a scenario decomposition technique. The number of scenarios considered is between 10 and 100 scenarios. For each scenario, when the deterministic solution is feasible, it is compared with the stochastic solution for the current scenario. The deterministic solution is only feasible for 10% of the scenarios, and induces losses of 9% in average.

L’industrie forestière est un secteur qui, même s’il est en déclin, se trouve au cœur du débat sur la mondialisation et le développement durable. Pour de nombreux pays tels que le Canada, la Suède et le Chili, les objectifs sont de maintenir un secteur florissant sans nuire à l’environnement et en réalisant le caractère fini des ressources. Il devient important d’être compétitif et d’exploiter de manière efficace les territoires forestiers, de la récolte jusqu’à la fabrication des produits aux usines, en passant par le transport, dont les coûts augmentent rapidement. L’objectif de ce mémoire est de développer un modèle de planification tactique/opérationnelle qui permet d’ordonnancer les activités pour une année de récolte de façon à satisfaire les demandes des usines, sans perdre de vue le transport des quantités récoltées et la gestion des inventaires en usine. L’année se divise en 26 périodes de deux semaines. Nous cherchons à obtenir les horaires et l’affectation des équipes de récolte aux blocs de coupe pour une année. Le modèle mathématique développé est un problème linéaire mixte en nombres entiers dont la structure est basée sur chaque étape de la chaine d’approvisionnement forestière. Nous choisissons de le résoudre par une méthode exacte, le branch-and-bound. Nous avons pu évaluer combien la résolution directe de notre problème de planification était difficile pour les instances avec un grand nombre de périodes. Cependant l’approche des horizons roulants s’est avérée fructueuse. Grâce à elle en une journée, il est possible de planifier les activités de récolte des blocs pour l’année entière (26 périodes). / Forest industry is a sector located at the heart of the debate on globalisation and sustainable development, even if it is in decline. For many countries like Canada, Sweden and Chile, the objectives are to maintain a flourishing sector without damaging the environment and to realize the finite nature of resources. It is important to be competitive and to operate effectively on forest territories, from harvesting to manufacturing products, through transport, in a context where costs increase rapidly. This master’s thesis is developing a tactical operational planning model to organize activities for a year to meet requests for factories, without losing sight of the transport of harvested quantities and inventory management factory. The year is divided into 26 periods of two weeks. We seek harvest teams schedules and assignment to harvest areas (units) for a year. The problem is formulated as a mixed integer programming model, whose structure is based on each stage of the forest supply chain. We choose to solve it by an exact method, branch-and-bound. We were able to assess how the direct resolution of our planning problem was difficult for instances with a large number of periods. However the rolling horizon approach has proved successful. In a day, we obtained the harvest activities planning for 26 periods.

Made available in DSpace on 2016-06-02T19:50:25Z (GMT). No. of bitstreams: 1 6346.pdf: 5901404 bytes, checksum: 2d78b0f5f68ac25a089acd315f55b157 (MD5) Previous issue date: 2014-06-09 / The production of sugar, ethanol and electricity from sugar cane necessarily involves harvesting and transportation of raw materials, which are expensive and complex operations and have significant influence on the quality of the industrial raw material. The literature reports several optimization approaches related to the planning of planting, harvesting and transporting of sugarcane, however the scheduling of harvesting fronts is underexplored. This thesis intends to contribute to the state-of-art of this important issue in the context of the Brazilian agribusiness. Optimization approaches to support scheduling decisions of harvesting fronts considering the balance of harvesting and transportation capacities, as well as good agronomic management are proposed. The approaches are inspired by the representation of the problem as a lot sizing and scheduling model with parallel machines and sequence-dependent setup costs and times, a modelling technique well studied in the production planning and control literature. Three variants of this formulation, based on mathematical programming models, were developed and tested in two real case studies of medium size sugar mills. Heuristic methods based on aggregation procedures and mathematical programming have also been studied and developed to solve large scaled problems found in practice. Among the three variants studied, one presented the best solution quality within the expected execution time. Important scenario analysis were done indicating that the schedule s fulfilment provides reduction of harvesting and transporting complexity to the following season, which can generate significant saves in the cases studied. Besides that, comparing the proposed scheduling method with one of the sector s practice, it can be generated also significant cost reduction in the cases studied. The results were analyzed according to a validation methodology (descriptive facet of tetraedrum) well known in the literature. / A produção de açúcar, álcool e energia elétrica a partir de cana-de-açúcar passa necessariamente pela colheita e transporte da matéria-prima, que são operações custosas, complexas e que interferem significativamente na qualidade da matéria-prima industrial. A literatura reporta várias abordagens de otimização relacionadas ao planejamento do plantio, da colheita e do transporte de cana-de-açúcar, todavia a programação das frentes de colheita é pouco explorada. Nesta tese pretende-se contribuir para o estado da arte deste importante tema no contexto do agronegócio brasileiro. Propõe-se abordagens de otimização para apoiar decisões de programação das frentes de colheita, considerando-se o equilíbrio das capacidades de colheita e transporte, bem como um bom manejo agronômico. As abordagens são inspiradas na representação do problema por meio de um modelo de dimensionamento de lotes e sequenciamento da produção em máquinas paralelas com custos e tempos de setup dependentes da sequência, bem estudado na literatura em contextos de planejamento e controle da produção. Para isso foram desenvolvidas três variantes desta formulação baseadas em programação matemática, voltadas para a programação das frentes de colheita, que foram testadas em dois estudos de caso reais de usinas de cana-de-açúcar de médio porte do setor. Métodos heurísticos baseados em procedimentos de agregação e programação matemática também foram estudados e desenvolvidos para a resolução dos problemas de grande porte encontrados na prática. Das três variantes estudadas, uma delas apresentou melhor qualidade da solução dentro de tempos computacionais aceitáveis para o problema. Análises de cenário importantes foram feitas indicando que o cumprimento da programação proporciona redução de complexidade da colheita e transporte na safra seguinte, podendo gerar economias significativas nos casos estudados. Além disso, a comparação dos resultados das abordagens aqui exploradas com o que é praticado no setor indica um potencial de redução de custos também significativo para os casos estudados. Os resultados foram analisados de acordo com uma metodologia de validação (faceta descritiva do tetraedro) conhecida na literatura.

L’industrie forestière est un secteur qui, même s’il est en déclin, se trouve au cœur du débat sur la mondialisation et le développement durable. Pour de nombreux pays tels que le Canada, la Suède et le Chili, les objectifs sont de maintenir un secteur florissant sans nuire à l’environnement et en réalisant le caractère fini des ressources. Il devient important d’être compétitif et d’exploiter de manière efficace les territoires forestiers, de la récolte jusqu’à la fabrication des produits aux usines, en passant par le transport, dont les coûts augmentent rapidement. L’objectif de ce mémoire est de développer un modèle de planification tactique/opérationnelle qui permet d’ordonnancer les activités pour une année de récolte de façon à satisfaire les demandes des usines, sans perdre de vue le transport des quantités récoltées et la gestion des inventaires en usine. L’année se divise en 26 périodes de deux semaines. Nous cherchons à obtenir les horaires et l’affectation des équipes de récolte aux blocs de coupe pour une année. Le modèle mathématique développé est un problème linéaire mixte en nombres entiers dont la structure est basée sur chaque étape de la chaine d’approvisionnement forestière. Nous choisissons de le résoudre par une méthode exacte, le branch-and-bound. Nous avons pu évaluer combien la résolution directe de notre problème de planification était difficile pour les instances avec un grand nombre de périodes. Cependant l’approche des horizons roulants s’est avérée fructueuse. Grâce à elle en une journée, il est possible de planifier les activités de récolte des blocs pour l’année entière (26 périodes). / Forest industry is a sector located at the heart of the debate on globalisation and sustainable development, even if it is in decline. For many countries like Canada, Sweden and Chile, the objectives are to maintain a flourishing sector without damaging the environment and to realize the finite nature of resources. It is important to be competitive and to operate effectively on forest territories, from harvesting to manufacturing products, through transport, in a context where costs increase rapidly. This master’s thesis is developing a tactical operational planning model to organize activities for a year to meet requests for factories, without losing sight of the transport of harvested quantities and inventory management factory. The year is divided into 26 periods of two weeks. We seek harvest teams schedules and assignment to harvest areas (units) for a year. The problem is formulated as a mixed integer programming model, whose structure is based on each stage of the forest supply chain. We choose to solve it by an exact method, branch-and-bound. We were able to assess how the direct resolution of our planning problem was difficult for instances with a large number of periods. However the rolling horizon approach has proved successful. In a day, we obtained the harvest activities planning for 26 periods.