Increasing effectiveness of use of the agents of production (efficiency) is needed to compensate for steadily rising costs of labor and equipment. Efficiency can be measured in various ways, depending on the type and scope of an operation. The methods available and the circumstances under which they can, and should, be used are the major concern of this thesis. Due to some peculiarities of primary forest production such as highly variable work conditions and irregular stand characteristics, many well known techniques of industrial engineering have not been used widely in forestry. Although progress to date has been limited, time study and several other work measurement techniques can be applied successfully. Time measurements have to be supplemented by costs and other data, to allow for comparison of alternatives. The production methods themselves should be analysed more carefully to find means for technological improvements. The role of the woods worker also deserves more attention because of his heavy and often dangerous work and his outdoor working conditions. In recent years the various activities of forest management, logging and mill supply have been viewed as part of a system which should be optimized for overall efficiency. Operations research has greatly increased the possibilities of studying the influence of variables which govern the system, although the systems approach has not yet been applied fully to an existing forest enterprise. Parts of the system or sub-systems may be complex enough to warrant the application of operations research, and its success should encourage increased research in this field. / Forestry, Faculty of / Graduate

M. S.

M. S.

In the context of forest products, a cutting order is a list of dimension parts along with demanded quantities. The cutting-order problem is to minimize the total cost of filling the cutting order from a given lumber grade (or grades). Lumber of a given grade is supplied to the production line in a random sequence, and each board is cut in a way that maximizes the total value of dimension parts produced, based on a value (or price) specified for each dimension part. Hence, the problem boils down to specifying suitable dimension-part prices for each board to be cut. The method we propose is adapted from Gilmore and Gomory's linear programming approach to the cutting stock problem. The main differences are the use of a random sample to construct the linear program and the use of prices rather than cutting patterns to specify a solution. The primary result of this thesis is that the expected cost of filling an order under the proposed method is approximately equal to the minimum possible expected cost, in the sense that the ratio (expected cost divided by the minimum expected cost) approaches one as the size of the order (e.g., in board feet) and the size of the random sample grow large. A secondary result is a lower bound on the minimum possible expected cost. The actual minimum is usually impractical to calculate, but the lower bound can be used in computer simulations to provide an absolute standard against which to compare costs. It applies only to independent sequences, whereas the convergence property above applies to a large class of dependent sequences, called alpha-mixing sequences. Experimental results (in the form of computer simulations) suggest that the proposed method is capable of attaining nearly minimal expected costs in moderately large orders. The main drawbacks are that the method is computationally expensive and of questionable value in smaller orders. / Graduation date: 2001

Thesis (Ph. D.)--Oregon State University, 2005. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Made available in DSpace on 2014-06-11T19:24:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-01-24Bitstream added on 2014-06-13T18:51:50Z : No. of bitstreams: 1 reboucas_fs_me_prud.pdf: 676967 bytes, checksum: b6d40c480a29167bae5341dc4dde58b1 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A atividade madeireira vem sendo desenvolvida no Brasil deste o início de sua colonização. Na Amazônia e especificamente no Acre, essa atividade só passa a ter uma importância econômica a partir da década de 1960, já que anterior a esse período os recursos madeireiros eram utilizados apenas como subproduto de outras atividades econômicas. É com a implantação da pecuária que o estado do Acre passa a ter grande quantidade da floresta desmatada para a formação de pastos. A madeira retirada passa então a ser utilizada também como um recurso econômico e, a partir daí, deixa de ser um meio, uma conseqüência de outra atividade e passa a ser um fim, uma nova atividade econômica a ser explorada. O município de Rio Branco, capital do estado, é a cidade onde a instalação de serrarias e depósitos de madeira sempre superou os demais municípios do estado. A escolha da cidade de Rio Branco para instalação de indústrias, seja madeireira ou outro tipo, está relacionada a fatos históricos de ocupação e também à uma maior infra-estrutura dentro da cidade, assim como também, a interligação por vias terrestres pavimentadas com outros municípios acreanos e também aos demais estados brasileiros. A exploração do recurso madeireiro era feito de modo tradicional, através de cortes seletivos com o aproveitamento das espécies de maior valor econômico no mercado consumidor. Deixavam-se, assim, rastros de destruição em toda a floresta. Esta depredação do ambiente não só se dava pela derrubada das árvores, mas também pelos equipamentos pesados utilizados para remoção e transporte da madeira até os pátios das empresas. Nos últimos anos a atividade madeireira tem estado mais sujeita à legislação ambiental específica. Passam a exigir critérios para a exploração da madeira, dentre eles destaca-se o manejo florestal, uma prática de elaboração e execução de um plano de atividades para a extração da madeira... / The wood extraction activity has been developed in Brazil since the beginning of its colonization. In Amazon and specifically in the State of Acre, such activity starts having an economical importance in the 1960’s, as in the previous period the wood resources were used only as a sub product derived from other economical actitivities. It is through the advent of raising cattle that the State of Acre starts having a great length of deforested area. The wood that is cut becomes, now, a new economical resource, and stops being a consequence of deforestation, but an activity to be explored. Rio Branco city, the capital of the State, is the city where the installation of wood store houses and lumber industries has surpassed the other towns around. The option of choosing Rio Branco as the site for the installation of lumber industries and others is related to historical facts of occupation and also to a bigger infrastructure in town, as well as, to the interconnection through paved roads and highways that link the other small towns to the main states and cities of Brazil. The exploration of wood was developed in a traditional way, by cutting only pre-selected trees that could represent a great economical value in the market. As result, signs of destruction were left along the forest. Such aggression to the environment could, not only happen because of lumbering, but also because of the heavy equipments that are used to move and carry the logs up to the patio of the companies. Throughout the last years, the lumbering activity has been submitted to the specific environmental legislation that demands criterion for wood exploration, and among them, there is the forest management, which consists on planning and execution of a set of measures that control the lumbering activity.

Resumo: A atividade madeireira vem sendo desenvolvida no Brasil deste o início de sua colonização. Na Amazônia e especificamente no Acre, essa atividade só passa a ter uma importância econômica a partir da década de 1960, já que anterior a esse período os recursos madeireiros eram utilizados apenas como subproduto de outras atividades econômicas. É com a implantação da pecuária que o estado do Acre passa a ter grande quantidade da floresta desmatada para a formação de pastos. A madeira retirada passa então a ser utilizada também como um recurso econômico e, a partir daí, deixa de ser um meio, uma conseqüência de outra atividade e passa a ser um fim, uma nova atividade econômica a ser explorada. O município de Rio Branco, capital do estado, é a cidade onde a instalação de serrarias e depósitos de madeira sempre superou os demais municípios do estado. A escolha da cidade de Rio Branco para instalação de indústrias, seja madeireira ou outro tipo, está relacionada a fatos históricos de ocupação e também à uma maior infra-estrutura dentro da cidade, assim como também, a interligação por vias terrestres pavimentadas com outros municípios acreanos e também aos demais estados brasileiros. A exploração do recurso madeireiro era feito de modo tradicional, através de cortes seletivos com o aproveitamento das espécies de maior valor econômico no mercado consumidor. Deixavam-se, assim, rastros de destruição em toda a floresta. Esta depredação do ambiente não só se dava pela derrubada das árvores, mas também pelos equipamentos pesados utilizados para remoção e transporte da madeira até os pátios das empresas. Nos últimos anos a atividade madeireira tem estado mais sujeita à legislação ambiental específica. Passam a exigir critérios para a exploração da madeira, dentre eles destaca-se o manejo florestal, uma prática de elaboração e execução de um plano de atividades para a extração da madeira... / Abstract: The wood extraction activity has been developed in Brazil since the beginning of its colonization. In Amazon and specifically in the State of Acre, such activity starts having an economical importance in the 1960's, as in the previous period the wood resources were used only as a sub product derived from other economical actitivities. It is through the advent of raising cattle that the State of Acre starts having a great length of deforested area. The wood that is cut becomes, now, a new economical resource, and stops being a consequence of deforestation, but an activity to be explored. Rio Branco city, the capital of the State, is the city where the installation of wood store houses and lumber industries has surpassed the other towns around. The option of choosing Rio Branco as the site for the installation of lumber industries and others is related to historical facts of occupation and also to a bigger infrastructure in town, as well as, to the interconnection through paved roads and highways that link the other small towns to the main states and cities of Brazil. The exploration of wood was developed in a traditional way, by cutting only pre-selected trees that could represent a great economical value in the market. As result, signs of destruction were left along the forest. Such aggression to the environment could, not only happen because of lumbering, but also because of the heavy equipments that are used to move and carry the logs up to the patio of the companies. Throughout the last years, the lumbering activity has been submitted to the specific environmental legislation that demands criterion for wood exploration, and among them, there is the forest management, which consists on planning and execution of a set of measures that control the lumbering activity. / Orientador: Eliseu Savério Sposito / Coorientador: Silvio Simione da Silva / Banca: Messias Modesto dos Passos / Banca: Jones Dari Goettert / Mestre

This thesis describes an optimization model for the allocation of logs from alternative sources for a series of successive time periods. The model was formulated as a multi-stage decision process and is solved by dynamic programming. The analytic framework consists of two connected recurrence equations, each incorporating two decision-variables. These two relationships, together with the feasibility regions defined for a hypothetical problem, describe the optimization process. The hypothetical allocation problem, used as a vehicle for model development, requires mill demands for quantities of pulplogs and sawlogs to be satisfied for three time periods. Logs are delivered from five available sources, four log-producing areas and an open log market, and temporary log surpluses are allowed. Only a limited quantity of logs is available from each source in each period, two of the four forest areas supply only pulplogs and a third area is inaccessible in one period. The variable unit costs of delivered logs differ not only between each source and period but are also dependent upon the magnitude of an allocation. In addition to satisfying mill demands for specified quantities of logs, there is a further requirement with regard to sawlogs. Average lumber prices are assumed to be dependent upon the tree species processed and variable log conversion costs are assumed to decrease with increase in log diameter. Consequently, the comparison of alternative allocation policies involves not only the sum of the variable delivered log costs but also a measure of the value of delivered sawlogs. In the thesis "sawlog net worth" is evaluated and combined with log production and log transportation costs to give a composite cost term, "net delivered log cost." This is the measure used to evaluate each allocation and is incorporated in the first of the two recurrence equations. This equation is used to derive minimum cost allocation policies for all possible quantities that may be allocated from each period. In the second equation the minimum costs derived from the first allocation process are combined with a second term to evaluate alternative allocations between periods. This second cost component is incurred when surplus logs are "cold-decked" for subsequent mill conversion. To ensure a sufficient flow of logs, and to take advantage of seasonal differences in "net delivered log costs," log surpluses are permitted. When log surpluses are "cold-decked" additional log handling costs are incurred which must be considered when alternative allocations between periods are evaluated. This requirement is satisfied by introducing the additional cost component into the second equation. The different derivations given for the "net delivered log costs" for five sources of logs demonstrate an important feature of the formulation: there is no requirement that costs must be linearly related to the quantity allocated. This freedom is well illustrated by the introduction of additional "fixed" costs which are dependent upon the magnitudes of the quantities allocated. In a demonstration of the flexibility of the formulation a complex log production system was assumed for source two. For each allocation from this source two optimal quantities were derived. The first was the quantity of sawlogs selected from specified log classes, the second was the optimal portion of the quantity of peeler logs developed that should be traded. An exchange could be made either for sawlogs, or for pulplogs, or both. With the development of this log allocation model a fresh approach to log production planning is now possible. The analytic framework is capable of extensive adaptation and the model itself can be readily modified to suit a variety of conditions. Whether used as described, or as part of a larger analytical system, the computational advantages of dynamic programming are now available to the planner. / Forestry, Faculty of / Graduate

Thesis (M.S.)--Oregon State College, 1954. / Typescript. Includes bibliographical references (leaves 50-51). Also available on the World Wide Web.

Thesis (M.S.)--Northwestern University, 1933. / Includes bibliographical references (p. 80).