In this thesis, we study a multi-period, multi-product, production planning problem for the lumber industry, and present a hierarchical approach to control and schedule lumber production in a sawmill. First, at the sawing unit, the lower level of the hierarchical structure, the combination of log classes, price lists and sawing patterns defines the expected output distribution in terms of lumber pieces. A price list, defining the value of outputs, is fed directly to the sawmill production control optimizer to select the best sawing patterns. This results in a broad variety of different lumber outputs. Second, at the upper level, a mixed integer programming model has been proposed to maximize the total revenue at the sawmill. The lumber outputs determined at the lower level are used as data at the upper level. Market demand, lumber inventory cost, and supply cost are considered over the planning horizon. The proposed model has been developed and implemented on a real-scale prototype sawmill.

Thesis (Ph. D.)--University of Washington, 1991. / Vita. Includes bibliographical references (leaves [87]-112).

The transition to a fossil-free industry is a current topic, and in Swedish industry, energytransition of existing energy systems is promoted to reduce climate impact. Energy transitioninvolves a structural change in the energy system with a focus on energy use and energysupply. To reduce global greenhouse gas emissions, the transition can be achieved throughelectrification and the use of biomass. Currently, sawmills combust significant amounts of biomass to meet the heat demandof industrial wood drying. As the biomass used is a by-product of the sawmills’ otherproduction processes, this combustion is usually considered sustainable and circular. However,some research indicates that increased biomass usage in several industrial sectors can leadto overexploitation of the resource with negative environmental impacts. Despite thesedisagreements, many argue that bio-based residual flows must be utilised efficiently to meetsociety’s future biomass needs. Against this background, it needs to be examined whether sawmills should continue tocombust biomass or whether an energy transition would be more economically and ecologicallysustainable. The aim of this study is to investigate how energy use in the sawmill industrywill change in the future and what potential consequences this change may have. In addition,the possibilities and feasibility of electrifying the drying process in the sawmill industryare investigated. To achieve this purpose, a literature search and an interview study wereconducted. The results from these parts form the basis for a scenario-based quantitativestudy of the consequences of different energy transition cases. The results show that future energy use in the sawmill industry will be affected by severalfactors. One important factor is the price of biomass, which can provide an incentive toelectrify the energy-intensive drying process. However, it can be challenging to make anelectrified drying process profitable, and until then energy efficiency will be prioritised ratherthan biomass replacement. The results also indicate that electrification of the drying processcan reduce the climate impact, assuming that the electricity source is fossil-free. The releasedbiomass can then be used more efficiently than incineration, and the optimal use may be toproduce long-life products. Clear knowledge gaps have been identified regarding the electrification of the drying processand its potential consequences. Since the sawmill industry is not ready for an energytransition today, there is time to fill these gaps and develop the electrifying processes. Furtherinvestigations should be conducted on various aspects of electrified drying through in-depthmodelling and analysis of the sawmill energy system. Additionally, future studies couldinvestigate the extent of the impact of sawmill biomass release on the surrounding energysystem.

The purpose of this research was to quantify the impact of the log variables: length, grade, and scaling diameter, on the cost of producing hardwood lumber, using the activity-based costing technique. The usual technique of calculating hardwood lumber product costs is based upon traditional cost accounting, where manufacturing costs are allocated to the products based upon the volume of each product that is produced. With the traditional cost accounting procedure, the variation in the resources used to process the logs is not taken into consideration. As a result, when the cost to manufacture the products is subtracted from the market value of the products, the resulting profit levels of the products may not be truly representative of the actual resources consumed in manufacturing the product. Using discrete-event simulation, two hardwood sawmills were modeled and a series of experiments were conducted which would not have been feasible to conduct on the mill floors. Results from the simulation experiments illustrated that the activity-based and traditional cost accounting techniques allocated different amounts of manufacturing costs to the products. The largest difference between the two cost accounting techniques was found to be the amount of raw material costs allocated to the products. For one of the sawmills modeled, log grade was identified as having the greatest influence on determining product costs and total manufacturing costs. Results from the model of the second sawmill however demonstrated that log diameter had a greater impact on determining product costs and total manufacturing costs. The commonality of the results from the two simulation models was that the differences in the volume of lumber produced, between the logs that were studied, was a critical component in determining which log parameter had the most effect on changing the dynamics of the sawmill system. To enable hardwood managers a more precise method of allocating raw material costs to the lumber products, a methodology was developed that uses the principles of activity-based costing to allocate raw material costs. The proposed methodology, termed the lumber yield method, uses lumber yield values from logs with similar characteristics to allocate raw material costs to the lumber products. Analysis of the output from the simulation models illustrated that with the lumber yield method, the amount of raw material costs allocated to the products was not significantly different than the amount allocated by the activity-based costing method. The calculated raw material costs of the products were however, found to be significantly different between the lumber yield method and the traditional volume costing method. / Ph. D.

A nation-wide survey of hardwood sawmills was conducted in the fall of 1999. The objectives of the survey were to determine the differences between adopters and non-adopters of scanning and optimizing technology, identify the company expectations of scanning and optimizing technology, and model the adoption decision process for future scanning and optimizing technology. These objectives were chosen because timely information was not available on the hardwood sawmill industry, and even less was known about the overall state of technology with the industry. The survey consisted of a mail questionnaire which was sent to over 2000 hardwood sawmills. The questionnaire was used to collect demographic, equipment, and preference scale information on the hardwood sawmill industry. The second part of this project used the Analytic Hierarchy Process to model the adoption decision process for future scanning and optimizing technology in hardwood sawmills. Data was collected through personal interviews with two hardwood sawmill groups including adopters and non-adopters of advanced scanning and optimizing technology. The interviewee rated the importance of the decision factors in the adoption decision process. They also rated the influence of four sawmill departments on the adoption decision process. The results from the mail survey found that the average yearly lumber production was 7.6 million board feet per sawmill. The most common type of scanning and optimizing technology, headrig optimization, was only in use by 27 percent of the responding mills. Advanced scanning and optimizing technology such as edger-optimizers and trimmer-optimizers were only in use by 10 percent and 5 percent of the respondents respectively. Adoption decision factors for scanning and optimizing technology were rated. Improved raw material recovery and increased lumber revenues were the two most highly rated factors. Accuracy of grading was the most highly rated factor for automated grading systems. The adoption decision model found that production related issues were most important in the decision process and that the production department was the most influential of the sawmill departments. Overall, scanning and optimizing technology adoption within the hardwood sawmill industry is low. For those that have adopted advanced scanning and optimizing technology, production issues were the driving factors. / Ph. D.

No description available.

This dissertation studies the establishment and demographic development of the sawmill communities that emerged in the Sundsvall district during the latter half of the 19th century.  The intention is to highlight the importance of the sawmill communities and their resident populations by discussing community construction from a demographic perspective as well as socially and symbolically. Based on church registers, this is a longitudinal study that includes information from 31 individual sawmill communities. This study has shown that the establishment and demographic development of the sawmill communities was not an instant process that necessarily followed the construction of the sawmill industries. The prerequisites of the geographical locations and year of establishment influenced population development, but the speed and size of the settlements were individual to each mill site. More prosperous times for the industry during the 1870s resulted in that migration increased consequently leading to quickly populated communities and larger registered core populations in residence. Migration to the sawmill communities from within the parishes was infrequent and the geographical backgrounds revealed that an extremely small proportion of the populations had been born within the district, implying a migratory hesitation among locally born. The sawmill populations were male-dominated due to the large groups of temporary workers inhabiting the communities, although, adult males barely made up one-third of the registered populations. The largest demographic group was children aged 0-14 years. The strong presence of children and high proportions of married individuals suggests that the sawmill communities were family oriented communities, more so than non-sawmill areas. Long-time settled families had usually formed kinship networks with other residents. This dissertation concludes that while time was important for the development of the sawmill communities, so were the registered populations residing in these communities. Residency would have been key in claiming belonging to the sawmill communities and to be considered as a real sawmill worker. Residency, family and kin therefore contributed to the construction of community structures, geographically, socially and symbolically.

<p>One of the great challenges facing society is to convert theglobal energy system to a sustainable process. Currently, 80%of the world´s energy is supplied through the combustionof fossil fuels. Not only are the fossil resources limited, theutilisation also increases the level of greenhouse gases in theatmosphere. The convertion to a sustainable energy system isproblematic since the technology needed to exploit mostnon-fossil energy sources is not yet fully developed, e.g.solar energy. Biofuel is an available renewable energy sourcewhich is already widely used in many countries. If an effectiveswitch-over from fossil fuels to biofuels is to be realised,biofuels must be viewed as a limited resource. Consequently, itis important that the handling, upgrading and utilisationprocesses involving biofuels are efficient so that itspotential can be fully exploited.</p><p>This thesis considers efficient biofuel utilisation andupgrading within the sawmill industry. The goal has been toanalyse not only the technical opportunities for energy savingsin the sawmill industry, but also to analyse the costeffectiveness and environmental impact of studied measures. Theheat demand of the sawmill industry is almost completelycovered by its own by-products; primarily bark, sawdust andwood chips. The increased demand and improved economic value ofwoody biofuels on the market is thus an incentive for thesawmill industry to place more focus on energy issues. Thesawmill industry also has a more or less constant heat loadover the year, which is a beneficial factor for integrationwith district heating networks, biofuel upgrading plants andcombined heat and power plants.</p><p>The conclusion of the study is that a variety of energyproducts such as heat, unrefined biofuel, pellets andelectricity can be efficiently produced in the sawmill industryand sold for profit to external customers. The payback periodsfor the proposed investments are moderate and both theemissions of volatile organic compounds and global CO2 aredecreased. Should the proposed measures be fully implemented atSwedish sawmills, about 2.8 TWh of biofuel could be savedannually, 0.5 TWh of waste heat could be sold as districtheating and 0.8 TWh of green electricity could be produced.Language: English</p><p><b>Keywords:</b>Sawmill industry, energy efficiency, heatrecovery, integration, biofuel, upgrading, district heating,fuel pellets, CHP, VOC, CO2</p>

O eucalipto é um gênero amplamente cultivado no Brasil desde o início do século XX. É utilizado principalmente na produção de carvão e polpa, apesar da aptidão para produção de toras para serraria. Para as espécies cultivadas no Brasil, as técnicas de manejo para serraria foram pouco desenvolvidas e delas depende a introdução efetiva da madeira serrada de eucalipto no mercado. O presente estudo objetivou identificar as variáveis do manejo florestal do Eucalyptus urophylla que determinam, física e temporalmente, a formação de madeira limpa (clear) em árvores manejadas para serraria. O experimento foi implantado em julho de 2013 na Estação Experimental de Ciências Florestais de Itatinga (E.E.C.F.I/ESALQ/USP) e consistiu de 4 espaçamentos, sendo eles (3 x 1), (3 x 2), (3 x 3) e (6 x 1,5) m. Realizou-se o primeiro inventário em janeiro de 2015, aos 18 meses de idade, com medições de atributos das árvores e dos galhos. As parcelas foram subdivididas pela metade e, também em janeiro de 2015, aplicou-se a desrama artificial (poda) até os 2,5 m do tronco em uma de cada par de subparcelas. Daí em diante foram realizadas medições de cicatrizes e incremento secundário (dendrômetros) tomadas periodicamente até fevereiro de 2016, aos 31 meses de idade. Em junho de 2015 foi feita a primeira amostragem destrutiva de toras para medição de espessura da casca e em fevereiro de 2016 uma segunda leva de toras foi amostrada e submetida a análise em laboratório. Esta amostragem não incluiu o tratamento sem poda devido à ausência de desrama natural. Toretes foram gradualmente processados em torno mecânico para observação em plano tangencial da madeira formada após a desrama artificial. Nesta etapa também mediu-se a espessura da zona de oclusão e de madeira clear. A zona de oclusão é essencialmente composta pelo exsudado secretado para proteção periférica da cicatriz na casca. A área calculada do anel de oclusão está altamente correlacionada à área do anel da casca. Portanto, a espessura da casca determina a espessura do anel de oclusão e a formação de clear se inicia quando o xilema secundário sobrepõe o ponto mais externo no plano tangencial marcado pelo exsudado. / Eucalyptus is a genus widely grown in Brazil since the beginning of the 20th century, traditionally used to produce fuel and pulp despite its potential for sawlog production. The silvicultural techniques developed for eucalyptus short rotation woody crops in Brazil have neglected essential traits for high quality sawlog production, without which eucalyptus solid wood is not marketable. The aim of the present study was to identify the variables in silvicultural management of Eucalyptus urophylla limiting, physical and temporally, clear wood formation. The experiment was established in July 2013 at the Itatinga Experimental Station, College of Agriculture \"Luiz de Queiroz\" (ESALQ), University of São Paulo (USP), Brazil, consisting of spacing trials of (3 x 1), (3 x 2), (3 x 3) e (6 x 1,5) m. Measurements o trees and branches attributes were first taken in January 2015, when trees were 18 months old. The plots were split in half (subdivided) and one of the subplots was addressed for a pruning trial in which all live and dead branches were removed to 2,5 m, also in January 2015From then on, wound occlusion and secondary growth (band dendrometers) were periodically measured until February 2016, when the trees were 31 months old. Destructive samplings were firstly carried out in June 2015, for bark thickness determination, and secondly in February 2016. The latter did not include unpruned subplots, once the trees had not yet shed the branches. Logs were debarked and processed in mechanical lathe while measurements of clear wood and occlusion zone were taken in the tangential plane. High correlation between occlusion zone ring area and bark ring area has been found. The occlusion zone of Eucalyptus urophylla is mainly composed by the exudate released by trees during the bark wound closure process. Therefore, the bark thickness establishes the occlusion ring thickness and clear wood formation starts after the secondary xylem overlaps the most external point in the tangential plane marked by the exudate.

In direct reference to the saying “time is money”, nowadays scenario simulations play a key role in the tasks people perform. Optimizing the time length of tasks and synchronizing them properly is essential to increased profits in any line of business. In this thesis the Bergkvist-Insjön sawmill yard process will be computer simulated. As the number of trucks arriving at the sawmill is unknown, the unexpected arrival of trucks would produce a high pressure on internal resources and handling operations. The aim of this paper is to optimize the usage of the resources in the Bergkvist-Insjön sawmill, by running three different scenarios built based on the real system simulation. Scenario number three, in which a log stacker only has the tasks to unload the trucks and supply the measurement station, has been found most efficient. In the simulation of this scenario, the number of logs processed by the sawmill is the highest one. Also, the time spent by the log stackers between their tasks is the shortest one from all scenarios. The results of this thesis revealed that the most efficient improvement of the sawmill yard would be gained by a different tasks’ priority for the operating log stackers.