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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.
51

Efeito do tratamento térmico sobre as propriedades de painéis OSB / Effect of thermal treatment on OSB panels properties

Mendes, Rafael Farinassi 12 January 2011 (has links)
O objetivo principal do presente estudo foi avaliar o efeito do tratamento térmico das partículas strand (pré-tratamento) e dos painéis (pós-tratamento) sobre as propriedades físicomecânicas dos painéis, visando principalmente à melhoria de sua estabilidade dimensional. O delineamento experimental se constituiu de sete tratamentos, com a avaliação de: Duas temperaturas de tratamento das partículas (200 e 240°C) por um período de 60 minutos; do póstratamento térmico dos painéis produzidos com e sem a aplicação de parafina na temperatura de 220°C e por um período de 12 minutos; e do aumento do teor de adesivo e a aplicação de parafina em painéis sem tratamento térmico. Para cada tratamento foram produzidos três painéis com densidade nominal de 0,65 g/cm³, colados com adesivo à base de fenol-formaldeído. O ciclo de prensagem dos painéis foi o seguinte: pressão de 35 kgf/cm², temperatura de 160ºC e tempo de 8 minutos. A partir dos painéis produzidos, corpos-de-prova foram obtidos para a realização de ensaios físicos (Teor de umidade, densidade aparente, absorção de água e inchamento em espessura) e mecânicos (Módulo de ruptura, Módulo de elasticidade e Ligação interna), conduzidos conforme as normas ASTM D 1037 (2006) e DIN 52362 (1982). Mediante à análise dos resultados dos ensaios foi possível extrair as seguintes conclusões: Os painéis produzidos com as partículas tratadas termicamente a 240°C apresentaram-se superiores aos outros tratamentos em todas as propriedades físicas avaliadas, sendo portanto o tratamento com a melhor estabilidade dimensional. O pós-tratamento térmico promoveu melhora significativa das propriedades físicas dos painéis sem comprometer as propriedades mecânicas. O pré-tratamento térmico teve efeito mais pronunciado sobre as propriedades dos painéis do que o pós-tratamento térmico, proporcionando a melhoria das propriedades físicas e a diminuição das propriedades mecânicas. O aumento do teor de adesivo e a aplicação de parafina não se mostraram tão eficientes na estabilidade dimensional dos painéis OSB quanto o tratamento térmico aplicado nas partículas na temperatura de 240°C. / The main objective of this study was to evaluate the effect of thermal treatment of strand particles (pre treatment) and panels (post-treatment) on the physical and mechanical properties of the panels, aiming primarily to improve the dimensional stability. The experimental design was consisted of seven treatments, with the evaluation of: two temperatures of particle treatment (200 and 240 °C) during 60 minutes; thermal post-treatment of the panels produced with and without the application of paraffin at 220 ° C during 12 minutes; and the increase in adhesive content and application of paraffin on the panels without thermal treatment. Three panels were produced for each treatment with nominal density of 0.65 g/cm ³, bonded with phenol-formaldehyde adhesive. The pressing cycle of the panels was as follows: 8- minute press time, pressure of 35 kgf/cm ², and temperature of 160 °C. From the panels produced, specimens were obtained to conduct physical tests (moisture content, bulk density, water absorption and thickness swelling) and mechanical (Modulus of Rupture, Modulus of elasticity and internal bonding), tests according to ASTM D 1037 (2006) and DIN 52 362 (1982) standard. Through the analysis of test results it was possible to conclude: The panels produced with the particles thermally treated at 240°C were superior to the others for all physical properties evaluated, and therefore it was treatment with better dimensional stability. The post-thermal treatment caused a significant improvement of the physical properties of the panels without compromising the mechanical properties. The prethermal treatment had an effect on the properties of the panels that was more pronounced than the post-heat treatment, providing improved physical properties and lower mechanical properties. The increase in adhesive content and the application of paraffin were not as efficient in the dimensional stability of OSB as the thermal treatment applied on the particles at 240 ° C.
52

Mechanical processing for improved products made from Swedish hardwood

Johansson, Jimmy January 2008 (has links)
Swedish hardwood is today used in the energy, pulp and mechanical hardwood industries. Only very small volumes of Swedish hardwood are, however, consumed by the mechanical industry that normally pays the highest timber price. The smallness of the volumes used for mechanical refinement is a result both of forestry not focusing on the production of hardwood for these uses, and of the fact that the mechanical hardwood industry, particularly the sawing industry, is not designed to process the existing raw material in an optimal manner. This thesis discusses the possibilities of improving the conditions for the mechanical refinement of hardwood. The aim of the work has been to investigate the possibilities of developing products and methods for processing of Swedish hardwood. The thesis proposes a new manufacturing system for Swedish hardwood to better utilize the inherent properties of the wood material. The system is based on the so-called PrimWood Method and the star-sawing concept. Compared to normally sawn wood, the sawing concept utilizes the raw material more efficiently with regard to volume yield, and increases the distance between knots in the sawn wood. The material produced has vertical annual rings which give the wood smaller movements as a result of moisture variations and a different textural appearance. Using the PrimWood Method for hardwood would make it possible to more closely match customer requirements regarding hardwood products. Since Swedish hardwood is nowadays mainly used indoors, a possible way of expanding the market would be to increase the outdoor use of the material. Here the durability is of great importance, and one important factor is then the capillary characteristics of the material. The thesis therefore focuses on the characterisation of the capillarity in wood for the future improvement of its durability. It is shown that with the material produced by the proposed manufacturing system, i.e. wood with vertical annual rings, the possibility of using hardwood outdoors increases, because the susceptibility to cracking decreases.
53

Outsourcing in the Wood Product Manufacturing Sector A Combined Customer and Supplier Perspective

Nordigården, Daniel January 2007 (has links)
Outsourcing can be defined as transferring an activity from internal to external control. This thesis studies outsourcing in the wood product manufacturing (WPM) sector from both a customer and supplier perspective. The research design is a multiple case study approach, and it is based on six Scandinavian companies in the door, floor and window industries and one larger supplier of raw material. This study provides an understanding of driving forces for outsourcing in a different context than previously studied and has identified cost reduction in combination with reallocating resources from non-core activities as main driving forces. Compared to several other industrial sectors, outsourcing strategies for the WPM firms have little to do with accessing external sources’ capabilities. In the literature, there is often a main focus on the strategic level of outsourcing, however, such heavy resource-based focus in terms of a core competence approach in the formulation of outsourcing strategies at the customer side risks forgetting that components can still be vulnerable to supplier failure. Here, more focus needs to be put on the operational level when considering outsourcing. This thesis illustrates customers considering outsourcing where there are not any given outsourcing supplier partners developed. At the same time, for the supplier side, forward integration and specialising by taking over outsourcing is complicated by an initial divergent production flow of sawn timber. When not all contexts have developed supplier markets for directly managing outsourcing, it should not be assumed that general outsourcing models are directly applicable. In general, the question of whether or not to outsource seems too complex to simply be considered as either “in or out”. A company needs safeguards when conducting outsourcing and in a situation where there is a non-developed supplier market, parallel in-house production becomes an alternative.
54

Position Of Design And The Designer In Low-tech Small And Medium Scale Furniture Industry In Turkey

Ozturk Sengul, Mehtap 01 February 2009 (has links) (PDF)
Increasing competition and technological improvements have created new challenges for the firms. In Turkey, low-tech small and medium scale furniture industry does not seem to be well equipped to compete in this respect due to their weak economic and cultural capital. Necessity of innovative and distinguishing design-led policies has already arisen for improving the position of the low-tech small and medium scale furniture producers. However, to generate effective policies for them, it is essential to understand the design process and production domain related to cultural factors which affect the position of design and the designer. Within this perspective, this thesis examines the position of design and the designer within the product development process in eight cases of small and medium scale furniture companies based on the data gathered from, firstly, in-depth interviews with the owners, and secondly, product development stories narrated by the owner, the designers and head of the production departments of the companies.
55

Effekten av demand-supply chain management : Fallstudie från trävaruindustrin

Lehnbom, Mia, Holmberg, Patrik January 2015 (has links)
Enligt Carlsson och Rönnqvist (2005) och Frayret et al. (2007) blir det allt viktigare att arbeta med supply chain management inom trävaruindustrin. En utmaning är att finna ett arbetssätt för att hantera variationen i kundens efterfrågan. Idag hanteras variationen oftast genom onödigt stor lagerhållning (Lee et al., 1997b; So och Zheng, 2003).                                                                                 Syftet med studien är att utreda påverkande faktorer som bidrar till en varierande efterfrågan inom trävaruindustrin samt föreslå hur uppkomsten av dessa kan undvikas. För att svara på syftet har tre frågeställningar tagits fram och en fallstudie genomfördes på ett hyvleri. Informationsinsamlingen har skett genom intervjuer av anställda från olika avdelningar samt litteraturstudier. Studien visar att det finns flera utmaningar när det är stor variation på efterfrågan såsom brist på tillgång till prognoser och kommunikationsbrist med kunder. Det medför att planeringen av råvaruåtgången försvåras och det leder till svårigheter att uppnå leveransprecision.   Slutsatsen visar att de påverkande faktorer som bidrar till en varierad efterfrågan är prisvariationer, orderstorlek och orderfrekvens. Prisvariationer kan undvikas genom ABC-indelning av produkterna utifrån produktefterfrågan. Prognoser underlättar uppskattning av efterfrågan men för ett fungerande prognosarbete krävs samsyn, nära relation samt god kommunikation mellan kund och leverantör. Problem med orderstorlek och orderfrekvens kan reduceras om kunden får avgöra orderstorleken utan att specifika krav måste uppfyllas. Slutsatsen visar även att faktorer såsom väderlek, trender, mode, helgdagar och rotavdragets eventuella försvinnande påverkar variationen i efterfrågan. / According to Carlsson & Rönnqvist (2005) and Frayret et al. (2007) supply chain management in the wood products industry is getting more important. One of the challenges is to find a way to deal with customer’s fluctuating demand. Traditional solution to handle fluctuating demand is large inventory (Lee et al., 1997b; So & Zheng, 2003), which causes often high inventory cost for effective supply chain management.   The aim of the study is to investigate factors that affect a fluctuating demand in the wood products industry and suggest how to reduce the fluctuating demand through related factors analysis in order to improve Demand-Supply chain management efficiency. For this pursose, a case study on a planing is conducted. To collect data, interviews with employees from different departments have been made along with literature studies. The study presents that there are many challenges for the fluctuation demand such as lack of forecasts and lack of communication with customers. This, in turn, will cause problems with planning of the raw material as well as difficulties to deliver the goods on time.   The conclusion shows that the factors affecting a fluctuating demand are price variations, the orders batch size and order frequency. Price variations can be improved by ABC classification of the products by product demand. Forecasts will make the estimation of demand easier, although, in order to use forecasts properly a joint vision, close relationships and good communication with customer and supplier is required. Problems regarding batch size and order frequency can be reduced if the customer is allowed to decide the batch size with no specific requirements. The study also shows that factors such as weather, trends, fashion, holidays and disappearance of ROT work affects the fluctuating demand.
56

The potential for forestry to reduce net CO₂ emissions /

Eriksson, Erik, January 2006 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2006. / Härtill 4 uppsatser.
57

The Effect of Steel Strapping Tensioning Technique and Fibre-Reinforced Polymer on the Performance of Cross-Laminated Timber Slabs Subjected to Blast Loads

Lopez-Molina, America Maria 09 October 2018 (has links)
Engineered wood products (EWP) are becoming extremely popular and a viable material option for the construction of residential, commercial, and hybrid buildings. Cross-laminated timber (CLT) is among one of the many EWP available in North America, which can be utilized for many different applications such as: walls, floors, and roofs. Despite the available requirements in the Canadian blast design standard (CSA, 2012) with regard to the design of wood structures, there are currently no provisions on how to retrofit timber structures to improve their performance when subjected to blast loads. The current study is aimed at investigating the effect of different retrofitting alternatives in order to improve the overall behaviour of CLT when exposed to out-of-plane bending. The experimental program examined the behaviour of seventeen reinforced CLT slabs. Testing was conducted at the University of Ottawa by means of a shock tube capable of simulating high strain rates similar to those experienced during a blast event. The current study was divided into two phases. The first consisted of CLT slabs retrofitted with steel straps where strap spacing, location, and order of installation was investigated. The second phase focused on the development of dynamic properties of CLT panels when reinforced with GFRP. Lay-up configuration and fabric orientation were among the parameters explored. The results from the experimental program show that reinforcing the panels with steel straps had minimal effect on the ultimate strength, but significant levels of post peak resistance and ductility was achieved. The horizontal straps were able to restrict the failure to small regions and to promote flexural failure by preventing rolling shear failure. It also eliminated flying debris and enhanced the ultimate strength, stiffness as well as ductility. Applying GFRP layers enhanced the overall behaviour of the slab resulting in a significant increase in peak resistance, ductility, and stiffness when compared to the dynamic results of an unretrofitted panel. The post peak resistance was also greatly improved. In particular, applying stacked quadraxial lay-up configuration significantly improved the ductility and resulted in the greatest post peak resistance. The effect of steel straps on damaged and retrofitted was relatively minimal, and only partial recovery of the resistance and the stiffness was achieved. GFRP with full confinement yielded better performance compared to the unretrofitted and undamaged counterpart. More work is needed to quantify the benefits of using GFRP in these applications.
58

Efeito do tratamento térmico sobre as propriedades de painéis OSB / Effect of thermal treatment on OSB panels properties

Rafael Farinassi Mendes 12 January 2011 (has links)
O objetivo principal do presente estudo foi avaliar o efeito do tratamento térmico das partículas strand (pré-tratamento) e dos painéis (pós-tratamento) sobre as propriedades físicomecânicas dos painéis, visando principalmente à melhoria de sua estabilidade dimensional. O delineamento experimental se constituiu de sete tratamentos, com a avaliação de: Duas temperaturas de tratamento das partículas (200 e 240°C) por um período de 60 minutos; do póstratamento térmico dos painéis produzidos com e sem a aplicação de parafina na temperatura de 220°C e por um período de 12 minutos; e do aumento do teor de adesivo e a aplicação de parafina em painéis sem tratamento térmico. Para cada tratamento foram produzidos três painéis com densidade nominal de 0,65 g/cm³, colados com adesivo à base de fenol-formaldeído. O ciclo de prensagem dos painéis foi o seguinte: pressão de 35 kgf/cm², temperatura de 160ºC e tempo de 8 minutos. A partir dos painéis produzidos, corpos-de-prova foram obtidos para a realização de ensaios físicos (Teor de umidade, densidade aparente, absorção de água e inchamento em espessura) e mecânicos (Módulo de ruptura, Módulo de elasticidade e Ligação interna), conduzidos conforme as normas ASTM D 1037 (2006) e DIN 52362 (1982). Mediante à análise dos resultados dos ensaios foi possível extrair as seguintes conclusões: Os painéis produzidos com as partículas tratadas termicamente a 240°C apresentaram-se superiores aos outros tratamentos em todas as propriedades físicas avaliadas, sendo portanto o tratamento com a melhor estabilidade dimensional. O pós-tratamento térmico promoveu melhora significativa das propriedades físicas dos painéis sem comprometer as propriedades mecânicas. O pré-tratamento térmico teve efeito mais pronunciado sobre as propriedades dos painéis do que o pós-tratamento térmico, proporcionando a melhoria das propriedades físicas e a diminuição das propriedades mecânicas. O aumento do teor de adesivo e a aplicação de parafina não se mostraram tão eficientes na estabilidade dimensional dos painéis OSB quanto o tratamento térmico aplicado nas partículas na temperatura de 240°C. / The main objective of this study was to evaluate the effect of thermal treatment of strand particles (pre treatment) and panels (post-treatment) on the physical and mechanical properties of the panels, aiming primarily to improve the dimensional stability. The experimental design was consisted of seven treatments, with the evaluation of: two temperatures of particle treatment (200 and 240 °C) during 60 minutes; thermal post-treatment of the panels produced with and without the application of paraffin at 220 ° C during 12 minutes; and the increase in adhesive content and application of paraffin on the panels without thermal treatment. Three panels were produced for each treatment with nominal density of 0.65 g/cm ³, bonded with phenol-formaldehyde adhesive. The pressing cycle of the panels was as follows: 8- minute press time, pressure of 35 kgf/cm ², and temperature of 160 °C. From the panels produced, specimens were obtained to conduct physical tests (moisture content, bulk density, water absorption and thickness swelling) and mechanical (Modulus of Rupture, Modulus of elasticity and internal bonding), tests according to ASTM D 1037 (2006) and DIN 52 362 (1982) standard. Through the analysis of test results it was possible to conclude: The panels produced with the particles thermally treated at 240°C were superior to the others for all physical properties evaluated, and therefore it was treatment with better dimensional stability. The post-thermal treatment caused a significant improvement of the physical properties of the panels without compromising the mechanical properties. The prethermal treatment had an effect on the properties of the panels that was more pronounced than the post-heat treatment, providing improved physical properties and lower mechanical properties. The increase in adhesive content and the application of paraffin were not as efficient in the dimensional stability of OSB as the thermal treatment applied on the particles at 240 ° C.
59

Investigating the Behaviour of Glulam Beams and Columns Subjected to Simulated Blast Loading

Lacroix, Daniel Normand January 2017 (has links)
The advancement in manufacturing technologies to produce high-performing engineered wood products (EWP) has allowed wood to be utilized beyond the traditional low-rise light-frame structures and to become a viable material option for much larger structures. Although glued-laminated timber (glulam) is included as a material option in the current blast code (CSA, 2012), its response to blast loading is not yet well documented. An experimental program investigating the behaviour of seventy glulam beams and columns was developed with focus on establishing the dynamic characteristics of glulam beams and columns with and without the effect of FRP reinforcement. A shock tube capable of simulating high strain rates similar to those experienced during blast was used. Thirty-eight beams with three different cross-sections were tested statically and dynamically to establish the high strain rate effects (dynamic increase factor). Six columns were also tested dynamically with axial load levels ranging from 15 to 75 % of the columns’ compression design capacity. Different retrofit configurations varying from simple tension reinforcement to U-shaped tension reinforcement with confinement using both unidirectional and bi-directional FRP were investigated on a total of twenty-six beams. A procedure capturing the strain-rate effects, variable axial load and FRP, was developed and found to be capable of predicting the flexural behaviour of the beams up to maximum resistance with reasonable accuracy when compared to experimentally obtained static and dynamic resistance curves. Implications on the design of both retrofitted and unretrofitted specimens are also discussed.
60

Advancement of field-deployable, computer-vision wood identification technology

Wade, Adam Carter 09 August 2022 (has links)
Globally, illegal logging poses a significant threat. This results in environmental damage as well as lost profits for legitimate wood product producers and taxes for governments. A global value of $30 to $100 billion is estimated to be associated with illegal logging and processing. Field identification of wood species is fundamental to combating species fraud and misrepresentation in global wood trade. Using computer vision wood identification (CVWID) systems, wood can be identified without the need for time-consuming and costly offsite visual inspections by trained wood anatomists. While CVWID research has received significant attention, most studies have not considered the generalization capabilities of the models by testing them on a field sample, and only report overall accuracy without considering misclassifications. The aim of this dissertation is to advance the design and development of CVWID systems by addressing three objectives: 1) to develop functional, field-deployable CVWID models for Peruvian and North American hardwoods, 2) test the ability of CVWID to solve increasingly challenging problems (e.g., larger class sizes, lower anatomical diversity, and spatial heterogeneity in the context of porosity), and 3) to evaluate the generalization capabilities by testing models on independent specimens not included in training and analyzing misclassifications. This research features four main sections: 1) an introduction summarizing each chapter, 2) a chapter (Chapter 2) developing a 24-class model for Peruvian hardwoods and testing its generalization capabilities with independent specimens not used in training, 3) a chapter (Chapter 3) on the design and implementation of a continental scale 22-class model for North American diffuse-porous hardwoods using wood anatomy-driven model performance evaluation, and 3) a chapter (Chapter 4) on the development of a 17-class models for North American ring-porous hardwoods, in particular examining the model's effectiveness in dealing with the greater spatial heterogeneity of ring-porous hardwoods.

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