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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.
1

The Swedish Forest Industry and Lessons for China: Production and Environmental Objectives on an Equal Footing?

Wang, Ying January 2013 (has links)
Abstract: The forest industry plays a key role in global economic development and environmental conservation. The Swedish forest industry has a leading position in world forest clusters. The strategy of the Swedish forest industry is giving the environmental and the production objective the same high priority. On the other hand, China, as the second largest economy in the world, operates the forest sector in a different way. The aim of this paper is first to look at how sustainable the Swedish forest industry is and learn what aspects of it can be possibly applied by China, by making a limited comparison between these two countries. Literature review is the main method, combining with SWOT-analysis and comparative study. After analyzing the environmental economic and social aspects of sustainable development within the forestry sector in both countries, a brief summary is made using SWOT-analysis, which highlights strength, weakness, future potential and threat. The study and analysis shows that a delicate balance between the production and the environmental objective is kept in Sweden. Even though the forest industry is one of the most energy intensive industries, Sweden has accumulated some experience in streamlining production line and enhancing the resilience of forests aiming for climate change mitigation. As the biggest developing country in the world, China’s forestry has developed extensively. China shows limitation in extraction and handling with forest resources, but also potential in the forestry industry. Though limited, this comparison gives some clues on how and what policies and measures could be applied in China. China could draw some experiences from Sweden in forestry development, technology innovation and operation patterns.
2

Potential of the New Zealand Forest Sector to Mitigate Climate Change

Loza-Balbuena, Isabel January 2009 (has links)
New Zealand is both an Annex I Party to the UNFCCC, and an Annex B country of the Kyoto Protocol. By ratifying the latter, NZ has committed to reduce greenhouse gas emission to 1990 levels. The country should take domestic actions and can also use any of the Kyoto Protocol flexible mechanisms. Afforestation and reforestation on low carbon density land has been recognised as a carbon sink and hence a possible mitigation option for climate change. The current situation for New Zealand is that at least over the first commitment period (2008-2012) the country is in deficit, because emissions have continued to grow over the 1990 level, there is an increase in the deforestation rate and lower rates of new planting. The objective of this study is to analyse the potential of the New Zealand forest sector as an integrated system to mitigate climate change. It also analyses the impact of different mechanisms on potential area of new land planting, management of stands, and the supply, allocation, and demand of wood, and wood products. The New Zealand forest industry carbon balance (i.e net atmospheric exchange minus emissions) is modelled for different national estate scenarios, log allocation of harvested volume and residues used for bioenergy. The net present value of these scenarios is estimated and the economic viability assessed. The level of incentives needed to increase the returns to an economically viable level is estimated in term of carbon unit value ($/tC). Moreover the land use economics at a project level (land market value vs land expectation value) is assessed. Incentives needed in monetary terms and carbon value are also estimated. The implications of discounting carbon benefits are discussed. It was found that the carbon balance of the whole industry should be analysed for policy development on climate change mitigation options. New planting, longer rotation ages, avoiding deforestation, and allocating additional harvested volume to sawmills showed positive impact to the atmosphere. New planting appeared to be not economically viable, thus incentives are needed. It is acknowledged that, there are emissions from the sector that were not included, and that data and models used need further research to improve the accuracy of the results. Moreover, assumptions on the economic issues and an analysis of simultaneous implementation of more than one mitigation option would also improve the results.
3

Number Recognition of Real-world Images in the Forest Industry : a study of segmentation and recognition of numbers on images of logs with color-stamped numbers

Munter, Johan January 2020 (has links)
Analytics such as machine learning are of big interest in many types of industries. Optical character recognition is essentially a solved problem, whereas number recognition on real-world images which can be one form of machine learning are a more challenging obstacle. The purpose of this study was to implement a system that can detect and read numbers on given dataset originating from the forest industry being images of color-stamped logs. This study evaluated accuracy of segmentation and number recognition on images of color-stamped logs when using a pre-trained model of the street view house numbers dataset. The general approach of preprocessing was based on car number plate segmentation because of the similar problem of identifying an object to then locate individual digits. Color segmentation were the biggest asset for the preprocessing because of the distinct red color of digits compared to the rest of the image. The accuracy of number recognition was significantly lower when using the pre-trained model on color-stamped logs being 26% in comparison to street view house numbers with 95% but could still reach over 80% per digit accuracy rate for some image classes when excluding accuracy of segmentation. The highest segmentation accuracy among classes was 93% and the lowest was 32%. From the results it was concluded that unclear digits on images lessened the number recognition accuracy the most. There are much to consider for future work, but the most obvious and impactful change would be to train a more accurate model by basing it on the dataset of color-stamped logs.
4

Förbehandling av skogsindustriellt slam för ett ökat metanutbyte vid rötning : En kombination av termisk och kemisk förbehandling / Pretreatment of forest industry sludge to increase the methane yield in the anaerobic digestion process : A combination of thermal and chemical pretreatment

Montelius, Josefine January 2014 (has links)
Vid tillverkning av massa och papper förorenas årligen 505 miljoner kubikmeter vatten som måste renas innan det släpps tillbaka till omgivningen. Vid reningen avskiljs först stora partiklar som sedan avvattnas och förbränns. Vattnet som blir kvar genomgår ytterligare en rening, varvid det bildas bioslam. Bioslammet innehåller mycket intracellulärt vatten, vilket gör det kostsamt och energikrävande att avvattna. Det är även sedan 2005 förbjudet att dumpa organiskt material, varför en mer ekonomiskt attraktiv behandling av slammet är anaerob nedbrytning. I denna nedbrytning omvandlas det organiska materialet till metan och koldioxid där metanet är den eftertraktade gasen. Bioslammet innehåller dock partiklar såsom träfiberrester och mikroorganismer med komplex struktur och är näringsfattigt. Någon form av sönderdelande förbehandling underlättar därför rötningsprocessen. I detta projekt undersöktes termisk förbehandling i kombination med kemisk förbehandling på bioslam från Stora Enso Skoghalls bruk på Hammarö. Själva rötningen skedde i två omgångar varav den första omgången med termisk förbehandling vid 70C och den andra vid 140C. Den kemiska förbehandlingen skedde med tillsats av lut (natriumhydroxid), kalk (kalciumhydroxid) och syra (fosforsyra) vid pH 9 och 11 för baserna och pH 2 och 4 för syran. Även neutrala prov (endast värmebehandling) och ett blankprov (ingen förbehandling) gjordes. Bioslammet ympades med kommunalt slam från Fiskartorpets reningsverk i Kristinehamn som har en mesofil bakteriekultur. Rötningen varade i 19 dagar per omgång i en temperatur på 35C och skedde satsvis i E-kolvar försedda med påsar för gasuppsamling. Totalt rötades 42 prov per omgång som utgjordes av sju mätpunkter á sex replikat för goda statistiska underlag. Resultaten gav en indikation för högst metanproduktion för proven behandlade med kalk vid 140C och för provet utan kemisk förbehandling vid 140C. Lägst produktion hade det kalkbehandlade provet vid pH 9 och 70C följt av blankprovet. Lutproven gav lägre metanproduktion vid 140C än vid 70C och fosforsyran hade så gott som oförändrad produktion mellan temperaturerna. Gemensamt för alla prover som behandlats vid 70C var att de fick en högre procentandel metan då de behandlats vid 140C. De resultat som erhållits är dock osäkra då det i vissa fall var stor spridning mellan provens biogasproduktion inom de enskilda förbehandlingsområdena. / In the pulp and paper process 505 million tons of water are polluted annually, which has to be purified before it is returned to the surrounding lakes. When the water is treated bigger particles are first separated to form sludge, then dewatered and finally incinerated. The excess water is further treated were a type of sludge  bio sludge  is formed. The bio sludge contains high concentration of intracellular water, why it is expensive and energy demanding to dewater. It is also forbidden to dump organic waste since 2005, why a more economically attractive treatment of the water is anaerobic digestion. In the digestion organic compounds is converted into methane and carbon dioxide where the methane is the desired gas. The bio sludge also contains fiber residues and microorganisms with complex structure and is nutrient-poor, which makes it hard to digest. Some kind of disintegrating pretreatment is needed and co-digestion with a more nutrient-rich sludge to facilitate the digestion process. In this project thermal pretreatment in combination with chemical pretreatment was examined on bio sludge from Stora Enso Skoghalls bruk at Hammarö. The anaerobe digestion was done by two rounds whereof the first round thermal pretreated at 70C and the second at 140C. The chemical pretreatment was done by additive of sodium hydroxide, calcium hydroxide and phosphoric acid at pH 9 and 11 for the bases and pH 2 and 4 for the acid. Also neutral samples (no chemical pretreatment) and a reference sample (no pretreatment) were done. The bio sludge were co-digested with municipal sludge from Fiskartorpets reningsverk in Kristinehamn which has a mesophilic bacterial culture. The anaerobic digestion lasted for 19 days per round at a temperature of 35C and were done batch wise in E-flasks provided with a small bag for gas collection. Totally 42 samples were made per round which consisted of seven measurement points and six replicates each for a good statistical basis. The results gave an indication of the highest methane production for the samples treated with calcium hydroxide at 140C and the neutral sample treated at 140C. The sample treated with calcium hydroxide at pH 9 and 70C gave the lowest production of methane followed by the reference sample. The samples treated with sodium hydroxide gave a lower methane production at 140C than at 70C while the acid treated samples had almost the same production at the two different temperatures. All the samples had in common a higher proportion of methane in the biogas when treated at 140C than at 70C. The results should be taken with caution since the distribution amongst the samples within the same pretreatment method sometimes is very high.
5

Flottning i Västerbotten : Avvecklandet av flottningen i Umeälven mellan 1930-1980

Svensson, Tilde January 2018 (has links)
This essay will present the driving forces behind the liquidation of log-driving from 1930 to log-drivings end in 1980 in Umeälven. The debate about the log-drivers status in the river was multifold. The locals saw log-driving as an inhibiting process where, besides work, nothing good came. The hydroelectric stations saw the log-driving as an unnecessary tool because the hydroelectric stations had a larger purpose and were more prosperous than the log-driving. The underlying factors that evoked the log-drivings dismantling were several. Local people, fishing, hydro, but also the increased demand for forest and technology development. The timber became less ”float-friendly” and the forest road network was developed so that trucks became a more efficient and cheaper alternative, which led to the fact that log-floating was an unnecessary tool for the forest industry.
6

Studies to Avoid Decreased Efficiency in Multiple Stage Biological Wastewater Treatment Plants: Concerning Forests Industry Effluents

Sandberg, Maria January 2008 (has links)
<p>Målet med den här studien är att förhindra effektivitetssänkningar i moderna biologiska reningsanläggningar för skogsindustriella avloppsvatten. Biologiska processer är vanligtvis effektiva när det gäller att reducera lättnedbrytbart organiskt material. Eftersom den utgörs av levande mikroorganismer (MO) är tekniken känslig. Toxiska ämnen kan döda en kultur av MO. Innan de har ökat i antal igen kommer reduktionseffektiviteten att vara påverkad för en ansenlig tid framöver. I ett pappers- och massabruk finns många typer av vätskor som oavsiktligt kan hamna i reningsanläggningen. I den här studien har svartluts inverkan på reduktionsgraden studerats.</p><p>Biologiska reningsverk har använts under en lång tid. De har utvecklats från att vara generella reningsverk till att bli konceptanläggningar i flera steg, där varje steg har designats för sitt eget syfte med specifika MO. I det här arbetet har ett MultiBio-koncept vid Gruvön Bruk studerats. En anläggning i laboratorieskala har byggts för svartlutsförsöken. Resultatet har jämförts mot simulerade värden och värden från bruket.</p><p>När ett spill av svartlut passerar genom en MultiBio späds det ut mellan varje steg. Halten av svartlut är hög i de första stegen vilka påverkas kraftigt. I de första stegen lever snabbväxande organismer som återhämtar sig på ett par dagar. De mer känsliga aktivslamstegen finns längre bak i reningsverket och är skyddade från toxiska koncentrationer av svartlut. Endast vid försök med 24-timmarstillsatser blev koncentrationen av svartlut så hög att den påverkade MO negativt.</p><p>Den biologiska processen i ett reningsverk kan störas om MO förnekas något essentiellt behov. En biologisk process har ett flertal behov, bland annat behöver aeroba MO löst syre. Eftersom syresättning av vattnet är energikrävande och kostsamt är det inte problemfritt att skapa en omgivning som ger hög effektivitet samtidigt som man strävar efter att sänka energiförbrukningen. I avhandlingen beskrivs ett tillvägagångssätt för att studera energieffektiv syresättning.</p> / <p>The aim of this study is to prevent efficiency reduction in modern wastewater treatment plants for forest industry effluents. Biological processes are usually efficient in reducing biodegradable organic material. Since the technique depends on living microorganisms (MO) it is sensitive. Toxic substances can kill the population. It takes considerable time for the MOs to grow in number and the treatment efficiency will be affected accordingly. In a pulp and paper mill, a number of liquors are handled that can reach the treatment plant by accident. In this study the impact of black liquor spills on treatment efficiency has been studied.</p><p>Biological treatment methods have been used for a long time. They have developed from general treatment plants to multiple stage concepts, where each stage is designed for its own purpose with specific MO cultures. In this thesis, a plant with the MultiBio concept, located at Gruvön Mill in Sweden has been studied. A laboratory scale MultiBio plant has been constructed for the trials in which efficiency during black liquor exposure has been measured. The measured laboratory results were evaluated by comparing them with simulated values and a mill case.</p><p>When a shock of toxic black liquor passing through a MultiBio concept, the black liquor is diluted between the compartments. The first compartments that are exposed to high concentrations of black liquor are affected negatively. The MOs in the first compartment are fast growing and recover in a few days. The more sensitive activated sludge compartments are located further on in the plant. A toxic concentration is found in the activated sludge compartments only when the duration of the spill is 24 hours or more.</p><p>Denying the MOs their needs can disturb biological treatments. Among many things, a biological process needs dissolved oxygen. Since aeration is energy consuming and expensive, there is a conflict between gaining high efficiency and, at the same time, decreasing the energy consumption. In this study, an approach to saving energy for aeration is initiated.</p>
7

Efficient treatment of forest industrial wastewaters : Energy efficiency and resilience during disturbances

Sandberg, Maria January 2012 (has links)
This work concerns the efficient treatment of wastewaters from pulp and paper mills by means of aerobic biological processes. For treatment processes there are many aspects of efficiency and the present study investigates both energy efficiency and purification efficiency during disturbances. Special focus is put on wood extractives, such as resin acids and fatty acids, since they can cause negative effects in fish and other organisms in the receiving waters. They can furthermore be toxic to microorganisms in a biological treatment plant. They also affect oxygen transfer, which is important for energy efficient aeration of aerobic biological treatment processes. This thesis includes five papers/studies and presents a strategy for efficient treatment of forest industrial wastewaters. The results should help creating resilient wastewater treatment strategies with efficient use of energy. One new strategy proposed here includes separation of extractives before the wastewater is treated biologically, and the use of the extra amount of sludge as an energy source, shifting the energy balance from negative to positive.
8

Big Data analytics for the forest industry : A proof-of-conceptbuilt on cloud technologies

Sellén, David January 2016 (has links)
Large amounts of data in various forms are generated at a fast pace in today´s society. This is commonly referred to as “Big Data”. Making use of Big Data has been increasingly important for both business and in research. The forest industry is generating big amounts of data during the different processes of forest harvesting. In Sweden, forest infor-mation is sent to SDC, the information hub for the Swedish forest industry. In 2014, SDC received reports on 75.5 million m3fub from harvester and forwarder machines. These machines use a global stand-ard called StanForD 2010 for communication and to create reports about harvested stems. The arrival of scalable cloud technologies that com-bines Big Data with machine learning makes it interesting to develop an application to analyze the large amounts of data produced by the forest industry. In this study, a proof-of-concept has been implemented to be able to analyze harvest production reports from the StanForD 2010 standard. The system consist of a back-end and front-end application and is built using cloud technologies such as Apache Spark and Ha-doop. System tests have proven that the concept is able to successfully handle storage, processing and machine learning on gigabytes of HPR files. It is capable of extracting information from raw HPR data into datasets and support a machine learning pipeline with pre-processing and K-Means clustering. The proof-of-concept has provided a code base for further development of a system that could be used to find valuable knowledge for the forest industry.
9

Bland rutiga skjortor och kapital : en studie om hur yrkesstatus kan påverka virkesköparrollen

Larsson, Susanna, Lénberg, Emma January 2017 (has links)
Syftet med denna uppsats är att undersöka hur status påverkar problematiken att rekrytera och bibehålla virkesköpare inom skogsbranschen. Denna kvalitativa studie har utgått från ett bolag som fått representera hela skogsbranschen. Det empiriska materialet har samlats in genom semistrukturerade intervjuer med sex personer inom bolaget och fyra studenter på jägmästarprogrammet inom SLU i Umeå. Utöver intervjuer skickades webbenkät till jägmästarprogrammets årskurs 4 och 5, vilket resulterade i 45 svar. Det empiriska materialet i studien har analyserats utifrån Webers (1983) teori om möjlighetsansamling och utestängningsmekanismer samt utifrån Bourdieus (1984) teori om status, baserat kulturellt-, ekonomiskt-, socialt- och symboliskt kapital.   De teman som tydligast framträdde utifrån den insamlade empirin var; den numerära ökningen, kunskap, identifikation, nätverk och frihet. Studien tyder på att status inom virkesköparrollen sjunkit i takt med att antalet virkesköpare ökat, samt att kunskapen som studenterna tar med sig från sina studier inte alltid är den kunskap som behövs som virkesköpare, vilket i sin tur resulterar i att studenterna inte identifierar sig med virkesköparrollen. Detta kan därmed ses som en grundorsak till varför virkesköpare inte ses som ett yrke man helst skulle vilja ha efter examen. I studien har det också visat sig att nätverk har stor inverkan på rollen och att de studenter som blir virkesköpare upplever rollen som svårare än de trott och att det gjort att man sökt sig vidare inom eller utanför företaget. Dessa aspekter kan ses som anledningar till att rollen har en negativ yrkesstatusförskjutning vilket kan vara en bidragande faktor till att det blivit svårare att rekrytera och bibehålla personer i virkesköparrollen. / The purpose of this paper is to investigate how occupational status affects the problem of recruiting and retaining timberbuyers in the forest industry. This qualitative study is based on a company that has represented the entire forest industry. The empirical material has been gathered through semi structured interviews with six people within the company and four students at the forestry program at SLU in Umeå. In addition to interviews, a web survey was sent to the students at the forestry program, grade 4 and 5, resulting in 45 answers. The empirical material of the study has been analyzed on the basis of Weber's (1983) theory of probability- and exclusion mechanisms as well as Bourdieu's (1984) theory of status, based in cultural, economic, social and symbolic capital.   The themes that most clearly emerged from the collected empirical material were; the numerical increase of timberbuyers, knowledge, identification, network and freedom. The study suggests that the status of the forester role has fallen as the number of timberbuyers grow, and that the knowledge that students bring from their studies is not always the knowledge needed as forester, which in turn results in the fact that the students don’t identify with the role of timberbuyer. This is understood to be one of the main reasons why it is not considered as a profession one would prefer to have after graduation. The study has also found that networks have a major impact on the role and that the students who become timberbuyers experience the role as more difficult than they thought. That makes it more likely that the new timberbuyers after a shorter period of time will move on to new roles within or outside the company. These aspects can be seen as a reason why the role has a negative occupational status shift, which can be a contributing factor to making it more difficult to recruit and retain people in the timberbuyer role.
10

Reducing waste with an optimized trimming model in production planning

Hallbäck, Sofia, Paulsson, Ellen January 2020 (has links)
In which ways can the process of trimming dispersion coated board products be optimized so as to reduce material waste and increase production efficiency? This is the question that this master thesis report seeks to answer. In paper production, alot of waste is generated when cutting production reels into customer reels. Some material waste are necessary in order to ensure good quality, however a large amount of the wastecould be reduced if the cutting process was to be optimized. During this project, carried out at a forest company, a mathematical optimization model was developed in order to reduce waste and save costs. This model is based on a cutting stock problem using column generation approach. It provides as its output cutting patterns and an optimal allocation of rolls for production purposes, which implies minimizing the number production rolls needed.The visualization of the results could also be used to achieve optimal stock levels, and easier keep track on how to use the material available in stock. Findings show that there are potential savings to be done. Simulations suggest an implementation of this model could result in material savings of around 7 %. This could also translateto environmental savings in CO2, where every decrease of one tonne material equals to adecrease in CO2emissions of 500 kg

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