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2121 Uppsatser om Clear-cutting - Sida 2 av 142

Programmerning av en industrikap med GRAPH 7

This essay is divided in several different parts, but all are tied up together by a fact that we want to increase productivity. We hope to do that by programming the PLC and to reach this with a better security for the person how are going to handle the cutting machine under it?s cutting process. We should as well look for some other ways to come up with better instructions and way to work and handle yourself during work. This programming is done in GRAPH7.

Flödesoptimering i begränsande resurs

Most companies have a bottleneck in their production, that is a constraining re-source. When the demand is higher than the capacity in the constraining resource it is impossible to produce the demanded output. This problem leads to delayed deliveries, unhappy customers and ultimately to decreased revenue. Bottlenecks therefore has a significant role in production and must be handled thereof.MW Power in Sävsjö, Sweden designs and manufactures water and steam boilers for the customer's unique needs. MW Power invested in a new plasma cutting ma-chine but the machine has not reached the expected capacity.

Tillväxtreaktion hos skärmträd i högskärm av gran i Medelpad :

Different methods for shelterwood cutting have been used in differ-ent parts of Europe since the middle ages. The use of shelter wood cutting in Norway spruce (Picea abies (L.) Karst.) forests in Sweden met a revival in the early 1990s as an alternative for the dominating Clear-cutting system when silvicultural costs increased dramatically for the latter. Shelterwood cutting systems involve some possible problems but also a lot of positive effects. Among the problems are increased risk of wind throw and damage of the remaining shelter trees caused by the cutting operation. Positive effects are for example a valuable growth in the remaining trees and increased biological di-versity. This study is based on a total of 79 trees from 4 different treatments in a spruce shelterwood, cut in 1994, in the middle of Sweden (62,4º N).

Vindfällning, tillväxt och plantuppslag i en 13-årig granskärm i Medelpad :

The interest for alternative forest regeneration methods increased significantly during the 1990´s after 50 years dominance of the Clear-cutting system (Holgén & Hånell 2000). One reason for this was that Clear-cutting was being more and more questioned by different envi-ronmental organizations and because the forest sector for economical reasons wanted to find cheaper ways to regenerate forests. In the beginning of the 1990´s two shelterwood experi-ments were established in a joint effort by Svenska Cellulosa Aktiebolaget (SCA) and the Dept of Silviculture, Swedish University of Agricultural Sciences (SLU). The experiments include various forms of cutting and shelterwood densities and represent productive spruce forests in central and north Sweden (Roggsjön in the province of Medelpad and Skikkis-jöberg in the province of Västerbotten, respectively ). The experiment next to Roggsjön has been reported earlier in three MSc theses, and is also the focus of this thesis.

Trakthyggesfria skogsbrukssätt : kunskap, förutsättningar och attityder

Forestry has three main aspects to take into consideration today; economical, ecological and socio-cultural. In order to reach the broad policy goals for sustainable forest management, an increased variety of management approaches are requested. Today Clear-cutting is the only method used in 96 % of the managed forests in Sweden. The Swedish National Board of Forestry has therefore initiated a project in order to investigate and develop Continuous Cover Forestry (CFF). This study is a part of this project.

Kvävestatus och risk för nitrifikation i två avverkade skogsområden i Halland

Nitrogen deposition leads to environmental damage in areas where the nitrogen deposition is high. Southwest Sweden receives an annual nitrogen deposition of up to 20 kg N/ha. Nitrogen that is not assimilated by the vegetation is accumulated in the soil, which may lead to nitrogen saturation and an elevated risk of nitrogen leaching. Nitrogen leaching from forest areas in southern Sweden has proven to be higher than from agricultural areas, which have been thought to be the main contributors to elevated nitrogen levels in rivers and lakes. The amount of nitrogen that leaches depends on the fraction of the total nitrogen in the soil that consists of nitrate, since nitrate is easily transported through the soil.

Ackumulation av CO2 och CH4 i istäckta boreala sjöar : Hur förändras ackumulationen i sjöar påverkade av avverkning jämfört med referenssjöar?

The aim of this report was to quantify the accumulation of carbon dioxide (CO2) and methane (CH4) in ice-covered lakes in winter (October-March) during three consecutive years, and to assess whether the concentrations of DIC and CH4, as well as the ratio DIC:CH4 differs between years and between lakes affected by clearcutting and untreated reference lakes. Water- and gas samples were collected from four boreal lakes (two affected by clearcutting and two untreated reference lakes) located in Västerbottens inland in spring. The lakes were found to accumulate on average 91, 55, and 84 mgCm-2d-1 during winters 2012-2013, 2013-2014, and 2014-2015, mostly originating from CO2. The concentrations of DIC (autumn and spring) were higher in the affected clear-cut lakes compared to reference lakes for all years, including the reference year (2012-2013) before Clear-cutting. No such difference was found for CH4 or the ratio DIC:CH4.

Effekt på värdeutfallet av sågad vara vid övergång från 30 till 60 cm moduler : - en fallstudie av Moelven

The purpose of this study is to explain how the value of sawn wood changes when sawn wood are cut in 30 respective 60 cm lengths. The raw material into the saw mill will mainly be bucked in 30cm and 60 cm modules. There will also be two alternatives where the timber will be bucked special lengths, 370, 490 and 550 cm but also in 490 and 550 cm.The method used for the study is to simulate both cutting and sawing the woods. For cutting the simulator Timan is used and for sawing the simulator Timberopt is used. When data is generatedfrom the simulators, calculations of some key figures is done and also how much the revenue need to be increased for the sawn wood in order to cover for the increased costs of changing sawn woodfrom 30 cm to 60 cm modulesThe conclusion is that the single biggest reason, impacting the value of the sawn wood is the cutting at the saw mill.When going from 30 to 60 cm modules, the impact will be that the customers to the saw mill must pay more to increase the revenue by at least 10% for the sawn wood in order to justifice the changein production.It is also possible to increase the value of the products further by bucking the timber in three lengths, 370, 490 and 550 cm, in order to get 12 % increase of the share of longer sawn wood (>= 480 cm)..

Hårdfräsning i verktygsstål : Förslitning av skäregg

This thesis work is made by Torbjörn Johansson on Karlstad University for Uddeholms AB. The assignment in this thesis work was to investigate tough cutting in three different tool steels: Vanadis 4 Extra, Vancron 40 and Sverker 21. The research was to compare the wear of the tool after cutting in each one of the tool steel alloys. The research was also made to see if the tool cutting in Vancron 40 has a better wear than the tool cutting in Vanadis 4 Extra and also compare the results with Sverker 21. All three of these alloys are a part of Uddeholms AB:s range of products, and is used in applications like forming tools and knife tools. Vancron 40 is a powder steel with a very good combination of mechanical properties like ductility, adhesive strength and hardness.

Detaljhänsyn efter slutavverkning : kvantitet och inverkan på framtida produktion hos SCA i Västerbotten

According to FSC (Forest Stewardship Council) shall at least a mean of 10 trees per hectare including riparian zones and other areas with high biological values be left in final felling. In addition large clear areas should not be created and all retained trees with high environmental value shall be spared. To leave trees in final felling means a lower cutting volume and hence a lower income from the cutting, but it also means that the production in the next generation becomes less because of competition. The aim of this study was to evaluate the effect retained trees have on the production in the new generation of forest, and to investigate if there is any way to lower this effect. The environmental care has also been estimated by the amount left in final felling.

Teknisk utredning av skärutrustning till skördare : En analys av den svenska marknaden

Husqvarna is a world leading producer of chainsaws with a well-established brand name. Husqvarna now has an interest in investigating the possibiltiy to expand their production of chains and guide bars to include cutting equipment for timber-harvesters.This project is a technical study which aims to answer questions about cutting equipment for timber-harvesters that have been decided in cooperation with Husqvarna. The questions have mainly been focused on forces, cutting speeds, service and maintenance -as well as general questions regarding the size of the Swedish market.Two methods have been applied to answer the questions. Interviews with retailers of harvesters, producers of harvester heads and harvester drivers.The main findings in this project show that there is a relatively small selection of harvester chains on the Swedish market. In contrast to the selection of harvester chains the selection of guide bars is quite large.

Virkesproduktionen under 80 år i ett fältförsök i Dalarna med olika skogsskötselsystem

I Sverige är trakthyggesbruk med kalhuggning det dominerande skötselsystemetmen intresset för kalhyggesfritt skogsbruk har ökat de senaste åren. Alternativentill kalavverkning är omdiskuterade och kritiseras ofta för att inte vara lönsamma.Målet med detta examensarbete är att analysera ett långtidsförsök med olikaskogsskötselsystem och att diskutera eventuella produktionsskillnader. De fem skötselåtgärdersom undersöktes var 1) kalavverkning med plantering av gran och tall,2) naturlig föryngring under fröträd, 3) blädningsbruk, 4) dimensionsavverkningoch 5) orörd skog (referensyta). Fältförsöket ligger på Siljansfors försökspark iDalarna och anlades 1923. Alla försöksytor har en areal av 1 ha.

Bors E23 - Framtagning av eldriven röravklippningsmaskin

Our Bachelor´s Thesis has been performed in co-operation with Bors Automation & Tool AB.Our task was to develop a servomotor powered tube cutting-machine with initial point fromtoday's hydraulic driven tube cutting machine Bors HYD 23. The purpose with the newconstruction was to achieve a more power-efficient tube cutting machine which could lowerthe power consumption, and also meet the market continued growing demand forenvironmental-conscious production.Bors Automation & Tool gave us relatively free hands in order to enable new thinking ideaswithout following their traditional constructional solutions.Our solution resulted in a construction based on a power source existing of a servomotordrivenrollerscrew, witch provides a more rational use of energy compared with the currentmethod.Bors Automation & Tool AB has decided to fabricate a prototype of Bors E 23 during theautumn of 2007, which they are planning to revile at the Tube 2008 exhibition in Düsseldorf,Germany.NOTE:Due to an agreement signed by the authors in the beginning of this project, no appendix is published at this time.If you want to wiew these documents, please contact the authors..

Förekomst & kostnad av kapsprickor i stormaskadad skog

The aim for this study where to investigate the frequency of cutting cracks in saw timber harvested in the storm-damaged forests in regions where the storms Hilde and Ivar hit. The idea for this work came from one of the region?s biggest actors, SCA Skog and Jämtlands district. The purpose where to find out how big proportion of the saw timber that contains cutting cracks, their financial cost in lost wood value and also give advice and suggestions on how to work against the frequency of cutting cracks. For the field-study some guidelines where used to make sure that the samples were taken under the same conditions, they were: ? The field-study must be performed under harvesting of storm-felled forest, which are horizontal/inclined trunks. ? The averaged sized tree will make it possible to harvest saw timber. ? The trunks can?t be root cut. A methodology called in Swedish ?Trissmetoden? was used because it is the most frequent used methodology in earlier performed studies and the only one that can be used I field. Under the field-study data were collected from 570 saw timber logs, 30 logs from each one of the tested harvesters.

Återväxt av blåbär (Vaccinium myrtillus L.) efter ångbehandling : orsaker till effektiv kontroll

Steam was used as a site preparation method to eliminate unwanted bilberry (Vaccinium myrtillus L.) in the boreal forest. The efficiency of steam to suppress bilberry was compared with prescribed burning and cutting the bilberry. Different combinations of steaming and/or cutting the bilberry were set up to investigate in which way steaming and cutting influenced the sprouting and regrowth of bilberry. The regrowth of the bilberry vegetation was monitored for 40 month. Steam was most efficient in suppressing bilberry.

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