Browsing by Subject "Skogsresursvetenskap och -teknologi"

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  • Lyytikäinen, Paavo (Helsingin yliopisto, 2015)
    Nature has been said to have relaxing effects on human. In today’s world, people’s life takes place mostly indoors so it is essential to seek relaxing effects also indoors. Decorative wood surfaces may bring those relaxing effects of nature to an indoor environment. This research focuses on researching the restorative effect of wooden surfaces through people’s preferences and the abilities of wooden surfaces. In this research, people’s preferences between different wooden surfaces were compared with the use of haptic and visual sensations. All the surfaces were lightly sanded to minimize the effects of pro-cessing and to concentrate merely on the comparison of different materials. The selected surface materials were conifer glulam, birch glulam, birch plywood, conifer plywood, MDF-board (Medium Density Fibreboard) and OSB-board (Oriented Strand Board). The study was divided into three sec-tions: the first section concentrated on people’s preferences towards wooden surfaces only with haptic sensations, the second part included only visual sensations and the third part included both haptic and visual sensations. The third section also included an open question for participants about the potential use of each wood material. Some of the participants also took part in a stress test during the third section. The stress test aimed to examine whether the participants’ heart rate and blood pressure lowered as they experienced the haptic and visual effects of wood material and if there were differ-ences between different materials. In the preference study people were instructed to rate the descriptiveness of different adjectives with all the wooden samples on a scale of 1–7 (1 very little, 7 very much). The three sections of the study made it possible to compare participants’ haptic and visual sensations. The visual sensations were observed to have more dominant effect than haptic sensations on the participants’ preferences. The visually most preferred wood materials were also found the most potential use for. These materials were instructed to be used in places they were seen whereas the less preferred materials were instructed to be used in hidden structures and to remain unseen. Both the heart rate and blood pressure lowered from the start of the test with all the materials except with OSB-board that caused a little rise of heart rate and blood pressure.
  • Lindberg, Aapo (Helsingfors universitet, 2016)
    In recent years objectives to increase fuelwood usage have created a need to develop new re-mote sensing based methods to map fuelwood reserves. Laser scanning (LiDAR) is a remote sensing method which has been used in traditional forest inventories on large forest areas. These inventories have mainly concentrated on the stem volume instead of the total tree bio-mass. Former studies concerning fuelwood inventory accuracy have been made on a sample plot level. The aim of this study was to determine the precision of LiDAR based fuelwood inventory on a forest stand level. Wood stem volume and biomass estimates were produced by using two dif-ferent methods: point cloud and digital terrain model. The estimates were compared with field inventory results and results from the multi-source National Forest Inventory. Of the two compared methods the point cloud method was found to be more accurate than the method based on digital terrain model. When the point cloud was used, the accuracy (RMSE %) of the most important fuelwood estimates were following: waste wood vol-ume 37.4 %, branch biomass 21.8 % and stump biomass 18.6 %. The study indicates that re-sults got by laser scanning are on similar level as results got with traditional standwise inventory. This study concentrated only to predict the amount of fuelwood on the forest stand level. The suitability of the stand for fuelwood harvesting was not estimated. In order to utilize LiDAR-based fuelwood inventory for wood acquisition in forest industry, methods to estimate the suita-bility of the stand for harvesting need to be developed.
  • Pietilä, Ilona (Helsingfors universitet, 2009)
    There is need for information about stands and their future development in forest planning decision making. This information is collected by inventories. In general inventory is repeated with some before-hand set intervals, irrespective of the method. Between inventories information is updated with growth models. Both inventory and using of growth models causes errors in forest planning results, for example in management options. Erroneous predictions can lead to wrong conclusions and inoptimal decisions. If the optimal result is known, economical losses caused by wrong conclusions can be described with so called inoptimality losses. The aim of this study was to answer the question how long forest inventory information, updated with growth models, can be used in forest planning purposes. Study approach was economical, so evaluation of information`s usefulness was based on inoptimality losses which arise when development of the stand is predicted incorrectly with growth models. The study material included 99 stands. Their development was simulated with the SIMO software for 60 years from present. In the 60 years period influencies of growth prediction errors were studied with inventory periods which lengths were 5, 10, 15, 20, 30 and 60 years. It was assumed that new error-free forest inventory information was received in the beginning of each of the inventory periods. In order to study effects of different inventory periods, it was assumed that the growth models were able to predict the true development of stands. Erroneous developments were yielded with error model which was developed for this study and added to the growth models. Inoptimality losses were calculated with the information derived from the optimization of stands` true and erroneous developments. Inoptimality losses increased when the inventory period became longer. Absolute inoptimality loss was approximately 230 eur/ha when the inventory period was 5 years and approximately 860 eur/ha when the inventory period was 60 years. Relative inoptimality loss was 3,3 % when the inventory period was 5 years and 11,6 % when the inventory period was 60 years. The average inoptimality losses were different between different development classes, site classes and main tree species. Study results show that the length of the updating period has an effect on the developing economical losses. It seems also that the inventory period should be different for example in different development classes. However, it is difficult to specify the optimal updating period because total losses are a sum of losses of inventory errors, losses of growth prediction errors and losses caused by other uncertainty sources. The effects of both inventory errors and growth prediction errors are different in different kinds of stands. So estimation of total losses and estimation of inoptimality losses caused by different error sources requires more research.
  • Näsärö, Olli-Pekka (Helsingin yliopisto, 2015)
    In October 2013 the Finnish legislation for the ratings of vehicles was changed. This change enabled heavier vehicles to operate in Finland. The highest rating of vehicle combination is 76 tons and it requires nine axle. For eight axle vehicle combinations the mass is 68 tons and for seven axle 64 tons This reformation is taken to use especially in the raw material transportation such as timber. In this study the highest permitted masses weren’t reached in all observations, neither for vehicles nor vehicle combinations. On average the masses were reached in all observations except the four axle trucks. The average vehicle mass for them were 31977 kg. While the mass of the combination or a single vehicle increases the axle load remains the same or even decreases. The total mass devices for several axle. Fully loaded vehicle’s bogie masses didn’t differ from the not fully loaded. However the highest permitted bogie masses weren’t reached in all cases. Especially bogie masses of the vehicles without a loader were under permitted masses. In the study there was done some calculations for increasing the loading space. In these cases the highest permitted vehicle mass-es were reached. In most of the cases also the double axle masses were reached. The road wear of vehicle combinations is decreasing while the amount of axle is increasing. The ESAL (Equivalent Single Axis Load) reaches it highest point in the combined vehicle which total mass is 64 tons (6,87). The smallest stress is 76 tons combinations (3.33). The stress was higher for 3+5-type vehicles (4,64) than 4+4-type (4,52) in this study. The stress was bigger for the combinations with a loader. The effectivity of the transportation changed in the range 7663-9443 kg/ESAL and it decreased while the amount of axle increased. The difference between 68 tons vehicle combinations was small. The transportation costs decrease while the total masses increase. The biggest difference, on average with relation to 60 tons vehicle combination, is on 76 tons combination (-18,53%). For the 3+5-type combination the difference is -11,52% and for the 4+4-type combination -9,38%, so there is a difference between these two combinations. The average annual transportation increases while the total mass of the vehicle combinations mass is increasing. The growth is between 8 and 26%. The average costs for the comparison combine were 5,85 €/m3 and the annual transportation 27700 m3.
  • Safdari, Pezhman (Helsingin yliopisto, 2015)
    Surface albedo, which is the fraction of reflected radiant energy by earth’s surface to incoming solar energy, plays an important role in earth energy budget and energy equilibrium. Different features of the earth’s surface have different reflectivity rates which affect albedo. Vegetation land-covers covering vast areas of earth’s surface such as agricultural land, forest, grassland and so on, have great impact on land surface albedo. The species composition, geographical distribution, and seasonal phenology of different vegetation land-covers have an impact on surface albedo and earth’s energy budget and, consequently, on climate change. The boreal zone covering latitudes between 60º – 70º N is one of the largest vegetation biomes on earth and has a significant impact on surface albedo. The boreal region is mostly covered by coniferous forests which are optically very dark and absorb most of the incoming solar energy. This low reflectivity is very influential during the times that earth’s surface is snow covered by masking the high reflectivity of the snow covered land surface. This has caused most studies to focus on the boreal vegetation land-cover albedo during the snow covered periods of the year. In this study, the effects of five different vegetation classes (agricultural, deciduous, coniferous, mixed forest and shrubland), three different latitudinal gradients (northern, middle and southern Finland), and the vegetation phenology during the growing season on surface albedo of vegetated areas of Finland for the year 2009 has been investigated. The results of the study showed that there is a significant difference between the albedo of different vegetation land-cover classes. The albedo of agricultural lands tends to be systematically the highest in all conditions while coniferous are the lowest. The vegetation land-cover albedo is generally lower in northern Finland compared to middle and south. There is a gradual increase in vegetation albedo until mid-July and after reaching a maximum level it starts to decrease towards the end of the growing season. The peak in albedo is reached about two weeks earlier in the north compared to the south possibly due to and longer days during its shorter growing season.
  • Onali, Harri (Helsingin yliopisto, 2017)
    The paper industry is one of the largest industrial sectors in India. In general, wood procurement processes play an important role in the operations of the paper industry, but there is very less research on India in this topic. The purpose of this study was to evaluate the present state of wood procurement in the Indian paper industry and finally to detect possible bottlenecks in the system. The data was collected by interviews from a total of 10 paper mills in India. Paper industry in India is entirely based on a plantation forestry, where private farming plays a very large role. Wood procurement begins with planning. The field officers cooperate with the vendors in the field. The vendors are private operators who trade directly with up to thousands of farmers and are therefore necessary for the successful operations. Wood is almost always harvested manually by axes and rarely with chain saws. Long-distance transport is mainly carried out by trucks which can carry about 15 to 20 tons of wood at a time. At the reception, the quality of the raw material and the papers are checked, and the load size is weighed. After reception, the wood is transported either to the wood yard or alternatively directly to the chipper. The load is unloaded either by loaders, or sometimes, but rarely, by hand. The results show clearly that the mills are dissatisfied with the present state of wood procurement. The biggest problem is that there the domestic supply is insufficient, which makes the wood raw material price very high and forces the industry to buy wood from abroad and longer distances which affect negatively to transport costs. In India, land ownings of farmers are also small and it complicates efficient wood procurement processes. In addition, farming trees does not interest the local people. Infrastructure is also weak and the use of trains in wood transport is difficult. Some mills stated that the policy plays too big role in determining the price of the raw material. In addition, expertise in supply chain management is weak and no suitable software is available.
  • Rautiainen, Mari (Helsingin yliopisto, 2014)
    Carbonization is thermochemical conversion, where biomass is thermally degraded in the absence of oxygen. Solid char, pyrolysis oil and non-condensable gases are produced from the biomass. Torrefaction is early phase of the carbonization in temperatures of 220–300 °C. Torrefied wood is promising as a renewable fuel for industrial use in coal co-combustion and gasification-combustion. Torrefaction and carbonization increase the higher heating value and fuel properties of wood compared to untreated wood. There’s a lack of knowledge in torrefaction and carbonization effects to higher heating value, carbon content and turn from endothermic to exothermic reaction of conifer zone wood species. Raw material was stemwood of birch (Betula pubescens) and pine (Pinus sylvestris) including bark. Trees were harvested from the Helsinki district and chipped, particle size 16 ? 8 mm. Samples were torrefied and carbonized at 250, 300, 350, 400 and 450 ?C without nitrogen flow. Carbon content (%), higher heating value (MJ/kg), mass yield (%) and turn of endothermic to exothermic reaction were inspected. Carbon content of untreated birch and pine increased from 47 % to 82 % (at 450 ?C). Higher heating value exceeded 26 MJ/kg at 300 ?C and 28 MJ/kg at 400 ?C, reaching bituminous coal’s values. Mass yield declined to 45–54 % of the initial mass at 300 °C. In low temperature, gradual exothermic peak was observable. In higher temperatures peak was evident. Carbonization and torrefaction improved the higher heating value and carbon content of wood but decreased the solid char yield.
  • Nurmi, Aleksi (Helsingin yliopisto, 2018)
    There is little information about timber quality in pine forest before they are sawn. Easy method to evaluate the timber quality before it is in sawmill would be an useful tool in forest business. Many studies have shown that pines outer quality correlates quite well with inner quality. It's possible that easy method for this is coming. This studies purpose is to evaluate Trestima –applications measurement accuracy and if it's possible to evaluate the timber quality. Trestima is used as mobile application and uses the phones camera. You just have to take pictures of forest and it calculates all basic information from them, like forest basal-area, height, number of stems, diameter at breast height and diameter at breast height distribution. There were two materials collected for this study. Teaching materials and test materials. The teaching material was used to teach timber quality for the Trestima. On test material was tested how well the Trestima-application estimated the timber quality. For testing Trestimas' overall accuracy the applications measurements were compared with the harvesters' data. In the study, the evaluation of the entire tree stock was achieved with the same accuracy as the traditional relascope evaluation. The relative RMSE was 23% in the hectare-specific state as in the bottom surface in the test material. In the middle diameter of the pine, at the bottom of the pine, the weighted average diameter was 11% relative RMSE and 13% in the arithmetic mean diameter. Based on the results of this study, the qualification and dbh-height distribution forecast do not work at a sufficient level for practical tools.
  • Lundberg, Henri (Helsingfors universitet, 2016)
    The use of forest chips has increased rapidly in the past 15 years and the usage must be increased even more in order to achieve the renewable energy usage goals. Forest chips are produced mainly from logging residues and stumps collected from clear cutting areas. One source is also small sized trees harvested from thinning areas. Increasing the use of forest chips could be possible, but the problem are the long transportation distances of the raw material. Most of the wood chip potential is located in Eastern and Central Finland and Kainuu, but the heat and power plants and demand are located by the sea. Transportation costs must be reduced to make usage possible. This was a pioneer study to develop working models for loading energy wood trucks. The aim of this study was to create systematic working models for loading logging residuals and stumps to bioenergy trucks to increase payload. The optimal load weight and its relation to transportation distance was also the point of interest. Twelve operators participated the study and the data was collected in Southern and Eastern Finland between April and September. The data set included 12 stump loads and 11 logging residual loads. The work researcher sat next to the driver, interviewed him about loading techniques and collected information about the loads. The loading events were also recorded by video camera for later performed time and observation studies. To compare the drivers the payloads were weighted. Drivers’ loadings where observed and analyzed with the payload weights and the loading times and as a result four different working models were developed. For stump material two different working models were described by the size of the stump: for small sized stump and normal sized stump. The working model for normal sized stumps was divided into two working models to achieve a large payload and an average payload with minimal loading time. For logging residues only one working model was necessary to describe. Working models consisted of systematic ways of work and different types of compressing methods and tricks. The average loading time towards one ton for stumps was 2.7 minutes and for logging residuals 2.2 minutes. Aiming for large payload is not always the most cost-efficient choice. The operator should consider the transportation distance as well as loading time along with the payload. The longer the driving distance the larger the payload should be. With shorter distances it is optimal to use less time for the loading even tough large payloads will not be achieved and use the spared time for driving of extra loads.
  • Stenman, Virpi (Helsingin yliopisto, 2019)
    In forest inventories, the field data is needed as a reference data, calibration and for assessing the accuracy. Gathering the field data needs resources, such as work forces, equipment and data management operations. This means that time and budget as well as quality must be carefully considered when National Forest Inventory activities are to be planned. Therefore, the development of cost efficient, simpler, safer and more accurate and reliable field data measurement methods and tools are topics of great interest. One of the field measurement variables is the upper stem diameter, which has been part of the NFI field data set until the 11th NFI. The measured upper stem diameter helps to produce more reliable tree stem volumes with 3-parameter Laasasenaho volume model. However, only if the quality of the measurements is on an adequate level. The upper stem diameter has been traditionally measured with parabolic caliper assembled in the top of the 5-meter aluminium rod. This equipment combination takes time to assemble and disassemble, it is not very compact to be carried around as well as it can be a health and safety issue during the thunderstorm. Therefore Criterion, laser-based dendrometer performance was further examined in this study as an optional measurement equipment for future upper stem diameter field measurements. The Criterion upper stem as well as dbh measurement precision was analysed based on the 326 sample tree measurements with Sonar, Caliper and Criterion. The standard error for Criterion was 17,26 mm in dbh measurements for all species and 10,36 mm in d6 measurements for all species. The reference standard errors from earlier studies were 2,70 mm for dbh with Steel Caliper and 7,00 mm for d6 with Caliper. When analysing the Criterion performance with reference to mean of the measurements, the standard error in dbh measuements for all species was 9,72 mm and for d6 measurements 7,07 mm. Furthermore, the accuracy and precision were analysed with Bland-Altman technique, which is a suitable method for comparing two measurements of the same variable when both have some errors. The Bland-Altman results supported the earlier findings. Within and between observer analysis showed that the impact in measurement accuracy or precision is not caused by the observers. The comparison of the sample tree volumes produced the results that the relative standard error was increased by 2,13 % for all species when 2-parameter volume model was compared with 3-parameter model. Likewise, the relative bias was increased by 1,53 %. In efficiency experiment the scenario where only one sample tree with measured d6 was chosen from each of the sample plot and dbh percentile of p70 was providing most accurate and precise sample plot volumes with RMSE of 3,92 m3/ha and bias -0.78 m3/ha. The results show that there is a real challenge to achieve reliable and accurate upper stem diameter measurements and therefore new measurement methods need to be further studied and analysed.