Utvärdering av precisionen i en autonom terrängfordonsplattforms kranspetspositionering

Skogsbranschen har möjlighet att fortsätta den teknologiska utvecklingen för att höja produktiviteten i skogen, men det krävs innovation, utveckling och investering. I de nordiska länderna bedrivs skogsbruk med kortvirkesmetoden, där en skördare och en skotare används. Kortvirkesmetoden har många arbetsmoment som skulle kunna autonomiseras, vilket skulle innebära ekologiska-, ekonomiska och sociala fördelar. Ett tidskrävande arbetsmoment för skotaren är kranarbetet, som består av att förflytta kranen, gripa stockar och lasta dessa i skotarens lastutrymme. Dessa arbetsmoment kräver hög noggrannhet och precision för att genomföras lyckosamt. I den här studien används en terrängfordonsplattform som har utvecklats för att autonomisera en skotares arbete. Syftet med studien var att undersöka precision och noggrannhet i terrängfordonsplattformens kranspetspositionering. Positioneringen utfördes på olika avstånd och vinklar från terrängfordonsplattformen samt med och utan last i gripen. Variansanalyser i programvaran Minitab gjordes för att fastställa om det fanns skillnader i kranspetspositioneringen beroende de testade behandlingarna. Kranspetsen positionerade sig 31 till 44 centimeter ifrån målpositionen, vilket var kranspetspositioneringens noggrannhet. Kranspetsen kunde genomföra återkommande positioneringar inom 2 centimeter till 3 centimeter från tidigare positioneringar, vilket var kranspetspositioneringens precision. Resultatet från variansanalysen visade signifikanta huvudeffekter av avstånd, vinkel och last. Det innebär att terrängfordonsplattformens kranspetspositioneringens noggrannhet och precision påverkades av olika avstånd och vinklar samt om gripen är lastad eller inte. Noggrannheten försämrades på längre avstånd och om gripen var lastad. De tio första och sista kranspetspositioneringarna utfördes med samma målposition för att utvärdera terrängfordonsplattformens maskininlärning för förbättrad kranspetspositionering. Det konstaterades det att under datainsamlingens gång hade terrängfordonsplattformen förbättrat kranspetspositioneringen med 1 cm. Studien visar att terrängfordonsplattformen kan autonomt placera kranspetsen vid en målposition med bra precision men med mindre bra noggrannhet. Detta är framsteg för den teknologiska utvecklingen inom skogsbruket och utveckling inom autonomisering.The forest industry has the opportunity to continue the technological development to increase productivity in the forest, but innovation, development and investment are required. In the Nordic countries, forestry is conducted using the cut-to-length method, where a harvester and a forwarder are used. The cut-to-length method has many work elements that could be autotomized, which would mean ecological, economic and social benefits. A time-consuming work element for the forwarder is the crane work, which consists of moving the crane, gripping logs and loading them into the forwarder's load space. These steps require high accuracy and precision to be completed successfully. This study uses an off-road vehicle platform that has been developed to autotomize a forwarder's work. The purpose of this study was to investigate the precision and accuracy of the off-road vehicle platform’s crane tip positioning. The crane tip positioning was performed at different distances and angles from the off-road vehicle platform and with and without load in the grapple. Analysis of variance in the Minitab software was done to determine if there was a difference in the crane tip positioning depending on the tested treatments. The crane tip was positioned 31 to 44 centimeter from the target position, which was the accuracy of the crane tip positioning. The crane tip could perform recurring positioning’s within 2 to 3 centimeter from previous positioning’s, which was the precision of the crane tip positioning. The results from the analysis of variance showed significant main effects of distance, angle and load. This means that the off-road vehicle platform's crane tip positioning accuracy and precision are affected by different distances and angles and whether the grapple is loaded or not. Accuracy deteriorated over longer distances and with load. The first ten and the last crane tip positioning’s were performed with the same target position to evaluate the off-road vehicle platform’s machine learning for improved crane tip positioning. It was found that during the data collection, the off-road vehicle platform had improved the crane tip positioning by 1 cm. The study shows that the off-road vehicle platform can autonomously place the tip of the crane at a target position with a good precision but with less good accuracy. Thi

Automatic Features Extraction From Time Series Of Passive Microwave Images For Snowmelt Detection Using Deep-Learning – A Bidirectional Long-Short Term Memory Autoencoder (Bi-Lstm-Ae) Approach.

The Antarctic surface snowmelt is prone to the polar climate and is common in its coastal regions. With about 90 percent of the planet\u27s glaciers, if all of the Antarctica glaciers melted, sea levels will rise about 58 meters around the planet. The development of an effective automated ice-sheet snowmelt monitoring system is therefore crucial. Microwave remote sensing instruments, on the one hand, are very sensitive to snowmelt and can see day and night through clouds, allowing us to distinguish melting from dry snow and to better understand when, where, and for how long melting has taken place. On the other hand, deep-learning (DL) algorithms, which can learn from linear and non-linear data in a hierarchical way robust representations and discriminative features, have recently become a hotspot in the field of machine learning and have been implemented with success in the geospatial and remote sensing field. This study demonstrates that deep learning, particularly long-short memory autoencoder architecture (LSTM-AE) is capable of fully exploiting archives of passive microwave time series data. In this thesis, An LSTM-AE algorithm was used to reduce and capture essential relationships between attributes stored as brightness temperature within pixel time series and k-means clustering is applied to cluster the leaned representations. The final output map highlights the melt extent in Antarctica

Nonlinear Equations Describing Beam Type Crossed Field Traveling Wave Tubes

The equations governing the behavior of beam type crossed-field traveling wave tubes are formulated and presented. The geometry is assumed to be two-dimensional. The electron beam is treated as a number of cylinders of charge and space charge forces are included by calculating the field due to such a cylinder when it is placed between two perfectly conducting planes. The nonlinear equations are re-expressed in terms of normalized variables which make them suitable for machine computation. A brief discussion of the procedure for solving these equations numerically is included

What drives Canidae to live in groups? : With focus on foraging, reproduction and antipredation

Different animals across the globe display a diverse amount of social structures but it’s not clearly understood why some animals choose to live solitary and some in pairs or groups. There are many clear advantages with hunting in groups, communal nursing and defending territories. In some families of the Canidae individuals from previous litters tend to stay in the family group and help to raise the new pups and provision both the pups and breeding female with food. These individuals may benefit from this by indirect fitness. They can continue to learn from their parents and still be provisioned with food and shelter by not dispersing their first year. There is also a theory that these individuals may thrive to acquire the alpha-status in their territory to benefit from the higher quality resources. This study aims to investigate what advantages the jackal (Canis- adustus, aureaus & mesomelas), bat-eared fox (Otocyon megalotis) and the red fox (Vulpes vulpes) has with their social structures. It is presented in this study that different species of Canidae benefit from different social structures in multiple ways that may depend on their choice of food and habitat, and they all have one thing in common, their helpers

Evaluation of Sennebogen 830E and Svetruck TMF 12/9 at a round wood terminal : an analysis between two machine systems

Syftet med arbetet var att jämföra timmerhanteringsmaskinerna Svetruck TMF 12/9 och Sennebogen 830E. De studerades under de förutsättningar som fanns inom en rundvirkesterminal, där timmerhanteringsmaskinerna analyserades som två olika maskinsystem. Maskinsystem A bestod av två Svetruck TMF 12/9 och maskinsystem B bestod av en Svetruck TMF 12/9 och en Sennebogen 830E. Dessa maskiner är intressanta att jämföra eftersom de bygger virkestravar på olika höjder och arbetar med materialet på olika sätt. Problemet med timmerhanteringsmaskiner på virkesterminaler är avsaknaden på studier om produktivitet, kostnader och hur maskinerna arbetar tillsammans. Arbetet ska bidra till att utöka litteraturen om terminaler. Arbetet är viktig eftersom det kommer hjälpa investerare att fatta beslut om maskinsystem vid terminaler samt att anpassa terminaler efter det maskinsystemet de väljer. I arbetet utförs tidsstudier på inspelat material vid Tövaterminalen utanför Sundsvall. Utifrån tidsstudierna kunde regressionsanalyser utföras för att skapa produktivitetsnormer. Varje timmerhanteringsmaskin utrustades med kameror för inspelning i ungefär 1,5 timmar. Materialet studerades utifrån de olika arbetsmoment timmerhanteringsmaskinerna genomförde. Det data analyserades sedan i programvaran MINITAB (Version 19.2) för att hitta samband med hjälp av regressionsanalyser. Regressionsanalyserna användes sedan till att skapa produktivitetsnormer vilket resulterade i produktivitet för respektive maskinsystem. Utöver det genomfördes kostnadskalkyler för att ge bredare förståelse om de olika maskinsystemen. Slutligen kunde en brytpunkt visa vilken körsträcka mellan travarna då maskinsystemen var likbördiga sett till produktivitet (m3fub/h) och kostnad (kr/m3fub). Resultatet visade att maskinsystem A var både produktivare och mer kostnadseffektivt än maskinsystem B, utifrån förutsättningarna på Tövaterminalen. Maskinsystemen var lika produktiva om körsträckan var 95 meter och lika kostnadseffektiva om körsträckan var 71 meter. Om körsträckan kortades ner blev maskinsystem A mer produktiv och kostnadseffektivt men om körsträckan förlängdes gynnades maskinsystem B.The reason with this study was to compare the material handling machines; Svetruck TMF 12/9 and Sennebogen 830E. These two machines were studied under the conditions at a round wood terminal in which the machines were analyzed as two separated machine systems. Machine system A was two Svetruck TMF 12/9 and machine system B was one Svetruck TMF 12/9 with one Sennebogen 830E. Comparing these machine systems is interesting due to their differences in building log piles and for investors, to help them decide what machine system to choose. The problem with material handlers at round wood terminals is the lack of studies regarding productivity, costs and how the machines work together. This study could be a good complement to the literature about terminals. The data in this study is based on work samples from recorded material at Tövaterminalen, Sundsvall. From the work samples, a regression analysis was made to build productivity models. Both material handlers at Tövaterminalen were equipped with video cameras to create recorded material for about 1,5 hours. The material was studied from the different operations, which the material handlers performed. Data gathered in the recorded material were later used in the program MINITAB (Version 19.2) to find connection by doing regression analysis. The regressions analyses were later used to build productive models, which further were used to determine the productivity for the machine systems. Cost calculations were also made as complement to the productivity. Later a breakpoint was found that described the length of the transport distance between log piles, when the productivity (m3fub/h) and later the cost (kr/m3fub), were the same for the machine systems. The result showed that machine system A was both more productive and cost efficient than machine system B, at Tövaterminalen. The machine systems had the same productivity if the transport distance between log piles was 95 meters. The machine systems had the same cost if the transport distance between log piles was 71 meters. If the transport distance between log pile was reduced, machine system A became more productive and cost efficient. If the transport distance between log piles was increased, system B became more productive and cost efficient

Turbogenerator Foundation Analysis under Wide-Range (Seismic in Particular) Excitation

Dynamics of turbogenerator foundation under wide-range (seismic in particular) excitation is being investigated. It is rather simple to get a solution for low- and high- frequency vibrations in case of a ribbed plate resting on elastic subgrade. As for practical purposes, it is a solution for intermediate parameter values that is of solution. It is shown here that the difficulties could be overcome by two-point fade-approximant method

Filtration of Lignin from a Lignocellulose-Based Ethanol Pilot Plant

An increasing demand for bio-based vehicle fuels and impending harsher regulations of CO2 emissions are driving the development of a second generation of ethanol fuel processes. These processes will increase yields and make new feedstocks available, as they are designed to handle lignocellulosic materials such as wood. In order to achieve a sound financial economy of such a process, as well as an acceptable degree of energy efficiency, it is of the utmost importance that the lignin produced has a high dry content. An experimental study was conducted on lignin slurry from a pilot plant in the north of Sweden, in which the lignin slurry was filtered, pressed, and characterized. The dewatering was evaluated with the classical filtration equation by determining the average specific filtration resistance of the filter cakes. Compared with previous work, relatively low values of the specific filtration resistance were obtained. It is probable that the low values were an effect of the high amount of cellulose fibers present in the lignin residue. Cellulose content of the material produced in a commercially viable process will be much lower and likely result in increased filtration resistance as shown in previous work. Determination of local filtration properties is necessary for efficient design and scale-up of dewatering equipment for compressible materials. To the authors' knowledge, the local results presented are the first such measurements on material that has been produced in a pilot plant