Strategy for developing a future support system for the Vasa warship and evaluating its mechanical properties

To maintain the integrity of the Vasa warship after salvage in 1961, conservation treatment with polyethylene glycol was carried out to prevent the collapse of cell walls. This treatment had negative effects on the strength and stiffness of the oak and the hull structure has been found to slowly deform over time. It is of interest to construct a three-dimensional numerical computer model to model and predict the deformation of the warship. This creates difficulties related to the complexity of measuring the detailed material properties that are required as input. In this context, a non-destructive methodology to predict the stiffness of the Vasa oak in terms of moduli of elasticity in the three principal directions of timber at critical positions in the ship would be useful. The twofold aim of the paper is to propose a strategy for a support system and to conduct an on-site assessment of the warship to predict the mechanical properties of the Vasa oak material. This paper also contains an up-to-date review of all essential mechanical data measured on the Vasa oak. The preliminary investigation using an X-ray technique to investigate the density properties produced promising results for future use in the evaluation of the mechanical performance. Based on these results, a procedure to establish the stiffness properties of the Vasa oak in terms of MOE was suggested, using a combination of data from previous measurements, in combination with extended tests on Vasa oak specimens and an X-ray-based density calibration procedure. The general complexity of the Vasa warship can be mainly attributed to large variations in the properties of Vasa oak due to surface degradation, chemical treatment and the disintegration of the cell-wall structure originating from centuries of waterlogged conditions. That causes difficulties when assessing mechanical and physical properties on a structural level. A combination of visual inspection together with X-ray investigation is of great importance to evaluate those properties and to obtain more accurate estimates. The results from evaluating mechanical properties can serve as input in a numerical model and serve as a foundation for decision-making relating to the modification of the support system

Mechanical performance of yew (Taxus baccata L.) from a longbow perspective

Yew (Taxus baccata L.) longbow was the preferred weapon in the Middle Ages until the emergence of guns. In this study, the tensile, compression, and bending properties of yew were investigated. The advantage of yew over the other species in the study was also confirmed by a simple beam model. The superior toughness of yew has the effect that a yew longbow has a higher range compared with bows made from other species. Unexpectedly, the mechanical performance of a bow made from yew is influenced by the juvenile-to-mature wood ratio rather than by the heartwood-to-sapwood ratio. A yew bow is predicted to have maximized performance at a juvenile wood content of 30-50%, and located at the concave side (the compressive side facing the bowyer). Here, the stiffness and yield stress in compression should be as high as possibl

Identification and thermochemical analysis of high-lignin feedstocks for biofuel and biochemical production

Background - Lignin is a highly abundant biopolymer synthesized by plants as a complex component of plant secondary cell walls. Efforts to utilize lignin-based bioproducts are needed. Results - Herein we identify and characterize the composition and pyrolytic deconstruction characteristics of high-lignin feedstocks. Feedstocks displaying the highest levels of lignin were identified as drupe endocarp biomass arising as agricultural waste from horticultural crops. By performing pyrolysis coupled to gas chromatography-mass spectrometry, we characterized lignin-derived deconstruction products from endocarp biomass and compared these with switchgrass. By comparing individual pyrolytic products, we document higher amounts of acetic acid, 1-hydroxy-2-propanone, acetone and furfural in switchgrass compared to endocarp tissue, which is consistent with high holocellulose relative to lignin. By contrast, greater yields of lignin-based pyrolytic products such as phenol, 2-methoxyphenol, 2-methylphenol, 2-methoxy-4-methylphenol and 4-ethyl-2-methoxyphenol arising from drupe endocarp tissue are documented. Conclusions - Differences in product yield, thermal decomposition rates and molecular species distribution among the feedstocks illustrate the potential of high-lignin endocarp feedstocks to generate valuable chemicals by thermochemical deconstruction

Mechanical behaviour of hardwoods : effects from cellular and cell wall structures

Syftet med den här avhandlingen var att undersöka mekaniska egenskaper hos olika arter av lövträd, och koppla egenskaperna till cell- och cellväggsstrukturen i materialet. Arterna som omfattades av undersökningen var Europeisk asp (Populus tremula), hybridasp (Populus tremula x Populus tremuloides) och ek (Quercus robur). Arterna inom familjen Populus, inklusive den snabbväxande hybridaspen, har på senare tid kommit att användas inom ett stort antal projekt inom genforskningen. Det har i sin tur ökat behovet av noggrannare bestämning av mekaniska egenskaper hos dessa arter. Ek har sedan tusentals år tillbaka varit ett populärt konstruktionsmaterial; något som har resulterat i ett stort antal arkeologiska ekfynd. Konservering av dessa inkluderar ofta dimensionsstabilisering med hjälp av polyetylen-glykol (PEG); en kemikalie som man vet påverkar de mekaniska egenskaperna. I vilken utstäckning detta sker är däremot inte helt klarlagt. Studien på euoropeisk asp och hybridasp inkluderade utveckling av en ny metod för provning av små juvenila prov i grönt tillstånd. Töjningsmätningar gjordes med hjälp av digital speckelfotografering (DSP). Axiell dragstyvhet och draghållfasthet var av speciellt intresse. Sämre mekaniska egenskaper hos hybridaspen korrelerade med medelvärden på densitet, som var lägre för hybriden än för den Europeiska aspen. Ek undersöktes i svällt tillstånd, där svällningen inducerades med hjälp av PEG (molekylvikt 600). Axiell dragstyvhet och draghållfasthet samt radiell tryckstyvhet och ytspänning undersöktes. Töjningsmätningar i axiell riktning gjordes med hjälp av videoextensiometer, medan töjning i radiell riktning gjordes med hjälp av DSP. Övrig karakterisering av materialet inkluderade scanning electron microscopy (SEM), röntgenmikrotomografi och wide angle X-ray scattering (WAXS) för bestämning av mikrofibrillvinkel. Axiell dragstyvhet och draghållfasthet påverkades bara marginellt av PEG-behandlingen. WAXS-mätningarna visade att mikrofibrillvinkeln i materialet var mycket liten. Därigenom blir de mekaniska egenskaperna i axiell riktning till stor del beroende av mikrofibrillerna, vilket samtidigt minimerar den mjukningseffekt som PEG-impregneringen har på cellväggsmatrisen. De mekaniska egenskaperna i radiell kompression påverkades däremot starkt negativt av impregneringen. Detta antogs bero på den försvagande och uppmjukande effekt som PEG:en har på de radiellt orienterade märgstrålarna i veden.The aim of this work was to investigate the mechanical properties of different hardwood species and relate the properties to the structure at the cellular and cell wall level. The species examined were European aspen (Populus tremula), hybrid aspen (Populus tremula x Populus tremuloides) and European oak (Quercus robur). The Populus species, including the fast-growing hybrid aspen, are used in a large number of projects using transgene technology, which also has raised the demand for a more extensive determination of mechanical properties of the species. Oak have been a popular construction material for thousands of years, esulting in a vast number of archaeological findings. Preservation of these often includes dimensional stabilization by polyethylene glycol (PEG), an impregnation agent which affects the mechanical properties. To which extent is not properly investigated, however. The study on European and hybrid aspen included development of a method for tensile testing of small, juvenile specimens in the green condition, where strain was measured using the digital speckle photography (DSP) technique. Mechanical performance of the species in terms of longitudinal tensile stiffness and strength were of special interest. Inferior mechanical properties of hybrid aspen corresponded well to mean values of density, which were lower for the hybrid aspen compared to European aspen. Oak was examined in the swollen state, where swelling was induced by PEG with molecular weight 600. Longitudinal tensile stiffness and strength as well as radial stiffness and yield strength in compression were compared. Longitudinal and radial strain was measured using video extensiometry and DSP, respectively. Additional characterization of the material included imaging from scanning electron microscopy (SEM), X-ray microtomography and determination of microfibril angle using wide angle X-ray scattering (WAXS). Tensile stiffness and strength in the axial direction were only slightly affected by PEG-impregnation. WAXS measurements showed that microfibril angles were close to zero which implicates that cell wall properties are strongly dependent on the microfibrils, and only marginally influenced by the plasticization effects from PEG on the lignin/hemicellulose matrix. In the radial direction, on the other hand, mechanical performance was strongly decreased by PEG-impregnation. This was believed to originate from softening of rays.QC 2010110

FEATURE EXTRACTION AND CLASSIFICATION OF TRANSIENT FAULT RECORDS

As the power distribution system grows and more sensors are added, more data is created every day. This data can be crucial for finding faults, but there is now so much data that it ends up being unused. This presents a valuable opportunity to gain crucial insights into the continuously expanding and increasingly complex power distribution system.  This thesis aims to utilize this valuable resource by finding a feature extraction method that can find valuable features in real-world data, use these features to cluster the data, separate different faults into different clusters, and develop a method for how these clusters can be classified, making it possible for an expert to classify large amounts of data quickly.  In the end, an autoencoder was used for the feature extraction. The features could be used to cluster both labeled and unlabeled real-world data. The clustering also made it possible to find errors in the labeled data, as the data from one class were clustered into two clusters. A method was developed that allowed the clusters of 32454 unlabeled datapoints to be accurately classified in approximately 30 minutes.  This thesis has successfully developed a method that can be used to get insights from large amounts of data, helping experts within the field of power engineering build the power distribution system of the future

FEATURE EXTRACTION AND CLASSIFICATION OF TRANSIENT FAULT RECORDS

As the power distribution system grows and more sensors are added, more data is created every day. This data can be crucial for finding faults, but there is now so much data that it ends up being unused. This presents a valuable opportunity to gain crucial insights into the continuously expanding and increasingly complex power distribution system.  This thesis aims to utilize this valuable resource by finding a feature extraction method that can find valuable features in real-world data, use these features to cluster the data, separate different faults into different clusters, and develop a method for how these clusters can be classified, making it possible for an expert to classify large amounts of data quickly.  In the end, an autoencoder was used for the feature extraction. The features could be used to cluster both labeled and unlabeled real-world data. The clustering also made it possible to find errors in the labeled data, as the data from one class were clustered into two clusters. A method was developed that allowed the clusters of 32454 unlabeled datapoints to be accurately classified in approximately 30 minutes.  This thesis has successfully developed a method that can be used to get insights from large amounts of data, helping experts within the field of power engineering build the power distribution system of the future

Effects of Cell Wall Structure on Tensile Properties of Hardwood : Effect of down-regulation of lignin on mechanical performance of transgenic hybrid aspen. Effect of chemical degradation on mechanical performance of archaeological oak from the Vasa ship.

Wood is a complex material and the mechanical properties are influencedby a number of structural parameters. The objective of this study has been toinvestigate the relationship between the structure and the mechanical propertiesof hardwood. Two levels were of special interest, viz. the cellular structureand morphology of the wood, and the ultra-structure of the cell wall. In thenext step, it was of interest to examine how the mechanical properties ofhardwood change with spontaneous/induced changes in morphology and/orchemical composition beyond the natural variation found in nature. Together, this constituted the framework and basis for two larger projects,one on European aspen (Populus tremula) and hybrid aspen (Populus tremulax Populus tremuloides), and one on European oak (Quercus robur). Amethodology was developed where the concept of relative density and compositemechanics rules served as two useful tools to assess the properties ofthe cell wall. Tensile testing in the longitudinal direction was combined withchemical examination of the material. This approach made it possible to revealthe mechanical role of the lignin in the cell wall of transgenic aspen trees,and investigate the consequences of holocellulose degradation in archaeologicaloak from the Vasa ship. The study on transgenic aspen showed that a major reduction in lignin inPopulus leads to a small but significant reduction in the longitudinal stiffness.The longitudinal tensile strength was not reduced. The results are explainableby the fact that the load-bearing cellulose in the transgenic aspen retained itscrystallinity, aggregate size, microfibril angle, and absolute content per unitvolume. The results can contribute to the ongoing task of investigating andpinpointing the precise function of lignin in the cell wall of trees. The mechanical property study on Vasa oak showed that the longitudinaltensile strength is severely reduced in several regions of the ship, andthat the reduction correlates with reduced average molecular weight of theholocellulose. This could not have been foreseen without a thorough mechanicaland chemical investigation, since the Vasa wood (with exception fromthe bacterially degraded surface regions) is morphologically intact and witha micro-structure comparable to that of recent oak. The results can be usedin the ongoing task of mapping the condition of the Vasa wood.QC 2011042

Avskaffande av revisionsplikten i småföretag- Hur påverkas berörda fåmansföretag?

The main issue: On the basis of the authors problem discussion has following questions came along: how will the closed companies be affected by a abolishing of demand on auditing? How could the abolishing of demand on auditing in Denmark and England relate to Swedish possible abolishing of auditing? Purpose: The purpose of this paper is to examine and describe how closed companies stand to abolishing of demand on auditing and which affects they think they will get. Method: The authors have chosen to use a qualitative method. With open questions can give space for discussions, which can give the authors better understanding. The empirical material consists of eight different closed companies. The subordinate data were collected before the interview occasion, this because to develop the interview questions. Conclusion: The authors has come to a conclusion that larger the closed company is, the more of them will keep audit. There are some concerns that the tax authority will introduce time-consuming controls for those companies who does not have audit. The banks look at the auditing as a good basic data of companies financial possibilities but yet they can see that the credit possibilities from case to case and have to adjust to the market. The economics crime authority means that the economics crimes is the largest among the small companies, and the risk for that is bigger if the demand on auditing is going to abolish. The Economic Crimes will reduce if the companies learned more about auditing, in the same time, those that want to be involved with such crimes will anyway find other solutions. In the paper it has been comparison with how the abolishing of demand on auditing has been in Denmark and England. There has been certain similarity with Sweden. The most companies in those named countries above, thinks that the cost for audit does not exceed the benefit. In Denmark, who recently has abolished the audit demand for small companies has yet no bigger differences, but a survey has claimed that this could change in a few years. England has had since 1993 an exception from the demand on auditing and it has appeared that most companies still keep the auditing in the firm; they mean it is an advantage for them. The advantage for these companies is that auditing provides a benefit and contributes to good public information for the society, which considers to be auditing target. Keyword: Abolishing of Demand on auditing and closed companiesProblemformulering: Utifrån författarnas problemdiskussion har följande forskningsfrågor kommit fram: Hur kommer fåmansföretagen påverkas av ett avskaffande av revisionsplikten? Hur kommer Danmark och Englands avskaffade revisionsplikt kunna relateras till Sveriges eventuella avskaffande av revisionsplikten? Syfte: Syftet med uppsatsen är att undersöka och beskriva hur fåmansföretagen själva ställer sig till avskaffandet av revisionsplikten och vilka effekter de tror att det kommer att ge för dem. Metod: Författarna har valt att utgå utifrån en kvalitativ metod i denna uppsats. Genom öppna frågor kan det ge fler möjligheter för en djupare diskussion, vilket ger författarna bättre förståelse. Det empiriska materialet består av åtta fåmansföretag. Sekundära data samlades in innan intervjutillfällena, detta för att utveckla intervjufrågorna. Slutsats: Författarna har kommit fram till att desto större fåmansföretag det rör sig om, desto fler av dem kommer att behålla revisionen. Det finns oro för att Skatteverket skall införa tidsödande kontroller för de företag som inte har revision. Bankerna ser revisionen som ett bra underlag på företagens finansiella möjligheter men ser dock på kreditmöjligheterna från fall till fall och måste även anpassa sig till sin marknad. Ekobrottsmyndigheten menar att ekobrott är störst bland de minsta företagen och att risken för ekobrott är större om revisionsplikten avskaffas. Det anses att vetskapen om revision gör att ekobrotten minskar, samtidigt som det sägs att de som vill syssla med ekobrott finner andra lösningar. Kostnaden för revisionen överstiger inte nyttan i de flesta företag och detta gäller även i Danmark och England. Danmark, som nyligen har avskaffat revisionsplikten för små företag har ännu inte fått några större skillnader, men en undersökning visar att detta kan förändras längre fram i tiden. England har sedan 1993 haft undantag från revisionsplikt för små företag och det har visat sig att flesta företag ändå behåller revisionen i företaget, då de anser att det är en fördel. Fördelen för dessa företag innebär att revisionen tillför en nytta och bidrar till en bra offentlig information för samhället, som anses vara revisionens främste intressent. Nyckelord: Revisionsplikt och fåmansföreta

Gör ditt bästa, dina studier är viktiga för din framtid : En studie om hur ungdomar som saknar gymnasiebehörighet uppfattar sina framtidastudie- och yrkesmöjligheter i ljuset av högstadieåren.

Varje år slutar mer än 15 000 elever grundskolan utan att nå gymnasiebehörighet, vilket ger begränsade möjligheter vad gäller yrkes- och studieframtid. Denna studie gör anspråk på att ge en röst till några av dessa ungdomar. Den syftar till att ge ökad kunskap och förståelse kring hur ungdomar utan gymnasiebehörighet uppfattar grundskolan och dess betydelse för hur de ser på framtida möjligheter. Studien är en kvalitativ studie med kontextuell analytisk ansats och det är elevernas uppfattningar och erfarenheter som är centrala. Insamling av empirin har skett genom semistrukturerade intervjuer med åtta ungdomar från tre olika skolor i en medelstor svensk stad. Intervjuerna har genomförts under de sista två månaderna av deras grundskoletid. Resultaten belyses ur ett relationellt perspektiv. I studien framträder flera faktorer av betydelse för elevers sätt att se både sig själva och sina möjligheter.  När elever är delaktiga vad gäller stödinsatser, när de känner sig sedda, uppmuntrade och har goda relationer med lärare, kamrater och andra vuxna i skolan påverkas deras självbild på ett positivt sätt och de tror sig kunna nå sina mål. Centralt i resultaten är hur negativa relationer blir begränsande för eleverna och påverkar deras självbild i hög grad vad gäller hur de ser sina framtida möjligheter. Likaså framträder en bild av hur elever betraktar egna tillkortakommanden som en grund för skolmisslyckanden i hög grad men de visar även medvetenhet om betydelsen av andra faktorer som lärares förhållningssätt, undervisnings- och stödsituationer samt övergripande styrning

Gör ditt bästa, dina studier är viktiga för din framtid : En studie om hur ungdomar som saknar gymnasiebehörighet uppfattar sina framtidastudie- och yrkesmöjligheter i ljuset av högstadieåren.

Varje år slutar mer än 15 000 elever grundskolan utan att nå gymnasiebehörighet, vilket ger begränsade möjligheter vad gäller yrkes- och studieframtid. Denna studie gör anspråk på att ge en röst till några av dessa ungdomar. Den syftar till att ge ökad kunskap och förståelse kring hur ungdomar utan gymnasiebehörighet uppfattar grundskolan och dess betydelse för hur de ser på framtida möjligheter. Studien är en kvalitativ studie med kontextuell analytisk ansats och det är elevernas uppfattningar och erfarenheter som är centrala. Insamling av empirin har skett genom semistrukturerade intervjuer med åtta ungdomar från tre olika skolor i en medelstor svensk stad. Intervjuerna har genomförts under de sista två månaderna av deras grundskoletid. Resultaten belyses ur ett relationellt perspektiv. I studien framträder flera faktorer av betydelse för elevers sätt att se både sig själva och sina möjligheter.  När elever är delaktiga vad gäller stödinsatser, när de känner sig sedda, uppmuntrade och har goda relationer med lärare, kamrater och andra vuxna i skolan påverkas deras självbild på ett positivt sätt och de tror sig kunna nå sina mål. Centralt i resultaten är hur negativa relationer blir begränsande för eleverna och påverkar deras självbild i hög grad vad gäller hur de ser sina framtida möjligheter. Likaså framträder en bild av hur elever betraktar egna tillkortakommanden som en grund för skolmisslyckanden i hög grad men de visar även medvetenhet om betydelsen av andra faktorer som lärares förhållningssätt, undervisnings- och stödsituationer samt övergripande styrning