The influence ofvariable amplitude loading on the fatigue strength of rhs corners

Rectangular hollow section (RHS) members are components widely used in engineering applications because of their good-looking, good properties in engineering areas and inexpensive cost comparing to members with other sections. The increasing use of RHS in load bearing structures makes it necessary to analyze the fatigue behavior of the RHS members. In this thesis, concentration will be given to the fatigue behavior of the RHS members under variable amplitude pure torsional loading. For the RHS members, failure will normally occur in the corner region if the welded regions are under full penetration. This is because of the complicated stress components' distributions at the RHScorners, where all of three fracture mechanics modes will happen. Mode I is mainly caused by the residual stresses that caused by the manufacturing process. Modes II and III are caused by the applied torsional loading. Stress based Findleymodel is also used to analyze the stress components. Constant amplitude fatigue tests have been done as well as variable amplitude fatigue tests. The specimens under variable amplitude loading gave longer fatigue lives than those under constant amplitude loading. Results from tests show an S-N curvewith slope around 5.

Lasikuitupinnoitteiden ja vinyyliesterihartsien yhteensopivuuden tutkiminen

Diplomityössä on haettu tietoa lasikuitupinnoitteiden ja vinyyliesterihartsien yhteensopivuudesta ja sen testaamisesta. Lujitemuovikomposiitissa hartsi sitoo materiaalit yhteen ja antaa rakenteelle kemiallisen kestävyyden, sitkeyden ja välittää kuormitukset kuitujen kannettaviksi. Vaadittavan lujuuden rakenteelle antaa lasikuitu. Se päällystetään valmistusvaiheessa pinnoiteaineella, sizingilla. Sillä on ratkaiseva merkitys hartsin ja lasikuidun väliin syntyvän rajapinnan muodostumisessa kovettumisprosessin aikana. Käytännössä rajapinnan toimivuutta ja materiaalien yhteensopivuutta tutkitaan makromekaanisilla lujuustesteillä. Menetelmät perustuvat rajapinnan leikkaus¬lujuuden määrittämiseen, mutta myös murtumamekanismeihin perustuvia testi¬menetelmiä käytetään. Mikrotason menetelmät, jotka perustuvat yksittäisen kuidun ja käytetyn hartsin välisen adheesion mittaamiseen ovat yleistyneet, mutta niistä saatujen tulosten ei ole vielä todettu riittävästi korreloivan makro¬mekaanisten lujuustestien kanssa. Työssä tutkittiin kahta eri makromekaanista testimenetelmää. Testeissä havaittiin eroja valittujen lasikuitupinnoitteiden ja vinyyliesterihartsien välillä. Hauras hartsi oli herkempi lasikuitupinnoitteen kemialle. Kun yhteensopivuus vinyyli-esterihartsin ja lasikuitupinnoitteen välillä oli huono, saatiin sekä poikittaisessa vetolujuustestissä että Mode I murtumissitkeystestissä heikko tulos. Pyyhkäisy¬elektronimikroskoopilla suoritettu mikrotason analyysi murtopinnasta vahvisti saatuja tuloksia ja se osoittautui toimivaksi menetelmäksi kuvantamaan ilmiöitä, jotka vaikuttavat yhteensopivuuteen vinyyliesterihartsin ja pinnoitetun lasikuidun välillä.

Pressure filtration characteristics of enzymatically hydrolyzed biomass suspensions

Enzymatic hydrolysis of lignocellulosic polymers is likely to become one of the key technologies enabling industrial production of liquid biofuels and chemicals from lignocellulosic biomass. Certain types of enzymes are able to hydrolyze cellulose and hemicellulose polymers to shorter units and finally to sugar monomers. These monomeric sugars are environmentally acceptable carbon sources for the production of liquid biofuels, such as bioethanol, and other chemicals, such as organic acids. Liquid biofuels in particular have been shown to contribute to the reduction of net emissions of greenhouse gases. The solid residue of enzymatic hydrolysis is composed mainly of lignin and partially degraded fibers, while the liquid phase contains the produced sugars. It is usually necessary to separate these two phases at some point after the hydrolysis stage. Pressure filtration is an efficient technique for this separation. Solid-liquid separation of biomass suspensions is difficult, because biomass solids are able to retain high amounts of water, which cannot be readily liberated by mechanical separation techniques. Most importantly, the filter cakes formed from biomaterials are compressible, which ultimately means that the separation may not be much improved by increasing the filtration pressure. The use of filter aids can therefore facilitate the filtration significantly. On the other hand, the upstream process conditions have a major influence on the filtration process. This thesis investigates how enzymatic hydrolysis and related process conditions affect the filtration properties of a cardboard suspension. The experimental work consists of pressure filtration and characterization of hydrolysates. The study provides novel information about both issues, as the relationship between enzymatic hydrolysis conditions and subsequent filtration properties has so far not been considered in academic studies. The results of the work reveal that the final degree of hydrolysis is an important factor in the filtration stage. High hydrolysis yield generally increases the average specific cake resistance. Mixing during the hydrolysis stage resulted in undefined changes in the physical properties of the solid residue, causing a high filtration resistance when the mixing intensity was high. Theoretical processing of the mixing data led to an interesting observation: the average specific cake resistance was observed to be linearly proportional to the mixer shear stress. Another finding worth attention is that the size distributions of the solids did not change very dramatically during enzymatic hydrolysis. There was an observable size reduction during the first couple of hours, but after that the size reduction was minimal. Similarly, the size distribution of the suspended solids remained almost constant when the hydrolyzed suspension was subjected to intensive mixing. It was also found that the average specific cake resistance was successfully reduced by the use of filter aids. This reduction depended on the method of how the filter aids were applied. In order to obtain high filtration capacity, it is recommended to use the body feed mode, i.e. to mix the filter aid with the slurry prior to filtration. Regarding the quality of the filtrate, precoat filtration was observed to produce a clear filtrate with negligible suspended solids content, while the body feed filtrates were turbid, irrespective of which type of filter aid was used.

Extraordinary mode of singing by Finlanders

London : Joseph Mawman 1802

Jeg strikker, derfor er jeg! : læring og identitet i uformelle læringsrum

The dissertation ´I knit, therefore I am!´ Learning and identity in informal space has two main purposes. The first purpose being an investigation of how new value attributions and thinking can generate novel and usable knowledge to the field of craftsmanship, and the second purpose being a display of a different and overlooked philosophical and cultural potential in a reflexive mode of expression, which is able to reflect the normative comprehension of craftsmanship. The dissertation focuses on learning and identity in informal spaces of learning and how it is possible to relate such a learning perspective to crafts training in educational establishments. The empirical foundation of this dissertation is ‘craftivism’. In the dissertation activists from the Nordic countries have been interviewed about what they do when they put up their textile graffiti on lamp posts and house walls. Three research problems are presented: 1) What stories do people who work as crafts activists, tell about ways of relating and methods of action when they make crafts? 2) What do these stories tell about learning and identity? 3) How may the research results influence training and education in craftsmanship? These questions are being asked in order to acquire new knowledge in two aspects; first aspect being knowledge about crafts in relation to techniques, tradition and the objects in crafts, and the second aspect being knowledge about learning and identity in informal spaces of learning. The dissertations theoretical foundation is post structural and sociocultural combined with hermeneutical-inspired qualitative interviews. The author’s position and pre-understanding is subject to discussion in relation to the informant; the performing activist, as the background for both of them is craftsmanship. Starting from cultural studies, it is possible to see the activist subject’s conditions of possibilities in the culture, as the activism of the sub-cultural phenomenon’s craft lights up through a performing approach to the individual’s actions. First the research material has been analysed for events of textile graffiti and possible themes in the events, after which the results have been summarised. Next the research material has been analysed for events about learning and identity due to the author’s wish of comprehending the background of and motivational force in activism. The analysis is divided in main perspectives with different dimensions. The results of the analysis show the activist subject’s construction of an individual who actively takes part in a community by e.g. creating joy, changing the world’s perception of sustainability or by feminizing the public space. By taking crafts over the borders (and away from the class room) crafts become contextualized in a novel fashion thus obtaining an independent status. In this fashion the dissertation writes itself into a new method of comprehending and performing traditional craftsmanship techniques.

Att tala om det osägbara : Nicolaus Cusanus cirkulära filosofi i verket De coniecturis med särskild hänsyn till Nelson Pikes tankar om unio mystica

In my dissertation called Speaking of the unsayable: The circular philosophy of Nicholas of Cusa in his work De coniecturis, I presuppose an internal (conceptual) relation between the personal experience of God of Nicholas of Cusa (1401-64) in 1438 and, on the other hand, his philosophy. I hence try to describe the precise character of this relation. Referring to the Norwegian scholars Egil Wyller and Viggo Rossvær, I assume that there is a circularity in Cusanus’ philosophy which appears as self-references (= a sentence refers to itself: A is explained by B and B is explained by A). Wyller finds three phases in the thought of Cusanus (1. De docta ignorantia I-III, 2. De coniecturis I-II, 3. all subsequent works). Rossvær finds it impossible to presuppose certain phases, as the philosophy of Cusanus continuously proceeds and remains open to new ideas. As Cusanus however treats his experience of God far more consciously in his second work De coniecturis than in De docta ignorantia, I find it possible to distinguish between the earlier Cusanus (De docta ignorantia including his earlier works) and the later Cusanus (De coniecturis, about 1444, as well as the following works). Cusanus creates a philosophy of language in outline expressed in De coniecturis, in which he presents two concepts of necessity, i.e. absolute necessity and logical, or reasonable, necessity. These are interrelated in the sense that the mind, or the self, logically affirms the absolute, or unsayable, necessity, which shows itself in the mind and which the mind affirms conjecturally. The endeavour conceptually to understand absolute necessity implies intuitive (or intellectual) contemplation, or vision (investigatio symbolica), in which the four mental unities (the absolute, the intellectual, the rational and the sensuous) work together according to the rules described in De coniecturis. In De coniecturis Cusanus obviously turns from a negative concept of the unsayable to a paradigmatic, which implies that he looks for principles of speaking of the unsayable and presents the idea of a divine language (divinaliter). However, he leaves this idea behind after De coniecturis, although he continues to create new concepts of the unsayable and incomprehensible. The intellectual language of absolute seeing is expressed in the subjunctive, i.e. conditionally. In order to describe the unsayable, Cusanus uses tautologies, the primary one of which is a concept of God, i.e. non aliud est non aliud quam non aliud (the non-other is non-other than the nonother). Wyller considers this the crucial point of the philosophy of Cusanus (De non aliud), described by the latter as the definition of definitions, i.e. the absolute definition. However, this definition is empty regarding its content. It demonstrates that God surpasses the coincidence of opposites (coincidentia oppositorum) and that he is “superunsayable” (superineffabilis), i.e. he is beyond what can be conceived or said. Nothing hence prevents us from speaking of him, provided that he is described as unsayable (= the paradigmatic concept of the unsayable). Here the mode of seeing is decisive. Cusanus in this context (and especially in his later literary production) uses modalities which concern possibility and necessity. His aim is to conduct any willing reader ahead on the way of life (philosophia mentalis). In De coniecturis II he describes the notion of human self-consciousness as the basis of spiritual mutuality in accordance with the humanistic tradition of his time. I mainly oppose the negatively determined concept of Christian mysticism presented by the German philosopher Kurt Flasch and prefer the presentation of Burkhard Mojsisch of the translogical and conjectural use of language in De coniecturis. In particular, I take account of the Scandinavian research, basically that of Johannes Sløk, Birgit H. Helander, Egil Wyller and Viggo Rossvær, who all consider the personal experience of God described by Cusanus a tacit precondition of his philosophy.