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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Konstruktionskoncept till att skapa wellpappsprover i laboratoriemiljö / Construction concept to create samples of corrugated cardboard in laboratory environment

Gussman Lennström, Anton, Lundberg, Selma January 2022 (has links)
Kraftliners är något som används till att skapa bland annat ytskiktet till pappersprodukten wellpapp. Wellpapp består av ett lager kraftliner på antigen en- eller vardera sidan av ett vågigt papper, kallat flute. På uppdrag av SCA R&D undersöker detta kandidatarbete möjligheten till att skapa en konceptuell prototyp till en maskin som kan konstruera wellpappsprover på deras laboratorium. Detta för att via tester kunna prediktera hur variationer i wellpappens struktur påverkar dess egenskaper. Arbetet utfördes med hjälp av en iterativ metod där koncept först togs fram och sedan utvärderades repetitivt tills ett slutgiltigt koncept var framtaget. Konceptframtagningen bestod av fem iterationer med faserna konceptgenerering, modellering, prototypframtagning, tester av prototyp och utvärdering. Arbetet resulterade i ett slutgiltigt koncept som ledde till en illustrerad prototyp i mindre skala som visar hur wellpappsprover skulle kunna skapas i SCA’s R&D-laboratorium. / Kraftliners are used to create, among other things, the surface layer for the paper product corrugated board. Corrugated board consists of a layer of kraftliner on either one or both sides of a wavy paper, called flute. On behalf of SCA R&D this bachelor's thesis investigates the possibility of creating a conceptual prototype for a machine that can create corrugated board samples in their laboratory. This is to be able to predict, via tests, how variations in the structure of the corrugated board affect its properties. The work was carried out using an iterative method where concepts were first developed and then evaluated repetitively until a final concept was developed. The concept development consisted of five iterations with the phases of concept generation, modeling, prototype development, prototype testing and evaluation. The work resulted in a final concept that led to an illustrated prototype on a smaller scale that shows how corrugated board samples could be created in SCA's R&D laboratory.
2

Humidity’s effect on strength and stiffness of containerboard materials : A study in how the relative humidity in the ambient air affects the tensile and compression properties in linerboard and fluting mediums

Strömberg, Frida January 2016 (has links)
The aim of this thesis was to investigate the difference between containerboard materials strength and stiffness properties in tension and compression, how the mechanisms behind compressive and tensile properties are affected by the relative humidity of the ambient air and how the relative humidity affects the compressive response of the fibre network. These properties are used to predict the lifetime performance of corrugated boxes and to prevent early collapses of the boxes and thereby waste or harm of the transported goods inside. The work also discusses the methods used to evaluate the different properties and how reliable the results are. The experimental part includes testing of linerboard and fluting materials from both virgin and recycled fibres, which have been conditioned at 50% and 90% relative humidity. The compression tests were filmed to evaluate if different compression failure modes can be related to the strength and stiffness of the material. The results indicated that the compressive strength and stiffness differ from the strength and stiffness values in tension at 90% relative humidity. Compressive strength is lower in both 50% and 90% relative humidity compared with the tensile strength. However, the compression stiffness shows a higher value than the tensile stiffness at 90% relative humidity. The study of the method for evaluating the compressive behaviour of the paper does not present a complete picture on what type of failure the paper actually experience.
3

Mechanics of paper webs in printing press applications

Kulachenko, Artem January 2006 (has links)
The mechanics of paper is a difficult subject because paper is a unique material. It is very thin, flexible at bending, unstable in compression and stiff at tension. Dealing with paper we have to account for orthotropy and heterogeneities created during the manufacturing process. This thesis addresses two topics in mechanics of paper webs in printing press applications. First is the dynamic behaviour of the travelling webs. Second is so-called “fluting” after heat-set web-fed offset printing. There are a number of challenges in simulating the dynamics of the paper web. It is necessary to include the influence of the paper web transport velocity. Due to initial sag or vibrations, gyroscopic forces affect the dynamics of the webs. Furthermore, the transport velocity reduces the stress stiffening of the web. A good theoretical model should account for large displacements and should be capable of simulating wrinkles, which is essentially a post-buckling phenomenon. Finally, the paper web is surrounded with air which reduces the natural frequencies substantially by “adding" mass to the paper. A non-linear finite element formulation has been developed in this study for simulation of travelling webs. The results of the studies shows that for the tension magnitudes used in the printing industry the critical web speed lies far above those used today. Speed limitations are rather caused by ink setting and tension control problems. If the web tension profile is skew, however, edge vibrations are inevitable even at small external excitations. Fluting is a permanent wavy distortion of the paper web after heat-set web offset printing. It is often seen in high quality printing products, especially in areas covered with ink. It is generally accepted that tension and heat are required to create fluting. However, there have been certain disputes as to the mechanism of fluting formation, retention and key factors affecting this phenomenon. Most of the existing studies related to fluting are based on linear buckling theories. A finite element model, capable of simulating a post-buckling behaviour has been developed and experimentally verified. Studies show that none of the existing theories can consistently explain fluting. A new basic mechanism of fluting formation has been proposed and numerically demonstrated. Fluting was explained as a post-buckling phenomenon due to small scale moisture variations developing during through-air drying. It was concluded that air permeability variation is the key factor affecting fluting tendency. Fluting is retained due to inelastic deformations promoted by high drying temperatures. / QC 20100906
4

Utbytets och malningens inverkan på NSSC-massans egenskaper / The impact of yield and refining on the properties of NSSC-pulp

Larsson, Markus, Kullander, Johan January 2010 (has links)
<p>Neutralsulfitkokning av björk möjliggör ett högt utbyte av hemicellulosa, vilket bidrar positivt till flutingens egenskaper och minskar vedkostnaden. Neutralsulfitkoket ska avbrytas när delignifieringen nått tillräckligt långt för att veden ska kunna defibreras skonsamt med en rimlig energiinsats, men innan nedbrytningen av hemicellulosa hunnit accelerera. Syftet med detta examensarbete var att undersöka utbytets och malningens inverkan på NSSC-massans egenskaper.</p><p>En laboratoriestudie genomfördes där massan kokades till olika utbyten och maldes vid olika insatser. Resultatet av den studien användes sedan för att ställa om kokaren och raffinörerna på lämpligt sätt vid fabriksförsöken. Massaprover togs ut efter det andra kvarnsteget och skickades för analys. De mest väsentliga egenskaperna för fluting testades genom CCT (Corrugated Crush Test), CMT (Concora Medium Test) och SCT (Short Span Compression test) men övriga konventionella egenskaper testades likväl. En avgörande egenskap för fluting är också dess krypstyvhet som undersöktes på laboratorie genom isokrona kryptester. För att få en djupare förståelse för NSSC-massans egenskaper samt kokningens och malningens inverkan på dessa utfördes även fiberkaraktärisering.</p><p>Resultatet visar att styrkan på NSSC-massan kan påverkas genom att variera både utbytet och effekten i raffinörerna. För att åstadkomma en signifikant styrkeökning krävs ett lågt utbyte tillsammans med en hög effekt i raffinörerna. Kraftiga ändringar av dessa parametrar leder dessvärre till att papperets egenskaper förändras i den grad att körbarheten på maskin kan påverkas. Studien visar även att fluting som uppfyller dagens riktvärden kan framställas kostnadseffektivt genom ett högt utbyte i kokaren och en hög insats i raffinörerna. Samtidigt erhålls då en ljusare massa, vilket kan vara betydande i vissa fall. Krypmätningarna visar samtidigt att malningen i positiv bemärkelse påverkar krypstyvheten medan utbytets inverkan är mer svårtolkat. Ett allt för högt utbyte verkar dock vara negativt ur krypstyvhetssynpunkt.</p> / <p>Neutral sulphite cooking of birch enables a high yield of hemicelluloses. This contributes positively to the properties of the flute, reduces the amount of wood needed and hence the cost. The neutral sulphite cook is to be terminated when the delignification has gone sufficiently far so that the wood can be refined mercifully with a reasonable energy input, but before the delignification has gone so far that the degradation of hemicelluloses has started to accelerate. The objective with this thesis was to examine how yield and refining affects the properties of the NSSC pulp.</p><p>A laboratory study was performed where the pulp was cooked to different yields and then beaten with different energy inputs. The results from this study were then used to determine how to set the boiler and the refiners appropriately in the paper mill trials. Pulp samples were collected after the second refiner and were then sent for analysis. The most important properties for flute were tested through CCT (Corrugated Crush Test), CMT (Concora Medium Test) and SCT (Short Span Compression test). More conventional properties were tested as well. Another important property for flute, the creep resistance, was tested in the laboratory through isochronous creep tests. To get a deeper understanding of the properties of NSSC-pulp, along with the effects of cooking and refining, fiber characterization was also performed.The results indicate that it is possible to affect the strength properties on the NSSC pulp by varying both the yield and the energy input in the refiners. To accomplish a large increase in strength, a relatively low yield is needed, along with increased refining. Large changes of those parameters may unfortunately lead to changes in paper properties in such a way that the runability on the paper machine is affected.</p><p>The results also indicate that it is possible to manufacture flute in a more cost efficient way by lowering the H-factor in the boiler while increasing the degree of refining, still keeping the strength properties above the critical values.A pulp with a higher brightness is also acquired when running the mill this way, which can be important in some aspects. The creep studies indicate that increased refining has a positive effect on the creep resistance. It is harder to make conclusions about the impact of yield, but it seems as though all too high yields affects the creep resistance negatively.</p>
5

Utbytets och malningens inverkan på NSSC-massans egenskaper / The impact of yield and refining on the properties of NSSC-pulp

Larsson, Markus, Kullander, Johan January 2010 (has links)
Neutralsulfitkokning av björk möjliggör ett högt utbyte av hemicellulosa, vilket bidrar positivt till flutingens egenskaper och minskar vedkostnaden. Neutralsulfitkoket ska avbrytas när delignifieringen nått tillräckligt långt för att veden ska kunna defibreras skonsamt med en rimlig energiinsats, men innan nedbrytningen av hemicellulosa hunnit accelerera. Syftet med detta examensarbete var att undersöka utbytets och malningens inverkan på NSSC-massans egenskaper. En laboratoriestudie genomfördes där massan kokades till olika utbyten och maldes vid olika insatser. Resultatet av den studien användes sedan för att ställa om kokaren och raffinörerna på lämpligt sätt vid fabriksförsöken. Massaprover togs ut efter det andra kvarnsteget och skickades för analys. De mest väsentliga egenskaperna för fluting testades genom CCT (Corrugated Crush Test), CMT (Concora Medium Test) och SCT (Short Span Compression test) men övriga konventionella egenskaper testades likväl. En avgörande egenskap för fluting är också dess krypstyvhet som undersöktes på laboratorie genom isokrona kryptester. För att få en djupare förståelse för NSSC-massans egenskaper samt kokningens och malningens inverkan på dessa utfördes även fiberkaraktärisering. Resultatet visar att styrkan på NSSC-massan kan påverkas genom att variera både utbytet och effekten i raffinörerna. För att åstadkomma en signifikant styrkeökning krävs ett lågt utbyte tillsammans med en hög effekt i raffinörerna. Kraftiga ändringar av dessa parametrar leder dessvärre till att papperets egenskaper förändras i den grad att körbarheten på maskin kan påverkas. Studien visar även att fluting som uppfyller dagens riktvärden kan framställas kostnadseffektivt genom ett högt utbyte i kokaren och en hög insats i raffinörerna. Samtidigt erhålls då en ljusare massa, vilket kan vara betydande i vissa fall. Krypmätningarna visar samtidigt att malningen i positiv bemärkelse påverkar krypstyvheten medan utbytets inverkan är mer svårtolkat. Ett allt för högt utbyte verkar dock vara negativt ur krypstyvhetssynpunkt. / Neutral sulphite cooking of birch enables a high yield of hemicelluloses. This contributes positively to the properties of the flute, reduces the amount of wood needed and hence the cost. The neutral sulphite cook is to be terminated when the delignification has gone sufficiently far so that the wood can be refined mercifully with a reasonable energy input, but before the delignification has gone so far that the degradation of hemicelluloses has started to accelerate. The objective with this thesis was to examine how yield and refining affects the properties of the NSSC pulp. A laboratory study was performed where the pulp was cooked to different yields and then beaten with different energy inputs. The results from this study were then used to determine how to set the boiler and the refiners appropriately in the paper mill trials. Pulp samples were collected after the second refiner and were then sent for analysis. The most important properties for flute were tested through CCT (Corrugated Crush Test), CMT (Concora Medium Test) and SCT (Short Span Compression test). More conventional properties were tested as well. Another important property for flute, the creep resistance, was tested in the laboratory through isochronous creep tests. To get a deeper understanding of the properties of NSSC-pulp, along with the effects of cooking and refining, fiber characterization was also performed.The results indicate that it is possible to affect the strength properties on the NSSC pulp by varying both the yield and the energy input in the refiners. To accomplish a large increase in strength, a relatively low yield is needed, along with increased refining. Large changes of those parameters may unfortunately lead to changes in paper properties in such a way that the runability on the paper machine is affected. The results also indicate that it is possible to manufacture flute in a more cost efficient way by lowering the H-factor in the boiler while increasing the degree of refining, still keeping the strength properties above the critical values.A pulp with a higher brightness is also acquired when running the mill this way, which can be important in some aspects. The creep studies indicate that increased refining has a positive effect on the creep resistance. It is harder to make conclusions about the impact of yield, but it seems as though all too high yields affects the creep resistance negatively.
6

Identifiering av lagerströmmar i elmotorer för framdrivning av tunga fordon : Utveckling av metod och programvara för att detektera lagerströmmar / Identification of Bearing Currents in Electric Motors for Heavy Vehicles : Development of Methodology and Software to DetectBearing Currents

Lindström, Jessica January 2023 (has links)
Klimatutmaningar, lagändringar och ett ökat miljötänk har tvingat transportsektorn att ställa om till eldrift. Batterier och elmotorer har utvecklats kraftigt och är nu ett alternativ även för tunga fordon. Ett vanligt förekommande problem med elmotorer i fordon är lagerströmmar, här kallat gnista eller blixthändelser. Dessa uppstår på grund av oönskade urladdningar i motorn och förorsakar skador på lagren i motorn. Syftet med motorlager är att avlasta och minska friktionen kring motoraxeln. För att förebygga problemet och se förbättringar eller försämringar av olika åtgärder som görs krävs att lagerströmmar kan identifieras utifrån mätdata. Detta examensarbete analyserar relevant forskning inom området för att sedan introducera en metod och en algoritm för att identifiera lagerströmmar i samarbete med Scania CV. Algoritmen består av tre olika parametrar som påverkar identifieringen av de oönskade strömmarna på olika sätt. Verktyget lyckades identifierade lagerströmmar i olika mätdata, och hittade skillnader i antalet blixthändelser mellan olika körningar av provobjektet. Dock krävs vidare utveckling av verktyget och möjligheten att bearbeta annan typ av data som exempelvis spänningar i motorn för atthitta bättre samband. / A changing climate, changing laws and an increased environmental consciousnesshas forced the transport sector to transition to electric power. Batteries and electric motors have seen a quick and powerful development which means that they are now an alternative even for heavy vehicles. A common problem with electric motors forvehicles is bearing currents. The bearing currents occur as a result of electrical discharges in the motor and can damage the bearings inside the motor. The purpose of motor bearings is to offload and reduce friction for the motor shaft. To prevent the issue and to see improvements or deteriorations from different preventativemeasures it is critical to be able to identify bearing currents from data. This thesis analyzes relevant research in the area before introducing a method and an algorithm for detecting bearing currents in cooperation with Scania CV. The algorithm is composed of three different parameters which affects the identification in different ways. The tool was able to identify bearing currents from various data and found differences between the number of bearing currents between different test runs of the motor. However, more development of the tool and the possibility to process different kinds of data like voltages inside the motor is needed to be able to find better patterns in the data.
7

Spiral Fluted Columns and the Mechanical Screw: The History of a Mathematical Idea in Ancient Architecture and Mechanical Technology

Henderson, Georgina Jane 03 September 2013 (has links)
This thesis examines the stone-carved architectural spiral fluted column from second-millennium B.C. Mesopotamia to the fourth-century A.D. Roman Empire, and establishes its relationship to technological devices such as water screws, screw presses, and other machines. Evidence from literary sources and archaeological records shows the increasing architectural use of the helical spiral during that time, particularly in structures such as theatres, nymphaea, colonnades and decorative gateways. The use of spiral designs on coins, sarcophagi, pottery and wall paintings is also discussed. The thesis presents: the mathematics of the spiral as applied in Mesopotamian architecture; spiral use in the Aegean Bronze and Iron Ages and the Greek and Roman worlds; and its use in technology and mechanical devices, specifically those of Archimedes and Hero. The conclusion summarises the evidence, demonstrating that the construction of the spiral fluted column evolved from that of the Archimedean water screw. / Graduate / 2015-08-20 / 0324 / 0346 / 0579 / ghenders@uvic.ca
8

Spiral Fluted Columns and the Mechanical Screw: The History of a Mathematical Idea in Ancient Architecture and Mechanical Technology

Henderson, Georgina Jane 03 September 2013 (has links)
This thesis examines the stone-carved architectural spiral fluted column from second-millennium B.C. Mesopotamia to the fourth-century A.D. Roman Empire, and establishes its relationship to technological devices such as water screws, screw presses, and other machines. Evidence from literary sources and archaeological records shows the increasing architectural use of the helical spiral during that time, particularly in structures such as theatres, nymphaea, colonnades and decorative gateways. The use of spiral designs on coins, sarcophagi, pottery and wall paintings is also discussed. The thesis presents: the mathematics of the spiral as applied in Mesopotamian architecture; spiral use in the Aegean Bronze and Iron Ages and the Greek and Roman worlds; and its use in technology and mechanical devices, specifically those of Archimedes and Hero. The conclusion summarises the evidence, demonstrating that the construction of the spiral fluted column evolved from that of the Archimedean water screw. / Graduate / 2018-08-20 / 0324 / 0346 / 0579 / ghenders@uvic.ca
9

Metodika výuky hry na zobcovou flétnu dětí od 4 do 6 let / Methodology of playing the flute of children from four to six years

Bezchlebová, Pavlína January 2012 (has links)
This thesis Methodology of playing the flute of children from 4 to 6 years deals with the problem of learn to play the flute preschool children. The theoretical part deals with the importance of this activity, its contribution to the children themselves. It focuses on the developmental characteristics of this period, the physical and mental maturity, the skills needed for learning to play flute. It also compares the methodology and the methodology of music education games on the soprano recorder for children of school age and younger children. The practical part deals with the specific methodology you learn to play the soprano flute - using the "color music". Describes the formation method, its advantages for the acquisition of flute playing children 4 to 6 years, application of methods in teaching and, not least, textbook design, the concept would be based on this method.

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