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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.
391

Vändpunkten Kristianstad : en stödgruppsverksamhet / The turning point Kristianstad : a support group activity.

Olausson, Amanda, Persson, Gina January 2011 (has links)
The aim of this study has been to investigate children and adolescent development in ”The turning point” children´s and adolescent program in Kristianstad. We also wanted to find out the support group leaders experiences concerning the children´s and the adolescents development in programs and how they apprehended their role as a support group leader. Our intension was also to study how the adolescent and the children considered their own development in the program. To carry through this study, we used two types of qualitative methods i.e. qualitative interviews with the support group leaders who used the ”Turning point”  method in their work with the children’s and adolescents groups. We also used qualitative content analysis on the children’s and the adolescents written answers in their evaluation forms. The support group leaders and the adolescents described a positive development through the programs. Both parts states that this development has been noticed by an increased openness about the abuse in the family. Other results was that the children and the adolescent answered that they had realized that they were not alone in their situation, had been helped by the programs, felt happier and had come to realize that they had an identity of their own.
392

Livia - mördare eller syndabock? : En utvärdering av de antika källorna kring kejsarinnan Livia och vad som talar för att hon mördade Augustus och dennes adoptivsöner för att göra sin egen son Tiberius till kejsare / Empress Livia – Murderer or wrongfully accused? : An overview of the ancient sources on the empress Livia and what that suggests that shemurdered her husband Emperor Augustus and his adoptive children to make way for herown son Tiberius as the emperor of Rome.

Steinvall, Alexander January 2009 (has links)
Empress Livia – Murderer or wrongfully accused? An overview of the ancient sources on the empress Livia and what that suggests that shemurdered her husband Emperor Augustus and his adoptive children to make way for herown son Tiberius as the emperor of Rome.This work will analyze the ancient roman sources by the great historians from that time;Tacitus, Suetonius and Cassius Dio, and their works discussing the murder conspiracy of theempress of Rome; Livia.Here I examine what these ancient sources tell about the possible involvement of Livia, on thedeath of Augustus himself and his adoptive sons. Each author to these ancient sources will beexamined and contextualized according to their contemporary time, but also their political andideological views of women in high position and Ceasarism itself. Their characteristics andstyles of their written account will also be examined.The following issues will be dealt with in this work:  What does the ancient sources of; Tacitus, Suetonius and Cassius Dio say about theconspiracy theory in which empress Livia is central.  What is known about the authors of these ancient sources and to what extant mighttheir political and ideological view affect their written account?  Can the allegations directed at Livia be the result of the fact that she was a highlyinfluential woman at her time, something which the ancient authors by romanstandards saw as unfit for a woman, and therefore is mistreated in the written sources?  If so, were all women with power under the same time and circumstances criticized inthe same way in which Livia is portrayed?  Are there any other aspects that have not been treated equally in the past by authorsand researchers, in which new questionable guidelines can be made? As is very important to point out, this work and essentially all others alike will not evenassume to solve the final question if empress Livias was guilty or not of murdering herhusband, Emperor Augustus and/or his adoptive sons. This work is to be foremost accepted asan appendix of other works regarding the same issue.
393

Livia - mördare eller syndabock? : En utvärdering av de antika källorna kring kejsarinnan Livia och vad som talar för att hon mördade Augustus och dennes adoptivsöner för att göra sin egen son Tiberius till kejsare / Empress Livia – Murderer or wrongfully accused? : An overview of the ancient sources on the empress Livia and what that suggests that shemurdered her husband Emperor Augustus and his adoptive children to make way for herown son Tiberius as the emperor of Rome.

Steinvall, Alexander January 2009 (has links)
<p>Empress Livia – Murderer or wrongfully accused?</p><p>An overview of the ancient sources on the empress Livia and what that suggests that shemurdered her husband Emperor Augustus and his adoptive children to make way for herown son Tiberius as the emperor of Rome.This work will analyze the ancient roman sources by the great historians from that time;Tacitus, Suetonius and Cassius Dio, and their works discussing the murder conspiracy of theempress of Rome; Livia.Here I examine what these ancient sources tell about the possible involvement of Livia, on thedeath of Augustus himself and his adoptive sons. Each author to these ancient sources will beexamined and contextualized according to their contemporary time, but also their political andideological views of women in high position and Ceasarism itself. Their characteristics andstyles of their written account will also be examined.The following issues will be dealt with in this work:</p><p> What does the ancient sources of; Tacitus, Suetonius and Cassius Dio say about theconspiracy theory in which empress Livia is central.</p><p> What is known about the authors of these ancient sources and to what extant mighttheir political and ideological view affect their written account?</p><p> Can the allegations directed at Livia be the result of the fact that she was a highlyinfluential woman at her time, something which the ancient authors by romanstandards saw as unfit for a woman, and therefore is mistreated in the written sources?</p><p> If so, were all women with power under the same time and circumstances criticized inthe same way in which Livia is portrayed?</p><p> Are there any other aspects that have not been treated equally in the past by authorsand researchers, in which new questionable guidelines can be made?</p><p>As is very important to point out, this work and essentially all others alike will not evenassume to solve the final question if empress Livias was guilty or not of murdering herhusband, Emperor Augustus and/or his adoptive sons. This work is to be foremost accepted asan appendix of other works regarding the same issue.</p>
394

Externe Vorspannung / External Prestressing

Borer, Erich Karl 02 September 2010 (has links) (PDF)
Mit der vorliegenden Arbeit soll ein Beitrag geleistet werden, die lokalen Tragmechanismen eines Brückenhohlkastens im Bereich der Feldumlenkstellen (Feldlisenen) zu untersuchen und zu optimieren. Beim Entwurf einer Brücke gewinnt die Frage der Dauerhaftigkeit u.a. in Deutschland und der Schweiz eine immer zentralere und grössere Bedeutung. Dadurch können die laufenden Kosten reduziert werden, während ausserhalb dieser beiden Länder im Allgemeinen mehr Gewicht auf die rationelle Fertigung und die Kostenersparnis in der Bauphase gelegt werden. Die Dauerhaftigkeit von extern vorgespannten Brücken mit ihren relativ geringen Wartungs- und Unterhalts- bzw. Instandstellungskosten sind das Hauptargument für diese Bauweise. Bei Vorspannung ohne Verbund sind für externe Spannglieder grössere Verankerungskonstruktionen erforderlich, weil die Spannglieder nicht im Steg selbst, sondern mit einem Mindestabstand zum Steg in Lisenen vorgespannt werden müssen. Über diese Verankerungsstellen werden in Hohlkastenbrücken grosse Kräfte konzentriert in die Stege, Boden- und Fahrbahnplatten eingeleitet. Im Sinne von Gewichtsreduktion des Brückenbauwerks sollen die Feldlisenen möglichst schlank und Platz sparend ausgeführt werden. Nur durch eine sorgfältige Bemessung und Konstruktion der Verankerungs- und Umlenkstellen kann die Voraussetzung für sichere und dauerhafte Brückenbauwerke gewährleistet werden. Die Bruchsicherheit ist dadurch nicht beeinträchtigt. Von grösstem Interesse ist jedoch die Gebrauchstauglichkeit, das heisst die Rissbreiten mit Rücksicht auf Korrosionsschäden in der Bewehrung. Bei den ersten in Deutschland extern vorgespannten Brücken schlug Prof. Eibl für den Stahl III vor, die Spannungen von 240 N/mm2 auf 220 N/mm2 zu begrenzen. In der Richtlinie für externe Vorspannung von 1998 wurden die Spannungen weiter auf 180 N/mm2 reduziert. Um eine unkontrollierte Rissbildung in den hoch bewehrten Verankerungskonstruktionen zu verhindern, sind genaue Kenntnisse der Kraftflüsse und für die Praxis taugliche Bemessungsmodelle notwendig. Die Geometrie und die statische Berechnung der gewählten Umlenkkonstruktion müssen entsprechend gewichtet werden. In dieser Arbeit werden an zwei Vergleichsmodellen die lokalen Tragmechanismen einer extern vorgespannten Hohlkastenbrücke im Bereich der Feldumlenkstelle (Feldlisene) untersucht. Mit linear-elastischen und nichtlinearen numerischen Berechnungen wird abgeklärt, ob unter dem Ansatz einer Spannungserhöhung im Bewehrungsstahl auf 285 N/mm2, die Gebrauchstauglichkeit noch gewährleistet werden kann. Den Berechnungen wird eine Krafteinleitung von 2 x 3 MN mit Umlenkkräften von 4 x 0,64 MN zu Grunde gelegt. Die Berechnungen zeigen, dass das Ziel, mit einer Bewehrung von As = 3,35 % m2/m unter Gebrauchslasten keine Rissbreiten über 0,2 mm auftreten, erreicht werden kann. Die Berechnungen werden zudem an einem Brückenmodell im Massstab 1:1 in einem Belastungsversuch an der Empa in Dübendorf auf ihre Aussagekraft und Richtigkeit überprüft und bestätigt. / This present work which is aimed at contributing to local carrying mechanisms of a bridging box girder in the field of belt reversals, should be investigated and optimized. In designing a bridge the main concern is that of durability; especially in Germany and Switzerland, this is invariably acquiring a more central meaning. In this way recurring expenses can be reduced, whilst beyond these two countries in general more weight is laid on the rational manufacture and cost saving in the construction phases. The durability of externally pre-stressed bridges with their relatively low maintenance and service as well as repair costs are the main arguments for this method of construction. Larger anchorage construction is necessary for pre-tensioning external tensions. This is because the tensions are themselves not placed on the ligament itself, but must be pre-stressed in pilaster strips with a minimum distance. Over these anchorage locations immense energy is concentrated in the large box girder bridges, and thus induced in the ligament, ground and track supporting layers. As far as weight reduction of the bridging structure is concerned, the field pilaster strips should be designed as thin as possible and also be able to save space. Only through careful measuring and construction of the anchor and turning points can the requirements for safe and lasting bridge construction works be guaranteed. The bridge safety is thus not affected. However, the greatest interest is that of userfriendliness, i.e. the width of the fissure with consideration of corrosion damages in the armouring. At the first external pre-stressed bridge in Germany, Prof. Eibl suggested that for the steel III, stressing of 240/Nmm2 should be limited to 220 N/mm2. In the guideline for external pre-stressing of 1998, the tensions were further reduced to 180 N/mm2. In order to prevent an uncontrolled crack formation in the highly armoured anchorage construction, concrete knowledge of the distribution of forces for the applicable measurement models is necessary. The geometry and the statistical calculation of the selected deflect construction must be weighed accordingly. In this project two comparative models were inspected, which tested the local load mechanism of an external pre-stressed box girder bridge in the field redirecting area. With linear elasticity and numerical calculations it is possible to clarify if the serviceability can be allowed under the accretion of a stress increase in the armouring steel to 285 N/mm2. The calculations are based on a load transmission of 2 x 3 MN with a deviation force of 4 x 0,64 MN. The calculations will have a force transmission of 2 x 3 MN with turning forces of 4 x 0.64 MN forming the basis. The calculations portray that the goal to avoid any fissures over 0,2 mm can be achieved, with an armoring of As = 3,35 % m2/m under the service load. Additionally, the calculations will be assessed of their validity and accuracy on a scale of 1:1 in a loading test at the EMPA (the Swiss Federal Laboratories for Materials Testing and Research) in Dübendorf and be therefore confirmed.
395

Higher Order Numerical Methods for Singular Perturbation Problems.

Munyakazi, Justin Bazimaziki. January 2009 (has links)
<p>In recent years, there has been a great interest towards the higher order numerical methods for singularly perturbed problems. As compared to their lower order counterparts, they provide better accuracy with fewer mesh points. Construction and/or implementation of direct higher order methods is usually very complicated. Thus a natural choice is to use some convergence acceleration techniques, e.g., Richardson extrapolation, defect correction, etc. In this thesis, we will consider various classes of problems described by singularly perturbed ordinary and partial differential equations. For these problems, we design some novel numerical methods and attempt to increase their accuracy as well as the order of convergence. We also do the same for existing numerical methods in some instances. We &macr / nd that, even though the Richardson extrapolation technique always improves the accuracy, it does not perform equally well when applied to different methods for certain classes of problems. Moreover, while in some cases it improves the order of convergence, in other cases it does not. These issues are discussed in this thesis for linear and nonlinear singularly perturbed ODEs as well as PDEs. Extrapolation techniques are analyzed thoroughly in all the cases, whereas the limitations of the defect correction approach for certain problems is indicated at the end of the thesis</p>
396

Externe Vorspannung / External Prestressing

Borer, Erich Karl 27 May 2010 (has links) (PDF)
Mit der vorliegenden Arbeit soll ein Beitrag geleistet werden, die lokalen Tragmechanismen eines Brückenhohlkastens im Bereich der Feldumlenkstellen (Feldlisenen) zu untersuchen und zu optimieren. Beim Entwurf einer Brücke gewinnt die Frage der Dauerhaftigkeit u.a. in Deutschland und der Schweiz eine immer zentralere und grössere Bedeutung. Dadurch können die laufenden Kosten reduziert werden, während ausserhalb dieser beiden Länder im Allgemeinen mehr Gewicht auf die rationelle Fertigung und die Kostenersparnis in der Bauphase gelegt werden. Die Dauerhaftigkeit von extern vorgespannten Brücken mit ihren relativ geringen Wartungs- und Unterhalts- bzw. Instandstellungskosten sind das Hauptargument für diese Bauweise. Bei Vorspannung ohne Verbund sind für externe Spannglieder grössere Verankerungskonstruktionen erforderlich. Dies, weil die Spannglieder nicht im Steg selbst, sondern mit einem Mindestabstand zum Steg in Lisenen vorgespannt werden müssen. Über diese Verankerungsstellen werden in Hohlkastenbrücken grosse Kräfte konzentriert in die Stege, Boden- und Fahrbahnplatten eingeleitet. Im Sinne von Gewichtsreduktion des Brückenbauwerks sollen die Feldlisenen möglichst schlank und Platz sparend ausgeführt werden. Nur durch eine sorgfältige Bemessung und Konstruktion der Verankerungs- und Umlenkstellen kann die Voraussetzung für sichere und dauerhafte Brückenbauwerke gewährleistet werden. Die Bruchsicherheit ist dadurch nicht beeinträchtigt. Von grösstem Interesse ist jedoch die Gebrauchstauglichkeit, das heisst die Rissbreiten mit Rücksicht auf Korrosionsschäden in der Bewehrung. Bei den ersten in Deutschland extern vorgespannten Brücken schlug Prof. Eibl für den Stahl III vor, die Spannungen von 240 N/mm2 auf 220 N/mm2 zu begrenzen. In der Richtlinie für externe Vorspannung von 1998 wurden die Spannungen weiter auf 180 N/mm2 reduziert. Um eine unkontrollierte Rissbildung in den hoch bewehrten Verankerungskonstruktionen zu verhindern, sind genaue Kenntnisse der Kraftflüsse und für die Praxis taugliche Bemessungsmodelle notwendig. Die Geometrie und die statische Berechnung der gewählten Umlenkkonstruktion müssen entsprechend gewichtet werden. In dieser Arbeit werden an zwei Vergleichsmodellen, die lokalen Tragmechanismen einer extern vorgespannten Hohlkastenbrücke im Bereich der Feldumlenkstelle (Feldlisene) untersucht. Mit linear-elastischen und nichtlinearen numerischen Berechnungen wird abgeklärt, ob unter dem Ansatz einer Spannungserhöhung im Bewehrungsstahl auf 285 N/mm2, die Gebrauchstauglichkeit noch gewährleistet werden kann. Den Berechnungen wird eine Krafteinleitung von 2 x 3 MN mit Umlenkkräften von 4 x 0,64 MN zu Grunde gelegt. Die Berechnungen zeigen, dass das Ziel, mit einer Bewehrung von As = 3,35 % m2/m unter Gebrauchslasten keine Rissbreiten über 0,2 mm auftreten, erreicht werden kann. Die Berechnungen werden zudem an einem Brückenmodell im Massstab 1:1 in einem Belastungsversuch an der Empa in Dübendorf auf ihre Aussagekraft und Richtigkeit überprüft und bestätigt. / This present work which is aimed at contributing to local carrying mechanisms of a bridging box girder in the field of belt reversals, should be investigated and optimized. In designing a bridge the main concern is that of durability; especially in Germany and Switzerland, this is invariably acquiring a more central meaning. In this way recurring expenses can be reduced, whilst beyond these two countries in general more weight is laid on the rational manufacture and cost saving in the construction phases. The durability of externally pre-stressed bridges with their relatively low maintenance and service as well as repair costs are the main arguments for this method of construction. Larger anchorage construction is necessary for pre-tensioning external tensions. This is because the tensions are themselves not placed on the ligament itself, but must be pre-stressed in pilaster strips with a minimum distance. Over these anchorage locations immense energy is concentrated in the large box girder bridges, and thus induced in the ligament, ground and track supporting layers. As far as weight reduction of the bridging structure is concerned, the field pilaster strips should be designed as thin as possible and also be able to save space. Only through careful measuring and construction of the anchor and turning points can the requirements for safe and lasting bridge construction works be guaranteed. The bridge safety is thus not affected. However, the greatest interest is that of userfriendliness, i.e. the width of the fissure with consideration of corrosion damages in the armouring. At the first external pre-stressed bridge in Germany, Prof. Eibl suggested that for the steel III, stressing of 240/Nmm2 should be limited to 220 N/mm2. In the guideline for external pre-stressing of 1998, the tensions were further reduced to 180 N/mm2. In order to prevent an uncontrolled crack formation in the highly armoured anchorage construction, concrete knowledge of the distribution of forces for the applicable measurement models is necessary. The geometry and the statistical calculation of the selected deflect construction must be weighed accordingly. In this project two comparative models were inspected, which tested the local load mechanism of an external pre-stressed box girder bridge in the field redirecting area. With linear elasticity and numerical calculations it is possible to clarify if the serviceability can be allowed under the accretion of a stress increase in the armouring steel to 285 N/mm2. The calculations are based on a load transmission of 2 x 3 MN with a deviation force of 4 x 0,64 MN. The calculations will have a force transmission of 2 x 3 MN with turning forces of 4 x 0.64 MN forming the basis. The calculations portray that the goal to avoid any fissures over 0,2 mm can be achieved, with an armoring of As = 3,35 % m2/m under the service load. Additionally, the calculations will be assessed of their validity and accuracy on a scale of 1:1 in a loading test at the EMPA (the Swiss Federal Laboratories for Materials Testing and Research) in Dübendorf and be therefore confirmed.
397

Effect [sic] des paramètres métallurgiques sur le comportement d'usinage des alliages 356 et 319 (étude de forage et de taraudage) /

Tash, Mahmoud, January 2005 (has links)
Thèse (D.Ing.) -- Université du Québec à Chicoutimi, 2005. / Bibliogr.: f. 240-252. Document électronique également accessible en format PDF. CaQCU
398

Investigation of novel cooling methods to enhance aerospace component manufacturing practices

Koen, Devan 12 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: The aerospace industry actively pursues innovation, especially in materials and their use in new applications, to improve their aircraft as well as their competitive position. Ti-6Al-4V has been available now for more than 50 years. Yet, in the new generation of aircraft using structural composites, a dramatic increase in the proportion of Ti-6Al-4V will be seen along with emerging application in automotive and chemical industries. This material possesses superior material properties compared to conventional materials such as steel and aluminium, although it is at the expense of machinability. Researchers are therefore actively searching for improved cutting technologies to improve production rates for Ti-6Al-4V. At higher cutting speeds than the industry norm of 60 - 90 m/min, machining becomes a challenge, resulting in low productivity on titanium parts. The limiting factor in the machining of Ti-6Al-4V is high tool temperatures of the order of 1000oC, caused by its resistance to absorb heat and good mechanical strength at elevated temperatures. The result is extreme temperatures that are concentrated on the cutting edge of the tool. The challenge to improve the tool life is therefore focused on removing heat from the insert. Liquid nitrogen was identified as a good candidate as coolant with the additional advantage of being environmentally friendly. The research presented investigates the use of a gravity feed enclosed liquid nitrogen cooling system to improve the tool life of the cutting inserts. The liquid nitrogen is contained on the insert rake face by means of a tool cap. To improve the effectiveness of the cooling method, a polycrystalline diamond (PCD) insert was used. This insert has a considerably higher thermal conductivity that aids in cooling the cutting edge. Tungsten carbide inserts are used for benchmark testing. The round tungsten carbide inserts with conventional cooling performed exceptionally well for machining titanium compared to square inserts, yielding exceptional tool life improvements while significantly increasing the material removal rate. Positive results were recorded with the liquid nitrogen cooling system when used with the polycrystalline diamond cutting insert. A number of far reaching performance issues are identified relating to the design of the tool cap that hindered clear scientific outputs. From a research perspective, the project makes a contribution to the knowledge base in this field. Additionally a new approach in cooling was investigated, resulting in clear indications of design changes required. / AFRIKAANSE OPSOMMING: Die lugvaart industrie streef aktief innovasie na, veral op die gebied van materiale en hul gebruike, om hul vliegtuie en kompeterende posisie in die mark te verbeter. Ti-6Al-4V is al vir meer as 50 jaar beskikbaar. ‘n Drastiese verhoging in die aanvraag na Ti-6Al-4V deur die lugvaart, motor en chemiese industrieë word verwag wanneer die volgende geslag vliegtuie wat koolstofvesel as strukturele materiaal begin gebruik, in produksie gaan. Die materiaal het beter materiaaleienskappe as konvensionele materiale soos staal en aluminium, maar dit kom egter teen die prys van masjieneerbaarheid. Ti-6Al-4V se masjienering bo die industrie norm van 60 – 90m/min is ‘n groot uitdaging. Navorsers soek daarom deurentyd na verbeterde sny tegnologieë om die produksie tempo van Ti-6Al-4V te verbeter. Die beperkende faktor vir Ti-6Al-4V masjienering is die temperatuur wat genereer word. Die weerstand van die materiaal om hitte te absorbeer en sy goeie meganiese eienskappe veroorsaak dat temperature in die beitel 1000oC bereik. Hierdie temperature word egter op die snykant van die beitel gekonsentreer. Die uitdaging is dus om hierdie temperature in die beitel te beheer. Vloeibare stikstof is geïdentifiseer as ‘n goeie kandidaat vir verkoeling met die bykomende voordeel dat dit omgewingsvriendelik is. Die navorsing wat hier uiteengesit word, ondersoek die gebruik van ‘n geslote kamer beitelverkoelingstelsel wat deur gravitasie met vloeibare stikstof voorsien word om die beitel leeftyd te verbeter. Die oppervlak van die beitel word in hierdie konsep direk aan die vloeibare stikstof blootgestel. Om die effektiwiteit van die stelsel te verbeter word van PCD beitels gebruik gemaak. Die beitel se verbeterde hittegeleidingsvermoë help om die beitel se snykant koel te hou. Tungstenkarbied beitels word gebruik om ‘n standaard te stel vir eksperimentele analise. Die ronde tungstenkarbied beitels en konvensionele verkoeling het verstommend goed presteer vir Ti-6A-4V masjienering in vergelyking met vierkantige beitels. Die materiaalverwyderingstempo is aansienlik verhoog sonder om die beitel se leeftyd in te boet. Positiewe resultate is waargeneem met die vloeibare stikstof sisteem saam met die PCD beitels. ‘n Aantal verreikende uitdagings is geïdentifiseer wat suiwer wetenskaplike afleidings bemoeilik. Hierdie probleme kan almal aan die ontwerp van die toerusting toegeskryf word. Die werk lewer egter steeds ‘n bydrae tot die kennis in die veld. ‘n Bykomende benadering vir verkoeling is ondersoek wat duidelik ontwerp-veranderings aandui.
399

Torneamento do aço endurecido AISI D6 utilizando mínima quantidade de fluido de corte / Turning of high hardness aisi d6 steel with minimum quantity of cutting fluid

Bonfá, Miguel Mandú 30 August 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Hardened steel is usually machined under dry condition. Application of an overhead flood cooling generally leads to premature tool failure because the heat generated that helps the shearing process needed to form the chips is reduced by its cooling action. This work proposes to study the application of MQF (Minimum Quantity of Cutting Fluid) when turning the heat treated hardened AISI D6 steel with PCBN (Polycrystalline Cubic Boron Nitride) tools and compare with the dry machining. The spray of a vegetable based cutting fluid was applied between the workpiece and the flank face of the tool. Overhead direction of the MQF and between the secondary flank face of the tool and the workpiece were also tested. Tool wear (VB), surface roughness (Ra, Rz e Rq) and cutting forces (Fx, Fy e Fz) were considered the output variables and the results were compared to those obtained when cutting in dry condition. The influence of the input parameters: cutting speed and feed rate, as well as their interactions were statistically analyzed. Considering the tool wear and the surface roughness, the application of the cutting fluid by the MQF technique in the direction between the flank face and the workpiece showed better results than the dry condition when employing the lowest feed rate of 0.05 mm/rev, regardless the cutting speed used. This cutting fluid application technique also presented good results when the cutting speed of 310 m/min was tested, regardless the feed rate employed. Therefore, this cutting speed should be recommended for high production in turning of AISI D6 steel with the MQF technique. The application of MQF through other directions (overhead and between the secondary flank face and the workpiece) also showed competitive results. / Aços temperados são geralmente usinados na condição a seco. A aplicação de uma refrigeração geralmente conduz a uma falha prematura da ferramenta porque o calor gerado durante o processo, que ajuda o cisalhamento, é reduzido pela ação refrigerante do fluido de corte. Este trabalho propõe estudar a aplicação do método de MQF (Minima Quantidade de Fluido) ao tornear o aço tratado termicamente, classe AISI D6, utilizando ferramenta de PCBN (Nitreto Cúbico de Boro Policristalino) e comparar com a condição a seco. A pulverização de um fluido de corte de base vegetal foi aplicada entre a peça de trabalho e a superfície de folga da ferramenta. A direção sobre-cabeça e entre a superfície de folga secundária e a peça também foram testadas em algumas condições de corte. O desgaste da ferramenta (VB), a rugosidade superficial (Ra, Rz e Rq) e as forças de usinagem (Fx, Fy e Fz) foram utilizadas como parâmetros de saída e seus resultados foram comparados com os resultados obtidos nos testes na condição a seco. As influências dos parâmetros de entrada: velocidade de corte e avanço, bem como suas interações, nas variáveis de saída (desgaste da ferramenta, rugosidade superficial e forças de usinagem) foram analisados através de métodos estatísticos. Considerando o desgaste da ferramenta e a rugosidade superficial da peça, a aplicação do fluido de corte pela técnica MQF na direção da superfície de folga principal apresentou melhores resultados que a condição a seco, quando se utilizou o menor avanço testado de 0,05 mm/rev, independente da velocidade de corte. Esta técnica também apresentou bons resultados quando a velocidade de corte de 310 m/min foi testada, independente do avanço. Assim, esta velocidade de corte deve ser recomendada para uma boa produção no torneamento do Aço AISI D6 com a técnica MQF. A aplicação do MQF nas outras direções (sobrecabeça e na superfície de folga secundária) também mostrou resultados competitivos. / Mestre em Engenharia Mecânica
400

Visual Communication between Truck Drivers and the Surroundings : - A Master’s Thesis Project for Increasing Communication and Reducing Accidents between HGV and VRUs

Styf, Emma January 2018 (has links)
In recent years, accidents between trucks and other vehicles have decreased while accidents be-tween trucks and vulnerable road-users have increased. The reason for this is unknown, which is why this Master’s Thesis project was initiated. The project is a co-operation between two students from two different universities, LTU and KTH, done for Volvo GTT in Gothenburg. A user study containing interviews and co-rides has been executed with truck drivers in the Gothenburg area during the autumn of 2017. A survey was also sent to different organizations for cyclists, motorcyclists, car drivers and to Facebook groups for the two universities. Critical situations mentioned by the truck drivers were chosen with the help of the survey answers from other road-users. Right hand turns with a truck that crosses a bike lane and intersections with a zebra crossing were the situations the project focused on, based on the Volvo Trucks Safety Report 2017 which stated those situations as the most dangerous. Serious accidents occurring when a truck turns right is when vulnerable road-users end up under the truck’s back wheels, which cuts corners. This made the project focus on trying to find a solution that could reduce this type of accident. The project also concentrated on increasing the commu-nication at intersections, based on the survey comments where it became clear that eye contact is insufficient, which led to focus on communication between trucks and fellow road-user instead. Through benchmarking, literature reviews and idea generation the final concept solution was cre-ated and developed after a workshop. The final concept solution is a turning projection that visualizes the dangerous area when a truck is turning and a light matrix in the front grille for increasing the understanding, visually, of the truck driver’s intentions of slowing down or speeding up. The final concept solution contains a zebra crossing projection in the front of the truck to facilitate the communication today, and in the future to even replace eye contact and gestures done between truck driver and fellow road-users at crossings. Further development of the concept solution includes choices and adaption of available technology and research concerning legislation for color usage on lights and projections to the front and sides of the trucks.

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