Abstract The effects of restoration and certain elements, nitrogen, sulphur, calcium and Misch metal, on the hot ductility of austenitic, high-alloyed austenitic and duplex stainless steels have been investigated by means of hot rolling, hot tensile, hot bending and stress relaxation tests. The results of these different testing methods indicated that hot rolling experiments using stepped specimens is the most effective way to investigate the relationship between the softening and cracking phenomena under hot rolling conditions. For as-cast, high-alloyed and duplex stainless steels with a low impurity level, the cracking tendency was observed to increase with increasing pass strain and temperature, being minimal for the small strain of 0.1. No cracking occurred in these steels when rolled in the wrought condition. It could be concluded that the cracking problems are only exhibited by the cast structure with the hot ductility of even partially recrystallised steel being perfectly adequate. However, the recrystallisation kinetics of the high-alloyed austenitic stainless steels, determined by stress relaxation and double-pass rolling tests, were found to be so slow that only partial softening can be expected to occur between roughing passes under normal rolling conditions. In the duplex steel, the restoration is fairly fast so that complete softening can occur within typical interpass times in hot rolling, while certain changes in the phase structure take place as well. Sulphur was found to be an extremely harmful element in duplex stainless steel with regard to their hot ductility so that severe cracking can take place with sulphur content above 30 ppm. However, the effect of sulphur can be eliminated by reducing its content and by calcium or Misch metal treatments that significantly increase the number and decrease the average size of the inclusions. It seems that the desulphurisation capacity of an element is the most important property for assessing its usefulness in reducing the detrimental influence of sulphur. The hot ductility of type 316L stainless steel determined by tensile tests was found to be better for nitrogen content of 0.05 wt-% than 0.02%, while in double-hit tensile tests the hot ductility values were identical. The mechanism whereby nitrogen affects hot ductility remains unclear but a retarding effect on static recrystallisation was observed.

Experiments are done using a smooth solid rigid homogeneous acrylic sphere rolling on an inclined plane which is submerged in water. The motivation for these experiments comes from a need to understand a class of solid-fluid interaction problems that include sediment transport, movement of gravel on ocean floor and river bed due to water currents. Experiments are performed in a glass water tank 15 cm wide by 14 cm deep by 61 cm long which can be tilted to desired angle. The sphere is released from rest on the inclined false bottom of the tank in quiescent water. Our experimental study has twofold aim: (1)to study the boundary layer separation, the three-dimensional eddying motion in the wake and the near-wake structure and(2) to establish hydrodynamic force coefficients by analyzing kinematical data of the sphere motion from start to till it attains terminal velocity. Experiments are carried out at moderate Reynolds number Rearound1500. Previous studies on the first problem exist in the literature for Reup to 350. Previous studies on the second problem do not clearly define the added-mass coefficient and the influence of the water tank side-walls on the drag coefficient. In the first study, the characterization of the wake is done using flow visualization methods (fluoresce in dye visualization and particle streak visualization) and Particle Image Velocimetry (PIV). Laser light sheet obtained from an argon ion continuous laser beam is taken in different orientations to illuminate the fluoresce in dye or 14 m silver-coated hollow glass spheres. These experiments show that the wake behind the rolling sphere up to 1.6 diameters (or 1.6D) downstream is confined within height 1.2Dand width1.2D. At about 1.8Ddownstream, the wake sways alternately on either side of the equatorial plane, moving in lateral-vertical direction and moving out of the confining region; this gives zigzag appearance to the wake. Also in these experiments, we observe that the flow separations from the surface of the rolling sphere show three separation zones. The eddies shed from the primary separation surface on the upper hemisphere are symmetrical about the equatorial plane with Strouhal number St=1.0. The primary separation is affected by the symmetrical secondary separations on the rear surface in the piggyback region — it is the region near the upper rear surface of the sphere behind the transverse equatorial plane and below the primary separation surface. The lower eddies below the primary separation zone are shed alternately on either side of the equatorial plane with shedding frequency St=0.5. Our experiments show that there is a viscous blockage of width 0.4Dat the crevice near the point of contact. On either side of the viscous blockage at the crevice, we see weak symmetric eddies. Based on our experimental observations, we proceed to build a simple physical model of the separated flow on the surface of the rolling sphere. In the second study, the motion of the sphere is photographed and paired data of the displacement and time is obtained for the sphere motion from the start of motion till terminal velocity is reached at about 4.5 sphere diameters from the point of release of the sphere. Equation of motion of the sphere is solved numerically treating added-mass coefficient Ca and drag coefficient Cd as parameters. Experimental data is fitted on these solutions and the best fit gives the values of the force coefficients. Theoretical value of Ca equal to 0.621 is confirmed experimentally. Value of Cd is found to be 1.23 at Re=990 and it is 1.06 at Re= 1900. Side-wall effects become important for ratio of diameter of sphere to width of tank greaterthan0.20.

En informatique, la vision par ordinateur s’attache à extraire de l’information à partir de caméras. Les capteurs de celles-ci peuvent être produits avec la technologie CMOS que nous retrouvons dans les appareils mobiles en raison de son faible coût et d’un encombrement réduit. Cette technologie permet d’acquérir rapidement l’image en exposant les lignes de l’image de manière séquentielle. Cependant cette méthode produit des déformations dans l’image s’il existe un mouvement entre la caméra et la scène filmée. Cet effet est connu sous le nom de «Rolling Shutter» et de nombreuses méthodes ont tenté de corriger ces artefacts. Plutôt que de le corriger, des travaux antérieurs ont développé des méthodes pour extraire de l’information sur le mouvement à partir de cet effet. Ces méthodes reposent sur une extension de la modélisation géométrique classique des caméras pour prendre en compte l’acquisition séquentielle et le mouvement entre le capteur et la scène, considéré uniforme. À partir de cette modélisation, il est possible d’étendre le calcul de pose habituel (estimation de la position et de l’orientation de la scène par rapport au capteur) pour estimer aussi les paramètres du mouvement. Dans la continuité de cette démarche, nous présenterons une généralisation à des mouvements non-uniformes basée sur un lissage des dérivées des paramètres de mouvement. Ensuite nous présenterons une modélisation polynomiale du «Rolling Shutter» et une méthode d’optimisation globale pour l’estimation de ces paramètres. Correctement implémenté, cela permet de réaliser une mise en correspondance automatique entre le modèle tridimensionnel et l’image. Pour terminer nous comparerons ces différentes méthodes tant sur des données simulées que sur des données réelles et conclurons. / Computer Vision, a field of Computer Science, is about extracting information from cameras. Their sensors can be produced using the CMOS technology which is widely used on mobile devices due to its low cost and volume. This technology allows a fast acquisition of an image by sequentially exposin the scan-line. However this method produces some deformation in the image if there is a motion between the camera and the filmed scene. This effect is known as Rolling Shutter and various methods have tried to remove these artifacts. Instead of correcting it, previous works have shown methods to extract information on the motion from this effect. These methods rely on a extension of the usual geometrical model of cameras by taking into account the sequential acquisition and the motion, supposed uniform, between the sensor and the scene. From this model, it’s possible to extend the usual pose estimation (estimation of position and orientation of the camera in the scene) to also estimate the motion parameters. Following on from this approach, we will present an extension to non-uniform motions based on a smoothing of the derivatives of the motion parameters. Afterwards, we will present a polynomial model of the Rolling Shutter and a global optimisation method to estimate the motion parameters. Well implemented, this enables to establish an automatic matching between the 3D model and the image. We will conclude with a comparison of all these methods using either simulated or real data.

Very often defects are present in rolled products. For wire rods, defects are very deleterious since the wire rods are generally used directly in various applications. For this reason, the market nowadays requires wire rods to be completely defect-free. Any wire with defects must be rejected as scrap which is very costly for the production mill. Thus, it is very important to study the formation and evolution of defects during wire rod rolling in order to better understand and minimize the problem, at the same time improving quality of the wire rods and reducing production costs. The present work is focused on the evolution of artificial defects during rolling. Longitudinal surface defects are studied during shape rolling of an AISI M2 high speed steel and a longitudinal central inner defect is studied in an AISI 304L austenitic stainless steel during ultra-high-speed wire rod rolling. Experimental studies are carried out by rolling short rods prepared with arteficial defects. The evolution of the defects is characterised and compared to numerical analyses. The comparison shows that surface defects generally reduce quicker in the experiments than predicted by the simulations whereas a good agreement is generally obtained for the central defect.

Ziel dieser Arbeit war die Entwicklung neuer Methoden zur Untersuchung zirkulärer RNA. Das erste Projekt dieser Arbeit beschäftigte sich mit der Erstellung eines universell einsetzbaren Protokolls zur Generierung einer funktionalisierten zirkulären RNA. Hierbei konnte zunächst erfolgreich eine Vorschrift zur Herstellung unmodifizierter circRNA etabliert werden. Im zweiten Schritt gelang auch die Generierung einer zirkulären RNA mit Alkin-Funktionalisierung. Geringe Ausbeuten gaben Anlass zur Entwicklung eines alternativen Verfahrens, bei dem die Zyklisierung von Kopf-Schwanz modifizierter RNA durch CuAAC vorgenommen werden sollte. Dabei konnte zunächst eine 5‘-azidmodifizierte RNA durch in vitro Transkription gebildet werden, die anschließend am 3‘-Terminus mit einem 3‘ alkinmodifizierten Baustein mit Aminfunktionalität versehen wurde. Daraufhin konnte erfolgreich eine Zyklisierung mittels CuAAC vorgenommen werden. Ein grundlegendes Problem bei diesen Arbeiten war der Nachweis, dass die gebildete RNA tatsächlich in zirkulärer Form vorlag. Im Rahmen des zweiten Projektes dieser Arbeit wurde ein Assay zur direkten Unterscheidung von zirkulären und linearen Transkripten etabliert. Mittels reverser Transkription konnte ein rolling circle Mechanismus mit dem zirkulären Transkript durchgeführt werden, was in einer multimeren cDNA resultierte. Nach Amplifizierung über qPCR ermöglichteeine Gelanalyse den Nachweis eines spezifischen Bandenmusters für das circRNA-Transkript, wohingegen das lineare Transkript lediglich eine monomere Bande generierte. Anschließend erfolgte die Weiterentwicklung des Assays zu einer spezifischen Nachweismethode für zirkuläre RNA in biologischen Proben.Dabei kann eine abschließende Gelanalyse zur Identifizierung von falsch-positiven Ergebnissen genutzt werden. Die hier etablierte Methode ermöglicht künftig einen schnellen und einfachen Nachweis von circRNA beim Screeningvon biologischen Proben. / Circular RNAs belong to the group of long, non-coding RNAs and have gene regulating functions, comparable to miRNA. However, the field of circRNA research is proceeding slowly due to the lack of efficient analytical methods. That‘s the reason why the development of new analytical methods plays a keyrole within characterisation and identification of circRNAs. This thesis comprises two projects dealing on one hand with the creation of a protocol for the generation of functional circRNA on and the other hand, an assay to differentiate circular and linear RNA. For the generation of circRNA a non-modified circRNA was produced as positiv control by using T4 RNA ligase 2. After the addition of a modification step with T4 RNA ligase 1, it was possible to generate circRNA with alkyne functionalization. Due to limited yields of modified circRNA, the protocol was adapted and a protocol for chemical ligation was established. In this new procedure a RNA with 5‘-azido modification was generated by in vitro transcription, followed by incorporation of a 3‘-alkyne modified building block with additional amine funktionality at the RNA-3‘-end. Consecutively, it was possible to perform a cyclization with the double modified RNA by CuAAC. The second project comprises the establishment of an assay in order to differentiate circular and linear RNA. A rolling circle mechanism was utilized by reverse transcription of a circular RNA transcript, resulting in a multimeric cDNA. Following DNA amplification by qPCR, a specific fragmentation pattern for circRNA was verified by gel electrophoresis. In contrast to this, for linear RNA, a monomeric DNA pattern was seen. Subsequently the assay was advanced to a detection method for circular RNA in biological samples. A final gel electrophoresis allows the identification of false-positive results. In the future, the here developed method can be applied for fast and easy detection of circRNAs in biological samples.

Bakgrund: Konventionell budgetering har fått utstå betydande kritik under de senaste decennierna, där många menar att den inte är lämplig i dagenssnabbrörliga och globala marknad. Ett flertal organisationer har övergett konventionell budgetering, och rörelsen eller filosofin berördetta kallas för Beyond Budgeting (BB). Grundprinciperna i denna filosofi är en organisationsstruktur där mer ansvar och tillit placeras hos den operativa delen av organisationer. Detta är menat att ge mer frihet till enskilda medarbetare men väcker frågor om agentteori och organisatorisk kontroll. Controllers traditionella roll har setts som ett verktyg för ledningen att utöva kontroll och motverka agentteorins moraliskarisk. Frågan är hur denna roll påverkas av en allt mindre strikt form av kontroll, vilka faktorer som kan tänkas påverka denna roll och hur rollen redan har förändrats. Syfte: Studiens syfte är att undersöka hur controllerrollen och budgetarbete ser ut i dagens organisationer samt om kritiken mot budgetarbete, så som filosofin BB beskriver den, faktiskt stämmer i dagens organisationer. Ytterligare undersöker studien till vilken grad BB som metod har implementerats i dessa organisationer. Metod: Semi-strukturerade intervjuer med sex stycken respondenter inom flertalet olika organisationer har agerat som empirisk data. Denna data harsedantranskriberats och analyserats i enlighet med den deduktiva ansatsen, där de teorier vi funnit har applicerats. Analysen skedde genom en tematisk analys där teman och kategorier funnits för att påvisa samband inför slutsatsen. Slutsats: Studien tyder på att controllers idag har en hög grad av kontroll över deras arbete samt att arbetet huvudsakligen är analytiskt och framåtblickande. Delar av respondenterna anser sig ha en beslutsfattande roll och arbetar huvudsakligen enskilt men har ett brett kontaktnät. Rollen kan till viss del beskrivas som en affärspartner men vi fann stora skillnader mellan respondenterna. Bland respondenterna var det vanligast att använda en toppstyrd budget, där enskilda affärsenheter har mindre inflytande. Denna budget kompletterades sedan med prognoser. Vi fann att delar av kritiken mot konventionell budgetering stämde in bland respondenternas organisationer, samt att aspekter av BB har implementerats. / Background: Conventional budgeting has endured a lot of criticism in the last decades as many argue it is not suitable for today's agile and globalized market. Several organizations have taken the step to abandon conventional budgeting and the movement, or philosophy, regarding this matter is known as Beyond Budgeting (BB). The core principle of this philosophy are an organizational structure where a higher degree of responsibility and trust is placed on the operative sections of the organization. By doing this a much higher degree of liberty is granted to partners in the organization, but it raises questions regarding agent theory and organizational control. The traditional role of the controller has been to function as a tool for upper management to exercise control and counteract the moral hazard of agency theory. The question then is how this role is affected by a much less strict form of control, and which factors can be seen to affect the role as well as which factors that have already affected it.   Purpose: The purpose of the study is to examine the role of the controller and how budgeting of modern organizations are handled as well as how the accurate the critique aimed at budgeting is, as it is described by the philosophy of BB. Furthermore, the study aims to examine to which degree the subject organizations has implemented or embraced the principles of BB.  Method: The study is built on semi-structured interviews with a total of six participants, based in several organizations, which have acted as the empirical data. This data has been transcribed and analyzed in accordance with the studies’ deductive approach upon which our studied theories have been applied. The analysis has been based on a thematic analysis where the goal has been to find common themes and categories.    Conclusion: The study has found that controllers today have a high degree of control regarding how they choose to perform their work, which has been found to be primarily analytical and forward-looking in nature. Some of the controllers consider themselves to have a decision-making role, and while their work is primarily done alone, they have a wide array of contacts. The role can to a degree be described as a business partner, but the study has found large differences among participants in this regard. Among the participants it was most common to use a conventional budget, set by upper management where local business units have limited influence. This budget was complemented with forecasts. The study also found that among the participant’s organizations, some of the critique towards conventional budgeting was accurate to a certain degree. In addition, we found that aspects of BB had been implemented.

Very often defects are present in rolled products. For wire rods, defects are very deleterious since the wire rods are generally used directly in various applications. For this reason, the market nowadays requires wire rods to be completely defect-free. Any wire with defects must be rejected as scrap which is very costly for the production mill. Thus, it is very important to study the formation and evolution of defects during wire rod rolling in order to better understand and minimize the problem, at the same time improving quality of the wire rods and reducing production costs. The present work is focused on the evolution of artificial defects during rolling. Longitudinal surface defects are studied during shape rolling of an AISI M2 high speed steel and a longitudinal central inner defect is studied in an AISI 304L austenitic stainless steel during ultra-high-speed wire rod rolling. Experimental studies are carried out by rolling short rods prepared with arteficial defects. The evolution of the defects is characterised and compared to numerical analyses. The comparison shows that surface defects generally reduce quicker in the experiments than predicted by the simulations whereas a good agreement is generally obtained for the central defect. / QC 20101105

Работа посвящена исследованию процесса радиально-сдвиговой прокатки прутков из титанового сплава ВТ22. Выполнен анализ напряженно-деформированного состояния радиально-винтовой прокатки двух заготовок из титанового сплава ВТ22 диаметром 130 мм и 105 мм с использованием программы QForm. Проведены расчеты основных параметров процесса прокатки горячекатаных прутков: назначен режим обжатий, определена частота вращения валков по проходам и временные характеристики процесса, рассчитаны энергосиловые параметры. Выполнены конструкторские расчёты рабочей клети стана винтовой прокатки. / The work is devoted to the study of the process of radial-displacement rolling of rods made of titanium alloy VT22. An analysis of the stress-strain state of radial-displacement rolling of two blanks made of titanium alloy VT22 with a diameter of 130 mm and 105 mm using the QForm program was performed. Calculations of the main parameters of the hot-rolled bars rolling process have been carried out: the compression mode has been assigned, the rotation frequency of the rolls along the passages and the time characteristics of the process have been determined, and the power parameters have been calculated. Design calculations of the working stand of the screw rolling mill have been performed.

The wheel-rail contact is at the core of all research related to vehicletrackinteraction. This tiny interface governs the dynamic performanceof rail vehicles through the forces it transmits and, like any high stressconcentration zone, it is subjected to serious damage phenomena. Thus,a clear understanding of the rolling contact between wheel and rail is keyto realistic vehicle dynamics simulation and damage analysis. In a multi-body dynamics simulation, the demanding contact problemshould be evaluated at about every millisecond for several wheel-rail pairs.Hence, a rigorous treatment of the contact is highly time-consuming.Simplifying assumptions are therefore made to accelerate the simulationprocess. This gives rise to a trade-o between the accuracy and computationaleciency of the contact model in use. Conventionally, Hertz+FASTSIM is used for calculation of the contactforces thanks to its low computational cost. However, the elliptic patchand pressure distribution obtained by Hertz' theory is often not realisticin wheel-rail contact. Moreover, the use of parabolic traction bound inFASTSIM causes considerable error in the tangential stress estimation.This combination leads to inaccurate damage predictions. Fast non-elliptic contact models are proposed by others to tacklethis issue while avoiding the tedious numerical procedures. The studiesconducted in the present work show that the accuracy of these models iscase-dependent. To improve the accuracy of non-elliptic patch and pressure estimation,a new method is proposed. The method is implemented in an algorithmnamed ANALYN. Comparisons show improvements in patch and, particularly,pressure estimations using ANALYN. In addition, an alternative to the widely-used FASTSIM is developed, named FaStrip. Unlike FASTSIM, it employs an elliptic traction boundand is able to estimate the non-linear characteristic of tangential stressdistribution. Comparisons show more accurate estimation of tangentialstress and slip velocity distribution as well as creep forces with FaStrip. Ultimately, an ecient non-elliptic wheel-rail contact model consistingof ANALYN and FaStrip is proposed. The reasonable computationalcost of the model enables it to be used on-line in dynamics simulationand its accuracy can improve the damage predictions. / <p>QC 20160202</p>

Particulate reinforced Al alloy composites (AlMCs) are recognized as important structural materials due to their lightweight, high modulus and strength and high wear resistance. In order to understand the effect of matrix, reinforcement and secondary processing techniques on the microstructure development and mechanical properties of AlMCs produced by powder metallurgy routes, Al alloy composites reinforced with three types of reinforcements by different secondary processing techniques have been produced and examined. Fabrication of Al or 6061Al alloy based composites reinforced with nano-sized SiC particles (~500nm), micro-sized (<25µm) quasicrystalline alloy particles (hereinafter referred to as “NQX”) and micro-sized Nb particles (~130µm) has been carried out by powder metallurgy routes followed by extrusion or cold rolling. After extrusion, a homogeneous distribution of secondary particles has been obtained with rare interfacial reaction products. The 6061Al/SiC composites exhibit superior mechanical properties than either monolithic alloys or composites reinforced with micro-sized particles with retained ductility while the 6061Al/NQX and 6061Al/Nb composites show limited improvement in tensile strength mainly due to their reinforcement size and poor interfacial bonding. After cold rolling, the evolution in microstructure, texture and strength has been analysed. A typical near β fibre texture with highest intensities near Copper and Brass orientations has been developed for 6061Al/NQX and 6061Al/Nb composites. For 6061Al/SiC composites, a randomized texture with very small grains has achieved due to the presence of the non-deformable SiC particles. Mechanical property tests including microhardness, three-point bending tests and tensile tests have been carried out on cold rolled samples and the results exhibit some level of improvement when compared with as-extruded samples due to work hardening. Finally, the work moves on to the general discussion based on the previous result chapters. The microstructural development related to reinforcement, matrix and interfacial areas during extrusion and cold rolling has been summarised and the correlation between microstructure and mechanical properties has been discussed. The thesis provides a thorough understanding of AlMCs produced by powder metallurgy routes in terms of matrix, reinforcement and processing techniques. It can provide reference to the future development of AlMCs for high strength applications.