Dissertations / Theses on the topic 'Controlled rolling'

Thermomechanical treatments involving recrystallisation controlled rolling process of hot rolling strip mills were simulated in a Gleeble-1500 testing machine. Five vanadium and one vanadium-titanium microalloyed HSLA steels were used for these simulations. Specimens of vanadium steels were heated to 1170°C to simulate slab reheating, prior to a 50% upset reduction at 1060°C, The specimens were then cooled rapidly to the simulated coiling temperatures of 950°C to 600°C and held for half an hour then air cooled to room temperature. Nitrogen analysis established that the maximum volume fraction of VN coincided with the minimum ferrite grain size at a simulated coiling temperature of 700°C. The resultant ferrite grain size indicated that the VN precipitated in the ferrite restricted the ferrite grain growth. The maximum VN precipitation that was observed at this temperature was considered to be a function of the vanadium diffusion in the ferrite and the temperature at which the austenite to ferrite transformation is completed. Quenched specimens following deformation at 1060°C showed that strain induced VN precipitation was detected when the equilibrium solubility product calculations predicted the formation of VN. The measured VN precipitation based upon nitrogen analysis, was less than that predicted. Comparison of detected VN at coiling temperatures of 600°C to 950°C for specimens subjected to 50% deformation at 1060°C with specimens without deformation showed that the deformation increased the VN precipitation. Using the experimentally determined ferrite grain size, volume fraction and mean particle size of the precipitated VN, the corresponding yield strength has been calculated for the range of coiling temperatures examined. These calculated yield strengths lie within the range determined experimentally on similar vanadium micro alloyed HSLA steels. The reheating behaviour of the vanadium-titanium steel was investigated by quenching specimens from 900°C to 1500°C after holding for half an hour at the respective temperatures. Insoluble nitrogen analysis indicated that VN completely dissolved below 1100°C and TiN started to dissolve in austenite at approximately 1300°C. The measured insoluble nitrogen content indicated the existence of TixV₁-xN. The measurement of size distribution of precipitates showed that the dissolution of precipitates of less than 10 nm resulted in abnormal austenite grain growth. It was thought that the results for AIN detected using the Beeghly method [Beeghly49, United Steel 62] were influenced by dissolution of the finer sized VN and TiN precipitates. This was because the detected AIN was in excess of that calculated from the equilibrium solubility for the remaining nitrogen content based upon the measured acid insoluble nitrogen content being combined as TiN. The nitrogen content detected as being associated with AIN was greater than that detected as the acid soluble nitrogen content that is defined as the total amount of nitrogen in the form of aluminium nitride, iron nitrides and interstitial nitrogen. X-ray diffraction of residues separated from specimens reheated at 900°C and 1350°C using 17% v/v dilute sulphuric acid showed that VN and TiN precipitates were present in the specimen reheated at 900°C, while there was only TiN detected at 1350°C, Precipitates extracted from reheated specimens using carbon replicas were identified using a convergent beam electron diffraction method. The indexing of dual spot diffraction patterns established that VN had precipitated on the surfaces of existing TiN precipitates with the same crystal orientation as the initial TiN. These dual spot diffraction patterns were not observed in specimens reheated above 11OO°C. The thermomechanical treatment of a vanadium-titanium steel in hot rolling strip mills was simulated using the Gleeble-1500 testing machine. The rolling was simulated by carrying out four passes each of 20% deformation on specimens at finish rolling temperatures of 1050°C to 850°C. An additional experiment involved a final deformation that varied from 10% to 30% for a finish rolling temperature of 1000°C. For all these finish rolling simulations, the specimens were rapidly cooled to a range of temperatures between 750°C and 600°C. The rapid cooling occurred at a rate of 10°C/s and having reached the simulated coiling temperature the specimens were subsequently slow cooled to represent the thermal behaviour in the coil. Insoluble nitrogen analysis showed that the quantity of nitrides decreased with the decreasing coiling temperature. While the finish rolling temperature and deformation percentage had no measurable effect on the final insoluble nitrogen content after coiling, the size of precipitates decreased with the decreasing coiling temperature and with increasing percentages of deformation. The final ferrite grain size decreased with the decreasing finish rolling temperature and with increasing percentages of deformation. The average ferrite grain size of specimens subjected to 30% final deformation at 1000°C, coiled at 750°C, 700°C, 650°C and 600°C was less than 10 µm. Finish rolling at 1000°C, 950°C and 900°C in the austenite recrystallisation region with four passes each of 20% deformation also achieved a fine ferrite grain size of under 10 µm provided that the coiling was performed at temperatures of 650°C or less. Interphase precipitation with the planar or non-planar morphologies was not observed in the thin foils or carbon replicas from the specimens subjected to the simulated thermomechanical treatments for the steels containing either vanadium, or the combination of vanadium and titanium. The observed precipitates in the ferrite phase in these steels were distributed on dislocations, within the ferrite and on the ferrite grain boundaries. The calculations based on the Hall-Petch equation showed that the lower yield strength for the specimens subjected to 20% and 30% deformation respectively at a finish rolling temperature of 1000°C and coiled at 750°C, 700°C, 650°C and 600°C increased as the coiling temperature decreased from 750°C to 600°C. The lower yield strength for specimens subjected to 30% final deformation was higher than that for 20% and the maximum lower yield strength occurred at the coiling temperature of 600°C for both 20% and 30% final deformations. The present experimental results showed that with appropriate coiling temperatures and a accelerated cooling rate the recrystallisation controlled rolling process for vanadium and vanadium-titanium steels can be used to produce a hot strip steel with a fine ferrite grain size of less than 10 µm. This means that the 70% to 80% deformation at around 800°C in the low temperature controlled rolling process was not necessary to obtain a fine ferrite grain size. Thus a fine grained strip steel can be produced in the existing hot strip rolling mills without exceeding the load limitation of a strip rolling equipment.

High strength steels have provided a unique opportunity for the automotive industry to achieve weight reduction via reduced material thickness whilst maintaining performance requirements such as crash worthiness. However, the initial success of HSLA steels was constrained by inconsistencies in the final mechanical properties. Although significant improvements in both mechanical and dimensional properties have since been made, increasingly stringent customer specifications for high strength steels mean that the challenge to reduce variability in automotive HSLA steel products and enure their continued competitiveness has never been greater. This investigation addresses the issues concerning the controlled hot rolling of Nb-HSLA strip steels through a series of laboratory and commercial trials, both to optimise the mechanical properties and uniformity of properties. Both sets of data established that: (i) the strength was decreased by reducing the soak temperature from 1250°C to 1150°C; (ii) the presence of furnace skid chills during soaking locally reduced the strength; (iii) lowering of the finishing temperature towards the Ars reduced the overall strength, but improved the coil-width property consistency, and; (iv) the existence of an optimum coiling temperature developed higher strengths and improved property consistency. The programme of work conducted also observed that by finishing near the Ars temperature, very fine ferrite subsurface grains are created which limit the fall in strength. Additionally, the commercial trials highlighted the need to compensate for the exposure-related cooling effects of the inner and outer most laps of the hot-rolled coil, thereby reducing any potential for developing further inconsistencies. Furthermore, the work undertaken has established that prudent additions of niobium, coupled with the use of a low finishing temperature and an optimum coiling temperature, will lead not only to higher strengths steels but also to significant improvements to the through-coil uniformity of properties

Motion controlling is a rapidly improving area of game technologies. In the last few years, motion sensing devices for video games such as Nintendo Wii, Microsoft Kinect for Xbox 360 and Sony PlayStation Move have gained popularity among players with many compatible motion controlled games. Microsoft Kinect for Xbox 360 provides a controller free interaction system in which the player controls games by using only body movements. Although Kinect provides a natural way of interaction, rolling action of body joints are not recognized within the standard motion sensing scope of the tool. Aim of this thesis is to provide an improved gameplay system with an increased degree of freedom by introducing rolling axis of movement using Microsoft Kinect for Xbox 360 for motion sensing. This improved gameplay system provides the players a more natural and accurate way of motion controlled interaction, eliminating unnatural gestures that are needed to be memorized to compensate for lacking of the roll movement recognition.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.
Includes bibliographical references (leaves 157-164).
The need for energy infrastructure has led to transportation of gases over long distances. The strength-grade of pipeline steels used for transportation of gases has been increasing to reduce the cost of the overall pipeline system. Along with higher strength, adequate fracture toughness and resistance to plastic buckling are required of pipes installed in earthquake- or frost-prone regions. To get higher strength with adequate deformability in low-alloy pipeline steels, plates for pipes are typically made today by thermo-mechanically-controlled rolling processes, which introduce strong crystallographic texture and anisotropy in the pipes. The plates are then cold-formed into pipes, which introduces further anisotropy and residual stresses in the pipe. In the current work, effects of various steps of the pipe manufacturing process, such as rolling, cold forming, etc., on residual stress, hardening moduli, plastic anisotropy, and eventually, to the buckling resistance of the pipe, are studied. Effects of various types of geometric perturbation on plastic buckling response of pipes are also studied.
(cont.) Due to the crystallographic texture and cold-forming, crystal plasticity-based constitutive models instead of Mises plasticity-based constitutive models may be better suited to model the pipe. In the current work, crystal plasticity-based material models are used to predict the buckling response of pipes. Results show that the buckling strain in uniaxial compression, predicted using a crystal plasticity-based model, is - 20% less than the one predicted using an "equivalent" Mises plasticity-based model, for a pipe with d/t ratio of 51. Further results show that variation in material properties and residual stresses caused by cold forming reduces the buckling strain by - 30%, for a pipe with d/t ratio of 51.
by Vaibhaw Vishal.
Ph.D.

This thesis presents a fuzzy logic controller aimed at maintaining constant tension between two adjacent stands in tandem rolling mills. The fuzzy tension controller monitors tension variation by resorting to electric current comparison of different operation modes and sets the reference for speed controller of the upstream stand. Based on modeling the rolling stand as a single input single output linear discrete system, which works in the normal mode and is subject to internal and external noise, the element settings and parameter selections in the design of the fuzzy controller are discussed. To improve the performance of the fuzzy controller, a dynamic fuzzy controller is proposed. By switching the fuzzy controller elements in relation to the step response, both transient and stationary performances are enhanced. To endow the fuzzy controller with intelligence of generalization, flexibility and adaptivity, self-learning techniques are introduced to obtain fuzzy controller parameters. With the inclusion of supervision and concern for conventional control criteria, the parameters of the fuzzy inference system are tuned by a backward propagation algorithm or their optimal values are located by means of a genetic algorithm. In simulations, the neuro-fuzzy tension controller exhibits the real-time applicability, while the genetic fuzzy tension controller reveals an outstanding global optimization ability.

This study aims to investigate and assess how the role of a business controller and his or her tasks are influenced by digitalization. This study will provide theoreticians and practitioners with a deeper insight of the requirements, skills, experiences, tasks and expectations that fall on the controller in a digital world. The controller's main tasks involve analysis, communication, reporting, data management and forecasting. There are potential tools for the tasks to be implemented effectively. We are during a digital revolution. This brings along changes and it requires the will of adaptation and development. To succeed in running a business, it requires planning, strategy, and qualified personnel. This requires knowledge, but also the right conditions in the workplace to do the job. With the analytical and technical tools available today, controllers can become an invaluable resource if they can master the tools and learn to interpret and understand the information that IT-systems can provide. Companies are also required to implement the right system. This study is based on the theory of digitization, the business controller role and role theory. Empirical data were collected through 50 job advertisements and five interviews. Through inquiry of empirics and theories and an analysis of this material, an understanding could be created about how the controller's role and tasks are influenced by digitalization. Specifically, the extent to which the controller uses digital tools and the demand that companies have for controllers' digital skills and experience. It also provides an insight into the role and expectations of the controller in a digital world. The conclusion of this study is that controllers use digital tools to a large extent. Which in turn places demands on digital experiences and skills. The digital revolution can be considered a fact, which entails the controller to consider and monitor digital development and change. The job advertisements show a clear tendency that digital experience and skills are a large part of what is demanded from companies. Despite the high demand for digital skills, the review of job advertisements shows that companies still only require a person with a financial education. The role of a business controller in Sweden has gone from being a financial controller and an accountant to a role that is now in a borderland between IT and finance. Which means that the role can now be considered as something of a hybrid. However, the empirical evidence in this study shows that this is not yet fully seen in practice. This study is written in Swedish.
Denna studie syftar till att undersöka och bedöma hur business controllerns roll och arbetsuppgifter influeras av digitaliseringen. Studien ska ge teoretiker och praktiker en större insikt kring vilka krav, kompetenser, erfarenheter, arbetsuppgifter och förväntningar som faller på controllern i en digital värld. Controllerns huvudsakliga arbetsuppgift är i grunden analys, kommunikation, rapportering, hantering av data samt prognostisering. Det finns potentiella hjälpmedel för att detta ska genomföras effektivt. Vi är mitt uppe i en digital revolution. Detta för med sig förändringar och det kräver viljan av anpassning och utveckling. För att lyckas driva en verksamhet krävs planering, strategi och kvalificerad personal. Det kräver att kunskap finns men också rätt förutsättningar på arbetsplatsen för att uträtta arbetet. I och med de analytiska och tekniska verktyg som idag finns tillgängliga, kan controllers bli en ovärderlig resurs om dessa kan bemästra verktygen och lära sig att tolka och förstå den information som IT-system kan tillgodose. Studien grundar sig på teori kring digitalisering, controllerns roll samt rollteori. Empiri har samlats in genom 50 platsannonser samt fem intervjuer. Genom granskning av empiri och teori samt en analys kring detta material kunde förståelse skapas kring hur controllerns roll och arbetsuppgifter influeras av digitalisering. Specifikt i vilken utsträckning controllern använder sig av digitala verktyg och vilken efterfrågan företag har på controllers digitala kompetenser och erfarenheter. Det ges även en insikt i vilken roll samt vilka förväntningar som faller på controllern i en digital värld. Slutsatsen av denna studie är att controllers använder sig av digitala verktyg i bred utsträckning. Vilket i sin tur ställer krav på digitala erfarenheter och kompetenser. Den digital revolutionen kan anses vara ett faktum vilket för med sig ett krav på att controllern ska beakta och följa med i den digitala utvecklingen och förändringen. I platsannonserna påvisas tydlig tendens att digital erfarenhet och kompetens är en stor del av det som efterfrågas från företag. Trotts den höga efterfrågan på digital kompetens visar granskningen av platsannonser att företag fortfarande enbart efterfrågar en person med ekonomisk utbildning. Rollen som controller har gått från att vara en “styrekonom” och revisor till att rollen nu befinner sig i ett gränsland mellan IT och ekonomi. Vilket för med sig att rollen nu kan anses vara något av en hybrid. Dock visar empirin i denna studie att detta ännu inte ses helt i praktiken.

Controllerrollen utvecklades inom organisationer i början av 1900-talet och har förändratsmycket över tidens gång. Controllern har gått från att ha en mer kameral roll till att ha fått en allt mer affärsinriktad och analyserande funktion inom företagen. Denna drastiska förändring av funktionen skedde på 1930-talet genom att Controllers Institute of America (CIA)startades, vilket ledde till att controllern fick den mer analyserande rollen. Inom företag iSverige och övriga Europa växte controller begreppet fram under 1970-talet. Men rollen som controller har fortfarande inte någon tydlig definition och kan se väldigt olika ut beroende på vilket företag controllern arbetar inom. Det finns även väldigt många olika typer av controllers, vilket ökar variationen av rollen. Uppsatsen syftar till att öka kunskapen om vaddet innebär att arbeta som controller; det vill säga vilka arbetsuppgifter och vilken kompetens som är vanligt förekommande inom yrket, vilka skillnader det finns mellan företag samt omdet finns en skillnad mellan hur controllern själv och övriga inom organisationerna definierar controllerrollen. Studien är genomförd med en kvalitativ metod och en abduktiv ansats. Materialet är insamlat via semistrukturerade intervjuer av både controllers och dessmedarbetare. Det genomfördes tio stycken intervjuer på fem olika företag, varav sju intervjuer var med controllers och tre intervjuer var med medarbetare. Resultatet blev att de intervjuade controllerna i studien gick att kategorisera som tre olika typer av controllers baserat på deras arbetsuppgifter och ansvarsområden; analytiker med inslag av kamrer, kamrer med inslag av analytiker samt en blandning av analytiker, pedagog och coach. Vi kan konstatera att vi märkt en viss skillnad i controllerrollen mellan företagen gällande företagsstorlek och hur rapporteringen är utformad, men inga större skillnader beroende på bransch. Avslutningsviskom vi fram till att de intervjuade controllerna och medarbetarna i stor utsträckning var överens kring vad controllerrollen innebär både i allmänhet och på de specifika företagen.
The role of a controller has existed within organizations since the beginning of the 20thcentury, but it has developed substantially over time. The controller initially had an accountant role and now they have an increasingly business oriented and analytical function within business organizations. In the 1930s, this drastic change of function in the role occurred by the Controllers Institute of America (CIA), which resulted in the controller getting a more analytical role. Within companies in Sweden and across Europe, the controller concept developed in the 1970s. However, the role of a controller still lacks a clear definition and the content in the role varies substantially across different business organizations. There are also many different types of controllers, which increases the role variation. The objective of this study is to increase the knowledge of the role of a controller; by studying which tasks and expertises that are included in the profession, the differences between companies and whether there is a difference between how the controller himself/herself and the others within the organizations define the role of a controller. The study is conducted with a qualitative study with an abductive approach. The empirics are collected via semi structured interviews with both controllers and related roles. The study was conducted by means of ten interviews across five different companies, of which seven interviews with controllers and three interviews with related roles. The controllers were categorized as three different types of controllers based on their duties and responsibilities; the analysts with elements of accountants, the accountant with elements of analysts and the mix of analyst, educator and coach. A noticeable difference in the role was noted between companies depending on their size and how their reporting is designed, but no major differences depending on industry. Finally, we concluded that the interviewed controllers and the related individuals largely agreed on controller role content in general as well as within each respective company.

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.

Sammanfattning     Det finns många definitioner av vad yrket controller innebär, vilket visar att yrkestiteln är svårdefinierad. Syftet med studien är att beskriva controllerns arbetsroll i medelstora tillverkande privata företag och om controllerns roll fokuserar mer mot styrorienterade uppgifter eller mer mot traditionella ekonomiuppgifter. Vi utformade därför följande frågeställning: Är dagens controller i tillverkande företag mer styrorienterad eller mer en traditionell ekonomichef? Vi valde att genomföra en kvalitativ studie eftersom det möjliggör en djupare förståelse och sedan använde vi oss av en deduktiv ansats där vi gick från teori till empiri. I vår teoretiska referensram har vi beskrivit olika egenskaper, färdigheter, roller och arbetssätt som ingår i controllerns yrke. Vår empiriska studie omfattade personliga intervjuer med fem controllers som kompletterades med en enkät där respondenterna fick rangordna sina arbetsuppgifter i förhållande till tiden. Resultatet visar att vi inte kan påvisa att controllern arbetar mer med styrorienterade uppgifter eller mer med ekonomiuppgifter, men däremot anser vi att controllern arbetar med både styrorienterade- och ekonomiuppgifter.   Nyckelord: Controller, Roll, Ekonomichef, Styrorienterad roll
Abstract     There are many definitions of what the profession controller imply, which indicates that the profession is difficult to define. The purpose of this study is to describe the controller's job role in medium-sized manufacturing companies within the private sector and if the controller’s role focuses more on controlling-oriented tasks or more on traditional business tasks. Therefore we enunciated the following framing of question: Is today’s controller in manufacturing companies more controlling-oriented or more a traditional chief financial officer? We chose to conduct a qualitative study because it enables a deeper understanding and then we chose a deductive approach where we went from theory to empiricism. In our theoretical framework we described various characteristics, skills, roles and ways of working as part of the controller's profession. Our empirical study involved personal interviews with five controllers, which were supplemented by a survey where the respondents ranked their tasks in relation to time. The result shows that we can’t demonstrate that the controller works with more controlling-oriented tasks or more with traditional business tasks, but we believe that the controller works with both controlling-oriented- and traditional business tasks.   Keywords: Controller, Role, Chief financial officer, Controlling-oriented

Sistemas de geração de referências para as malhas de controle de laminadores a frio têm proporcionado elevados níveis de produtividade e de qualidade do material processado. No caso de falha da unidade de processamento responsável pela execução do sistema de geração de referências, a operação do laminador fica comprometida e necessita-se de um modo de operação emergencial. Nesse trabalho é desenvolvido um sistema alternativo para geração de referências que visa substituir o modo de operação de emergência de consulta a tabelas de referências pré-calculadas da planta em questão. O sistema de geração de referências desenvolvido, assim como o sistema usado em condições normais de operação, é composto por uma função custo que avalia o nível de produtividade e de qualidade que um conjunto de referências pode proporcionar. A função custo é minimizada pelo método simplex de Nelder e Mead e as variáveis do processo envolvidas na função custo são avaliadas por um modelo de laminação a frio composto somente por equações algébricas, enquanto que o sistema usado em condições normais de operação usa um modelo clássico, composto por equações algébricas e integrais. A comparação entre o sistema usado em condições normais de operação e o sistema desenvolvido mostrou que apesar desse sistema ser mais simples, menos preciso e robusto, as referências por ele calculadas são aceitáveis e podem proporcionar resultados superiores que o modo de operação de emergência baseado na consulta a tabelas.
Setup generation systems for cold mill control loops have provided rolling mill operation with high levels of quality and productivity. In case of malfunctioning in the process unit responsible to execute the setup generation system, the normal procedure for the operation of the mill is interrupted, being necessary the use of an emergency operation mode. This work develops an alternative system for references generation which aims to replace the current emergency operation mode based on pre-calculated, not continuous, setup tables for the rolling mill. The developed references generation system, like the normal system used during mill operation, is composed by a cost function which evaluated the mill quality and productivity operation level which a set of references may propose. The cost function is minimized using the Nelder and Mead simplex method and the process variables involved in the cost function are evaluated by a cold rolling mill model composed only by algebraic equations, while the normal operation system uses a classical model, made up by integrals and algebraic equations. Comparing the existing main setup system to the developed reference system it was observed that, despite its simplicity, less accuracy and less robustness, references calculated using this system were accurate enough to achieve better results than the one emergency table mode has provided.

I problemdiskussionen lyfts att litteraturen och forskningen utgår från att en controller är en ekonom som arbetar med ekonomistyrning. Enligt min erfarenhet stämmer inte detta för verksamhetscontrollers i statliga myndigheter. Syftet med uppsatsen är att öka kunskapen om rollen som verksamhetscontroller i statliga myndigheter. Forskningsfrågorna är vilka krav ställer myndigheterna vid rekrytering av verksamhetscontrollers och hur beskriver de arbetsuppgifterna? Vad innehåller tertialuppföljningarna? Metoden har varit att genom en diskursanalys studera innehållet i tertialuppföljning på Socialstyrelsen, Statens institutionsstyrelse och Tullverket. Dessutom har myndigheternas rekryteringsannonser som avser verksamhetscontroller analyserats. Slutsatsen är att arbetsuppgifterna för verksamhetcontrollers på myndighetsnivå är likartade och det ingår inte ekonomiska arbetsuppgifter. De förefaller dock ha olika mandat. Arbetsuppgifterna på avdelnings-/ kompetenscenternivå skiljer sig mellan och inom myndigheterna och inte heller dessa verksamhetscontrollers har ekonomiska arbetsuppgifter. Kraven som ställs på utbildning och erfarenhet har stor spännvidd och ibland har man krav på att den sökande ska ha ekonomisk bakgrund. Min slutsats är att rollen som verksamhetscontroller på avdelnings-/ kompetenscenternivå är under utveckling och att rollen på myndighetsnivå är tydligare.
In literature and research the definition of a controller is an economist working with financial control. According to my knowledge this is not correct for controllers focused on operations management in government agencies The purpose of this thesis is to increase the knowledge of the role as a controller focused on operations management in state agencies. The questions to be answered are what demands does government agencies have when they recruit operations management controllers and how do they describe the  assignments? What is included in the four month follow ups? The method has been by discourse analysis study the content in the four month follow ups at the National Board of Health and Welfare, the National Board of Institutional Care and the Swedish Customs. In the thesis the agencies recruitment ads for controllers focused on operations management is also analyzed. The conclusion is that the assignments for controllers focused on operational management on the agency-wide level is similar between the agencies and few financial assignments are included. The assignments for the lower levels differ within and between the agencies and financial assignment are not included. The controllers at the agency-wide level seem to have different mandates between the agencies. The agencies demands for education and experience varies widely and some of the ads have demands for a background in  finances. My conclusion is that the controller at the department level is under development and the role at the agency-wide level is more distinct.

Este trabalho faz uma introdução à evolução dos processos de laminação a frio, acionamento e controle dos mesmos, com foco na laminação de encruamento. O principal objetivo é estabelecer um modelo linear dos sistemas de acionamento, que permita o projeto de um controle multivariável. Pretende-se que a robustez do controle multivariável contribua para a eliminação de defeitos associados aos processos de bobinamento e desbobinamento. A eliminação destes defeitos traz um grande retorno econômico em função do grande volume de produção destas instalações. Para isto é desenvolvido um modelo matemático do sistema completo. No modelo são evidenciadas não linearidades associadas à variação dos diâmetros e inércias das bobinas na desenroladeira e enroladeira. Para solucionar esse problema as parcelas contendo as não linearidades são removidas do modelo. Posteriormente essas parcelas são repostas através de malhas feedforward no controle. Para validar o modelo são projetados controladores PID semelhantes aos utilizados no laminador real. Com os resultados obtidos através de simulação, discute-se a validade do modelo comparando-os com os dados do processo real. A partir desse modelo é desenvolvido o modelo linear em espaço de estados, a ser utilizado no projeto do controlador robusto multivariável. Em seguida é desenvolvido o projeto deste controlador multivariável utilizando a técnica LQG/LTR. Finalmente, são discutidos os resultados das simulações, comparando-os com os dados reais da planta. De um modo geral, os resultados apontam para uma boa aproximação entre a planta real e o modelo proposto.
This work is an introduction to the evolution of the processes of cold rolling, drive and control, focusing on skinpass rolling. The main objective is to establish a model of linear drive systems, allowing the design of a multivariable control. It is intended that the robustness of multivariable control contributes to the elimination of defects associated with processes of coiling and uncoiling. The elimination of these defects poses a great economic return due to the large volume of production of these facilities. To achieve this deal it was developed a mathematical model of the complete system. Nonlinearities associated with variation in diameters and inertia reels in desenroladeira and reel are evidenced in the model. To solve this problem the terms containing nonlinearities were removed from the model and, subsequently reintroduced by feedforward control loops. To validate the model, PID controllers were designed in a similar way to those used in real mill. With the results obtained by simulation, we discuss the validity of the model by comparing them with the actual process data. From this model it was developed a linear state space model to be used in the design of robust multivariable controller. After that it was developed the design of this multivariable controller using the technique LQG / LTR. Finally, it was discussed the simulation results, comparing them with actual data of the plant. Overall, the results point to a good approximation of the real plant and the proposed model.

Abstract The presumed dominance of the traditional annual budgeting process as a cornerstone of management control has been called into question in recent years. Various new developments in budgeting have been seen replacing or complementing organisations’ conventional budgeting. The dissertation provides a comprehensive picture of these new budgetary practices and their implications for management accounting work, through investigation of the fragmentation among various purposes of budgeting and of the ways in which the role of controller and new budgetary practices can complement each other. The dissertation is composed of four inter-related essays, which provide qualitative evidence of how firmly established practices such as budgeting change and what implications the change has for the conflicting purposes of budgeting. It also provides insight into the ways controllers are able to build holistic view of the totality of budgetary control and compile new accounting information. The empirical findings presented in the dissertation give rise to novel concept of fragmentation, which can be defined as an arrangement wherein a new mix of diverse controls is used to serve several purposes of budgeting and a single budgeting process is either replaced with or complemented by other control mechanisms. Fragmentation can serve as a common denominator for recent developments in budgeting but also aid in understanding the variation in new budgetary practices. Fragmentation of budgeting makes the boundaries of a budgetary system blurred but also enables designing flexibility into the control system itself. For the role of controller, fragmented budgetary practices mean co-ordinating the linkages between various budget-related methods, wider communication and interaction with organisational actors, new business-oriented skills related to key purposes of budgeting, and a growing professional role in increasing the ‘realism’ of accounting information in the lateral budgetary planning process
Tiivistelmä Perinteisen vuosibudjetoinnin valta-asemaa johdon ohjausjärjestelmien kulmakivenä on alettu kyseenalaistaa viime vuosina. Budjetoinnin uudet kehityssuuntaukset näyttäisivät joko korvaavan tai täydentävän vakiintunutta budjetointikäytäntöä organisaatioissa. Tämä väitöskirja tarjoaa kokonaisvaltaisen kuvan uusista käytännöistä, sekä niiden vaikutuksista johdon laskentatoimen työhön. Väitöskirja tutkii budjetoinnin eri tehtävien pirstaloitumista sekä sitä, miten controllerin rooli ja uudet budjetointikäytännöt voivat toimia toisiaan täydentävästi. Väitöskirja muodostuu neljästä toisiinsa liittyvästä esseestä, jotka tuovat laadullisen tutkimuksen keinoin esille, kuinka vakiintunut käytäntö, kuten budjetointi, muuttuu, ja mitä vaikutuksia tällä muutoksella on budjetoinnin eri tehtäviin. Tutkimus tarjoaa myös käsityksen siitä, miten kontrollerit muodostavat kokonaiskuvan budjetoinnillisesta ohjausjärjestelmästä ja tuottavat uutta laskentatoimen informaatiota. Tämä väitöskirja kuvaa budjetoinnin muutosta käsitteellä pirstaloituminen (fragmentation). Se voidaan määritellä järjestelyksi, jossa uutta, erilaisten ohjausmenetelmien yhdistelmää käytetään palvelemaan budjetoinnin eri tehtäviä, ja jossa yksittäinen budjetointiprosessi joko korvautuu tai täydentyy muilla ohjausmekanismeilla. Tämä käsite tarjoaa yhteisen nimittäjän viimeaikaisille budjetoinnin kehityssuuntauksille, mutta auttaa myös ymmärtämään paremmin budjetoinnin eri variaatioita. Budjetoinnin pirstaloituminen hämärtää budjetointijärjestelmän rajat, mutta mahdollistaa myös joustavuuden suunnittelun järjestelmään itsessään. Kontrollerin roolin näkökulmasta budjetoinnin pirstaloituminen merkitsee budjetoinnin eri menetelmien välisten yhteyksien koordinointia, laajempaa kommunikaatiota ja vuorovaikutusta organisaation eri toimijoiden kanssa, uusien liiketoimintaorientoituneiden taitojen lisääntymistä sekä ammatillisen roolin korostumista laskentainformaation realismin parantamisessa budjetoinnin lateraalisessa suunnitteluprosessissa

Este trabalho inicia descrevendo as principais teorias de laminação que têm sido empregadas nos últimos anos na determinação das condições ideais para operação de laminadores a frio. Estas condições ideais estão ligadas a um conjunto de referências dos controladores do sistema, visando a máxima produtividade do laminador e a melhor qualidade da chapa laminada. As principais contribuições desta tese são: (i) proposta de um novo procedimento não iterativo para a determinação inicial de referências para redução em cada cadeira de um laminador de tiras a frio, originado do algoritmo iterativo do fator beta, introduzido por R. M. Guo; (ii) em seguida, é feito uso do modelo de Bland e Ford para cálculo de força e torque de laminação, utilizando o esquema de reduções sugerido pelo algoritmo de inicialização. A partir deste ponto, emprega-se o algoritmo de otimização de Nelder e Mead. A contribuição da tese para esta fase de otimização consiste na proposta da função objetivo a ser minimizada. Esta função objetivo leva em conta os principais atributos de qualidade e produtividade do laminador, ou seja, espessura, planicidade e utilização de toda a potência disponível, igualmente distribuída por todas as cadeiras; (iii) finalmente, visando garantir máxima precisão para as previsões do modelo, é proposto um algoritmo de otimização para ser utilizado em um esquema de adaptação, tendo em vista as dificuldades de se estimar duas importantes variáveis do processo de laminação: o coeficiente de atrito e o limite de escoamento. São também apresentados resultados obtidos à partir de um laminador tandem de 4 cadeiras, industrial, no qual foram implantados alguns dos métodos propostos.
This work begins describing the main rolling theories which have been employed during the recent years, in order to achieve the ideal conditions for the operation of tandem cold rolling mills. These optimum conditions are connected to a set of references used by the main systems regulators, aiming at getting the best quality of the strip and the maximum productivity of the mill. The main contributions of this thesis are: (i) proposal of a new non-iterative procedure to initial reduction calculation for each stand of a tandem cold mill, based on the iterative beta factor algorithm introduced by R.M. Guo; (ii) Use of Bland and Ford model for roll force and roll torque calculation, starting from the initial reduction schedule proposed by the non-iterative initialization algorithm and optimized by the Nelder and Mead method. The contribution of this thesis for this optimization phase consists in its proposal for an objective function to be minimized. This objective function takes into consideration the main product quality and process productivity attributes, i.e., thickness, flatness and the use of maximum available power, evenly distributed among all stands; (iii) finally, aiming at ensuring maximum precision for the model predictions, it is proposed an optimization algorithm to be used by an adaptation strategy, considering the difficulties to estimates two main rolling mill process variables: friction and yield stress coeficientes. Results extracted from an industrial four stand tandem cold mill, on which some of the proposal theories were implemented, are presented and discussed.

Sammanfattning Kandidatuppsats i företagsekonomi Ekonomihögskolan, Linnéuniversitetet VT 16 Författare: Viktor Odenbrink, Louis Perikala, Viktor Johansson Handledare: Tom Karlsson Titel: Controllerrollen inom den offentliga sektorn Bakgrund och problem: Det existerar många studier om controllerrollen inom den privata sektorn, studier inom den privata sektorn belyser också vilka arbetsuppgifter och egenskaper som är relevanta för en controller. Däremot råder det delade meningar om controllerrollen inom den offentliga sektorn, vissa studier säger att rollen skiljer sig åt och andra forskare skriver att rollen är densamma inom båda sektorer. Vi vill med denna studie belysa vad det innebär att vara controller inom den offentliga sektorn och vilka arbetsuppgifter och egenskaper som är relevanta för rollen. Syfte: Syftet med denna studie är att beskriva vad det innebär att vara en controller inom den offentliga sektorn och vilka arbetsuppgifter och egenskaper som är av vikt. Detta för att skapa mer kunskap om den offentliga controllerrollen. Metod: En kvalitativ forskningsansats har legat till grund för studien. Forskningen ses som en kvalitativ intervjustudie. Empirin har inhämtats genom semistrukturerade intervjuer med controllers samt med ekonomer med arbetsuppgifter likt en controller inom den offentliga sektorn. Slutsats: Den stora skillnaden i vad det innebär att vara controller inom den offentliga och privata sektorn är att en controller inom den offentliga sektorn betonar vikten av att få vara med och bidra till välfärd och samhällsnytta. Arbetsuppgifterna och egenskaperna är svåra att placera in i en specifik controllerroll och det rör sig snarare mot en hybridroll, där controllern bör ha inslag från kamrerrollen, den analytiska rollen, pedagogiska rollen och coachrollen. Nyckelord: Offentliga sektorn, controller, arbetsuppgifter, egenskaper
Abstract Bachelor Thesis in Business Administration School of Business and Economics, Linnaeus University, Växjö 2016 Authors: Viktor Odenbrink, Louis Perikala, Viktor Johansson Supervisor: Tom Karlsson Title: The role of a controller within the public sector Background: There are many studies on the role of controllers within the private sector, studies in the private sector focus on the work assignments and characteristics that are relevant for a controller as well. However, there are different opinions and interpretations regarding the role of controller in the public sector, some studies say that the roles differs while other researchers state that the roles are similar in both sectors. Our goal with this study is to shed light on what it means to be a controller within the public sector and the work assignments and characteristics that are relevant to the role. Purpose: The purpose of this study is to describe what it means to be a controller within the public sector and the work assignments and characteristics that are of importance. This is to create more knowledge about the role of a controller within the public sector. Method: A qualitative research approach has been the basis for this study. The research is seen as a qualitative interview. The empirical data has been collected through semi-structured interviews with controllers and economists with similar duties as a controller within the public sector. Conclusion: The big difference in what it means to be a controller within the public and private sector is that a controller within the public sector emphasizes the need to be involved in the contribution to the welfare and social benefits. The work assignments and characteristics are difficult to place in a specific segment and this points towards a so called hybrid role, which means that the controller should have elements from all the segments which include the role of an accountant, the analytical role, the pedagogical role and lastly the so called coaching role. Keywords: Public sector, controller, work assignments, characteristics

Described in this thesis are efforts to advance our understanding of single molecule machines through the synthesis and study of an array of nanovehicles. In the first chapter, nanoscale transport is explored through the synthesis and solution-based studies of a photoactive, metal-ion-chelating nanocar. Utilizing an appended photoactive dipyridylethylene moiety as a metal chelating unit, it is expected that this molecule, upon photoirradiation, will form a strong bidentate ligand for carrying metal ions along surfaces. Following this, in the second chapter, directional control and propulsion are explored through the synthesis of motorized nanocars. Studies towards a dual-motored nanocar as well as the synthesis of an ultra-fast motorized nanocar are described. The third chapter covers our efforts to complement previous STM studies, where single molecule fluorescence spectroscopy is used for imaging and mechanistic elucidation of translational movement of fluorescently-tagged nanovehicles. The synthetic routes towards these molecules are covered, as well. In chapters 4 and 5, various nanovehicles are synthesized using contrasting approaches. In chapter 4, self-assembly methods mirroring those used in biological construction are used to produce nanocars and nanotrains. Moieties of 2-pyridones and terpyridyl groups were used for self-assembling via hydrogen bonding and metal complex formation, respectively. Traditional organic synthesis is used to build carborane-wheeled nanovehicles in chapter 5. These molecules are expected to move in predetermined patterns on atomically smooth surfaces, depending on their specific configuration of axles and wheels. Finally, in chapter 6, nanocomponentry is explored through the synthesis and studies of molecular devices such as azobenzene-fullerene switches and fullerene-oligo(phenylene ethynylene) molecular wires. The presence of fullerenes and oligo(phenylene ethynylene)s (OPEs) in azobenzene derivatives was found to have a large effect on the photoisomerization behavior of the molecules. Lastly, a series of fullerene-terminated oligo(phenylene ethynylene) (OPEs) molecular wires have been synthesized as potential molecular electronic devices. Electronic properties such as the energy levels and the distribution of HOMOs and LUMOs of fullerene-terminated OPEs have been calculated using ab initio method at the B3LYP/6-31G(d) level.

碩士
國立臺灣大學
材料科學與工程學研究所
86
The fabrication technology of controlled rolling re-bar was introduced from Europe, Since controlled rolling re-bars with lower cost conform conventional high strength re-bars standard(ASTM A706), it is much widely used. The object of this article is to examine the mechanical properties, and the results could be a referenc for revising re-bar standards. It is observed that the exterior structure of controlled rolling re-bar is tempered martensite, a decomposed martensite with carbides size of about 0.2■m, while the interior structure is pearlite plus ferrite structures. The controlled rolling re-bars revealed similar tensile strength while exhibited higher yield strength compared with ordinary ones, thus resulting in lower tensile to yield strength ratio. After the 180 degree bending test, there were no microcrack at it''s tensile stressed surface region. Regard the joining of re-bars, the strength of the controlled rolling re-bars doesn''t lowered after mechanical joining; the strength of the controlled rolling re-bars did decrease after gas joining which is about 10% lower than initial controlled rolling re-bars. It is recommended that mechanical joining should be employed for joining the controlled rolling re-bars while gas joining could be used for conventional high strength re-bars.

Controlled hot strip rolling is one of most important processes in the steel industry since approximately 200 million metric tons of steel are hot-rolled to flat products with gauges from less than 2 mm up to 25 mm annually. As has been widely recognized, runout table cooling is essential to the control of final mechanical properties and flatness of a steel strip in a hot strip mill. Therefore, a very significant effort has been mounted worldwide to quantify the thermal and metallurgical phenomena during runout table operation over the past decades. However, very limited cooling data has been obtained for industrial conditions even today, and the information available is not well understood. As a result, even though many of the runout table operations are considered to be relatively under control, little is known about what is really happening during water jet impingement and how far these operations are from the optimum This is the motivation behind this pioneer investigation. The ultimate goal of the research is to perform some industrial scale water jet impingement experiments and to employ the experimental data obtained to simulate runout table operation and further to gain a better understanding of the relationship among thermal profiles of a steel strip and adjustable processing parameters during runout table operation. A comprehensive literature survey has been created in which the knowledge accumulation on water jet impingement boiling heat transfer and modelling of controlled runout table heat transfer has been highlighted. A full-scale pilot runout table facility has been designed and constructed, which is the very first full-scale runout table test rig ever built in a laboratory worldwide. With the aid of the test rig, more than thirty water jet impingement tests have been conducted to attempt to quantify the relationship between the thermal evolution of a heated steel plate which is undergoing water jet impingement and the adjustable processing parameters during the cooling process. A 2-D finite element (FEM) numerical model and a transient inverse heat conduction (T-IHCP) model have been developed and implemented so as to calculate heat fluxes and heat transfer coefficients along the impinging surface of a heated steel plate based on thermal measurements at several discrete positions inside the steel plate. Experimental data obtained was used to modify the established AISI ROT model to improve its predictive capability on the prediction of coiling temperatures at Company S. Then, the modified AISI ROT model was validated by comparing its prediction to plant measurement for 24 mill coils from the company. Very good agreement was found. Downcoiler thermal model was also validated by comparing its prediction with industrial measurement. Very good agreement was also met in this regard. The applications of both the AISI ROT model/modified AISI ROT model and downcoiler thermal model to the steel industry have also been explored. Obtained experimental data was also well discussed and analyzed with the purpose of improvement of a runout table operation by altering adjustable processing parameters, such as cooling water temperature, jet impingement velocity, water flux, water jet diameter and water jet arrangement. With the help of experimental measurement and recorded visual observation, heat transfer mechanisms involved during water jet impingement cooling have also been discussed. This work has contributed new knowledge to water jet impingement boiling heat transfer and its application to runout table operation not only in the process modelling but in the process control. As a consequence, the progress has already led to a better understanding on the controlled runout table cooling practice in a hot strip mill.

Rolling mill automation systems started nearly in 1960s when the servo system was introduced to the metal forming industry. During the past decades, hydraulic control systems have found increased applications in rolling mills in an attempt to cope with the harsh environment conditions and the high power demands for metal forming. During the rolling process, both rolling speed and rolling load must be controlled in accordance with the independently varying torque that disturbs the control system. This project is concerned with the development of an electro-hydraulic control system in order to control both rolling speed and rolling load with minimum number of components. A mathematical model of a pressure compensator is constructed and a simulation program based on Matlab-Simulink is developed to simulate both the static and the dynamic characteristics of the entire control system. The control system has very good flexibilities to various rolling mill requirements, and it is very convenient to adjust due to different variable load demands. An experimental setup composed of real time control software and a hydraulic test bed is built in order to validate the compensator mathematical model and verify the control system simulation results. The simulation and experimental results are compared and discussed.

Stress Corrosion Cracking (SCC) is a damaging form of environmental corrosion found in pipeline steels that forms in the presence of a high pH environment. SCC forms at the surface of gas pipes under damaged coatings and propagates towards the inner wall of the pipe until a critical depth is reached and the internal pressure ruptures the pipe. Prior to considering the role that crystallographic texture had on SCC, the accepted SCC mechanism was unable to explain why adjacent sections of pipe suffered differing levels of SCC damage. When comparing the crystallographic textures of adjacent pipes that suffered differing levels of SCC damage, it was observed that crystallographic texture, produced during manufacturing, was markedly different. The primary aim of this thesis was to analyse the influence that manufacturing has on the crystallographic texture development in pipeline steels and to investigate the effect that has on the subsequent SCC susceptibility. The project was executed in three main phases; the first phase involved laboratory rolling pipeline steel under different rolling schedules and characterising the resulting mechanical and microstructural properties. The second phase consisted of characterising the crystallographic texture of the produced steels. The final stage involved testing the SCC susceptibility of the produced steels and determining which material properties influenced the susceptibility. During laboratory scale rolling, recrystallized, hot and warm rolling processes were undertaken with the influence these manufacturing processes had on the steel investigated. Of the three rolling schedules, only recrystallized rolling met the minimum specifications necessary for an API 5L X70 grade steel whilst the other two resulted in suboptimal mechanical properties. All three rolling schedules produced bainitic structures with upper bainite dominant in the recrystallized rolling whilst granular bainite and polygonal ferrite mixtures, typical of X70 steels, were observed in the hot and warm rolled steels. When investigating the crystallographic texture of the produced steels, all three rolling schedules produced crystallographic textures reminiscent of those identified in steel rolling literature. Recrystallized rolling resulted in (001)[110], (001)[110], (110)[110] and (110)[001] textures in the quarter plane. Hot rolling resulted in (112)[110] textures joined along the y-fibre to (554)[225] along the quarter plane. Warm rolling produced textures between recrystallized rolling and hot rolling. SCC testing was undertaken in a cyclic LIST apparatus where samples were loaded in a 1NNa2CO3 + NaHCO3 solution for 10 cycles with the resulting cracks investigated. It was observed that recrystallized rolling had the worst SCC susceptibility with a crack velocity of 2:27x10-7 mm/s followed by hot rolling with a crack velocity of 1:16x10-7 mm/s and finally warm rolling with the lowest susceptibility of 8:70x10-8 mm/s. It was identified that SCC susceptibility was strongly linked to the grain size and yield strength with larger grains and higher yield stresses resulting in higher crack velocities. With regards to crystallographic texture, increases in f111g<112>, (332)[113], (554)[225], (112)[110] and (113)[110] textures and decreasing the proportion of (110)[110] corresponded to lower crack velocities.
Thesis (Ph.D.) -- University of Adelaide, School of Mechanical Engineering, 2020

碩士
元智大學
機械工程研究所
87
This paper presents a study for developing a simulation system for hot rolling during finishing mill process based on graphic user interface. The simulation system is developed from a numerical exactly thermal model. According to the exit temperature , velocity data, and quantity of water spray, or water curtain, this dynamic simulation system can be applied to calculate the changing of temperature during the finishing milling process by off line mode; As the result agrees to the one calculated by numerical thermal model. That is the RMS error is lower than 5C. Resulting from the success of simulator development, this project can be moved forward to the development of feedforward controller for canceling the influence of skin mark. This study mentions two feedforward control schemes for skin mark problem. That is Disturbance Measurement FeedForward Controller（DM_FFC）, and Dynamic Target_Temperature FeedForward Controller（DT_FFC）. By using of the different processes of extracting skin mark information from temperature data, the skin mark can be completely canceled with suitable feedforward gain and the inverse of non-linear water efficiency function. Both of the above schemes for feedforward controller can be utilized to achieve the goal to cancel the skin mark by 95%. The correlation coefficient is introduced for feedward gain self-tuning. From the correlation coefficient and the variation of feedforward gain, the relationship function is obtained for feedforward gain tuning. Since those feedforward controller schemes are developed from the simulation system, based on the numerical thermal model, the influence of parameter deviations on feedforward controllers is regarding as a crucial information. At the end of this study, the evaluation for robust test is conducted. Resulting as, the feedforward controllers can still be working fine for canceling the skin mark by 90%, when there is +20% parameter deviations of thermal model.

Development of electric vehicles is motivated by global concerns over the need for environmental protection. In addition to its zero-emission characteristics, an electric propulsion system enables high performance torque control that may be used to maximize vehicle performance obtained from energy-efficient, low rolling resistance tires typically associated with degraded road-holding ability. A simultaneous plant/controller optimization is performed on an electric vehicle traction control system with respect to conflicting energy use and performance objectives. Due to system nonlinearities, an iterative simulation-based optimization approach is proposed using a system model and a genetic algorithm (GA) to guide search space exploration. The system model consists of: a drive cycle with a constant driver torque request and a step change in coefficient of friction, a single-wheel longitudinal vehicle model, a tire model described using the Magic Formula and a constant rolling resistance, and an adhesion gradient fuzzy logic traction controller. Optimization is defined in terms of the all at once variable selection of: either a performance oriented or low rolling resistance tire, the shape of a fuzzy logic controller membership function, and a set of fuzzy logic controller rule base conclusions. A mixed encoding, multi-chromosomal GA is implemented to represent the variables, respectively, as a binary string, a real-valued number, and a novel rule base encoding based on the definition of a partially ordered set (poset) by delta inclusion. Simultaneous optimization results indicate that, under straight-line acceleration and unless energy concerns are completely neglected, low rolling resistance tires should be incorporated in a traction control system design since the energy saving benefits outweigh the associated degradation in road-holding ability. The results also indicate that the proposed novel encoding enables the efficient representation of a fix-sized fuzzy logic rule base within a GA.