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Eindwerk bij Arcelor Gent: De sturing van een bestaande gasbrander, gebruikt om verdelerbakken op te warmen, ombouwen, zodat de brander als droogbrander kan gebruikt worden. De temperatuurregeling, oorspronkelijk uitgevoerd door een analoge PID regelaar, implementeren in het bestaande stuurprogramma (step7 Siemens). De installatie aanpassen volgens de normeringen en de wensen van het bedrijf. Een real-time controle van de toestand van de installatie mogelijk maken, evenals een grafisch ondersteunde bediening voor de operatoren. De automatisering optimaliseren door de aanbouw van een touchpaneel. Thesis at Arcelor Gent . Changing the regulation of an existing preheat station for tundish heating in such a way that the station can be used as a dry-station (increasing the air/gas ratio). Implementing the temperature-regulation, first executed by an analogue PID regulator, into the PLC control-program (Step7 Siemens). Changing the installation according to the normalisation and the demands of the factory. Realize a real-time logging on the status of the burner, together with a graphic support on WINCC for the operators. Improve the automatisation with a touch-screen.

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Eerst wordt de oprichting van Colruyt en in welke domeinen Colruyt actief is, uitgelegd. Daarna zal de werking van een luchtgroep aan bod komen (nut, doel en werking luchtgroepen, maar ook hoe de gewenste temperatuur en vochtigheid wordt bereikt) Vervolgens is er een kleine theoretische thermodynamische uiteenzetting. Daarna zullen de componenten van de PLC (welke kaarten, CPU's ...) en benamingen van de elementen (actuatoren) worden besproken. Als derde onderwerp zal de programmatie aan bod komen. Eerst zullen de bestaande standaarden i.v.m. PLC-programmatie worden behandeld, dan zal standaardisatie via functieblokken worden uitgelegd, om vervolgens de eigenlijke standaardisatie van de luchtgroepen te bespreken. Als laatste onderwerp zullen de luchtgroepen worden besproken die koelen. The first subject that will be discussed is the creation of the Colruyt group (their activities, etc.). Further, the HVAC process used in Colruyt will be explained (the use, the goal and how the HVAC works, but also how the requested temperature and humidity is obtained). Then there will be a little explanation about the thermo dynamical process in an HVAC installation, which heats a building. The components of a PLC will be discussed (which CPU's, card's, etc.), and also how the active elements are named. Another subject is the existing standards of the PLC programs. Then the function blocks and the new program philosophy are taken into consideration. Installations which cools rooms will be the last main subject.

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In orthodontic treatment, for many decades, panoramic radiographs and lateral cephalograms are considered the standard two-dimensional radiographic techniques required for treatment planning and follow up. Nevertheless, both imaging techniques present with several limitations such as geometric distortion and superimposition of anatomical structures. During recent years, there has been an upward trend in utilizing 3D images, especially from CBCT, as an aid in orthodontic diagnosis and treatment planning but the scientific evidence is still lacking in many aspects. Therefore, the primary goal of this doctoral thesis was to investigate the use of 3D images in orthodontics compared to conventional 2D modalities including panoramic radiography and lateral cephalography. Subsequently, an attempt was made to develop 3D reference systems to increase the reproducibility of several crucial cephalometric landmarks in 3 dimensions. Finally, the Frankfort horizontal plane was revisited, focusing more on its 3D version.This thesis begins with Chapter 1, explaining the general principles of orthodontic treatment planning and imaging modalities traditionally used to achieve the information needed to perform an orthodontic treatment. At the end of the chapter, the overall aims and hypotheses of this doctoral project were presented in detail. In Part I: Chapter 2, a systematic review on 3D cephalometry was presented. This systematic review focused on the scientific evidence for the diagnostic efficacy of 3D cephalometry, especially for landmark identification and measurement accuracy. It was clearly observed that this topic is fairly new and the scientific evidence of the diagnostic efficacy of 3D cephalometry is still limited and more concrete studies need to be performed. Methods of conducting research in this area are very crucial as radiation exposure to young patients is one of the main factors for ethical concern.In Part II, it was aimed to investigate and compare the use of panoramic radiography and the 3D data. In the first chapter of part II, Chapter 3, an attempt was made to compare in vitro subjective image quality and diagnostic validity of reformatted panoramic views from CBCT with digital panoramic radiographs, regarding orthodontic treatment planning. Results revealed that although digital panoramic radiograph still showed better image quality, some reformatted panoramic view from particular CBCT devices could achieve comparable image quality and visualization of anatomical structures. Next in this panoramic imaging part, the agreement between CBCT and panoramic radiographs for initial orthodontic evaluation was assessed. Chapter 4 showed that the agreement between CBCT and panoramic radiograph was good and CBCT could offer the same amount of information necessary for initial orthodontic evaluation.Subsequently, cephalometric imaging modalities were investigated in Part III of this doctoral thesis, beginning with Chapter 5. In thischapter, the linear measurement accuracy of three imaging modalities: two lateral cephalograms and one 3D model from CBCT data, was evaluated. The results showed better observer agreement for 3D measurements. The accuracy of the measurements based on CBCT and 1.5-meter SMD cephalogram was better than a 3-meter SMD cephalogram. These findings have confirmed that the linear measurements accuracy and reliability of 3D measurements based on CBCT data was good when compared to 2D techniques. Chapters 6, 7 and 8 concentrated on the reproducibility of cephalometric landmarks in 3 dimensions and attempted to develop a more robust system for 3D cephalometry. In Chapter 6, a new reference system was designed in Maxilim® software to improve the reproducibility of the sella turcica landmark in 3D. The results showed that the new reference system offered high precision and reproducibility for sella turcica identification in 3 dimensions.In Chapter 7, this time, a new reference system was developed in order to systematically improve the reproducibility of mandibular cephalometric landmarks (Pog, Gn, Me and point B) in 3D. It offered moderate to good overall precision and reproducibility for mandibular cephalometric midline landmark identification.Chapter 8 was the last study on 3D cephalometry in this doctoral thesis. The aim was to evaluate the Frankfort horizontal plane (FH), which is widely used in 3D cephalometric analysis. In this chapter, the precision and reproducibility of landmarks that form the Frankfort horizontal plane (Po, Or) and newly chosen landmarks (IAF, ZyMS) was investigated. The angular differences of optional planes compared to the Frankfort plane in 3D were measured. It was demonstrated that the precision and reproducibility of Po and Or was moderate. IAM and ZyMS showed good precision and reproducibility. From the newly proposed planes, the ones closest to the original FH are the plane formed by connecting Or-R, Or-L and mid-IAF (Plane 3) and the plane formed by connecting Po-R, Po-Land mid-ZyMS (Plane 4). This study demonstrated the possibility of using new planes when traditional FHs were not feasible.Lastly, in Chapter 9, the general discussion and conclusions were thoroughly discussed and presented. The findings of the present doctoral thesis elaborated the use of 2D and 3D images for orthodontic treatment and showed the possibility and new development to improve the use of 3D cephalometry. Although the scientific evidence on clinical use of 3D cephalometry is still limited, this project helps to provide a solid base for future studies. New studies should focus on the implementation of 3D cephalometry in clinical practice and evaluate how this new technology may improve the treatment outcome of orthodontic patients. In the near future, one ultra-low dose CBCT scan may be able to yield all necessary information and replace a cascade of 2D radiographic images while still keeping the ALARA principle. Whether those strategies are equally valid, remains to be proven.

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