Lämpötilanmittaus magneettikuvausympäristössä optista tehon- ja tiedonsiirtoa käyttäen

Lääketieteellisen magneettikuvantamisen yhteydessä on tarpeen mitata mm. potilaan lämpötilaa. Kuvantamisessa käytettävät kentät asettavat suuret vaatimukset kuvauksen aikana käytettäville mittalaitteille. Magneettikuvausympäristöön soveltuva lämpötilanmittausjärjestelmä on mahdollista toteuttaa käyttämällä sekä lämpötilatiedon että sähkötehon siirtämiseen valokuitua, jolloin järjestelmä on täysin galvaanisesti erotettu. Valokuidusta tuleva optinen teho muunnetaan sähkötehoksi valosähkömuuntimella. Tämä diplomityö keskittyy magneettikuvauksessa käytettävän lämpötilanmittausjärjestelmän suunnitteluun. Haasteena oli optisesta tehonsiirrosta johtuva tarve minimoida tehonkulutus ja lämpötilamittauksen tarkkuusvaatimus. Järjestelmän prototyyppi voidaan rakentaa suunnittelun mukaisesti. Diplomityössä suunnittelutuloksia testattiin koekytkennän avulla ja näin varmistuttiin mittausperiaatteen toimivuudesta.

Sähköisen ja optisen signaalin käyttö samalla piirilevyllä

Työssä tutkittiin sähköisen ja optisen signaalin siirtoa samalla piirilevyllä. Optisen siirtotien komponentit ja niiden toiminta esiteltiin teoriakappaleessa. Valosignaalin vaimentumisilmiö selitettiin pääasiassa johtuvan absorption ja sironnan vaikutuksesta. Sironnan ja absorption vaikutusta valokuidussa käytettävään aallonpituusalueeseen tutkittiin ja esiteltiin valon yleisin modulaatiomenetelmä WDM. Työssä esiteltiin myös dispersion aiheuttama aikahajonta. Optisen signaalin siirrossa piirilevyllä keskityttiin valokanava- ja free-space-siirtoon. Valokanavamateriaalin vaikutusta heijastuksiin optisessa tiedonsiirrossa piirilevyllä tutkittiin. Nykyisten piirilevyjen tuotantomenetelmien käytön mahdollisuutta valokanavapiirilevyn valmistuksessa tutkittiin eri materiaaleille. Moduulien sisäisten tiedonsiirtoteiden integroinnin yleistymistä tulevaisuudessa perusteltiin. Lopuksi työssä esiteltiin kolme uutta keksintöä liittyen optiseen tiedonsiirtoon. Tarkoituksena oli esittää alan moninaisuutta ja uusien sovellusten mahdollisuuksia.

Building an Access Network for Triple-Play Services

This final project was made for the Broadband department of TeliaSonera. This project gives an overview on how internet service provider might build an access network so that they can offer triple-play services. It also gives information on what equipment is needed and what is required from the access, aggregation and edge networks. The project starts by describing the triple-play service. Then it moves on to optical fiber cables, the network technology and network architecture. At the end of the project there is an example of the process and construction of the access network. It will give an overview of the total process and problems that a network planner might face during the planning phase of the project. It will give some indication on how one area is built from the start to finish. The conclusion of the project presents some points that must be taken into consideration when building an access network. The building of an access network has to be divided to a time span of eight to ten years, where one year is one phase in the project. One phase is divided into three parts; Selecting the areas and targets, Planning the areas and targets, and Documentation. The example area gives indication on the planning of an area. It is almost impossible to connect all targets at the same time. This means that the service provider has to complete the construction in two or three parts. The area is considered to be complete when more than 80% of the real estates have fiber.

Muovien laserhitsaus modernissa optisen kuitukaapelin tuotannossa

Tämän diplomityön päämääränä oli tutkia nykyisen optisen markkinasektorin nykytilaa ja ennakoida mahdollista tulevaa kapasiteetin tarpeen kasvua merkittävän taantumakauden jälkeen. Erityistä huomiota käytettiin kaapelin valmistuksen vaiheisiin ja näitä vastaaviin laitteisiin. Tätä kautta selvitettiin nykyisten markkinoilla toimivien laiteratkaisujen ominaisuudet. Työssä havaittiin kuitukaapeleiden rakenneratkaisujen muuttuvan asennettavuuden parantamisen ja kaapeleiden paremman kestävyyden suuntaan. Näiden muuttuessa tulevat valmistustekniikat ja menetelmät kehittymään vastaamaan uusia ratkaisuja. Laserhitsausmenetelmällä voidaan laajentaa kaapeleiden rakenneratkaisujen ja materiaalivaihtoehtojen valikoimaa perinteisen extruusiotekniikan rinnalle. Työ avaa uusia toteutusmandollisuuksia kaapelinvalmistusprosessiin, sekä antaa pohjaa uusien kaapelirakenteiden tuomiseen globaaleille optisen kuitukaapelin markkinoille.

Particle detector link system modifications in RE1/1 sector

The large hadron collider constructed at the European organization for nuclear research, CERN, is the world’s largest single measuring instrument ever built, and also currently the most powerful particle accelerator that exists. The large hadron collider includes six different experiment stations, one of which is called the compact muon solenoid, or the CMS. The main purpose of the CMS is to track and study residue particles from proton-proton collisions. The primary detectors utilized in the CMS are resistive plate chambers (RPCs). To obtain data from these detectors, a link system has been designed. The main idea of the link system is to receive data from the detector front-end electronics in parallel form, and to transmit it onwards in serial form, via an optical fiber. The system is mostly ready and in place. However, a problem has occurred with innermost RPC detectors, located in sector labeled RE1/1; transmission lines for parallel data suffer from signal integrity issues over long distances. As a solution to this, a new version of the link system has been devised, a one that fits in smaller space and can be located within the CMS, closer to the detectors. This RE1/1 link system has been so far completed only partially, with just the mechanical design and casing being done. In this thesis, link system electronics for RE1/1 sector has been designed, by modifying the existing link system concept to better meet the requirements of the RE1/1 sector. In addition to completion of the prototype of the RE1/1 link system electronics, some testing for the system has also been done, to ensure functionality of the design.

Spectrometrical Monitoring of Laser Sintering Process of Ceramic Material

This thesis is done as a part of project called FuncMama that is a project between Technical Research Centre of Finland (VTT), Oulu University (OY), Lappeenranta University of Technology (LUT) and Finnish industrial partners. Main goal of the project is to manufacture electric and mechanical components from mixed materials using laser sintering. Aim of this study was to create laser sintered pieces from ceramic material and monitor the sintering event by using spectrometer. Spectrometer is a device which is capable to record intensity of different wavelengths in relation with time. In this study the monitoring of laser sintering was captured with the equipment which consists of Ocean Optics spectrometer, optical fiber and optical lens (detector head). Light from the sintering process hit first to the lens system which guides the light in to the optical fibre. Optical fibre transmits the light from the sintering process to the spectrometer where wavelengths intensity level information is detected. The optical lens of the spectrometer was rigidly set and did not move along with the laser beam. Data which was collected with spectrometer from the laser sintering process was converted with Excel spreadsheet program for result’s evaluation. Laser equipment used was IPG Photonics pulse fibre laser. Laser parameters were kept mainly constant during experimental part and only sintering speed was changed. That way it was possible to find differences in the monitoring results without fear of too many parameters mixing together and affecting to the conclusions. Parts which were sintered had one layer and size of 5 x 5 mm. Material was CT2000 – tape manufactured by Heraeus which was later on post processed to powder. Monitoring of different sintering speeds was tested by using CT2000 reference powder. Moreover tests how different materials effect to the process monitoring were done by adding foreign powder Du Pont 951 which had suffered in re-grinding and which was more reactive than CT2000. By adding foreign material it simulates situation where two materials are accidently mixed together and it was studied if that can be seen with the spectrometer. It was concluded in this study that with the spectrometer it is possible to detect changes between different laser sintering speeds. When the sintering speed is lowered the intensity level of light is higher from the process. This is a result of higher temperature at the sintering spot and that can be noticed with the spectrometer. That indicates it could be possible to use spectrometer as a tool for process observation and support the idea of having system that can help setting up the process parameter window. Also important conclusion was how well the adding of foreign material could be seen with the spectrometer. When second material was added a significant intensity level raise could be noticed in that part where foreign material was mixed. That indicates it is possible to see if there are any variations in the material or if there are more materials mixed together. Spectrometric monitoring of laser sintering could be useful tool for process window observation and temperature controlling of the sintering process. For example if the process window for specific material is experimentally determined to get wanted properties and satisfying sintering speed. It is possible if the data is constantly recorded that the results can show faults in the part texture between layers. Changes between the monitoring data and the experimentally determined values can then indicate changes in the material being generated by material faults or by wrong process parameters. The results of this study show that spectrometer could be one possible tool for monitoring. But to get in that point where this all can be made possible much more researching is needed.

Communication Solutions for LVDC Island Networks

Production and generation of electrical power is evolving to more environmental friendly technologies and schemes. Pushed by the increasing cost of fossil fuels, the operational costs of producing electrical power with fossil fuels and the effect in the environment, like pollution and global warming, renewable energy sources gain con-stant impulse into the global energy economy. In consequence, the introduction of distributed energy sources has brought a new complexity to the electrical networks. In the new concept of smart grids and decen-tralized power generation; control, protection and measurement are also distributed and requiring, among other things, a new scheme of communication to operate with each other in balance and improve performance. In this research, an analysis of different communication technologies (power line communication, Ethernet over unshielded twisted pair (UTP), optic fiber, Wi-Fi, Wi-MAX, and Long Term Evolution) and their respective characteristics will be carried out. With the objective of pointing out strengths and weaknesses from different points of view (technical, economical, deployment, etc.) to establish a richer context on which a decision for communication approach can be done depending on the specific application scenario of a new smart grid deployment. As a result, a description of possible optimal deployment solutions for communication will be shown considering different options for technologies, and a mention of different important considerations to be taken into account will be made for some of the possible network implementation scenarios.

Weldability of powder bed fusion fabricated stainless steel 316L sheets to cold rolled sheet metal

Weldability of powder bed fusion (PBF) fabricated components has come to discussion in past two years due to resent developments in the PBF technology and limited size of the machines used in the fabrication process. This study concentrated on effects of energy input of welding on mechanical properties and microstructural features of welds between PBF fabricated stainless steel 316L sheets and cold rolled sheet metal of same composition by the means of destructive testing and microscopic analysis. Optical fiber diameter, laser power and welding speed were varied during the experiments that were executed following one variable at a time (OVAT) method. One of the problems of welded PBF fabricated components has been lower elongations at break comparing to conventionally manufactured components. Decreasing energy input of the laser keyhole welding decreased elongations at break of the welded specimens. Ultimate tensile strengths were not affected significantly by the energy input of the welding, but fracturing of the specimens welded using high energy input occurred from the weld metal. Fracturing of the lower energy input welds occurred from the PBF fabricated base metal. Energy input was found to be critical factor for mechanical properties of the welds. Multioriented grain growth and formation of neck at fusion zone boundary on the cold rolled side of the weld was detected and suspected to be result from weld pool flows caused by differences in molten weld pool behaviour between the PBF fabricated and cold rolled sides of the welds.

The intrinsic mechanisms of softwood fiber damage in brown stock fiber line unit operations Lappeenranta 2010

The effects of pulp processing on softwood fiber properties strongly influence the properties of wet and dry paper webs. Pulp strength delivery studies have provided observations that much of the strength potential of long fibered pulp is lost during brown stock fiber line operations where the pulp is merely washed and transferred to the subsequent processing stages. The objective of this work was to study the intrinsic mechanisms which maycause fiber damage in the different unit operations of modern softwood brown stock processing. The work was conducted by studying the effects of industrial machinery on pulp properties with some actions of unit operations simulated in laboratory scale devices under controlled conditions. An optical imaging system was created and used to study the orientation of fibers in the internal flows during pulp fluidization in mixers and the passage of fibers through the screen openings during screening. The qualitative changes in fibers were evaluated with existing and standardized techniques. The results showed that each process stage has its characteristic effects on fiber properties: Pulp washing and mat formation in displacement washers introduced fiber deformations especially if the fibers entering the stage were intact, but it did not decrease the pulp strength properties. However, storage chests and pulp transfer after displacement washers contributed to strength deterioration. Pulp screening proved to be quite gentle, having the potential of slightly evening out fiber deformations from very deformed pulps and vice versa inflicting a marginal increase in the deformation indices if the fibers were previously intact. Pulp mixing in fluidizing industrial mixers did not have detrimental effects on pulp strength and had the potential of slightly evening out the deformations, provided that the intensity of fluidization was high enough to allow fiber orientation with the flow and that the time of mixing was short. The chemical and mechanical actions of oxygen delignification had two distinct effects on pulp properties: chemical treatment clearly reduced pulp strength with and without mechanical treatment, and the mechanical actions of process machinery introduced more conformability to pulp fibers, but did not clearly contribute to a further decrease in pulp strength. The chemical composition of fibers entering the oxygen stage was also found to affect the susceptibility of fibers to damage during oxygen delignification. Fibers with the smallest content of xylan were found to be more prone to irreversibledeformations accompanied with a lower tensile strength of the pulp. Fibers poor in glucomannan exhibited a lower fiber strength while wet after oxygen delignification as compared to the reference pulp. Pulps with the smallest lignin content on the other hand exhibited improved strength properties as compared to the references.