Gas Temperature and Radiative Heat Transfer in Oxy-fuel Flames

This work presents measurements of the gas temperature, including fluctuations, and its influence on the radiative heat transfer in oxy-fuel flames. The measurements were carried out in the Chalmers 100 kW oxy-fuel test unit. The in-furnace gas temperature was measured by a suction pyrometer and by an optical system based on FTIR-spectroscopy. The radiation intensity was measured by a Narrow Angle Radiometer and the gas radiation was calculated with a Statistical Narrow Band model. The overall agreement between the two temperature measurement techniques was good. The optical system showed a lower temperature than the suction pyrometer in the low velocity regions of the furnace, a difference which is likely to be an effect of the purge gas added in the optical probe. The measured temperature fluctuations were evaluated by modeling of the gas radiation. The influence from the measured fluctuations on the radiative heat transfer shows no effect of turbulence-radiation interaction. However, by comparing with temperature fluctuations in other flames it can be seen that the fluctuations measured here are relatively small. Further research is needed to clarify to which extent the applied methods can account for the turbulence-radiation interaction in the investigated flame

Measurement and Modeling of Particle Radiation in Coal Flames

This work aims at developing a methodology that can provide information of in-flame particle radiation in industrial-scale flames. The method is based on a combination of experimental and modeling work. The experiments have been performed in the high-temperature zone of a 77 kWth swirling lignite flame. Spectral radiation, total radiative intensity, gas temperature, and gas composition were measured, and the radiative intensity in the furnace was modeled with an axisymmetric cylindrical radiation model using Mie theory for the particle properties and a statistical narrow-band model for the gas properties. The in-flame particle radiation was measured with a Fourier transform infrared (FTIR) spectrometer connected to a water-cooled probe via fiber optics. In the cross-section of the flame investigated, the particles were found to be the dominating source of radiation. Apart from giving information about particle radiation and temperature, the methodology can also provide estimates of the amount of soot radiation and the maximum contribution from soot radiation compared to the total particle radiation. In the center position in the flame, the maximum contribution from soot radiation was estimated to be less than 40% of the particle radiation. As a validation of the methodology, the modeled total radiative intensity was compared to the total intensity measured with a narrow angle radiometer and the agreement in the results was good, supporting the validity of the used approach

Taajuusmuuttajan ylijännite- ja maasulkusuojauksen suunnittelu

Frequency converters operate in an electrically harsh environment where frequency converters are exposed to over voltages in the power-distribution networks. The exposure to the over voltages has observed to cause reliability problems in the rectifier diodes and the surge suppression varistors of the frequency converters. Another reliability problem is earth faults. Low-impedance earth faults causes decays of the IGBTs in the inverter bridge. Additionally, a high-impedance earth fault can cause disturbances in the motor control. Objective of this thesis is to increase the robustness of frequency converter connected to a single-phase AC supply against power-grid over voltages and earth faults. In this thesis the improvement of the surge suppression in a frequency converter was investigated by simulating the operation of different surge suppression topologies. Additionally, three earth-fault detection circuits are developed. The operation of these circuits was verified by simulations and practical measurements. According to the results in this thesis, reliable surge suppression in a single-phase frequency converter could be implemented with a varistor before the rectifier bridge, which is placed between the input AC-supply phase and neutral, combined with small differential-mode inductor between the intermediate-DC-link capacitors and the varistor. The reliability of the varistor could be increased by increasing the voltage rating of the varistor or by utilizing series connected varistor and gas discharge tube. The investigation regarding the earth-fault detection revealed that a PCB-coil based Rogowski coil and shunt-current measurement in both DC potentials utilizing a linear optocoupler offers an alternative to a summation current transformer based earth-fault detection in a frequency converter. The Rogowski coil offers a low-coast solution. The detection utilizing linear optocoupler offers a compact solution.Taajuusmuuttajat joutuvat usein toimimaan sähkönlaadun kannalta vaikeassa ympäristössä, missä taajuusmuuttajat altistuvat sähköverkon ylijännitteille. Sähköverkon ylijännitteiden on huomattu aiheuttavan luotettavuusongelmia taajuusmuuttajan tulosilloissa ja ylijännitteiltä suojaavassa varistorissa. Ylijännitteiden lisäksi taajuusmuuttajan lähdössä tapahtuvien maasulkujen on huomattu aiheuttavan ongelmia taajuusmuuttajien toiminnassa. Lähdössä tapahtuva matalaimpedanssinen maasulku aiheuttaa vaihtosuuntaajasillan IGBT:iden rikkoutumisia. Korkeaimpedanssinen maasulku aiheuttaa ongelmia moottorisäädössä. Tämän työn tutkimuskysymys on miten yksivaiheisesti sähköverkkoon kytketyn taajuusmuuttajan ylijännitesuojausta ja maasulunsuojausta voitaisiin parantaa. Tässä työssä tutkittiin ylijännitesuojauksen parannusmahdollisuuksia vertailemalla erilaisten ylijännitesuojaustopologioiden toimintaa simuloinneilla. Lisäksi työssä kehitettiin kolme erilaista summavirranmittaukseen perustuvaa maasulunhavainnointipiiriä. Piirien toimintaa tutkittiin simuloinnein ja mittauksilla. Työssä saatujen tulosten perusteella taajuusmuuttajan tulopuolelle, tulovaiheen ja nollajohtimen väliin, asetettu metallioksidivaristori tarjoaisi luotettavan ylijännitesuojauksen kun varistorin ja jännitevälipiirin kondensaattoreiden väliin asetetaan pieni eromuotoinen kuristin. Varistorin luotettavuutta voidaan kasvattaa kasvattamalla varistorin nimellisjännitettä tai käyttämällä sarjaan kytkettyä kaasupurkausputkea ja varistoria. Tämän työn maasulkuun liittyvä tutkimus osoittaa, että summavirran mittaaminen piirikortille integroidulla Rogowski-kelalla tai hyödyntämällä lineaarioptioerotinta ja virranmittausvastuksia kummassakin tasajännitevälipiirin potentiaalissa tarjoaa vaihtoehdon perinteisesti maasulun valvonnassa käytetylle summavirtamuuntajalle. Piirikortille integroitu Rogowski-kela tarjoaa edullisen ratkaisun maasulun valvontaan. Vaihtoehtoisesti, lineaarioptioerotinta käyttävä ratkaisu tarjoaa kompaktin ratkaisun maasulunvalvontaan

Partnership or wholly owned subsidiary as an expansion method when entering the international marketplace

In today's global economy, most companies are, interested, if not forced, to expand their business internationally. In addition, the international marketplace has been more open to small and medium enterprises (SME), and not only to multi-national enterprises (MNE), which was the situation before. We find it interesting to investigate SME software firms, and their activity on the international marketplace. This since the software industry, still is quite young, and has seen tremendous growth the last 30- some years. Therefore, the over all purpose of this thesis is to gain a deeper understanding in how SME software firms expand on the international marketplace. The extent of our thesis is to find out what mode of entry SME software firms prefer when entering new international markets, and factors leading to the decision of one entry mode and/or the other. We have conducted a qualitative case study by analysing data collected from interviews with two software firms. Our findings of this study indicate that SME software firms have partnership as their default mode of entry and that the benefit, return on investment, from partnerships are greater than from wholly owned subsidiaries (WOS). Furthermore, our findings of this study indicate that it is crucial for a company's success on the international marketplace, to have a clear expansion strategy, and also be able to execute on it. In addition, it is of utter importance to recruit the best possible partner in order to have a successful international expansion.Validerat; 20101217 (root

Integration of Design Thinking in a Stage-Gate process

Den välkända linjära Stage-Gate processen har genom åren blivit till en av de vanligaste produktutvecklingsprocesserna för de flesta stora företag inom tillverkningsindustrin. Innovation och teknologi sker i snabb takt och ny teknik utvecklas ständigt vilket innebär att företagen också måste anpassa sig för att fortsätta vara konkurrenskraftiga. De iterativa produktutvecklingsprocesserna har tagit över alltmer under de senaste åren, en av dessa är Design Thinking. Forskning om samexistensen av dessa båda processer inom samma organisation är mycket begränsad, syftet är därför med denna studie att öka kunskapen kring hur företag kan arbeta med integrering av iterativa processer, mer specifikt, Design Thinking i en Stage-Gate process. Studien inleddes med en litteraturstudie där kunskap och förståelse för iterativa och linjära utvecklingsprocesser skapades. Datainsamling med stöttning av denna teoretiska bakgrund genomfördes i form av en intervjustudie där tillämpning av processerna Design Thinking i kombination med Stage-Gate på arbetsplatser undersöktes. Resultatet av intervjustudien analyserades för att besvara frågor kring strategier och tillvägagångssätt för hur och när Design Thinking kan implementeras i en linjär process teoretiskt och praktiskt. I studien har tre internationellt väletablerade företag deltagit, dessa tre företag har tidigare erfarenhet av att arbeta med Design Thinking och valdes till detta projektet då de har tydligt strukturerade arbetsprocesser kopplat till ämnet. Gemensamt för företagen som deltog i studien är att de alla ser vikten att arbeta iterativt i utvecklingsprojekt och att de upplever stora möjligheter i form av bland annat stora tidsbesparingar bara organisationerna vågar investera den tid som krävs för upplärning. De är också enade om att en involverad användare är avgörande för ett lyckat projekt, men att vid implementeringen finns en rad utmaningar som övervinns genom att fatta rätt beslut. Företagen har anpassat Design Thinking och Stage-Gate processerna efter sin bransch och nuvarande processtruktur, vilket resulterat i att denna rapport inte beskriver en generellt anpassad process utan flera alternativa processer.The famous linear Stage-Gate process has over the years become the standard product development process for most large manufacturing companies. Technological innovation is occurring at a fast-pace and new technologies are constantly being developed, meaning that companies must adapt if they want to remain competitive. The iterative product development processes have become in recent years increasingly popular, among them, Design Thinking. Since research on the coexistence of these both processes within the same organization is very limited. The purpose of this study is to increase knowledge about how companies can work with the integration of iterative processes, more specifically Design Thinking in a Stage-Gate process. The study began with a literature research with the aim to acquire knowledge and understanding of iterative and linear development processes linked to process structure and user involvement. Part of the study was based on an empirical study in the format ofsemi-structured interviews in order to collect data with the support of the theoreticalbackground. The interviews aimed to investigate the possible combination of DesignThinking and Stage-Gate within the same organization. The results of these interviews were analyzed in the interest of answering questions about strategies and approaches to how and when Design Thinking can be implemented in a linear process. Three internationally well-established companies have participated in the study. These three companies have previous experience of working with Design Thinking and were selected for this study because they have successfully implemented these processes. The companies that participated in this study had something in common, they all see the importance of working iteratively in development projects and they have seen considerable opportunities in the form of time savings if they are willing to invest the time required for training. They also agree that user involvement is crucial for a successful project, but the implementation faces a number of challenges that can be overcome by making the right decisions. The companies have adapted Design Thinking and Stage-Gate processes according to their sector and current process structure, which results in this report not describing a generally adapted process but several alternative processes

Integration of Design Thinking in a Stage-Gate process

Den välkända linjära Stage-Gate processen har genom åren blivit till en av de vanligaste produktutvecklingsprocesserna för de flesta stora företag inom tillverkningsindustrin. Innovation och teknologi sker i snabb takt och ny teknik utvecklas ständigt vilket innebär att företagen också måste anpassa sig för att fortsätta vara konkurrenskraftiga. De iterativa produktutvecklingsprocesserna har tagit över alltmer under de senaste åren, en av dessa är Design Thinking. Forskning om samexistensen av dessa båda processer inom samma organisation är mycket begränsad, syftet är därför med denna studie att öka kunskapen kring hur företag kan arbeta med integrering av iterativa processer, mer specifikt, Design Thinking i en Stage-Gate process. Studien inleddes med en litteraturstudie där kunskap och förståelse för iterativa och linjära utvecklingsprocesser skapades. Datainsamling med stöttning av denna teoretiska bakgrund genomfördes i form av en intervjustudie där tillämpning av processerna Design Thinking i kombination med Stage-Gate på arbetsplatser undersöktes. Resultatet av intervjustudien analyserades för att besvara frågor kring strategier och tillvägagångssätt för hur och när Design Thinking kan implementeras i en linjär process teoretiskt och praktiskt. I studien har tre internationellt väletablerade företag deltagit, dessa tre företag har tidigare erfarenhet av att arbeta med Design Thinking och valdes till detta projektet då de har tydligt strukturerade arbetsprocesser kopplat till ämnet. Gemensamt för företagen som deltog i studien är att de alla ser vikten att arbeta iterativt i utvecklingsprojekt och att de upplever stora möjligheter i form av bland annat stora tidsbesparingar bara organisationerna vågar investera den tid som krävs för upplärning. De är också enade om att en involverad användare är avgörande för ett lyckat projekt, men att vid implementeringen finns en rad utmaningar som övervinns genom att fatta rätt beslut. Företagen har anpassat Design Thinking och Stage-Gate processerna efter sin bransch och nuvarande processtruktur, vilket resulterat i att denna rapport inte beskriver en generellt anpassad process utan flera alternativa processer.The famous linear Stage-Gate process has over the years become the standard product development process for most large manufacturing companies. Technological innovation is occurring at a fast-pace and new technologies are constantly being developed, meaning that companies must adapt if they want to remain competitive. The iterative product development processes have become in recent years increasingly popular, among them, Design Thinking. Since research on the coexistence of these both processes within the same organization is very limited. The purpose of this study is to increase knowledge about how companies can work with the integration of iterative processes, more specifically Design Thinking in a Stage-Gate process. The study began with a literature research with the aim to acquire knowledge and understanding of iterative and linear development processes linked to process structure and user involvement. Part of the study was based on an empirical study in the format ofsemi-structured interviews in order to collect data with the support of the theoreticalbackground. The interviews aimed to investigate the possible combination of DesignThinking and Stage-Gate within the same organization. The results of these interviews were analyzed in the interest of answering questions about strategies and approaches to how and when Design Thinking can be implemented in a linear process. Three internationally well-established companies have participated in the study. These three companies have previous experience of working with Design Thinking and were selected for this study because they have successfully implemented these processes. The companies that participated in this study had something in common, they all see the importance of working iteratively in development projects and they have seen considerable opportunities in the form of time savings if they are willing to invest the time required for training. They also agree that user involvement is crucial for a successful project, but the implementation faces a number of challenges that can be overcome by making the right decisions. The companies have adapted Design Thinking and Stage-Gate processes according to their sector and current process structure, which results in this report not describing a generally adapted process but several alternative processes

Reduced epilepsy development in synapsin 2 knockout mice with autistic behavior following early systemic treatment with interleukin-6 receptor antibody

BACKGROUND: Individuals with autism spectrum disorder (ASD) have an increased risk of developing epilepsy. Both ASD and epilepsy have been associated with increased levels of immune factors in the blood, including the proinflammatory cytokine interleukin 6 (IL-6). Mice lacking the synapsin 2 gene (Syn2 KO) exhibit ASD-like behavior and develop epileptic seizures. Their brains display neuroinflammatory changes including elevated IL-6 levels. We aimed to investigate the effect of systemic IL-6 receptor antibody (IL-6R ab) treatment on seizure development and frequency in Syn2 KO mice.MATERIAL AND METHODS: Weekly systemic (i.p.) injections of IL-6R ab or saline were given to Syn2 KO mice starting either early in life at 1 month of age, before seizure debut or at 3 months of age, directly after seizure debut and continued for 4 or 2 months, respectively. Seizures were provoked by handling the mice three times per week. The neuroinflammatory response and synaptic protein levels in the brain were determined by ELISA, immunohistochemistry and western blots. In an additional group of Syn2 KO mice, with IL-6R ab treatment early in life, ASD-related behavioral tests including social interaction and repetitive self-grooming, as well as cognitive memory and depressive-/anxiety-like tests, and actigraphy measurements of circadian sleep-awake rhythm were analyzed.RESULTS: The IL-6R ab treatment reduced seizure development and frequency in Syn2 KO mice when initiated before, but not after, seizure debut. However, early treatment did not reverse the neuroinflammatory response or the imbalance in synaptic protein levels in the brain previously reported in Syn2 KO mice. The treatment did not affect social interaction, performance in memory, depressive-/anxiety-like tests or the sleep-awake rhythm of Syn2 KO mice.CONCLUSION: These findings suggest the involvement of IL-6 receptor signaling during epilepsy development in Syn2 KO mice, without significant alterations of the immune reaction in the brain, and independently of cognitive performance, mood and circadian sleep-awake rhythm

The MHC class II transactivator modulates seeded alpha-synuclein pathology and dopaminergic neurodegeneration in an in vivo rat model of Parkinson's disease

Background: Abnormal folding, aggregation and spreading of alpha-synuclein (αsyn) is a mechanistic hypothesis for the progressive neuropathology in Parkinson's disease (PD). Spread of αsyn between cells is supported by clinical, neuropathological and experimental evidence. It has been proposed that a pro-inflammatory micro-environment in response to αsyn can promote its aggregation. We have previously shown that allelic differences in the major histocompatibility complex class two transactivator (Mhc2ta) gene, located in the VRA4 locus, alter MHCII expression levels, microglial activation and antigen presentation capacity in rats upon human αsyn over-expression. In addition, Mhc2ta regulated dopaminergic neurodegeneration and the extent of motor impairment. The purpose of this study was to determine whether Mhc2ta regulates αsyn aggregation, propagation and dopaminergic pathology in an αsyn pre-formed fibril (PFF)-seeded in vivo model of PD. Methods: The DA and DA.VRA4 congenic rat strains share background genome but display differential microglial antigen presenting capacity due to different Mhc2ta alleles in the VRA4 locus. PFFs of human αsyn or BSA solution were injected unilaterally to the striatum of DA and DA.VRA4 rats two weeks after ipsilateral administration of recombinant adeno-associated virus (rAAV) vectors carrying human αsyn or GFP to the substantia nigra pars compacta. Behavioural assessment was performed at 2, 5 and 8 weeks while histological evaluation of αsyn pathology, inflammation and neurodegeneration as well as determination of serum cytokine profiles were performed at 8 weeks. Results: rAAV-mediated expression of human αsyn in nigral dopaminergic neurons combined with striatal PFF administration induced enhanced αsyn pathology in DA.VRA4 compared to DA rats. Mhc2ta thus significantly regulated the seeding, propagation and toxicity of αsyn in vivo. This was reflected in terms of wider extent and anatomical distribution of αsyn inclusions, ranging from striatum to the forebrain, midbrain, hindbrain and cerebellum in DA.VRA4. Compared to DA rats, DA.VRA4 also displayed enhanced motor impairment and dopaminergic neurodegeneration as well as higher levels of the proinflammatory cytokines IL-2 and TNFα in serum. Conclusions: We conclude that the key regulator of MHCII expression, Mhc2ta, modulates neuroinflammation, αsyn-seeded Lewy-like pathology, dopaminergic neurodegeneration and motor impairment. This makes Mhc2ta and microglial antigen presentation promising therapeutic targets for reducing the progressive neuropathology and clinical manifestations in PD