Plasmonic effects in nanosized particles enhance the interaction between light and matter due to the localized surface plasmon resonance, with potential applications such as all-optical transistors and optical computers. Commonly, the dynamics of nanoparticles’ optical properties are assessed via pump-probe spectroscopy, where a plasmonic structure is exited by an initial laser, the pump. Thereafter a second, less intense laser, a probe, interacts with the now excited structure at a time delay. Through measurements of the probelight transmitted by the matter, the optical dynamics of the structure are monitored. Similar methodologies can potentially be used for other applications as well, such as all-optical switching. This study focuses on an implementation of a numerical finite element method model simulating a pump-probe experiment to predict the effects of different geometries and evaluate experimental data. The simulations are split into three parts. Initially, periodically spaced nanoparticles are excited by the pump laser. Then the model estimates the internal thermal dynamics of the excited nanoparticles and in turn, determines the change in complex permittivity. Lastly, the probe-matter interaction is modeled. To evaluate the model, a comparison with another model was performed. Furthermore, simulations of periodically spaced gold dimer nanoparticles in air were done to investigate how dimers affect transmitted light. For a probe light polarization rotated 45◦ against the axis parallel to the dimer, a change in rotation of 6◦ over 35 fs was induced by the pump, indicating a potential switching mechanism.

No description available.

No description available.

The SNTEMP (U.S. Fish and Wildlife Service), QUAL2E (U.S. Environmental Protection Agency), and RQUAL (Tennessee Valley Authority) stream temperature prediction models were evaluated. All models had high predictive ability with the majority of predictions, >80% for Back Creek (Roanoke County, VA) and >90% for the Smith River tailwater (SRT) (Patrick County, VA), within 3°C of the measured water temperature. Sensitivity of model input parameters was found to differ between model, stream system, and season. The most sensitive of assessed parameters, dependent on model and stream, were lateral inflow, starting-water, air, and wet-bulb temperature. All three models predicted well, therefore, selecting a model to assess alternative water management scenarios was based on model capabilities. The RQUAL model, used to predict SRT temperatures under alternative hydropower release regimes, illustrated potential thermal habitat improvement for brown trout (Salmo trutta) compared to existing conditions. A 7-day/week morning 1 hr release was determined to best concurrently increase occurrence of brown trout optimal growth temperatures (+10.2% mean), decrease 21°C (state standard) exceedances (99% prevention), and decrease hourly changes in temperature (-1.6°C mean) compared to existing thermal conditions. The SNTEMP model was used to assess thermal habitat under flow, shade, and channel width changes occurring from future urbanization within the Back Creek watershed. Predictions reveal that additional urban development could limit thermal habitat for present fish species by elevating summer mean daily temperature up to 1°C and cause 31°C (state standard) exceedances compared to existing conditions. Temperature impacts were lessened by single rather than cumulative changes suggesting mitigation measures may maintain suitable thermal habitat. / Master of Science

Fatigue cracking is one primary distress in asphalt pavements, dominant especially in later years of service. Prediction of mixture fatigue resistance is critical for various applications, e.g., pavement design and preventative maintenance. The goal of this work was to develop a tool for prediction of binder aging level and mixture fatigue life in pavement from unaged binder/mixture properties. To fulfill this goal, binder oxidation during the early fast-rate period must be understood. In addition, a better hourly air temperature model is required to provide accurate input for the pavement temperature prediction model. Furthermore, a user-friendly software needs to be developed to incorporate these findings. Experiments were conducted to study the carbonyl group formation in one unmodified binder (SEM 64-22) and one polymer-modified binder (SEM 70-22), aged at five elevated temperatures. Data of SEM 64-22, especially at low temperatures, showed support for a parallel-reaction model, one first order reaction and one zero order reaction. The model did not fit data of SEM 70-22. The polymer modification of SEM 70-22 might be responsible for this discrepancy. Nonetheless, more data are required to draw a conclusion. Binder oxidation rate is highly temperature dependent. Hourly air temperature data are required as input for the pavement temperature prediction model. Herein a new pattern-based air temperature model was developed to estimate hourly data from daily data. The pattern is obtained from time series analysis of measured data. The new model yields consistently better results than the conventional sinusoidal model. The pavement aging and fatigue analysis (PAFA) software developed herein synthesizes new findings from this work and constant-rate binder oxidation and hardening kinetics and calibrated mechanistic approach with surface energy (CMSE) fatigue analysis algorithm from literature. Input data include reaction kinetics parameters, mixture test results, and pavement temperature. Carbonyl area growth, dynamic shear rheometer (DSR) function hardening, and mixture fatigue life decline are predicted as function of time. Results are plotted and saved in spreadsheets.

Abstract The target in this thesis was to study selected special measurements in a basic oxygen furnace (BOF) and develop a model to predict the steel temperature at the end of the oxygen blow. Furthermore, the work aimed at increasing knowledge on measurements and phenomena in the converter and in this way improve the possibility of more efficient monitoring and control of the process. Special measurements were investigated to obtain more knowledge about their usability in running the converter process. Analysing the measurement results also led to new process knowledge. The usage of a Radio Wave Interferometer (RWI) was seen as beneficial as it makes it possible to see the rising trend of the liquid surface level in advance and to perform some corrective actions to avoid excessive foaming and possible splashing out from the converter. Acoustic measurement could also detect trends in advance, but it was found to be sensitive to disturbing noise from the surroundings. Splashing measurement gives information about the current state of the slag but not advance information. Nevertheless, the measurements revealed several factors that usually increase splashing. It would be best to use the knowledge from two different measurements, for example RWI and splashing measurement, to predict increasing splashing, which causes significant iron losses. The development of the models for end temperature prediction and additional materials provided a lot of knowledge about the factors affecting the temperature. Factors that were used in grouping were the BOF number, heat size and end carbon content. However, there were many heats that did not satisfy the target. Furthermore, there is a need for additional research into temperature progress and its control in BOF. It would also be useful to study the effect of additional materials more systematically. There are other factors, such as the oxygen flow rate and lance height, which affect the temperature that are not included in the models. Some of the factors are measurable and some are not. There is still a need for more research in this area. This work strengthens the impression that the converter process is a complex one. It was noticed; as always in process development, that continuous monitoring and efforts are required to observe the changes in process conditions, raw materials or running practices. Otherwise, the benefit of the improvements and models will be lessened. However, it would be possible to set acknowledged routines and warnings into the improved monitoring system to help the operators notice the need for system tuning. A monitoring system would provide financial benefits in terms of having fewer reblowings, better yield and better quality of final product. Savings in raw materials can also be attained as the controllability of the process becomes better. As the monitoring system contains a database of guidelines, it would form a good basis for new employees to become familiar with the process and thus facilitate their training. / Tiivistelmä Tämän opinnäytteen tarkoitus oli tutkia teräskonvertterin valittuja erikoismittauksia ja kehittää malli ennustamaan teräksen lämpötilaa happipuhalluksen lopussa. Työn tarkoituksena oli lisätä tietämystä mittauksista ja ilmiöistä konvertterissa ja tällä tapaa lisätä mahdollisuuksia prosessin tehokkaampaan monitorointiin ja ohjaukseen. Erikoismittauksia tutkittiin lisätietämyksen saamiseksi niiden käytettävyydestä konvertteriprosessin ajossa. Mittausten analysointi tuotti myös uutta prosessitietämystä. Radioaaltointerferometrin (RWI) käyttö koettiin hyödylliseksi, koska on mahdollista havaita kuonan pinnankorkeuden nousu ennakkoon ja suorittaa joitakin korjaavia toimenpiteitä liiallisen kuohumisen ja lopulta roiskumisen estämiseksi ulos konvertterista. Äänimittaus voi myös havaita trendin ennakkoon, mutta huomattiin sen olevan herkkä ympäristön häiriöäänille. Roiskemittaus antaa tietoa kuonan sen hetkisestä tilasta, mutta ei ennakkoon. Mittaukset toivat kuitenkin esiin useita tekijöitä, jotka yleensä lisäävät roiskumista. Olisi parasta käyttää kahden eri mittauksen tietoa, RWI ja roiskemittaus, ennustettaessa lisääntyvää roiskumista, joka aiheuttaa huomattavia rautahäviöitä. Loppulämpötilan ennustamiseen kehitetyn mallin ja lisäainemallin kehittäminen antoi paljon tietoa tekijöistä, jotka vaikuttavat lämpötilaan. Tekijät, joita käytettiin ryhmittelyssä, olivat konvertterinumero, panoskoko ja loppuhiilipitoisuus. Mallin soveltamisesta huolimatta jäi edelleen useita sulatuksia, jotka eivät osuneet tavoitteeseen. On edelleen tarve teräskonvertterin lämpötilakäyttäytymisen ja sen hallinnan lisätutkimukselle konvertterissa. Myös lisäaineiden vaikutusta lämpötilaan olisi hyödyllistä tutkia systemaattisemmin. On edelleen muita tekijöitä, esimerkiksi hapen virtausnopeus ja lanssin korkeus, jotka vaikuttavat lämpötilaan, mutta jotka eivät ole mukana malleissa. Osa näistä tekijöistä on mitattavia suureita ja osa ei. Lisätutkimukselle on edelleen tilaa tällä alueella. Tämä työ vahvistaa edelleen käsitystä, että konvertteriprosessi on monimutkainen. Huomattiin, kuten aina prosessikehityksessä, että jatkuvaa kehitystyötä pitää tehdä prosessiolosuhteiden, raaka-aineiden ja ajopraktiikoiden muutosten huomaamiseksi. Muuten parannusten ja mallien antama hyöty heikkenee. Monitorointijärjestelmään olisi mahdollista kehittää rutiineja ja varoituksia operaattorien avuksi, jotta he huomaisivat järjestelmävirityksen tarpeen. Monitorointijärjestelmä toisi taloudellista hyötyä, mm. lisäpuhallusten vähentymisen, lopputuotteen paremman saannon ja laadun muodossa. Raaka-ainesäästöjä voidaan saavuttaa prosessin ohjattavuuden parantuessa. Monitorointijärjestelmän sisältäessä sääntötietokannan, se luo hyvän pohjan uusille työntekijöille tutustua prosessiin ja näin heidän koulutuksensa onnistuisi helpommin.

Current flow in the electrical grid is changing due to the introduction of new generators and loads.Specifically, weak Overhead lines, are a constraint for the introduction of wind farms located farfrom the central network. The current situation requires smart solutions to improve the transportationcapabilities of these grid’s components. Among the different possibilities, Dynamic Line Rating(DLR), is emerging as the most interesting solution from both the economic and technical points ofview. The presented Thesis work investigates the performance of DLR from both the theoretical andpractical perspectives.The theory behind DLR is based on the development of a thermal model able to estimate the precisetemperature experienced by OHLs conductor under different climate conditions. Since 1972, whenthe first investigation on DLR have been published, different thermal models have been developed,each with a different precision level. The first part of the thesis concerns the investigation of IEEE738 standard accuracy.The standard analysis highlighted weaknesses on the theoretical approach employed on the forcedconvective cooling calculation. Specifically the wind direction effect is estimated as the conductorwas a perfect cylinder. A wind tunnel test has been performed in order to verify the effect of theconductor’s strands on the total thermal equilibrium. The results show that an inclined wind-conductor relative direction can have a more important impacton the line rating than foreseen with the IEEE thermal model. Since the wind tunnel test has been thefirst experience of this kind pursued at KTH, the presence of few different laboratory set-updeficiencies did not allow to draw a definitive and precise conclusion on the necessary IEEE formulacorrection.The practical side of the Thesis project includes an extensive literature research on the differentdevices that can be employed for dynamic line rating and a real-case study analysis. The analysis isperformed in order to evaluate which can be the best solution when the introduction of new windenergy supply increase the load on a pre-existent OHL. Results show that, in the selected region,Värmland, in the southwestern Sweden, DLR has the prerequisites to allow the exploitation of thehigh wind energy resource at the lower expenses. Wind energy production is often associated with anincreased cooling on the line’s conductors. This means that higher current levels can be withstoodavoiding the need for expensive lines’ upgrading. For the selected hot-spot, in 2015, DLR wouldhave allowed a transport capability improvement of 69.6% during the summer and of 26.7% duringthe winter. It is also reported that a load equal to the SLR during the winter period would have causedserious overheating transients of the conductor. Overall DLR proved to allow technical and economicbenefit for the system operator. / Flödet genom elnätet förändras på grund av införandet av ny generering och nya typer av laster.Specifikt är svaga luftledningar en begränsning för installation av vindkraft som ligger långt fråndet centrala nätet. Den nuvarande situationen kräver smarta lösningar för att förbättratransportkapaciteten i elnätet. Bland de olika möjligheterna finns Dynamic Line Rating (DLR) somframstår som den mest intressanta lösningen från både ekonomiska och tekniska synvinklar. Det härexamensarbetet behandlar resultatet av DLR från både teoretiska och praktiska perspektiv.Den teoretiska grunden för DLR är baserad på utvecklingen av en termisk modell som kan skattatemperaturen i luftledningar under olika klimatförhållanden. Examensarbetets första del behandlaren undersökning av IEEE 738 standarden (DLR standard). IEEE 738 standarden utgår från ledarensom en perfekt cylinder. Något som har en effekt bland annat i effekten av vindriktning. Ettvindtunnel test har utförts för att verifiera effekten av fler kardelers effekt på den totala termiskajämvikten. Resultaten visar att antalet kardeler har en betydande effekt på den termiska jämviktenoch då alltså även på DLR.Den andra delen av examensarbetet innehåller en omfattande litteratursökning på de olikaapparaterna som kan användas till DLR samt en praktik undersökning/analys. Analysen utförs föratt utvärdera vilken lösning som kan vara den bästa vid införandet av mer vindkraft, som ökarbelastningen på en redan existerande luftledning. Resultaten visar att, i det valda området,Värmland, i sydvästra Sverige, har DLR förutsättningar för att medge ökat utnyttjandet av den storavindkraft resurs som finns där till relativt låga kostnader. Slutsatsen av examensarbetet är att DLR ger tekniska och ekonomiska fördelar tillsystemoperatören.

This study is comprised of two separate parts: (1) modeling thermochemical nonequilibrium processes, and (2) flow field simulations of spark-induced plasma. In the first part, the methodology and literature for modeling thermochemical nonequilibrium processes in partially ionized air is presented and implemented in a zero-dimensional solver, termed as NEQZD. The solver was verified for a purely reacting flow case as well as two thermochemical nonequilibrium flow cases. A three-temperature electron-electronic model for thermochemical nonequilibrium partially ionizing air mixture was implemented and demonstrated the ability to capture additional physics compared to the legacy two-temperature model through the inclusion of electronic energy nonequilibrium. In the second part of this work, full scale axisymmetric simulations of the flow field produced by the abrupt heat release of spark-induced plasma were presented and analyzed for two electrode configurations. The heat release was modeled based on data from experiments and assumed that all electrical power supplied to the electrodes is converted to thermal energy. It was found that steeper electrode walls lead to a greater region of hot gas, a stronger shock front, and slightly larger vortices.

No description available.

Bilindustrin förflyttar sig mer och mer från bensinmotorn till det mer miljövänliga alternativet den batteridrivna motorn. För att denna övergång skall gå smidigt behöver man hålla en viss standard bensinmotorn har satt för tillgång och prestanda på marknaden. En av de större skillnaderna som finns mellan motorerna är livslängden och en av de viktigaste aspekterna man bör hålla koll på för att gå framåt inom teknologin är temperatur-hantering av batteriet. Målet med arbetet är att skapa en modell för minimumtemperaturen av en CATL 620 C batteri modul. Projektet är avgränsat till körning i kallt klimat. Verktygen som använts har varit MATLAB och dess funktioner för regression, filtrering och diagram som har använts för att analysera fram ett godtyckligt resultat av modellen. Resultaten har bearbetats och jämförts med den gamla modellen och ramverket som använts för att skapa modellen. I många fall är den bättre än den gamla modellen och den följer kurvaturen på den gamla väl i de flesta scenariona men det finns problemfall. Ett av de stora kvarvarande problemområdena är då de största influenstemperaturerna för modellen fluktuerar kraftigt. / The vehicle industry is moving away from combustion engines towards the more environmentally affordable solution electrical engines. For this transition to go smoothly the Battery-electric vehicles needs to have a certain standard that was present in the earlier engine types when it comes to availability and performance. One of the bigger differences is the longevity of the vehicles. A big part of solving that problem in a lithium-ion battery is temperature management. The aim of the project is to create a minimum temperature model of a CATL 620 C battery module. The project is limited to acquired test data from cold climate driving. The tool to solve this was with the help of MATLAB and its functions for regression, filtering and plotting to help us analyse together a viable solution. The results were compared to the old model and the framework for building the model. The model is better than the old model in a lot of cases but there are still problem-areas, especially regarding areas where the influencing temperatures are heavily fluctuating. It seems to follow the dynamics of the framework most of the time otherwise but there are still question marks regarding driving in other type of environments than what has been provided from the test-scenarios