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The NordBatt Conferences: The Journey so Far and the Future Ahead
Get PDFAll great things have humble beginnings. In 2013 when NordBatt started, we had no lithium-ion battery manufacturing in the Nordic countries and we had rather few EVs on the roads, although things were clearly starting to move – Tesla Model S in fact topped the monthly new car sales of Norway in September that very year. Yet, even if the field was advancing and lively, relatively few Nordic research groups were doing any kind of battery R&D. Now, in 2023, almost everything is different; batteries and “electrify everything” are seen, not only by us, as the next industrial revolution – it is a topic gathering considerably many more actors in academia as well as in the whole ecosystem of batteries
Advanced characterization techniques of photonic devices with frequency combs
Get PDFIntegrated photonics has witnessed remarkable progress in the last decades.Measuring photonic devices in amplitude and phase provides insight intotheir performance. Swept wavelength interferometry is a prominent techniquefor the broadband characterization of the complex response. Itleverages continuous advances in rapidly tunable laser sources but isprone to systematic errors associated with frequency calibration. Thisthesis focuses on the non-destructive measurement of ultralow-loss photonicdevices using swept wavelength interferometric technique. We overcomeissues associated with nonlinear tuning by calibrating the frequencyof the laser on the fly with the aid of a frequency comb. We apply theconcept to diverse components of relevance including microresonatorsand spiral waveguides. This technique enables diagnosing waveguidesfor the loss and potential defects and is instrumental in optimizing devicefabrication ecosystems. The measured phase response of microresonatorsallows for untangling the coupling condition and provides insightinto microresonator-waveguide systems. The later part of this thesiscovers the linear (stepped and multi-heterodyne) methods for spectraland temporal characterization of frequency combs. The linear heterodynemethod provides unprecedented sensitivity and bandwidth rangeof measurement. In addition, we provide an overview and comparativeassessment of the state-of-the-art in the field
A Multi-level Pseudo Single Active Bridge (PSAB) DC-DC Converter for Offshore DC Wind Turbines
No full textThe three-phase single active bridge (SAB) converter suffers from large second harmonic currents in the ac-link, low transformer utilization, and large required dc-link capacitors. This has led to a focus on the dual active bridge (DAB) converters in the literature, even for unidirectional applications like dc wind turbines. In these applications, the load-side transistors of the DAB converter transfer power for a small fraction of the fundamental period. This means investment in chips that are not used to the maximum of their potential. This paper proposes a hybrid of the SAB and DAB converters to solve this issue. The proposed converter can be controlled by phase shift modulation and performs similarly to a DAB converter. It is shown that this converter’s total installed transistor apparent power is 40% and 45% less than that of conventional dual active bridge (DAB) and multi-level DAB converters, respectively
Application of the ESHO-QA guidelines for determining the performance of the LCA superficial hyperthermia heating system
Get PDFPurpose: This study aimed to assess the quality of the lucite cone applicator (LCA), the standard applicator for superficial hyperthermia at the Erasmus MC Cancer Institute, using the most recent quality assurance guidelines, thus verifying their feasibility. Materials and methods: The assessment was conducted on each of the six LCAs available for clinical treatments. The temperature distribution was evaluated using an infrared camera across different layers of a fat-muscle mimicking phantom. The maximum temperature increase, thermal effective penetration depth (TEPD), and thermal effective field size (TEFS) were used as quality metrics. The experimental results were validated through comparison with simulated results, using a canonical phantom model and a realistic phantom model segmented from CT imaging. Results: A maximum temperature increase above 6 \ub0C at 2 cm depth in the fat-muscle phantom for all the experiments was found. A mean negative difference between simulated and experimental data was of 1.3 \ub0C when using the canonical phantom model. This value decreased to a mean negative difference of 0.4 \ub0C when using the realistic model. Simulated and measured TEPD showed good agreement for both in silico scenarios, while discrepancies were present for TEFS. Conclusions: The LCAs passed all QA guidelines requirements for superficial hyperthermia delivery when used singularly or in an array configuration. A further characterization of parameters such as antenna efficiency and heat transfer coefficients would be beneficial for translating experimental results to simulated values. Implementing the QA guidelines was time-consuming and demanding, requiring careful preparation and correct setup of antenna elements
Vacuum-Seal Waveguide Feedthrough for Extended W-Band 67-116 GHz
Get PDFThis article describes the design and performance of a vacuum-seal waveguide feedthrough with ultrawide RF band 67-116 GHz. We describe first the initial drivers behind the chosen design, then we present the results of the numerical simulations and optimization and provide thereafter the results of the RF and vacuum tests of the fabricated devices. The demonstrated RF performance is very close to the one expected from the simulation with an insertion loss less than 0.3 dB and a return loss better than 20 dB. Simultaneously, the feedthrough shows excellent vacuum isolation, Helium gas leak rate of < 2x10(-8) mbar center dot L/s is demonstrated, which allows using such a device in various space and ground applications
Mechanical, Morphological, and Charge Transport Properties of NDI Polymers with Variable Built-in Π-Conjugation Lengths Probed by Simulation and Experiment
No full textMechanically deformable polymeric semiconductors are a key material for fabricating flexible organic thin-film transistors (FOTFTs)-the building block of electronic circuits and wearable electronic devices. However, for many pi-conjugated polymers achieving mechanical deformability and efficient charge transport remains challenging. Here the effects of polymer backbone bending stiffness and film microstructure on mechanical flexibility and charge transport are investigated via experimental and computational methods for a series of electron-transporting naphthalene diimide (NDI) polymers having differing extents of pi-conjugation. The results show that replacing increasing amounts of the pi-conjugated comonomer dithienylvinylene (TVT) with the pi-nonconjugated comonomer dithienylethane (TET) in the backbone of the fully pi-conjugated polymeric semiconductor, PNDI-TVT100 (yielding polymeric series PNDI-TVTx, 100 >= x >= 0), lowers backbone rigidity, degree of texturing, and pi-pi stacking interactions between NDI moieties. Importantly, this comonomer substitution increases the mechanical robustness of PNDI-TVTx while retaining efficient charge transport. Thus, reducing the TVT content of PNDI-TVTx suppresses film crack formation and dramatically stabilizes the field-effect electron mobility upon bending (e.g., 2 mm over 2000 bending cycles). This work provides a route to tune pi-pi stacking in pi-conjugated polymers while simultaneously promoting mechanical flexibility and retaining good carrier mobility in FOTFTs
On the Asymptotic Behaviour of Superexponential L\ue9vy Processes
Get PDFWe study tail probabilities of superexponential infinite divisible distributions as well as tail probabilities of suprema of L\ue9vy processes with superexponential marginal distributions over compact intervals
Validation of D-T fusion power prediction capability against 2021 JET D-T experiments
Get PDFJET experiments using the fuel mixture envisaged for fusion power plants, deuterium and tritium (D-T), provide a unique opportunity to validate existing D-T fusion power prediction capabilities in support of future device design and operation preparation. The 2021 JET D-T experimental campaign has achieved D-T fusion powers sustained over 5 s in ITER-relevant conditions i.e. operation with the baseline or hybrid scenario in the full metallic wall. In preparation of the 2021 JET D-T experimental campaign, extensive D-T predictive modelling was carried out with several assumptions based on D discharges. To improve the validity of ITER D-T predictive modelling in the future, it is important to use the input data measured from 2021 JET D-T discharges in the present core predictive modelling, and to specify the accuracy of the D-T fusion power prediction in comparison with the experiments. This paper reports on the validation of the core integrated modelling with TRANSP, JINTRAC, and ETS coupled with a quasilinear turbulent transport model (Trapped Gyro Landau Fluid or QualLiKiz) against the measured data in 2021 JET D-T discharges. Detailed simulation settings and the heating and transport models used are described. The D-T fusion power calculated with the interpretive TRANSP runs for 38 D-T discharges (12 baseline and 26 hybrid discharges) reproduced the measured values within 20 % . This indicates the additional uncertainties, that could result from the measurement error bars in kinetic profiles, impurity contents and neutron rates, and also from the beam-thermal fusion reaction modelling, are less than 20 % in total. The good statistical agreement confirms that we have the capability to accurately calculate the D-T fusion power if correct kinetic profiles are predicted, and indicates that any larger deviation of the D-T fusion power prediction from the measured fusion power could be attributed to the deviation of the predicted kinetic profiles from the measured kinetic profiles in these plasma scenarios. Without any posterior adjustment of the simulation settings, the ratio of predicted D-T fusion power to the measured fusion power was found as 65%-96% for the D-T baseline and 81%-97% for D-T hybrid discharge. Possible reasons for the lower D-T prediction are discussed and future works to improve the fusion power prediction capability are suggested. The D-T predictive modelling results have also been compared to the predictive modelling of the counterpart D discharges, where the key engineering parameters are similar. Features in the predicted kinetic profiles of D-T discharges such as underprediction of ne are also found in the prediction results of the counterpart D discharges, and it leads to similar levels of the normalized neutron rate prediction between the modelling results of D-T and the counterpart D discharges. This implies that the credibility of D-T fusion power prediction could be a priori estimated by the prediction quality of the preparatory D discharges, which will be attempted before actual D-T experiments
A ground-borne noise prediction model for railway traffic in tunnels in bedrock
Get PDFHuman life has become more manageable by the expansion of railway lines. However, despite providing convenience, railways increase noise and vibration in residential areas. Vibrations and noise generated by railways may harm human health, cause cosmetic damage and have an adverse impact on the environment. In order to reduce the effects of train-induced noise and vibration, efficient and accurate models for the prediction of ground-borne noise and vibration are required.Various analytical, theoretical, and experimental models have been developed to predict ground-borne noise. There is generally a lack of published information about parameters for ground-borne noise prediction concerning Swedish conditions with bedrock of high quality. Some investigations are reported, and a few consultancy companies have their own developed models, which are generally not publicly available. In fact, overall, the input data used to form these models and the methods of validation are not publicly available. Moreover, the statistical nature of the source and transfer paths requires that uncertainties are accurately handled in the model.This work aims to develop a model for ground-borne noise prediction for underground tunnels, to be used in Swedish Transport Administration projects. The methodology is formulated for three different stages based on precision and available information: location stage, planning stage, and construction stage. The first two stages correspond to planning and designing a railway track. The third stage involves the construction stage where more detailed information may be acquired. The prediction model presented here is developed for Swedish bedrock up to 1 kHz and formulated as a source term and several correction terms. These terms take into account various aspects, including train speed, distance attenuation, ground-to-building coupling, vibration levels on different floors and walls, how the room properties affect sound pressure levels within rooms, and different track treatments. Moreover, uncertainties are estimated using the standard deviation of each term. The required data are gathered from measurements in the G\ue5rda tunnel in Gothenburg combined with existing data from measurements in the \uc5sa tunnel close to Varberg.As a result, a comprehensive model is suggested for ground-borne noise prediction in Swedish Transport Administration projects. However, the model is still under development, will be sent upon referral, and may undergo improvements