| 1. |
- Rinman, Sven
(författare)
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Källan till ett skoltal av Runeberg
- 1933
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Ingår i: Samlaren. - Uppsala : Svenska Litteratursällskapet. - 0348-6133 .- 2002-3871. ; N.F. 14, s. 181-190
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 2. |
- Saarinen, Linn, 1980-
(författare)
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A hydropower perspective on flexibility demand and grid frequency control
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The production and consumption of electricity on the power grid has to balance at all times. Slow balancing, over days and weeks, is governed by the electricity market and carried out through production planning. Fast balancing, within the operational hour, is carried out by hydropower plants operating in frequency control mode. The need of balancing power is expected to increase as more varying renewable energy production is connected to the grid, and the deregulated electricity market presents a challenge to the frequency control of the grid.The first part of this thesis suggests a method to quantify the need for balancing or energy storage induced by varying renewable energy sources. It is found that for high shares of wind and solar power in the system, the energy storage need over a two-week horizon is almost 20% of the production.The second and third part of the thesis focus on frequency control. In the second part, measurements from three Swedish hydropower plants are compared with the behaviour expected from commonly used power system analysis hydropower models. It is found that backlash in the guide vane and runner regulating mechanisms has a large impact on the frequency control performance of the plants.In the third part of the thesis, the parameters of the primary frequency control in the Nordic grid are optimised with respect to performance, robustness and actuator work. It is found that retuning of the controller parameters can improve the performance and robustness, with a reasonable increase of the actuator work. A floating deadband in the controller is also discussed as a means to improve performance without increasing the actuator work.
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| 3. |
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| 4. |
- Bora, Kangkana, et al.
(författare)
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Automated classification of Pap smear images to detect cervical dysplasia
- 2017
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Ingår i: Computer Methods and Programs in Biomedicine. - : Elsevier. - 0169-2607 .- 1872-7565. ; 138, s. 31-47
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Tidskriftsartikel (refereegranskat)abstract
- Background and objectives: The present study proposes an intelligent system for automatic categorization of Pap smear images to detect cervical dysplasia, which has been an open problem ongoing for last five decades. Methods: The classification technique is based on shape, texture and color features. It classifies the cervical dysplasia into two-level (normal and abnormal) and three-level (Negative for Intraepithelial Lesion or Malignancy, Low-grade Squamous Intraepithelial Lesion and High-grade Squamous Intraepithelial Lesion) classes reflecting the established Bethesda system of classification used for diagnosis of cancerous or precancerous lesion of cervix. The system is evaluated on two generated databases obtained from two diagnostic centers, one containing 1610 single cervical cells and the other 1320 complete smear level images. The main objective of this database generation is to categorize the images according to the Bethesda system of classification both of which require lots of training and expertise. The system is also trained and tested on the benchmark Herlev University database which is publicly available. In this contribution a new segmentation technique has also been proposed for extracting shape features. Ripplet Type I transform, Histogram first order statistics and Gray Level Co-occurrence Matrix have been used for color and texture features respectively. To improve classification results, ensemble method is used, which integrates the decision of three classifiers. Assessments are performed using 5 fold cross validation. Results: Extended experiments reveal that the proposed system can successfully classify Pap smear images performing significantly better when compared with other existing methods. Conclusion: This type of automated cancer classifier will be of particular help in early detection of cancer.
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| 5. |
- Lee, Kian Keat, et al.
(författare)
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Effects of hydrothermal carbonization conditions on the textural and electrical properties of activated carbons
- 2016
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Ingår i: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 107, s. 619-621
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Tidskriftsartikel (refereegranskat)abstract
- The influence of the hydrothermal conditions used for preparing precursors was studied with respect to the properties of the resulting KOH-activated carbons (KOH-ACs). The influence of the hydrothermal temperature (180 vs. 240 degrees C) was only minor on the textural properties of the KOH-ACs. However, the hydrothermal conditions did affect the electrical conductivity of the KOH-ACs. A higher conductivity was observed for the ACs prepared from precursors at the higher temperature and shorter reaction time. This study highlights an overlooked relationship in-between the degree of condensation in the precursors prepared from hydrothermal carbonization and the electrical conductivity of the corresponding ACs.
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| 6. |
- Steiber, Annika, 1968, et al.
(författare)
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A corporate system for continuous innovation: The case of Google Inc.
- 2013
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Ingår i: European Journal of Innovation Management. - : Emerald. - 1460-1060. ; 16:2, s. 243-264
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Tidskriftsartikel (refereegranskat)abstract
- History is full of companies that were once innovative leaders but lost their innovative ability. The purpose of this paper is to explore, from a firm-level perspective, organizational characteristics for continuous innovation in rapidly changing industries. Findings from 28 interviews at Google Inc. are compared to previous research on organizational characteristics for continuous innovation. Google’s organization can be viewed as a dynamic and open corporate system for continuous innovation, involving the entire organization and supported by an innovation-oriented and change-prone top management and board. The relative importance of eight organizational characteristics in this corporate system is elaborated upon. The importance of factors such as culture and the selection of individuals, identified in the empirical study, needs to be considered by managers, and might influence their understanding of how to sustain continuous innovation over time. This paper provides, from a firm-level perspective and based on a unique access to empirical data, increased understanding of organizational characteristics conducive to continuous innovation in rapidly changing industries, and highlights the importance of characteristics that received less emphasis in previous research literature. There is a need for further empirical research contributing to the development of a more comprehensive analytical framework for continuous innovation, including the role of culture and selection/facilitation of self-organizing individuals in innovation processes; and to study how to organize for both continuous innovation and continuous improvements.
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| 7. |
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| 8. |
- Perret, E., et al.
(författare)
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Structural, magnetic and electronic properties of pulsed-laser-deposition grown SrFeO3-delta thin films and SrFeO3-delta/La2/3Ca1/3MnO3 multilayers
- 2017
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Ingår i: Journal of Physics. - 0953-8984 .- 1361-648X. ; 29:49
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Tidskriftsartikel (refereegranskat)abstract
- We studied the structural, magnetic and electronic properties of SrFeO3-delta (SFO) thin films and SrFeO3-delta/La2/3Ca1/3MnO3 (LCMO) superlattices that have been grown with pulsed laser deposition (PLD) on La0.3Sr0.7Al0.65Ta0.35O3 (LSAT) substrates. X-ray reflectometry and scanning transmission electron microscopy (STEM) confirm the high structural quality of the films and flat and atomically sharp interfaces of the superlattices. The STEM data also reveal a difference in the interfacial layer stacking with a SrO layer at the LCMO/SFO and a LaO layer at the SFO/LCMO interfaces along the PLD growth direction. The x-ray diffraction (XRD) data suggest that the as grown SFO films and SFO/LCMO superlattices have an oxygen-deficient SrFeO3-delta structure with I4/mmm space group symmetry (delta <= 0.2). Subsequent ozone annealed SFO films are consistent with an almost oxygen stoichiometric structure (delta approximate to 0). The electronic and magnetic properties of these SFO films are similar to the ones of corresponding single crystals. In particular, the as grown SrFeO3-delta films are insulating whereas the ozone annealed films are metallic. The magneto-resistance effects of the as grown SFO films have a similar magnitude as in the single crystals, but extend over a much wider temperature range. Last but not least, for the SFO/LCMO superlattices we observe a rather large exchange bias effect that varies as a function of the cooling field.
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| 9. |
- van de Beek, Jan-Jaap, et al.
(författare)
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Three non-pilot-based time and frequency estimators for OFDM
- 1998
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Time-domain Maximum-Likelihood (ML) estimators of time and frequency o¤sets are derived for three Orthogonal Frequency Division Multiplexing (OFDM) signal models: a pulse-shaped one-shot OFDM signal, a stream of multiple OFDM signals and an OFDM signal in a dispersive channel environment. We then develop structures to simplify their implementation. Simulation results show the relative performance and strengths of each of these three estimators.
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| 10. |
- De Milito, A, et al.
(författare)
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Plasma levels of soluble CD27: a simple marker to monitor immune activation during potent antiretroviral therapy in HIV-1-infected subjects
- 2002
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Ingår i: Clinical and experimental immunology. - : Oxford University Press (OUP). - 0009-9104 .- 1365-2249. ; 127:3, s. 486-494
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Tidskriftsartikel (refereegranskat)abstract
- Plasma levels of soluble CD27 (sCD27) are elevated in diseases characterized by T cell activation and are used as a marker of immune activation. We assessed the usefulness of determining plasma sCD27 as a marker for monitoring immune activation in HIV-1-infected patients treated with highly active antiretroviral therapy (HAART). A first cross-sectional examination of 68 HIV-1-infected and 18 normal subjects showed high levels of sCD27 in HIV-1 infection; plasma sCD27 was correlated to HIV-1 viraemia and inversely correlated to CD4+ T cell count. Twenty-six HIV-1-infected patients undergoing HAART were studied at baseline and after 6, 12, 18 and 24 months of therapy. Seven additional patients under HAART were analysed at baseline, during and after interruption of therapy. In the total population, HAART induced a significant and progressive reduction, but not a normalization, of plasma levels of sCD27 after 24 months. A full normalization of plasma sCD27 was observed in the virological responders (undetectable HIV-1 RNA at months 18 and 24) and also in patients with moderate immunodeficiency at baseline (CD4+ T cell count >200 cells/mm3). Changes in plasma neopterin paralleled the changes in sCD27 but only baseline sCD27 levels were predictive of a greater increase in CD4+ T cell count during the follow-up. Discontinuation of therapy resulted in a rapid increase of sCD27 plasma levels associated with viraemia rebound and drop in CD4+ T cell count. Our findings suggest that plasma sCD27 may represent an alternative and simple marker to monitor immune activation during potent antiretroviral therapy. HIV-1-induced immune activation can be normalized by HAART in successfully treated patients where the disease is not advanced.
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