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| 2. |
- Ameur, Adam, et al.
(författare)
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SweGen : a whole-genome data resource of genetic variability in a cross-section of the Swedish population
- 2017
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Ingår i: European Journal of Human Genetics. - : NATURE PUBLISHING GROUP. - 1018-4813 .- 1476-5438. ; 25:11, s. 1253-1260
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Tidskriftsartikel (refereegranskat)abstract
- Here we describe the SweGen data set, a comprehensive map of genetic variation in the Swedish population. These data represent a basic resource for clinical genetics laboratories as well as for sequencing-based association studies by providing information on genetic variant frequencies in a cohort that is well matched to national patient cohorts. To select samples for this study, we first examined the genetic structure of the Swedish population using high-density SNP-array data from a nation-wide cohort of over 10 000 Swedish-born individuals included in the Swedish Twin Registry. A total of 1000 individuals, reflecting a cross-section of the population and capturing the main genetic structure, were selected for whole-genome sequencing. Analysis pipelines were developed for automated alignment, variant calling and quality control of the sequencing data. This resulted in a genome-wide collection of aggregated variant frequencies in the Swedish population that we have made available to the scientific community through the website https://swefreq.nbis.se. A total of 29.2 million single-nucleotide variants and 3.8 million indels were detected in the 1000 samples, with 9.9 million of these variants not present in current databases. Each sample contributed with an average of 7199 individual-specific variants. In addition, an average of 8645 larger structural variants (SVs) were detected per individual, and we demonstrate that the population frequencies of these SVs can be used for efficient filtering analyses. Finally, our results show that the genetic diversity within Sweden is substantial compared with the diversity among continental European populations, underscoring the relevance of establishing a local reference data set.
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| 4. |
- Andreasson, Jesper, 1977-, et al.
(författare)
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Våldsbejakande extremism och radikalisering: En översikt : [Violent extremism and radicalization: an overview]
- 2018
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Ingår i: Young, Marginalised but not Radicalised. - London : IARS Publications. - 9781907641466 ; , s. 152-175
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- In Sweden, the understanding of processes of radicalization and the development of preventive work against violent extremism can be said to be framed by a few specific political decisions that were formative for the policies developed. These are dealt with in the text. Among other things, the result shows that the security discourse and preventive work are often mixed up at the policy level, which has repercussions in research and prevention. One important key to developing the work on security and prevention lies in the need for further knowledge development regarding everything from methods and field studies to policy practices. Apart from providing an account of developments in Sweden, there are also arguments for a more skeptical, reflexive, and critical attitude towards all forms of simplified categorizations of young people, which risks stigmatizing individuals and groups. By starting from a critical and reflexive social education perspective, it will become possible to contribute to understanding and to an analysis of social contexts, risks, and negative spirals. The ambition of trying to predict which individuals will potentially commit crimes of terror represents a dead end. On the other hand, there are possibilities of identifying risk environments, subcultural groups that cultivate extreme opinions, and then to approach these groups in various ways in order to develop effective social pedagogical work and positive and GLM-based trajectories for young people at risk for radicalisation.
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| 5. |
- Augustin, Tim, et al.
(författare)
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System Design of Fast Actuator for Vacuum Interrupter in DC Applications
- 2018
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Ingår i: 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538643730 ; , s. 527-530
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Konferensbidrag (refereegranskat)abstract
- One of the major challenges of DC circuit breakers is the required fast mechanical actuator. In this paper, a Thomson coil actuator system for a vacuum interrupter is designed. Active damping is used to decelerate the moving contacts. Challenges are discussed, especially concerning the power supply needed for the Thomson coil actuator. The design philosophy is explained and FEM simulation results are presented. The results indicate that a wide range of combinations of drive circuit capacitance and voltage fulfill the requirements for armature acceleration. However, active damping requires a very careful selection of drive circuit voltage and timing of applied damping.
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| 6. |
- Bissal, Ara, et al.
(författare)
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Electric to Mechanical Energy Conversion of Linear Ultrafast Electromechanical Actuators Based on Stroke Requirements
- 2015
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Ingår i: IEEE transactions on industry applications. - 0093-9994 .- 1939-9367. ; 51:4, s. 3059-3067
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Tidskriftsartikel (refereegranskat)abstract
- The operational efficiency of ultrafast actuators used as drives in high-voltage direct-current breakers is at best 5%. To boost their efficiency, the design of the energizing circuit is crucial. A multiphysics finite-element method model coupled with a SPICE circuit model that is able to predict the performance of the actuator with an accuracy of at least 95% has been developed and verified experimentally. Several variants of prototypes and models have been simulated, built, and tested. It was shown that one of the main problems leading to low efficiencies is the stroke of the drive. However, there is a possibility to increase the efficiency of the electric to mechanical energy conversion process of the studied Thomson coil (TC) and double-sided coil (DSC) to a maximum of 54% and 88%, respectively, if their stroke is minimized. These efficiencies are idealistic, and these were obtained with clamped armature studies. The efficiency of the actuator can be increased at the expense of increasing the complexity and the cost of the contact system by designing a switch with several series-connected contacts that is encapsulated in a medium with a high dielectric strength. Another proposed solution is to design a current pulse with a rise time that is considerably shorter than the mechanical response time of the system. Parametric variations of capacitances and charging voltages show that the TC and the DSC can achieve efficiencies up to 15% and 23%, respectively. Regardless of the chosen method, the DSC has a superior efficiency compared to a TC.
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| 7. |
- Bissal, A., et al.
(författare)
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Hybrid multi-physics modeling of an ultra-fast electro-mechanical actuator
- 2015
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Ingår i: Actuators. - : MDPI AG. - 2076-0825. ; 4:4, s. 314-335
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Tidskriftsartikel (refereegranskat)abstract
- The challenges of an HVDC breaker are to generate impulsive forces in the order of hundreds of kilonewtons within fractions of a millisecond, to withstand the arising internal mechanical stresses and to transmit these forces via an electrically-insulating device to the contact system with minimum time delay. In this work, several models were developed with different levels of complexity, computation time and accuracy. Experiments were done with two mushroom-shaped armatures to validate the developed simulation models. It was concluded that although the electromagnetic force generation mechanism is highly sensitive to the mechanical response of the system, the developed first order hybrid model is able to predict the performance of the breaker with good accuracy.
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| 8. |
- Bissal, Ara, et al.
(författare)
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Multiphysics modeling and experimental verification of ultra-fast electro-mechanical actuators
- 2015
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Ingår i: International journal of applied electromagnetics and mechanics. - 1383-5416 .- 1875-8800. ; 49:1, s. 51-59
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a multi-physics computational tool has been developed to accurately model and build high performance ultra-fast actuators. The research methodology is based on a finite element method model coupled with a circuit model. Electromagnetic, thermal, mechanical, and algebraic equations are implemented in Comsol Multiphysics and verified with laboratory experiments of a built prototype. A simplified model is preferred as long as its underlying assumptions hold. However, in the presence of large current and force densities, nonlinearities such as deformations may occur. Such phenomena can only be captured by the use of the developed comprehensive multi-physics simulation model. Although this model is computationally demanding, it was shown to have an accuracy of at least 95% when compared with experiments.
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| 9. |
- Bissal, Ara, et al.
(författare)
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On the design of a linear composite magnetic damper
- 2015
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Ingår i: 2015 IEEE International Magnetics Conference, INTERMAG 2015. - : IEEE conference proceedings. - 9781479973224
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Konferensbidrag (refereegranskat)abstract
- In recent years, ultra-fast actuators have become key elements in the development of high voltage direct current (HVDC) breakers for multiterminal grids which represent a huge progress in modern power transmission [1]. After fulfilling their operation these actuators need to be decelerated using controllable forces to avoid deforming vital components incorporated in the system. In this paper, a dedicated damper is proposed based on a magnet array that induces eddy currents in a composite metal tube resulting in an efficient braking response. Several topologies are investigated by simulations and experiments. The theory behind eddy current damping is explained in [2]. The main requirements for such dampers are reliability, robustness, and ease of construction. The expected durability of these kind of dampers is longer than the breaker itself which guarantees extremely good reliability within HVDC systems.
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| 10. |
- Bissal, Ara, et al.
(författare)
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On the Design of a Linear Composite Magnetic Damper
- 2015
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Ingår i: IEEE transactions on magnetics. - : IEEE Press. - 0018-9464 .- 1941-0069. ; 51:11
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Tidskriftsartikel (refereegranskat)abstract
- High-voltage direct current (HVdc) breakers are the key components in the realization of multiterminal HVdc grids. In the presence of fault current, these breakers should be able to deliver impulsive forces to swiftly open the metallic contacts. After the acceleration phase, the moving armature should be decelerated using controllable forces to avoid plastically deforming fragile components integrated in the system. In this paper, finite-element method-based simulation models, complimented with small-scale and large-scale experimental prototypes, were utilized to benchmark different damping topologies. It was found that a Halbach-based configuration can deliver a damping force that is almost two and a half times larger than its sequel. Its sequel, composed of vertically stacked oppositely oriented magnets, is easier to assemble and is also capable of generating a considerable damping force. Finally, it has been shown that both these schemes, inserted in a composite tube, have a potential to be used as dampers in HVdc breakers.
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