| 841. |
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| 842. |
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| 843. |
- Gustafsson, Mats, et al.
(författare)
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Antenna Q and Stored Energy Expressed in the Fields, Currents, and Input Impedance
- 2015
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 63:1, s. 240-249
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Tidskriftsartikel (refereegranskat)abstract
- Although the stored energy of an antenna is instrumental in the evaluation of antenna Q and the associated physical bounds, it is difficult to strictly define stored energy. Classically, the stored energy is either determined from the input impedance of the antenna or the electromagnetic fields around the antenna. The new energy expressions proposed by Vandenbosch express the stored energy in the current densities in the antenna structure. These expressions are equal to the stored energy defined from the difference between the energy density and the far field energy for many but not all cases. Here, the different approaches to determine the stored energy are compared for dipole, loop, inverted L-antennas, and bow-tie antennas. We use Brune synthesized circuit models to determine the stored energy from the input impedance. We also compare the results with differentiation of the input impedance and the obtained bandwidth. The results indicate that the stored energy in the fields, currents, and circuit models agree well for small antennas. For higher frequencies, the stored energy expressed in the currents agrees with the stored energy determined from Brune synthesized circuit models whereas the stored energy approximated by differentiation of input impedance gives a lower value for some cases. The corresponding results for the bandwidth suggest that the inverse proportionality between the fractional bandwidth and Q-factor depends on the threshold level of the reflection coefficient.
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| 844. |
- Gustafsson, Mats, et al.
(författare)
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Physical Bounds and Optimal Currents on Antennas
- 2012
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 60:6, s. 2672-2681
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Tidskriftsartikel (refereegranskat)abstract
- Physical bounds on the directivity Q-factor quotient and optimal current distributions are determined for antennas of arbitrary shape and size using an optimization formulation. A variational approach offers closed form solutions for small antennas expressed in the polarizability of the antenna structure. Finite sized antennas are solved using Lagrangian parameters in a method of moments formulation. It is also shown that the optimal charge density for a small antenna can be generated by several current densities. Numerical examples for small and large antennas are used to illustrate the results.
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| 845. |
- Gustafsson, Mats, et al.
(författare)
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Stored electromagnetic energy and antenna Q
- 2015
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Ingår i: Progress In Electromagnetics Research. - 1070-4698 .- 1559-8985. ; 150, s. 13-27
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Tidskriftsartikel (refereegranskat)abstract
- Decomposition of the electromagnetic energy into its stored and radiated parts is instrumental in the evaluation of antenna Q and the corresponding fundamental limitations on antennas. This decomposition is not unique and there are several proposals in the literature. Here, it is shown that stored energy defined from the difference between the energy density and the far field energy equals the energy expressions proposed by Vandenbosch for many but not all cases. This also explains the observed cases with negative stored energy and suggests a possible remedy to them. The results are compared with the classical explicit expressions for spherical regions where the results only differ by the electrical size ka that is interpreted as the far-field energy in the interior of the sphere.
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| 846. |
- Gustavsson, Elin, et al.
(författare)
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Surrogate antigens as targets for proteome-wide binder selection
- 2011
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Ingår i: New Biotechnology. - : Elsevier BV. - 1871-6784 .- 1876-4347. ; 28:4, s. 302-311
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Tidskriftsartikel (refereegranskat)abstract
- In the last decade, many initiatives have been taken to develop antibodies for proteome-wide studies, as well as characterization and validation of clinically relevant disease biomarkers. Phage display offers many advantages compared to conventional antibody generation by immunization and hybridoma technology, since it is an unlimited resource of affinity reagents without batch-to-batch variation and is amendable for high throughput. One of the major bottlenecks to proteome-wide binder selection is the limited supply of suitable target antigens representative of the human proteome. Here, we provide proof of principle of using easily accessible, cancer-associated protein epitope signature tags (PrESTs), routinely generated within the Human Protein Atlas project, as surrogate antigens in phage selectionsfor the retrieval of target specific binders. These binders were subsequently tested in western blot, immunohistochemistry and protein microarray application to demonstrate their functionality.
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| 847. |
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| 848. |
- Haghbin, Saeid, 1977, et al.
(författare)
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An Integrated 20-kW Motor Drive and Isolated Battery Charger for Plug-In Vehicles
- 2013
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Ingår i: IEEE transactions on power electronics. - 0885-8993 .- 1941-0107. ; 28:8, s. 4013-4029
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Tidskriftsartikel (refereegranskat)abstract
- For vehicles using grid power to charge the battery, traction circuit components are not normally engaged during the charging time, so there is a possibility to use them in the charger circuit to have an on-board integrated motor drive and battery charger. An isolated high-power three-phase integrated motor drive and charger based on a split-phase permanent magnet motor is presented in this paper. The motor winding connections are reversible by a relay-based switching device for traction and battery charging. In traction mode, the motor is a classical three-phase motor, but in charging mode it is a rotating isolating transformer providing a three-phase voltage source for the inverter to charge the battery. A mathematical model of the motor with six stator windings is presented for an arbitrary phase shift in windings. For the charging mode, the split-phase motor grid synchronization process and charge control are explained including the developed controller. A 20-kW system is designed and implemented to verify the proper operation of the proposed system. Simulation and practical results are provided to show the system performance in terms of functionality, dynamic response, and efficiency. Moreover, some discussions, recommendations, and limitations are provided to give more practical insights.
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| 849. |
- Hallonsten, Olof, et al.
(författare)
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Analyzing structural stratification in the Swedish higher education system : data contextualization with policy-history analysis
- 2013
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Ingår i: Journal of The American Society For Information Science And Technology. - : Wiley. - 1532-2882 .- 1532-2890. ; 64:3, s. 574-586
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Tidskriftsartikel (refereegranskat)abstract
- 20th century massification of higher education and research in academia is said to have produced structurally stratified higher education systems in many countries. Most manifestly, the research mission of universities appears to be divisive. Authors have claimed that the Swedish system, while formally unified, has developed into a binary state, and statistics seem to support this conclusion. This article makes use of a comprehensive statistical data source on Swedish higher education institutions to illustrate stratification, and uses literature on Swedish research policy history to contextualize the statistics. Highlighting the opportunities as well as constraints of the data, the article argues that there is great merit in combining statistics with a qualitative analysis when studying the structural characteristics of national higher education systems. Not least the article shows that it is an over-simplification to describe the Swedish system as binary; the stratification is more complex. On basis of the analysis, the article also argues that while global trends certainly influence national developments, higher education systems have country-specific features that may enrich the understanding of how systems evolve and therefore should be analyzed as part of a broader study of the increasingly globalized academic system.
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| 850. |
- Hallonsten, Olof, et al.
(författare)
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Commissioning the University of Excellence : Swedish research policy and new public research funding programmes
- 2012
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Ingår i: Quality in Higher Education. - : Informa UK Limited. - 1353-8322 .- 1470-1081. ; 18:3, s. 367-381
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Tidskriftsartikel (refereegranskat)abstract
- In many countries, current research policy is dominated by managerialism and excellence, manifesting the aim of making universities into national strategic assets in the globally competitive knowledge economy. This article discusses these policy trends and their mirror in recent developments in public funding for academic research, with special attention to Sweden. A review of the language in three consecutive Swedish governmental research bills from the past 10 years shows a clear policy shift towards the promotion of excellence and strategic priority on the level of higher education institutions. Reforms to the funding system, especially the launch of specific strategic excellence funding programmes, are introduced to put the policy in practice. While the policy shift itself might be discursive, the changes to the funding system clearly show a determination on behalf of the Swedish government to increase strategic profiling and the pursuit of excellence in research on behalf of universities. © 2012 Copyright Taylor and Francis Group, LLC.
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