| 1. |
- Hu, J., et al.
(författare)
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A multi-agent system for distribution grid congestion management with electric vehicles
- 2014
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Ingår i: Engineering applications of artificial intelligence. - : Elsevier BV. - 0952-1976 .- 1873-6769. ; 38, s. 45-58
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Tidskriftsartikel (refereegranskat)abstract
- Electric vehicles (EVs) are widely regarded as valuable assets in the smart grid as distributed energy resources in addition to their primary transportation function. However, connecting EVs to the distribution network and recharging the EV batteries without any control may overload the transformers and cables during peak hours when the penetration of EVs is relatively high. In this study, a two level hierarchical control method for integrating EVs into the distribution network is proposed to coordinate the self-interests and operational constraints of two actors, the EV owner and Distribution system operator (DSO), facilitated by the introduction of the fleet operator (FO) and the grid capacity market operator (CMO). Unlike the typical hierarchical control system where the upper level controller commands the low level unit to execute the actions, in this study, market based control are applied both in the upper and low level of the hierarchical system. Specifically, in the upper level of the hierarchy, distribution system operator uses market based control to coordinate the fleet operators power schedule. In the low level of the hierarchy, the fleet operator use market based control to allocate the charging power to the individual EVs, by using market based control, the proposed method considers the flexibility of EVs through the presence of the response-weighting factor to the shadow price sent out by the FO. Furthermore, to fully demonstrate the coordination behavior of the proposed control strategy, we built a multi-agent system (MAS) that is based on the co-simulation environment of JACK, Matlab and Simulink. A use case of the MAS and the results of running the system are presented to intuitively illustrate the effectiveness of the proposed solutions.
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| 2. |
- Memisevic, E., et al.
(författare)
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Vertical InAs/GaAsSb/GaSb tunneling field-effect transistor on Si with S = 48 mV/decade and Ion = 10 μA/μm for Ioff = 1 nA/μm at VDS = 0.3 V
- 2017
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Ingår i: 2016 IEEE International Electron Devices Meeting, IEDM 2016. - 9781509039012 ; , s. 1-19
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Konferensbidrag (refereegranskat)abstract
- We present a vertical nanowire InAs/GaAsSb/GaSb TFET with a highly scaled InAs diameter (20 nm). The device exhibits a minimum subthreshold swing of 48 mV/dec. for Vds = 0.1-0.5 V and achieves an Ion = 10.6 μA/μm for Ioff = 1 nA/μm at Vds = 0.3 V. The lowest subthreshold swing achieved is 44 mV/dec. at Vds= 0.05 V. Furthermore, a benchmarking is performed against state-of-the-art TFETs and MOSFETs demonstrating a record high I60 and performance benefits for Vds between 0.1 and 0.3 V.
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| 3. |
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| 4. |
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| 5. |
- Larsson, Matilda, et al.
(författare)
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In-vivo assessment of radial and longitudinal strain in the carotid artery using speckle tracking
- 2010
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Ingår i: 2010 IEEE International Ultrasonics Symposium Proceedings. - : IEEE. - 9781457703829 ; , s. 1328-1331
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Konferensbidrag (refereegranskat)abstract
- Ultrasound-based algorithms are commonly used to assess mechanical properties of arterial walls in studies of arterial stiffness and atherosclerosis. Speckle tracking based techniques used for estimation of myocardial strain can be applied on vessels to estimate strain of the arterial wall. Previous elastography studies in vessels have mainly focused on radial strain measurements, whereas the longitudinal strain has been more or less ignored. However, recently we showed the feasibility of speckle tracking to assess longitudinal strain of the carotid artery in-silico. The aim of this study was to test this methodology in-vivo. Ultrasound images were obtained in seven healthy subjects with no known cardiovascular disease (39 ± 14 years old) and in seven patients with coronary artery disease (CAD), (69 ± 4 years old). Speckle tracking was performed on the envelope detected data using our previous developed algorithm. Radial and longitudinal strains were estimated throughout two cardiac cycles in a region of interest (ROI) positioned in the posterior vessel wall. The mean peak systolic radial and longitudinal strain values from the two heart cycles were compared between the groups using a student's t-test. The mean peak radial strain was -39.1 ± 15.1% for the healthy group and -20.4 ± 7.5% for the diseased group (p = 0.01), whereas the mean peak longitudinal strain was 4.8 ± 1.1% and 3.2 ± 1.6% (p = 0.05) for the healthy and diseased group, respectively. Both peak radial and longitudinal strain values were thus significantly reduced in the CAD patient group. This study shows the feasibility to estimate radial and longitudinal strain in-vivo using speckle tracking and indicates that the method can detect differences between groups of healthy and diseased (CAD) subjects.
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| 6. |
- Lind, Erik, et al.
(författare)
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Improved breakdown voltages for type I InP/InGaAs DHBTs
- 2008
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Ingår i: 20th International Conference on Indium Phosphide and Related Materials, 2008. IPRM 2008. - 1092-8669. ; , s. 504-507
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Konferensbidrag (refereegranskat)abstract
- We have investigated the base-collector breakdown voltage of type I InGaAs/InP DHBTs, which is shown to be dominated by band-to-band tunneling in the base-collector grade. By optimizing the grade we obtain a 20% increase in the breakdown voltage compared with traditional grades.
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| 7. |
- Persson, Olof, et al.
(författare)
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Interface characterization of metal-HfO2-InAs gate stacks using hard x-ray photoemission spectroscopy
- 2013
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Ingår i: AIP Advances. - : AIP Publishing. - 2158-3226. ; 3:7
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Tidskriftsartikel (refereegranskat)abstract
- MOS devices based on III-V semiconductors and thin high-k dielectric layers offer possibilities for improved transport properties. Here, we have studied the interface structure and chemical composition of realistic MOS gate stacks, consisting of a W or Pd metal film and a 6- or 12-nm-thick HfO2 layer deposited on InAs, with Hard X-ray Photoemission Spectroscopy. In and As signals from InAs buried more than 18 nm below the surface are clearly detected. The HfO2 layers are found to be homogeneous, and no influence of the top metal on the sharp InAs-HfO2 interface is observed. These results bridge the gap between conventional photoemission spectroscopy studies on various metal-free model samples with very thin dielectric layers and realistic MOS gate stacks. (C) 2013 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
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| 8. |
- Sebelius, Sara, et al.
(författare)
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Identification of urea decomposition from an SCR perspective : A combination of experimental work and molecular modeling
- 2013
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Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 231, s. 220-226
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Tidskriftsartikel (refereegranskat)abstract
- For the automotive industry selective catalytic reduction (SCR) is the most effective way to get rid of poisonous nitrogen oxides (NOX) in the exhaust. Urea is used as precursor for the reducing agent ammonia. The stricter legislation on NOX emissions for heavy duty vehicles in Euro 6 makes it even more important to optimize the conversion of urea to ammonia.Competing with ammonia formation is the formation of two byproducts commonly observed in the SCR system, biuret and cyanuric acid. These byproducts are formed before the SCR catalyst in the trucks. In the literature different possibilities on the reaction pathway to biuret and cyanuric acid are described. The aim of this study is to understand which of these pathways that is more likely to occur.In this study, the decomposition and synthesis pathways from urea to biuret and cyanuric acid were identified by a combination of laboratory experiments and Density Functional Theory (DFT) calculations. This is the first DFT study on these reactions performed without the influence of a catalyst. Accordingly, this is a study of the reactions where they do occur, before and not over the catalyst. A new gas phase FTIR method for urea and its byproducts was developed.
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| 9. |
- Wang, C. H., et al.
(författare)
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InAs hole inversion and bandgap interface state density of 2 x 10(11) cm(-2) eV(-1) at HfO2/InAs interfaces
- 2013
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 103:14
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Tidskriftsartikel (refereegranskat)abstract
- High-k/InAs interfaces have been manufactured using InAs surface oxygen termination and low temperature atomic layer deposition of HfO2. Capacitance-voltage (C-V) curves revert to essentially classical shape revealing mobile carrier response in accumulation and depletion, hole inversion is observed, and predicted minority carrier response frequency in the hundred kHz range is experimentally confirmed; reference samples using conventional techniques show a trap dominated capacitance response. C-V curves have been fitted using advanced models including nonparabolicity and Fermi-Dirac distribution. For an equivalent oxide thickness of 1.3 nm, an interface state density D-it = 2.2 x 10(11) cm(-2) eV(-1) has been obtained throughout the InAs bandgap. (C) 2013 AIP Publishing LLC.
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| 10. |
- Wernersson, Lars-Erik, et al.
(författare)
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A combined chemical vapor deposition and rapid thermal diffusion process for SiGe Esaki diodes by ultra-shallow junction formation
- 2005
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Ingår i: IEEE Transactions on Nanotechnology. - 1536-125X. ; 4:5, s. 594-598
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Tidskriftsartikel (refereegranskat)abstract
- SiGe Esaki diodes have been realized by rapid thermal diffusion of phosphorous into an SiGe layer grown by ultra-high-vacuum chemical-vapor-deposition on an Si p(+)-substrate for the first time. The phosphorous-doped SiGe forms the n(+)-electrode, while heavily boron-doped Si0.74Ge0.26 and Si substrate is used for the p(+) electrode. The diodes show a peak current density of 0.18 kA/cm(2), a current peak-to-valley ratio of 2.6 at room temperature, and they exhibit only a weak temperature dependence. Cross-sectional transmission microscopy showed a good crystalline quality of the strained Si0.74Ge0.26 layer even after the diffusion step at 900 degrees C.
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