| 1. |
- Dahmardeh, M., et al.
(författare)
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High-aspect-ratio, 3-D micromachining of carbon-nanotube forests by micro-electro-discharge machining in air
- 2011
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Ingår i: Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS). - 1084-6999. - 9781424496327 ; , s. 272-275
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper reports micro-electro-discharge machining of vertically aligned carbon nanotube forests for the formation of high-aspect-ratio, three-dimensional microstructures in the material. The developed forest machining method is a dry process performed in air, generating high-frequency pulses of electrical discharge to locally machine the nanotubes in order to create target shapes in a forest. With this approach, forest microstructures can be fabricated to have varying shapes along their height, unachievable with conventional pre-patterned chemical vapor deposition growth techniques. The use of the pulses with a minimized discharge energy defined with 35 V and 10 pF in the discharge generation circuit leads to an aspect ratio of 20 with the smallest feature of 5 μm in forests without disordering the vertical orientation of the nanotubes. Micromachining of multilayer geometries as well as arrayed needle-like microstructures with angled surfaces is demonstrated.
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| 2. |
- Tiwari, S., et al.
(författare)
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Design considerations and laboratory testing of power circuits for parallel operation of silicon carbide MOSFETs
- 2015
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Ingår i: 17th European Conference on Power Electronics and Applications, EPE-ECCE Europe 2015, Geneva, Switzerland, 8-10 September. - 9789075815221
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Konferensbidrag (refereegranskat)abstract
- In this paper, the impact of using parallel SiC MOSFETs as the switching device is investigated. Measurement considerations for a double pulse test are discussed, and the influence of the load inductor characteristic and the voltage measurement technique on the measurement results is demonstrated. It is shown that the inductor load can produce high frequency oscillations of up to 10 % of the load current in the switching current, which can wrongly be associated with the switching device. It is also shown that the standard earth connection of passive voltage probes can induce an extra stray inductance in the measurement loop, which can lead to a measurement of an extra overvoltage of up to 50 V, which is not due to the actual switching. Moreover, the dependency of turn-on and turn-off losses on the load current and the dc-link voltage is presented. It is shown that doubling the load current would increase the switching losses more than the double amount. Therefore, use of two parallel MOSFETs instead of a single one would decrease the total switching losses for a given load current. On the other hand, the parallel configuration is shown to have a higher overvoltage than one single MOSFET for a similar load current. This, however, can be reduced by a higher gate resistance which will eventually keep the total switching loss of parallel configuration equal to the single MOSFET configuration for a given load current. Finally, it is also shown that switching losses can be greatly decreased by decreasing the gate resistance, but this leads to a higher overvoltage on the device. Therefore, the final choice for design is a compromise between the switching losses and the overvoltage.
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| 3. |
- Alvén, Jennifer, 1989, et al.
(författare)
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A Deep Learning Approach to MR-less Spatial Normalization for Tau PET Images
- 2019
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Ingår i: Medical Image Computing and Computer Assisted Intervention : MICCAI 2019 - 22nd International Conference, Proceedings - MICCAI 2019 - 22nd International Conference, Proceedings. - Cham : Springer International Publishing. - 1611-3349 .- 0302-9743. - 9783030322441 - 9783030322458 ; 11765 LNCS, s. 355-363
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Konferensbidrag (refereegranskat)abstract
- The procedure of aligning a positron emission tomography (PET) image with a common coordinate system, spatial normalization, typically demands a corresponding structural magnetic resonance (MR) image. However, MR imaging is not always available or feasible for the subject, which calls for enabling spatial normalization without MR, MR-less spatial normalization. In this work, we propose a template-free approach to MR-less spatial normalization for [18F]flortaucipir tau PET images. We use a deep neural network that estimates an aligning transformation from the PET input image, and outputs the spatially normalized image as well as the parameterized transformation. In order to do so, the proposed network iteratively estimates a set of rigid and affine transformations by means of convolutional neural network regressors as well as spatial transformer layers. The network is trained and validated on 199 tau PET volumes with corresponding ground truth transformations, and tested on two different datasets. The proposed method shows competitive performance in terms of registration accuracy as well as speed, and compares favourably to previously published results.
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| 4. |
- Deumal, M., et al.
(författare)
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Constrained clipping for peak power reduction of multicarrier systems by tone reservation
- 2007
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Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. - 1424402662 ; , s. 2195-2199
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Konferensbidrag (refereegranskat)abstract
- In this paper we introduce a new method to limit the peak factor of a multicarrier signal based on tone reservation. A peak-reducing signal is computed by clipping the original OFDM symbol. The peak-reducing signal is forced to have the constraints of tone reservation, so that when added to the original signal, the peak factor is reduced without increasing the BER and the out-of-band radiation. The proposed method has low computational complexity requirements and is fast-converging. Moreover, simulation results show that it has higher PAPR-reduction capabilities than other PAPR-reducing methods based on TR in the literature. © 2007 IEEE.
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| 5. |
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| 6. |
- Golestani, S.J., et al.
(författare)
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Transmission network expansion planning considering unit commitment problem simultaneously
- 2010
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Ingår i: IEEE PES Innovative Smart Grid Technologies Conference Europe, ISGT Europe 2010; Gothenburg; Sweden; 11 October 2010 through 13 October 2010. - 9781424485109 ; , s. Art. no. 5638905-
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Konferensbidrag (refereegranskat)abstract
- Transmission Network Expansion Planning (TNEP) is an important part of power system planning in new structured power market. Its goal is to minimize the network construction and operational cost while satisfying the demand increase, considering technical and economic conditions. Since change in Unit Commitment (UC), influences transmission lines, this paper presents an Integer Coded Genetic Algorithm (ICGA) to solve both problems together. Genetic algorithm can consider all generation and network constraints. Also random behavior of genetic algorithm can simulate real probabilities such as uncertainty in generation. Considering uncertainty for some units, in each iteration, it can find out the probability of congestion for each line. After all iterations it can highlight the transmission lines which need expansion, because of high congestion probability. Simulation results of the proposed idea are presented for IEEE30-bus network.
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| 7. |
- Mateos, J., et al.
(författare)
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Room temperature THz detection and emission with semiconductor nanodevices
- 2013
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Ingår i: Proceedings of the 2013 Spanish Conference on Electron Devices, CDE 2013. - 9781467346689 ; , s. 215-218
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Konferensbidrag (refereegranskat)abstract
- In this paper we present the advances on the fabrication of THz emitters and detectors obtained within the framework of the European ROOTHz project. Two types of devices are explored, self-switching diodes and slot-diodes, using both narrow bandgap and wide bandgap semiconductors. This broad approach allows us to improve the frequency and power generated by Gunn diodes and the responsivity and noise of detectors at THz frequencies.
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| 8. |
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