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| 2. |
- Fu, Ying, 1964, et al.
(författare)
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Photoluminescence spectra of doped GaAs films
- 2004
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Ingår i: Applied Physics A. - : Springer Science Business Media. - 0947-8396 .- 1432-0630. ; 79:3, s. 619-623
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the dependence of the photoluminescence (PL) spectrum on the doping level and the film thickness of n-GaAs thin films, both experimentally and theoretically. It has been shown theoretically that modification of the PL spectrum of p-type material by p-type doping is very small due to the large valence-band hole effective mass. The PL spectrum of n-type material is affected by two factors: (1) the electron concentration which determines the Fermi level in the material; (2) the thickness of the film due to re-absorption of the PL signal. For the n-type GaAs thin films under current investigation, the doping level as well as the film thickness can be very well calibrated by the PL spectrum when the doping level is less than 2 x 10(18) cm(-3) and the film thickness is in the range of the penetration length of the PL excitation laser.
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| 3. |
- Fu, Zhan, et al.
(författare)
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Evaluation of the difference between the driving behaviour of a Speech based and a speech-visual based task of an in-car computer
- 2004
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Ingår i: The 8th International Conference on Spoken Language Processing, Interspeech 2004, ICSL. Jeju Island, Korea.
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Konferensbidrag (refereegranskat)abstract
- To select the right modality for the interaction between drivers and the in-vehicle information system (IVIS) is crucial for safety reasons. This paper presents an experimental study to dress on this subject. The study was carried out on a 160 degree car-driving simulation lab. There are 10 subjects participated in the experiment. We compared the subjects driving behavior on speech input/output only and speech input with speech+visual output interaction modalities with a simple IVIS. To judge the safety status of subjects driving performance, two independent variables which includes the average division of over speed and the average division of the car out of lane were measured as dangerous extent. Result indicates that it is not significant differences of driving performance by using synthetic speech to replace the visual display in the IVIS. It indicated that the visual presentation of a multi-modal IVIS can be acts as redundancy or complementary modality for auditory presentation, which will aids in relieving the resource demand.
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| 5. |
- Johnson, Henric, et al.
(författare)
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SOLA : A One-bit Identity Authentication Protocol for Access Control in IEEE 802.11
- 2002
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Konferensbidrag (refereegranskat)abstract
- Given the wide deployment of IPSec/VPN (Virtual Private Networks) technology, there might be a redundancy in security protection in some configurations. Various commercial companies have replaced 802.11 security with IPSec/VPN to protect the wireless LAN (Local Area Network). How to do it in an efficient and lightweight way is a challenging research problem. This paper introduces a new lightweight identity authentication protocol, SOLA (Statistical One-bit Lightweight Authentication), for access control well suited for IEEE 802.11 networks with IP connections. This protocol prevents unauthorized access on a per packet basis. Since SOLA only adds one identity bit to each packet it will have a low impact on the network bandwidth and power consumption. The performance and efficiency of the SOLA protocol together with IEEE 802.11 is analyzed and evaluated via simulation.
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| 6. |
- Li, Z-F, et al.
(författare)
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Determination of carrier-transfer length from side-wall quantum well to quantum wire by micro-photoluminescence scanning
- 2003
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Ingår i: Journal of Electronic Materials. - : Springer Science Business Media. - 0361-5235 .- 1543-186X. ; 32:8, s. 913-916
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Tidskriftsartikel (refereegranskat)abstract
- Micro-photoluminescence (mu-PL) line scanning across a single V-groove, GaAs/AlGaAs quantum wire (QWR) has been performed at room temperature, revealing a clear spatial-dependence of the PL. After fitting each PL spectrum by multi-Gaussian line shapes, intensity profiles of each PL component from confined structures have been obtained as functions of the scanning position. The PL quenching of a side-wall quantum well (SQWL) has been recognized in a certain area in the vicinity of the QWR and is interpreted by carrier transfer into the QWR within effective transfer length. By simulating the carrier-transfer process from SQWL to QWR as a convolution of a step function for carrier distribution and a Gaussian function for exciting laser irradiance, the effective transfer length of about 1.8+/-0.3 mum has, therefore, been concluded.
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