| 1. |
- Jonsson, Kenneth, et al.
(författare)
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Traffic compensated luminance estimation
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Active control of street light sources based on sensor data is desired to meet requirements on traffic safety and environmental protection. In this report, we summarise the results of a research study focusing on some of the fundamental problems occurring when performing real-world sensor measurements for lighting control. In particular, we present results on the impact of traffic and the relationship between sensor angle and measured road surface luminance. Moreover, we present a comparison between different approaches to estimating the veiling luminance in tunnel lighting applications.
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| 2. |
- Lindgren, Mikael, 1963-, et al.
(författare)
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CHARACTERIZATION OF REFLECTIVITY AND GEOMETRY FOR SOFT CAR TARGETS
- 2019
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Ingår i: Proceedings of the 29th Session of the CIE. - Wien. - 9783902842749 ; , s. 1753-1767
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper reports on results from a study of characteristics for 3D soft surrogate vehicle targets. Such targets are used extensively for testing and verification of optical sensor systems for Advanced Driver Assistance Systems and Automated Driving. However, the influence of wear-and-tear on the vehicle target is not well known. Consequently, no clear requirement exists on how many collisions a soft target can be exposed to before it no longer performs well.Important characteristics for optical sensor systems are surface reflectance in the relevant wavelength range and geometry of the soft target. We report on measurements of spectral reflectivity and geometry performed before, during and after an accelerated ageing campaign involving 100 rear-end collisions at 50 km/h. The reflectivity was found to change very little while the geometry was strongly affected.
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| 3. |
- Lindgren, Mikael, 1963-, et al.
(författare)
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Characterization of visual and IR reflectivity for soft car targets
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Advanced Driver Assistance Systems (ADAS) and Automated Driving (AD) vehicles rely heavily on optical sensors. Extensive testing of optical sensors is required and typically performed at test tracks like AstaZero. Soft surrogate targets are used for safety reasons, but the optical characteristics of surrogate targets may differ considerably from that of real vehicles. During tests the quality of the soft surrogate targets deteriorates due to repeated impacts and reassembly of the targets, and there is a need for methods to secure the quality of the soft surrogate targets over time.RISE has conducted a project together with Volvo Cars and Veoneer to develop and validate accurate and repeatable measurement methods of the optical characteristics of 3D soft car targets. The goal is to support international standardisation (ISO) with standard methods enabling future verification and calibration of optical characteristics of active safety 3D soft car targets.The poster presents results from optical measurements on soft car targets and real cars, performed in the project. One target was subjected to 100 rear-end collisions during which the reflectivity was measured.
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| 4. |
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| 5. |
- Lindgren, Mikael, 1963
(författare)
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Picosecond Infrared Detection and Optical Mixing in YBa2Cu3O7-δ Thin Films
- 1994
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Studies of infrared photoresponse in high Tc superconducting YBa2Cu3O7-.delta. (YBCO) thin films are presented in this dissertation. Detectors fabricated from YBCO films of different thicknesses have been investigated, in terms of responsitivity, speed, and detection mechanisms, by the use of semiconductor lasers at near infrared wavelengths and a CO2 laser at 10.6 µm wavelength. Granular films, thicker than the optical penetration depth, showed only bolometric response and response times in the nanosecond range. Detectors patterned in films from different laboratories displayed large variations in responsivity, which could not be explained by material characterization. When epitaxial films of the same thickness as the optical penetration depth were used, major improvements were observed. Both the speed and the responsivity were considerably higher. The response was found to be mainly bolometric but, for the shortest laser pulses, indications of a vortex depairing response mechanism was found. By the use of even thinner films and a special detector structure, a high speed detection mechanism attributed to nonequilibrium phenomena was revealed. An electron heating mechanism, with the quasiparticles at an elevated temperature compared with the phonons of the superconductor, fitted well with our measured data. Furthermore, the detector was operated as a mixer for infrared radiation at intermediate frequencies up to 18 GHz. Based on the electron heating model, the bandwidth of the electron heating mechanism was calculated to be 130 GHz. The photoresponse from a single YBCO grain boundary Josephson junction was also studied. A bolometric response was found, in which the critical current of the junction was reduced as the impinging radiation raised the temperature. The flexibility of a Josephson junction type bolometer was also discussed.
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| 6. |
- Lindgren, Mikael, 1963, et al.
(författare)
-
Traffic compensated luminance estimation
- 2015
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Ingår i: 28th CIE Session, 28 jun - 4 jul 2015 Manchester UK.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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