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- Murari, A., et al.
(författare)
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Measuring the radiation field and radiation hard detectors at JET : Recent developments
- 2008
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 593:3, s. 492-504
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Tidskriftsartikel (refereegranskat)abstract
- Since in ITER the radiation field will be much more demanding than that of present day devices, research programmes at JET are aimed at developing radiation hard diagnostics and related components. Initially, significant efforts are devoted to determining the radiation field of both the plasma and in the immediate environment with better accuracy. New developments in MCNP calculations and dedicated measurements provide useful information about the radiation field in the Torus Hall, even during non-operational periods. The effect of using Beryllium in the near future for JET first wall, is being assessed. New materials for activation samples are under consideration and will be tested to improve the calibration accuracy of JET neutron diagnostics. The long-term goal of this work is to obtain spectrometric information from an appropriate combination of different materials. Several studies are under way to modify the radiation field at the detectors by using LiH or pure water as neutron filters, to alleviate the problem of the background in gamma-ray measurements. A suite of radiation hard detectors for neutrons, magnetic field and charged particles are being developed. Super-heated fluid neutron detectors, used for yield and imaging, are being upgraded, in order to provide a broadband spectrometric capability. Chemical vapour deposited diamond diodes are being qualified as counters and as spectrometers. Prototypes of Hall probes made of InSb have been installed on the machine and have provided some preliminary results. Si-on-insulator detectors are under development for use in neutral particle analysers and are currently being bench-tested. Some attention is being devoted to optical components, fibres and mirrors, and to investigating radiation hard electronics using reconfigurable Field Programmable Gate Arrays.
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- Arraigada, M, et al.
(författare)
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Determination of Road Deflections from Traffic Induced Accelerations
- 2007
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Ingår i: International Journal on Road Materials and Pavement Design. - 1468-0629 .- 2164-7402. ; 8:3, s. 399-421
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Tidskriftsartikel (refereegranskat)abstract
- Vertical elastic pavement deflections from moving vehicles provide valuable information for assessing the structural behaviour of a road under real loads. Various types of sensors can be installed in a road for deflection monitoring. This paper explores the use of accelerometers. It discusses the problems involving the calculation of deflections from measured acceleration by double integration due to the amplification of measurement errors in the acceleration signal. It proposes a simple algorithm to correct integration errors and obtain deflections from acceleration measurements. It also presents a laboratory testing method to evaluate the performance of two accelerometers for their suitability in road applications. In addition, using a selected accelerometer, pavementdeflections at a wheel tracking test site are calculated and discussed.
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- Arraigada, M, et al.
(författare)
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Evaluation of Accelerometers to Determine Pavement Deflections under Traffic Loads
- 2008
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Ingår i: Materials and Structures. - : Springer Science and Business Media LLC. - 1359-5997 .- 1871-6873. ; 42:6, s. 779-790
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this work was to study the use of accelerometers to measure pavement deflections due to traffic loads. To this end, accelerometers were embedded in two sites: the full scale load simulator Circular Test Track (CTT) and the A1 motorway in Switzerland. Deflections were derived from acceleration measurements using an algorithm that double integrates the measured signal and corrects any errors derived from the procedure. In the motorway, deflections were monitored using a set of three magnetostrictive deflectometers. Additionally, the pavement's material viscoelastic parameters determined in the laboratory were incorporated in Finite Element (FE) models to estimate the theoretical deflections. The calculated deflections were then compared to the measured and to the theoretical deflections. Deflections calculated from acceleration showed a reasonable qualitative correlation to those measured by magnetostrictive deflectometers. In addition, the FE models revealed the inability of the accelerometers to measure very slow or quasi-static motion.
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