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- Förstberg, Johan, 1949-, et al.
(författare)
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Influence of different conditions of tilt compensation on motion and motion-related discomfort in high speed trains
- 1998
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Ingår i: Vehicle System Dynamics. - : Swets & Zeitlinger. - 0042-3114 .- 1744-5159. ; 29, s. 729-734
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Tidskriftsartikel (refereegranskat)abstract
- Train speed may be increased by constructing new railways with improved curve geometry or by using tilting trains. The tilting system compensates the lateral acceleration felt by the passengers in curves by tilting the car body, thus allowing trains to run 25-30 % faster on existing curved tracks with maintained good ride comfort. Although motion sickness in tilting trains seems to be a small problem for most passengers it can be a problem to those prone to nausea. To investigate the incidence of motion related discomfort and how different tilt compensation strategies influence the occurrence of such discomfort, a full-scale test ride was conducted on a curved track with a tilting train. Seventy healthy volunteers were employed, selected for high subjective sensitivity to nausea. Three conditions were tested using three different cars under three days. The test ride lasted about 3 hours. Four times per test ride the subjects answered a questionnaire concerning vegetative symptoms, fatigue, sleepiness and nausea. The test persons' overall estimation of average ride comfort was good in all conditions, however, some persons reported motion related discomfort due to motion sickness. A 55% degree of tilt compensation of the lateral acceleration (in the track plane) instead of the normal 70%, reduced the number of test persons reporting dizziness and nausea by about 30 - 50%. Discomfort correlates very poorly with a motion dose (time integrated) of vertical acceleration but instead correlates better with a motion dose of roll angle acceleration.
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- Ödkvist, Lars, et al.
(författare)
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Otolithic tests in Menière’s disease
- 1995
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Ingår i: Ménièr's Disease, 1995. - 8798242253 ; , s. 259-265
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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- Ödkvist, Lars, et al.
(författare)
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The subjective horizontal in eccentric rotation influenced by peripheral vestibular lesion
- 1996
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Ingår i: Acta Oto-Laryngologica. - : Informa Healthcare. - 0001-6489 .- 1651-2251. ; 116:2, s. 181-184
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Tidskriftsartikel (refereegranskat)abstract
- Peripheral vestibular equilibrium disorders may originate in various parts of the labyrinth or the vestibular nerve. Traditionally, the function of the lateral semicircular canals has been assessed with caloric irrigation, and sometimes falsely been interpreted as a vestibular nerve lesion. the vertical semicircular canals are not easily assessed. Caloric testing with the head in different positions is not very helpful, but the canals may pairwise be tested using specific rotational techniques. Often the otolithic organs, capable of detecting linear acceleration forces, are forgotten as a source of vertigo and dizziness. We have implemented horizontal rotatory testing with the subject seated eccentrically facing the direction of rotation as a means of assessing otolithic function. the subject experiences a lateral tilt and is instructed in darkness to put a short light bar in the position he thinks a water surface would have, which is identical to his perceived tilt. in 39 normal subjects, a theoretical tilt of 24° was estimated as approximately 19.5°, and the standard deviation was 6°. A side difference index was proposed to be normal if below 25%. the preliminary findings in a few patients with known labyrinthine lesions are presented. We propose that otolithic as well as lateral semicircular canal functions are useful to monitor in patients with suspected peripheral equilibrium disorders.
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