| 1. |
- Wahlberg, Bo, 1959-
(författare)
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On Model Reduction In System Identification
- 1986
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Ingår i: Proceedings of the American Control Conference. ; , s. 1260-1266
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Konferensbidrag (refereegranskat)abstract
- It is shown how to use model reduction in system identification. An identification algorithm is proposed which is to be based on the least-squares identification method and either of the three model-reduction techniques: frequency-weighted L**2 model reduction, model reduction via a frequency-weighted balanced realization or frequency-weighted optimal Hankel-norm model reduction. The frequency-weighted L**2 model reduction is optimal in a minimum variance sense, while the advantage of the two other model-reduction techniques is that a consistent identification algorithm with a closed-form solution is obtained.
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| 2. |
- Kellman, PJ, et al.
(författare)
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Concurrent motion in infant event perception
- 1987
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Ingår i: Infant Behavior and Development. - : Elsevier BV. - 0163-6383 .- 1879-0453. ; 10:1, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Infant sensitivity to motion relationships specifying certain complex events, such as a person walking, has recently been demonstrated, but the perceptual principles underlying early event perception are not well understood. Retinal motion toward a common point (concurrent motion) specifies translation in depth to adult perceivers in the absence of conflicting information (Börjesson & von Hofsten, 1973). We tested this principle of event perception with 28 16-week-old infants. One group was habituated in a dark room to a concurrent motion: three points of light moving in a frontoparallel plane toward and away from a central point (not seen). After habituation, the room was illuminated, and looking time was tested to alternate presentations of two displays. In one display (depth motion), three lights were attached to a triangle actually moving in depth; in the other display (surface motion), the three lights moved visibly along the surface of a fronto-parallel stationary triangle. If concurrent motion, in the absence of conflicting information, specifies motion in depth to infants, they were expected to look longer after habituation at the surface motion display. A control group tested infants' relative interest in the two test displays with no prior habituation period. Control-group infants marginally preferred the depth movement display. The habituation group responded three times as much to the surface motion display, suggesting that motion in depth had been perceived during habituation. Specification of motion in depth by concurrency of relative proximal stimulus motions seems to be an operative principle in infants' perception; moreover, at least some principles of early event perception are unrelated to person perception or biological motion. The relation of these results to recent findings in infant object perception is discussed.
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| 3. |
- Byers, John A., et al.
(författare)
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Effective attraction radius : A method for comparing species attractants and determining densities of flying insects
- 1989
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Ingår i: Journal of Chemical Ecology. - 0098-0331. ; 15:2, s. 749-765
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Tidskriftsartikel (refereegranskat)abstract
- The catches of bark beetles (Coleoptera: Scolytidae) were compared between attractive traps releasing semiochemicals and passive traps (cylindrical sticky screens hung, at 10 heights of 0.7-11.5 m, on poles). A central attractive-trap pole was surrounded by three passive-trap poles spaced 50 or 100 m away at the apices of an equilateral triangle. The catches of Tomicus piniperda and other scolytid species on the attractive-trap pole baited with host monoterpenes, or the catches of Ips typographus attracted to synthetic pheromone, were compared to passive trap catches in a Scots pine forest or in a Norway spruce clear-cut, respectively. Information about flight height distributions of the above scolytid species, and Hylurgops palliatus, Cryphalus abietis, Pityogenes chalcographus, P. quadridens, P. bidentatus, and Trypodendron domesticum were obtained on the passive and attractive trap poles. A new method is presented for determining the densities of flying insects based on the passive trap's dimensions and catch, duration of test, and speed of insect. Also, a novel concept, the effective attraction radius (EAR), is presented for comparing attractants of species, which is independent of insect density, locality, or duration of test. The EAR is obtained by the ratio of attractive and passive trap catches and the dimensions of the passive trap, and thus should correlate positively with the strength of the attractant and the distance of attraction. EARs are determined from catch data of T. piniperda and I. typographus as well as from the data of previous investigations on the same or other bark beetles.
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