4,284 research outputs found

    Dynamics of Oscillators Coupled by a Medium with Adaptive Impact

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    In this article we study the dynamics of coupled oscillators. We use mechanical metronomes that are placed over a rigid base. The base moves by a motor in a one-dimensional direction and the movements of the base follow some functions of the phases of the metronomes (in other words, it is controlled to move according to a provided function). Because of the motor and the feedback, the phases of the metronomes affect the movements of the base while on the other hand, when the base moves, it affects the phases of the metronomes in return. For a simple function for the base movement (such as y=γx[rθ1+(1r)θ2]y = \gamma_{x} [r \theta_1 + (1 - r) \theta_2] in which yy is the velocity of the base, γx\gamma_{x} is a multiplier, rr is a proportion and θ1\theta_1 and θ2\theta_2 are phases of the metronomes), we show the effects on the dynamics of the oscillators. Then we study how this function changes in time when its parameters adapt by a feedback. By numerical simulations and experimental tests, we show that the dynamic of the set of oscillators and the base tends to evolve towards a certain region. This region is close to a transition in dynamics of the oscillators; where more frequencies start to appear in the frequency spectra of the phases of the metronomes

    Surface analysis of space telescope material specimens

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    Qualitative and quantitative data on Space Telescope materials which were exposed to low Earth orbital atomic oxygen in a controlled experiment during the 41-G (STS-17) mission were obtained utilizing the experimental techniques of Rutherford backscattering (RBS), particle induced X-ray emission (PIXE), and ellipsometry (ELL). The techniques employed were chosen with a view towards appropriateness for the sample in question, after consultation with NASA scientific personnel who provided the material specimens. A group of eight samples and their controls selected by NASA scientists were measured before and after flight. Information reported herein include specimen surface characterization by ellipsometry techniques, a determination of the thickness of the evaporated metal specimens by RBS, and a determination of trace impurity species present on and within the surface by PIXE

    Reproduction of an isolated Iranian cichlid, Iranocichla hormuzensis

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    The reproductive biology of the Iranian cichlid, Iranocichla hormuzensis Coad, 1988, was investigated for 13 consecutive months in lower Mehran River, from August 2008 through August 2009. Four hundred and eighty six individuals (252 males and 234 females) were captured using a seine net (5 mm mesh size). The observed sex ratio was 1M: 0.93F (χ², df = 1, P = 0.414). Mean ± SD of total length (TL) values in males and females were 70.34 ± 8.16 and 62.08 ± 6.51 mm, respectively. The frequency of 56-65 mm size class was higher in females and the 66-75 mm size class in males. A gonadosomatic index (GSI) analyses of females indicated that the reproductive period was during February-June, with a peak in March. Fecundity was best correlated with total body mass (M) (linear regression, r2 = 0.62) condition factor (linear regression, r2 = 0.62) and total length (TL) (linear regression, r2 = 0.56).The absolute fecundity ranged between 48-167 eggs with a Mean ± SD of 107 ± 35.2. Egg diameters ranged from 0.58 to 2.93 mm

    Characterization of Conjugated Polymer Actuation under Cerebral Physiological Conditions

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108056/1/adhm201300610-sup-0001-S1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/108056/2/adhm201300610.pd
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