No abstract available

No abstract available

[en] Microcantilever sensors are ultrasensitive devices with miniaturized size and fast responding capability. However, they are generally designed to operate in a very narrow frequency range, which has limited their applications. We present here an all-optical technique that enables efficient actuation and rapid tuning of the vibration behaviors of microcantilevers. In particular, the resonant frequency of a microcantilever beam can be continuously tuned remotely by a laser induced photothermal effect to cover a large range with boosted vibration amplitude, beneficial for improving the detection threshold for force and mass. The underlying principles for photothermal actuation and elastic nonlinearity are discussed in detail. A verification experiment proves its potentials in detecting acoustic waves with frequencies far from the initial resonant frequency of the microcantilever. (paper)

[en] This thesis describes the Princeton-NRAO Phase II pulsar survey, carried out at 390 MHz using the 92-m telescope in Green Bank, West Virginia. This search is the first to have sensitivity to pulsars with periods as short as 0.004 s over a large portion of the galatic plane. Twenty new pulsars were discovered and 67 previously known ones were detected. Though 6 pulsars were detected with periods below 0.200 s, none were found with periods shorter than 0.100 s. This result places strong upper limits on the population of short-period pulsars, and effectively rules out the existence of a large, previously unobserved pulsar population with periods between 0.005 and 0.100 s. The observed period distribution is in good agreement with that predicted by the model of Lyne, Manchester, and Taylor (1985), and can be accounted for without invoking either late turn-on or spin-up of pulsars

[en] Very recently Farhat et al (2011, Phys. Rev. B 84 235105) suggested that arrays of invisibility cloaks may find important applications in low-interference communication, noninvasive probing, sensing and communication networks and so on. We report on the first experimental realization of such an array of broadband invisibility cloaks that operates in the visible frequency range. The wavelength and angular dependences of the cloak array performance have been studied. (paper)

[en] An elementary derivation is given for the shape of the wake pattern of a boat traveling at constant velocity in deep water. We find essentially the same results as those found in standard treatments, but our mathematics is easier. All results follow from the fact that the group velocity is half the phase velocity

[en] This study was conducted based on interdisciplinary approach, physics, and vocal music science, it could be used as an alternative activity to support student learning about a sound wave. The aim of this study was to analyze the voices of the school choir singers using Android App namely Spectroid… The result showed that 16 of 18 singers had been in the right position based on their type of voice. There are two singers had not been in the right position because they positioned in a bass group which their voice could not reach the minimum limit of Bass frequency. The Soprano group which had the frequency range 148.6 Hz-1045.6 Hz, 6 of 8 singers could be in mezzosoprano and 4 of them could be in Alto. The Tenor group (96.4 Hz-697.0 Hz), 1 of 2 singers could be in Baritone but both of them could not be in Bass. The Bass group (81.4 Hz – 493.8 Hz), 2 of 4 singers are true Bass but all of them could be in Baritone and 1 of them could be in tenor. All of 4 singers in Alto group (171.2 Hz-702.0 Hz), only positioned in Alto. (paper)

[en] The lumped parameter model of this novel MR Mount was established and nonlinear mathematical state equations of bond graph model for the MR mount is developed. Finally, its dynamical performance is analyzed and predicted. The results show that the dynamic stiffness (400N/mm) in the frequency range 0-20Hz and the dynamic stiffness (500-700n/mm) in the frequency range 0-25Hz are effective for the isolation of road and powertrain source excitation. (paper)

[en] The complex conductivity of a MgB₂ film has been investigated in the frequency range 4<ν<30 cm^-1 and for temperatures 2.7< T<300 K . The overall temperature dependence of both components of the complex conductivity is reminiscent of BCS-type behavior, although a detailed analysis reveals a number of discrepancies. A peak in the temperature dependence of the real part of the conductivity is detected for frequencies below 9 cm^-1 . The superconducting penetration depth follows a T² behavior at low temperatures

[en] Observation data on gravimagnetic disturbances of the ultra-low frequency range during large earthquakes are given. An experimental result, which reflects the increase in evolving gravimagnetic process of the Earth’s geospheres during preparation of a seismic event, is analyzed. The conditions of origination and evolution of gravimagnetic disturbances are specified.