1,721,022 research outputs found
Performance of a vibration isolator with sigmoidal force-deflection curve
Full text linkThis paper presents a theoretical insight on the performance of a vibration isolator consisting of a combination of linear mechanical springs arranged to achieve a specific form of geometric nonlinearity. In particular, positive and negative stiffness nonlinearities are combined to achieve a sigmoidal shape of the force-deflection curve, which is proven to be beneficial for vibration isolation purposes when the amplitude of vibration is relatively large. Such behaviour is fundamentally different from that of the classical quasi-zero-stiffness isolator, which presents a low dynamic stiffness at the equilibrium configuration and is thus effective for relatively low amplitude of vibration. The analytical findings are validated by numerical simulations, providing useful guidelines for the design of such isolators
Diode-pumped 2 μm optical oscillator for high-resolution spectroscopy and frequency metrology
No full textWidely tunable single-frequency erbium-ytterbium phosphate glass laser
No full textA tunable, single-frequency, diode-pumped miniature Er:Yb:glass laser of high power is described. The laser exhibits two intervals of continuous tuning, from 1549 to 1563 nm (Δλ=14 nm) and from 1531 to 1540 nm (Δλ=9 nm), respectively. For an input pump power of 140 mW, a single frequency output power of 20 mW at 1563 nm has been obtained. The tuning characteristics are found to be strictly related to the gain-loss balance of the laser cavity. © 1996 American Institute of Physics
Precision Impedance Measurements by the Three-Voltage Method with a Novel High-Stability Multiphase DDS Generator
No full textImpedance measurement by means of a high-stability multiphase DDS generator, with the three-voltage method
No full textFrequency-Noise Sensitivity and Amplitude-Noise Immunity of Discriminators Based on Fringe-Side Fabry-Perot Cavities
No full textExploiting nonlinearity for the design of linear oscillators: Application to an inherently strong nonlinear X-shaped-spring suspension
Full text linkThis paper proposes a paradigm shift in the perspective of designing nonlinear oscillators, i.e., the exploitation of nonlinearity to achieve a linear behaviour to good engineering purposes. An elastic suspension with four inclined springs is studied, which has an inherently strong geometric nonlinear stiffness characteristic. Such a configuration has attracted remarkable research efforts in last couple of years, because, compared to other classical nonlinear spring configurations, it has more design parameters, which can be wisely selected to attain a tailored force–displacement characteristic. A particular relationship among these parameters is found so that the overall characteristic becomes exactly linear. Compared to the use of classical linear springs mounted along the direction of motion, the proposed configuration with inclined springs has the potential to allow more freedom in the dimensioning of an engineering device. Also, while the equivalent spring obtained is linear, the equivalent damping is not, and this has the potential advantage of practically realising a linear elastic behaviour with the benefit of geometrical nonlinear damping. Experiments are performed for validation on a prototype device, and results confirm the linear behaviour predicted by the theoretical analysis
A multiphase direct-digital-synthesis sinewave generator for high-accuracy impedance comparison
No full textFrequency stabilization of frequency-doubled Nd:YAG lasers at 532 nm by Frequency Modulation Spectroscopy technique
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