Role of nonlinear coupling and density fluctuations in magnetic-fluctuation-induced particle transport

Three-wave nonlinear coupling among spatial Fourier modes of density and magnetic fluctuations is directly measured in a magnetically confined toroidal plasma. Density fluctuations are observed to gain (lose) energy from (to) either equilibrium or fluctuating fields depending on the mode number. Experiments indicate that nonlinear interactions alter the phase relation between density and magnetic fluctuations, leading to strong particle transport.     

All-fiber integrated 10 GHz repetition rate femtosecond laser source based on Raman compression of pulses generated through spectral masking of a phase-modulated diode

We report the development of a 10?GHz repetition rate all-fiber integrated femtosecond source tunable around 1.55?μm. A phase modulator and sharp spectral filter are used to convert the output of a tunable CW diode to a 10?GHz pulse train. These pulses are compressed using Raman soliton adiabatic compression in a 21?km long length of fiber to generate sub-300-fs duration pulses at a 10?GHz repetition rate. By tuning the wavelength of the diode and appropriate filtering, similar performance was achieved over a 20?nm bandwidth.     

Patterns of breath support in projection of the singing voice

Recordings of the rib cage and abdominal motions and acoustic output were obtained from five professional opera singers during performance of an aria recorded with two levels of voice projection. The condition of greater projection resulted in a significant increase in the acoustic power in the frequency band 2-4 kHz, relative to the power in the 0-2 kHz band, and a decrease in the mean expiratory flow, implying a move to more efficient vocalization with the greater projection. Also, the condition of greater projection resulted in a larger rib cage, particularly in the lateral dimension, but only a small decrease in the abdominal lateral dimension, suggesting that the greater abdominal support required for a larger projection is obtained by increased activation of abdominal muscles acting medially.     

Vacuum moulding of a superplastic in two dimensions

A mathematical model is proposed for the process of vacuum superplasticforming. The model exploits the fact that in most industrialapplications the sheet aspect ratio (thickness/sheet width)is small. After an initial consideration of some of the moregeneral properties and the literature of superplastic materials,the elastic/plastic deformation of an internally-inflated thin-walledcylinder is examined. Plates of arbitrary geometry are thenconsidered. A quasisteady model in which the sheet moves througha sequence of steady states is developed. Some simplified closed-formsolutions are examined, but for general cases a system of nonlinearpartial differential equations must be solved numerically. Anefficient and accurate semi-explicit numerical scheme is proposedand a simplified stability analysis is presented; the methodis then used to compute properties of superplastic vacuum mouldedsheets in a number of practically motivated cases.