Processing neutral tone under the non-attentional condition: a mismatch negativity study.

The neutral tone is a unique tone form in Mandarin as it distinguishes from four canonical tones or full tones on the one hand and integrates phonetic, morphological, syntactical and prosodic information on the other hand. Research to date has been focusing on its unique and variant acoustic features. However, little is known about how native Mandarin speakers process such a unique tone. In the present study, the mismatch negativity was used to explore the comparison-based pre-attentive change detection of Mandarin neutral tone. The mismatch negativity at the time window of 400-800 ms post-first-tone onset was obtained by subtracting event-related potentials to standard neutral tone from event-related potentials to a deviant natural tone. The source analysis of mismatch negativity showed the cortex generator was located at the left temporal lobe. The data suggest that Chinese native speakers process neutral tone automatically under non-attentional conditions, as revealed by the mismatch negativity data aligned with a neutral tone, and that neutral tone does exist as an automatically recognizable one in native Mandarin speakers' tone system.

A microNewton thrust stand for average thrust measurement of pulsed microthruster.

A torsional thrust stand has been developed for the study of the average thrust for microNewton pulsed thrusters. The main body of the thrust stand mainly consists of a torsional balance, a pair of flexural pivots, a capacitive displacement sensor, a calibration assembly, and an eddy current damper. The behavior of the stand was thoroughly studied. The principle of thrust measurement was analyzed. The average thrust is determined as a function of the average equilibrium angle displacement of the balance and the spring stiffness. The thrust stand has a load capacity up to 10 kg, and it can theoretically measure the force up to 609.6 µN with a resolution of 24.4 nN. The static calibrations were performed based on the calibration assembly composed of the multiturn coil and the permanent magnet. The calibration results demonstrated good repeatability (less than 0.68% FSO) and good linearity (less than 0.88% FSO). The assembly of the multiturn coil and the permanent magnet was also used as an exciter to simulate the microthruster to further research the performance of the thrust stand. Three sets of force pulses at 17, 33.5, and 55 Hz with the same amplitude and pulse width were tested. The repeatability error at each frequency was 7.04%, 1.78%, and 5.08%, respectively.