Perceptual Space of Superimposed Dual-Frequency Vibrations in the Hands.

The use of distinguishable complex vibrations that have multiple spectral components can improve the transfer of information by vibrotactile interfaces. We investigated the qualitative characteristics of dual-frequency vibrations as the simplest complex vibrations compared to single-frequency vibrations. Two psychophysical experiments were conducted to elucidate the perceptual characteristics of these vibrations by measuring the perceptual distances among single-frequency and dual-frequency vibrations. The perceptual distances of dual-frequency vibrations between their two frequency components along their relative intensity ratio were measured in Experiment I. The estimated perceptual spaces for three frequency conditions showed non-linear perceptual differences between the dual-frequency and single-frequency vibrations. A perceptual space was estimated from the measured perceptual distances among ten dual-frequency compositions and five single-frequency vibrations in Experiment II. The effect of the component frequency and the frequency ratio was revealed in the perceptual space. In a percept of dual-frequency vibration, the lower frequency component showed a dominant effect. Additionally, the perceptual difference among single-frequency and dual-frequency vibrations were increased with a low relative difference between two frequencies of a dual-frequency vibration. These results are expected to provide a fundamental understanding about the perception of complex vibrations to enrich the transfer of information using vibrotactile stimuli

Perceived Intensity Model of Dual-Frequency Superimposed Vibration

IEEEThis paper presents a model for estimating the perceived intensity of a superimposed dual-frequency vibration from the perceived intensities of its two component vibrations. Based on the previous findings in the literature, we hypothesize that the three variables follow the Pythagorean relationship. Two psychophysical experiments were performed for verification with a wide range of single-frequency and superimposed vibrations applied to the fingertip. In Experiment I, we measured the perceived intensities of a large number of single-frequency vibrations and found a psychophysical magnitude function. Experiment II was designed based on the results of Experiment I in order to test the research hypothesis. For the 108 dual-frequency vibrations tested, the Pythagorean model showed 4.0\% of average error in estimating the perceived intensity of a dual-frequency vibration from those of its two components. This model is robust and practical, and can be useful for any tactile interaction applications that make use of superimposed vibrations.11Nsciescopu

Moving Clusters within a Memetic Algorithm for Graph Partitioning

Most memetic algorithms (MAs) for graph partitioning reduce the cut size of partitions using iterative improvement. But this local process considers one vertex at a time and fails to move clusters between subsets when the movement of any single vertex increases cut size, even though moving the whole cluster would reduce it. A new heuristic identifies clusters from the population of locally optimized random partitions that must anyway be created to seed the MA, and as the MA runs it makes beneficial cluster moves. Results on standard benchmark graphs show significant reductions in cut size, in some cases improving on the best result in the literature

A NIR-Light-Driven Twisted and Coiled Polymer Actuator with a PEDOT-Tos/Nylon-6 Composite for Durable and Remotely Controllable Artificial Muscle

In this paper, we proposed a novel light-driven polymer actuator that could produce remotely controllable tensile stroke in response to near infrared (NIR) light. The light-driven polymer actuator was composed of a twisted and coiled nylon-6 fiber (TCN) and a thin poly(3,4-ethylenedioxythiophene) doped with p-toluenesulfonate (PEDOT-Tos) layer. By adopting dip-coating methodology with thermal polymerization process, we constructed a thin and uniform PEDOT-Tos layer on the surface of the three-dimensional TCN structure. Thanks to the PEDOT-Tos layer with excellent NIR light absorption characteristic, the NIR light illumination via a small LEDs array allowed the multiple PEDOT-Tos coated TCN actuators to be photo-thermally heated to a fairly consistent temperature and to simultaneously produce a contractile strain that could be modulated as high as 8.7% with light power. The actuation performance was reversible without any significant hysteresis and highly durable during 3000 cyclic operations via repetitive control of the LEDs. Together with its simple structure and facile fabrication, the light-driven actuator can lead to technical advances in artificial muscles due to its attractive benefits from remote controllability without complex coupled instruments and electromagnetic interference

Frequency ratios (<i>f</i>₂/<i>f</i>₁) and the maximum sums of relative maximum perceptual disparity () for the three frequency conditions.

<p>Frequency ratios (<i>f</i>₂/<i>f</i>₁) and the maximum sums of relative maximum perceptual disparity () for the three frequency conditions.</p

Three dissimilarity matrices of the three sets of vibration stimuli measured in Experiment. I.

<p>Three dissimilarity matrices of the three sets of vibration stimuli measured in Experiment. I.</p