Suppressing harmonic vibrations of a miniature cryogenic cooler using an adaptive tunable vibration absorber based on magneto-rheological elastomers

This paper presents dynamic performances of an adaptive tunable vibration absorber (TVA) designed to suppress the main harmonic disturbance of a miniature linear cryogenic cooler, which is being used in space applications such as an observation satellite. The adaptive TVA employs a magneto-rheological elastomer (MRE) for a variable stiffness element. This study first investigates the shear modulus change of MRE samples with respect to the magnetic flux density, which varies through the alignment of particle chains. The MRE with the maximal shear modulus change is mounted for the TVA on a prototype cooler, which emulates the characteristics of a miniature cryogenic cooler. Using the test setup, a series of vibration tests are performed to evaluate the performance and efficacy of the MRE TVA and its re-tuning ability. The experimental results show that the MRE TVA is able to robustly suppress the vibration of the cooler even when the frequency of resonant vibration is changed up to 87% from its initial frequency.     

Note: High speed optical profiler based on a phase-shifting technique using frequency-scanning lasers

We present a high speed optical profiler (HSOP) using frequency-scanning lasers for three-dimensional profile measurements of microscopic structures. To improve upon previous techniques for implementing the HSOP, we developed frequency-scanning lasers and a compact microscopic interferometer. The controller of the HSOP was also modified to generate proper phase-shifting steps. For measurements of step height specimens, the HSOP showed results comparable with a commercial optical profiler, even with much higher measurement speeds (up to 30 Hz). The typical repeatability of step height measurement was less than 1 nm. We also present measurements of microscopic structures to verify the HSOP's ability to perform high speed inline inspection for the semiconductor and flat-panel display industries.     

Note: Interpolation for evaluation of a two-dimensional spatial profile of plasma densities at low gas pressures

An interpolation algorithm for the evaluation of the spatial profile of plasma densities in a cylindrical reactor was developed for low gas pressures. The algorithm is based on a collisionless two-dimensional fluid model. Contrary to the collisional case, i.e., diffusion fluid model, the fitting algorithm depends on the aspect ratio of the cylindrical reactor. The spatial density profile of the collisionless fitting algorithm is presented in two-dimensional images and compared with the results of the diffusion fluid model.     

Ultrastructural investigation of intact orbital implant surfaces using atomic force microscopy

This study examined the surface nanostructures of three orbital implants: nonporous poly(methyl methacrylate) (PMMA), porous aluminum oxide and porous polyethylene. The morphological characteristics of the orbital implants surfaces were observed by atomic force microscopy (AFM). The AFM topography, phase shift and deflection images of the intact implant samples were obtained. The surface of the nonporous PMMA implant showed severe scratches and debris. The surface of the aluminum oxide implant showed a porous structure with varying densities and sizes. The PMMA implant showed nodule nanostructures, 215.56 ± 52.34 nm in size, and the aluminum oxide implant showed crystal structures, 730.22 ± 341.02 nm in size. The nonporous PMMA implant showed the lowest roughness compared with other implant biomaterials, followed by the porous aluminum oxide implant. The porous polyethylene implant showed the highest roughness and severe surface irregularities. Overall, the surface roughness of orbital implants might be associated with the rate of complications and cell adhesion. SCANNING 33: 211–221, 2011. © 2011 Wiley Periodicals, Inc.     

Performance Comparisons Between Thumb-Based and Finger-Based Input on a Small Touch-Screen Under Realistic Variability

The potential benefits of thumb-based touch interaction have not been fully exploited due to its usability problems and performance deterioration. Despite the well-known problems, mobile phone users often prefer thumb-based input method in their daily context of use. Without understanding input performance under realistic variability, design solutions may not address the problems adequately. This research aims to evaluate performance of one-handed thumb-based input compared to cradled finger-based input for the large number of users and varying task conditions. By investigating performance under a range of user- and task-variability, common patterns can be identified to help infer realistic performance in context of use. For this experiment, 259 participants were recruited balanced on gender and age. They performed user testing of moving an icon on a mobile touch-screen. Overall, the one-handed thumb input showed a 30% reduction in throughput compared to the cradled finger-based input, with significant reduction in speed and accuracy. Reduced throughput is attributed to inaccuracy rather than speed. In addition, the partial effects of touch position, dragging direction, and target size were investigated and quantified. In conclusion, performance could maintain constant throughput only for the finger-based input of limited task conditions, when realistic variability was introduced. Also, high variance of throughput for the thumb-based input led to poor conformity to Fitts’s law. The findings have implications for design of thumb-based touch interface to offset performance reduction and characterizing performance measure for thumb-based input method.     

Paternal and Maternal Information and Communication Technology Usage as Their Very Low Birth Weight Infants Transition Home From the NICU

Little is known about how differently mothers and fathers of very low birth weight (VLBW) infants use information and communication technology (ICT), especially during the vulnerable transition from the neonatal intensive care unit (NICU) to home. This study aims to qualitatively compare and contrast the two groups’ usage of technology. In-depth, semistructured phone interviews were conducted with 25 parents of 16 VLBW infants who had been hospitalized in the NICU. Grounded theory facilitated the understanding of interview data. This article discusses the patterns that emerged around the use of ICT between the two groups and discusses the implications for health information seeking, privacy and misinformation, online social networking, learning technology, choosing a health care provider, and health care communication.     

Are Stereotypes Relative to Gender Usage Applicable to Virtual Worlds?

Common stereotypes of virtual game or community users are often portrayed as young and socially inept male addicts. Recent studies, however, defy many of the common prejudices about game or community users. As an extension of recent research, this study looks at gender differences in Virtual Worlds and finds that female users are actually a driving force behind the recent success of online communities. The study results indicate that female users more actively participate in social life, information seeking, and building activities in Virtual Worlds than their male counterparts. Similarly, female users have greater appreciation for the value of Virtual Worlds, although both male and female users recognize Virtual Worlds as a highly useful entertainment tool.     

Fast response fringe‐field switching mode liquid crystal development for shutter glass 3D

A type of fast response time (RT) liquid crystal (LC) was developed to adopt in fringe‐field switching (FFS) mode for shutter glass 3D display device, the average gray to gray level (GTG) RT can reduce from 7.43 ms to 4.48 ms at a refreshing rate of 60 Hz, and the transmittance can increase by 15.4% compared with conventional LC based on the same cell gap. Meanwhile, the correlation among optical efficiency, correlative color temperature (CCT) of module and retardation of LC for FFS mode was studied. Transmittance is proportional to the retardation of LC; however, the CCT is inversely proportional to the retardation. The fast response LC can keep almost the original optical efficiency and CCT.     

Extraction of enhanced evoked potentials using wavelet filtering

In order to remove physiological artefacts and gain the improved evoked potentials, we propose a filtering method using the multi-resolution wavelet transform. The wavelet transform is repeatedly performed until all resolution levels are obtained. It decomposes the measured evoked potentials into scale coefficients corresponding to low frequency components and wavelet coefficients corresponding to high frequency components. In the wavelet domain, artefacts are dispersed mainly at the wavelet coefficients rather than the scaling coefficients. Thus, when the inverse wavelet transform is performed, this method shrinks the wavelet coefficients to reduce artefacts with shrinkage functions. By repeatedly performing the inverse wavelet transform, an evoked potential having the reduced artefacts and background noise is obtained. In this study, quantitative evaluation with simulation data and actual clinical data were conducted. As a result, characteristic peaks of evoked potential could be gained removing background EEG and artefacts using suggested shrinkage function. It was improved more than 0.2–1.6Db compared to the conventional averaging method. Also, the system for measuring and analyzing evoked potentials using DSP is implemented.