New Foot Pressure Activated Sensory Compensation System for Posture-Control Enhancement in Amputees

A computerized foot pressure activated sensory compensation system using subsensory electrical stimulation combined with visual-auditory biofeedback was developed. The proposed system was used for enhancing standing balance and gait performance for amputees. In this pilot study, we hypothesized that the static balance with single limb support and gait performance during treadmill walking could be improved by providing proprioceptive neuromuscular facilitation using subsensory stimulation and visual-auditory biofeedback in amputee, respectively. To test this hypothesis, five unilateral transtibial amputees who consecutively wore prosthetics over two years were recruited. Experimental results show a reduction in all of the postural sway indexes and increase in single-leg support time index during single-leg quiet standing by applying subsensory stimulation. With visual-auditory biofeedback for providing clue for heel contact and toe push-off condition during treadmill ambulation, an improvement in all four dynamic gait performance indexes in amputees was verified. These findings suggest that the proposed system with subsensory electrical stimulation and visual-auditory biofeedback mechanisms may be effective in compensating sensory loss and improving posture control for amputees.     

Simple chemical etching of Sm2TM17 magnet alloys for metallography purposes

Chemical etching for metallography of four Sm₂TM₁₇ permanent magnet alloys, typically Sm(Co/Fe/Cu/Zr)_7.3–7.5, was extensively studied. It was found that a selective etching process (SEP) with Nital is powerful for proper revealing of the complex microstructure for metallographic examinations under optical and scanning electron microscopes. The scanning electron microscopy metallographs thus obtained were comparable to those from transmission electron microscopy and complementary to those from potentiostatic etching technique. The SEP was found to be applicable to alloys with higher Zr (2.5 wt.% and above) and Fe (13 wt.% and above). The factors controlling the partitioning tendency of Fe and Cu atoms during step aging and the amount of coherent strain field around the microconstituents would affect the morphology of the etched microstructure, and are discussed in detail.     

Proposed modification to the CIECAM02 colour appearance model to include the simultaneous contrast effects

A modified CIECAM02 colour appearance model, named CIECAM02‐m2, is proposed to enable CIECAM02 to predict the simultaneous contrast effect. The structure of the CIECAM02‐m2 is a development from CIECAM02, and contains two different procedures for modifying the reference white; one is for lightness and the other is for hue. The model was tested using a data set accumulated in this study and the LUTCHI data. The CV values for three colour attributes between predictions and experimental data were used to evaluate the accuracy of the model. The low CV values obtained show the performance of the CIECAM02‐m2 model to predict the simultaneous contrast effect satisfactorily. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 121 – 129, 2007     

Spectral analysis of malfunction mode in endmilling

For the investigation of the chatter modes, the power spectrum of the parametric time series model was adopted and analyzed at several mixed conditions of different revolution. This paper describes a methodology for an application of several time series such asAR (forward-backward, burg, least square, Yule Walker, geometric lattice, instrumental variable),ARX (least square, instrumental variable),ARMAX, ARMA, Box Jenkins, Output Error. To estimate the chatter mode using their spectral analysis their results were compared with one another. As a result, it was proven that several time series methods can be used for chatter mode estimation. Among them, theARX, ARMAX and instrumental variable methods (iv4) are more desirable and reliable than the other algorithm for the exact calculation of the chatter mode in endmilling. Among three cutting forces, the z direction cutting force,Fz, has more powerful characteristics of chatter occurring than the cutting forces,Fx andFy, in the sense that weak mode is calculated exactly and there is no shifted or pseudo mode in the estimated power spectra of endmilling forces.     

The analysis of ultrasonic signals by partial discharge and noise from the transformer

This paper presents the analysis of ultrasonic signals by the partial discharge in a model transformer as well as by corona in the air at a shielded high-voltage laboratory. In addition, various noises onsite, a 345-kV substation, were measured and analyzed, for example, the vibration by core magnetostriction, cooling pump, cooling fan, onload tap changer (OLTC) operation, OLTC filtering unit operation, and air discharge pulse by corona on the transmission line. Therefore, electrical and mechanical noises onsite were removed using the proper narrow bandpass filter and the noise discrimination algorithm. Also, the developed online ultrasonic detector was applied to detect partial discharge in a 154-kV transformer with a warning level in C/sub 2/H/sub 2/ gas. As a result of an internal inspection, the source of partial discharge was found at the estimated position based on ultrasonic detection and its reliability was verified.     

Hydrolysis induced formation of macrovoids in poly(methyl methacrylate)

In the PMMA with saturated methanol and ethanol desorbed in the distilled water, because of the phase inversion, the macrovoids are produced. The size and the quantity of macrovoids near the surface layer are larger than those inside of the specimens. If the hydrolysis temperature is lower, the macrovoids formed tend to be of close‐type. On the contrary, if the temperature is higher, there will be open‐type macrovoids. Because of the occurrence of macrovoids, the size of which is smaller than the visible wavelength, the light will scatter, thereby reducing the transmittance of the specimens. The transmittance decreased as the hydrolysis temperature and hydrolysis time was increased. This phenomenon is much obvious when using ethanol, instead of methanol, as the solvent. The scattering intensity of the specimens after hydrolysis is inversely proportional to the visible wavelength with an exponent, n, in the range from 0.03 to 2.40 for methanol and 0.02 to 0.15 for ethanol. The exponent is equal to 4 corresponding to the Rayleigh scattering. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3451–3465, 2006     

Cover Picture: Direction‐Dependent Homoepitaxial Growth of GaN Nanowires (Adv. Mater. 2/2006)

GaN nanowires with vastly different morphologies depending upon their growth direction can be produced by direct nitridation and vapor transport of Ga in disassociated ammonia, report Sunkara and co‐workers on p. 216. Nanowires grown along the c‐direction develop hexagonal‐prism island morphologies, while wires grown along the a‐direction form uniform, belt‐shaped morphologies. A “ballistic” phenomenon involving the 1D transport of adatoms on the non‐polar surfaces of <0001> GaN nanowires is proposed to explain the prismatic island morphologies.     

FPGA realization of a neural-network-based nonlinear channel equalizer

The software simulation as well as the hardware implementation of equalizers for transmissions through nonlinear communication channels based on artificial neural networks structure is presented in this paper. We consider four-quadrature-amplitude-modulation technique as an example and compare the performance of two different structures of equalizer, namely, the linear least-mean-square-based equalizer (LIN) and the functional link artificial neural networks (FLANN). The learning curve and symbol error rate for the two structures are respectively evaluated by computer simulation. Besides, the systems have been implemented using field-programmable-gate-array devices. As FLANN uses functions to expand the dimensionality of the input signals, it has about the same system complexity as LIN. But FLANN can achieve fast processing speed under parallel processing structure. Simulation results have demonstrated that FLANN presents much better error performance than LIN, especially when the communication channel is highly nonlinear.     

Germanium pMOSFETs with Schottky-barrier germanide S/D, high-/spl kappa/ gate dielectric and metal gate

Schottky-barrier source/drain (S/D) germanium p-channel MOSFETs are demonstrated for the first time with HfAlO gate dielectric, HfN-TaN metal gate and self-aligned NiGe S/D. The drain drivability is improved over the silicon counterpart with PtSi S/D by as much as /spl sim/5 times due to the lower hole Schottky barrier of the NiGe-Ge contact than that of PtSi-Si contact as well as the higher mobility of Ge channel than that of Si.     

Developing Concept-Based User Interfaces for Scientific Computing

Although drawings and graphs can express complex concepts, such methods can't be computationally analyzed. Researchers have developed visual approaches and paradigms that scientists can use to capture and represent scientific models in a computational form that they can link to and integrate with data sets and applications.