Preparation of smooth potassium hexatitanate nanofilms by sol–gel method

New nanosmooth potassium hexatitanate films have been prepared on crystalline Si (111) and ITO glass substrates by sol–gel method using Ti(n-OC₄H₉)₄ and CH₃COOK as precursors. Atomic force microscopy (AFM) topographic images were analyzed to select the optimal preparation conditions for the films. It is shown that the films consist of flat particles with the ratio of diameter to height around 11. The root mean square (RMS) roughness of the films based on the measurement of an area of 2,000 nm × 2,000 nm in AFM images is 6.4 nm. The crystal growth process of potassium hexatitanate film was characterized by XRD, Raman spectra, and TEM. The results showed that the crystal growth of potassium hexatitanate nanofilm is a confined growth mechanism. Electrochemical measurements demonstrated that the photocurrent of potassium hexatitanate film electrode is more stable than that of TiO₂ film electrode.     

Laser cladding of Zr65Al7.5Ni10Cu17.5 amorphous alloy on magnesium

Laser cladding of amorphous alloy Zr₆₅Al_7.5Ni₁₀Cu_17.5 on magnesium substrate was conducted using the blown powder method. The thickness of the coating was about 1.5 mm. The resulting microstructure, wear resistance and corrosion resistance of the coating were studied. The results of the XRD and TEM analyses showed that up to a depth of 1.1 mm, the coating had an amorphous structure, and no apparent crystalline structures were found. The coated specimen exhibited wear and corrosion resistance superior to that of the uncoated specimen: the wear loss was significantly reduced, some thirteen-fold; and the corrosion current was lowered by three orders of magnitude.     

Moving target location and imaging using dual-speed velocity SAR

Velocity synthetic aperture radar (VSAR) is an effective tool for slowly moving target detection, location and imaging. However, it may mislocate fast moving targets because of the azimuth location ambiguity. The VSAR is generalised from flying with single speed to flying with dual-speed to resolve the azimuth location ambiguity. This new system is named dual-speed velocity SAR (DS-VSAR). Using DS-VSAR, the locations of both slowly and fast moving targets can be estimated accurately, and in the meantime the clutter can be suppressed. Some numerical examples are given to prove the effectiveness of DS-VSAR     

T - Vmin addressing mode and an improved equivalent circuit model for ferroelectric liquid crystal displays

The authors describe an improved model for modelling the electro-optical response of a ferroelectric liquid crystal display and discuss its applicability. The model includes the direct coupling of applied electric fields to dielectric permittivity, an effect not accounted for in previous equivalent circuits. Compared with previous models, the new model has more capability in optical response prediction and device setup optimisation when the dielectric biaxiality of ferroelectric liquid crystals is of a relatively high value. In the improved model, different trends of switching time are observed as drive voltage rises in cases of positive anisotropy and negative anisotropy. The bend in tau-V_min mode, that is, the minimum pulse area for switching directors, is measured and the mechanism of optical contrast enhancement and switching process complemented by high-frequency ac pulses is clearly explained. Results obtained from the improved model compare favourably with that obtained from numerical models and from testing of a real cell     

Detection of Moisture and Methanol Gas Using a Single Electrospun Tin Oxide Nanofiber

This letter reports the fabrication of a gas sensor based on a single tin oxide nanofiber made from dimethyldineodecanoate tin using electrospinning and metallorganics decomposition techniques. The fabricated sensor has been used to detect moisture and methanol gas. It showed high sensitivity to both gases and the response times of the complete testing system are in the range of 108-150 s for moisture, and 10-38 s for methanol gas, respectively.     

Facial expression recognition using radial encoding of local Gabor features and classifier synthesis

Primarily motivated by some characteristics of the human visual cortex (HVC), we propose a new facial expression recognition scheme, involving a statistical synthesis of hierarchical classifiers. In this scheme, the input images of the database are first subjected to local, multi-scale Gabor-filter operations, and then the resulting Gabor decompositions are encoded using radial grids, imitating the topographical map-structure of the HVC. The codes are fed to local classifiers to produce global features, representing facial expressions. Experimental results show that such a hybrid combination of the HVC structure with a hierarchical classifier significantly improves expression recognition accuracy when applied to wide-ranging databases in comparison with the results in the literature. Furthermore, the proposed system is not only robust to corrupted data and missing information, but can also be generalized to cross-database expression recognition.     

Experimental study on fitness of one-piece casting osseointegrated implant frameworks with relation to fixture abutment positions

An experiment on fitness of one-piece casting osseointegrated implant frameworks was performed among three fixture abument positions where other conditions were controlled. The result revealed that there was statistically significant differences in dimensional change among the three fixture abument positions. In terms of the relation between abument position and fitness, the more backward the abument position was, the worse the osseointegrated framework fitness was. The frameworks showed deformations in "arch form" and "warp" in three dimensions.     

Three-dimensional optical bit-memory recording and reading with a photorefractive crystal: analysis and experiment

We analyze the three-dimensional refractive-index distribution that is induced locally when a laser beam is focused onto a very small region in a photorefractive crystal. The formation of the index distribution is deduced from the temporal behavior of the electron density distribution in the crystal under non-steady-state conditions. The density distribution is computed by the use of a set of the recurrence relations that was derived from Kukhtarev's equations, which describe the transport of electrons in time. In particular, we calculated the index distribution formed in Fe-doped LiNbO(3) crystals. To verify the validity of our analysis, we read, by using a phase-contrast microscope, refractive-index dots that were recorded in Fe-doped LiNbO(3) crystals. A good agreement was obtained between experimental results and the calculated phase-contrast images when the characteristics of the imaging system are taken into account. We also found that the induced index change is largest when the c axis of the LiNbO(3) crystal is oriented parallel to the polarization direction of the reading beam. Under this optimal condition, we succeeded in recording up to 10 layers of readable data in a LiNbO(3) crystal.