Preparation of monophasic titanium sub-oxides of Magnéli phase with enhanced thermoelectric performance

Titanium sub-oxides of Magnéli phase are considered as earth-abundant, non-toxic materials for thermoelectric application at high temperature, but very limited investigation has been reported mainly owing to the difficulty lying in obtaining monophasic material. Herein we describe a facile strategy to prepare monophasic Ti₉O₁₇ and Ti₄O₇ powder, in which the single Ti₉O₁₇ phase is obtained for the first time. After spark plasma sintering, the thermoelectric properties of monophasic Ti₉O₁₇ and Ti₄O₇ ceramics are studied comparatively. Despite the one magnitude lower electrical conductivity, Ti₉O₁₇ shows higher power factor compared with Ti₄O₇ due to the large Seebeck coefficient. Moreover, with the low electronic thermal conductivity, sub-micron scaled grain size and nano-scaled crystallographic shear plane, the Ti₉O₁₇ ceramic exhibits even lower thermal conductivity compared to Ti₄O₇, leading to a ZT of 0.16 at 764 K, which is the best thermoelectric performance among reported Magnéli phases.     

A high resolution multi‐view 3D display using switchable liquid crystal lens

A 4.4‐inch 2D/3D switchable full high definition (FHD) six‐view 3D display with 3D resolution greater than 170 ppi has been accomplished. In addition to adopting low temperature polysilicon technology (LTPS), which is most suitable for high resolution displays, a new RGBW pixel arrangement using four‐square sub‐pixels has been devised. In 2D, a resolution greater than 500 ppi, accompanied with high luminance, has been achieved. A new liquid crystal lens (LCL) has been exploited for 2D/3D switching. By employing a special multielectrode structure and dedicated manufacturing process, an optical focal ratio less than 20%, which is essential for low 3D cross talk for a six‐view 3D display, has been attained by adopting the LCL. In the vertical direction of the display, there is no cross talk increase when the viewing position is changed because of the new pixel structure. The strong focal strength of the LCL combined with a revised high‐density multi‐view design give rise to a wide 3D viewing angle greater than 20 degrees in the horizontal direction and minimum cross talk less than 10%.     

A Static Analysis Method for a Classical Linear Logic Programming Language

In this paper, we propose a new static analysis method which is applicable for a classical linear logic programming language.Andreoli et al. proposed a static analysis method for the classical linear logic programming language LO, but their method did not cover multiplicative connectives which are important for a resource-sensitive feature of linear logic.Our method, in contrast, covers multiplicative conjunction in addition to multiplicative disjunction and linear implication. An abstract proof graph, an AND-OR graph representing all possible sequent proofs, is constructed from a given program and goal sequent. The graph can be repeatedly refined by propagating information to eliminate unprovable nodes from the graph.We applied our prototype analyzer for a sorting program written in Forum. The sorting program was improved about 1000 times faster than the ordinary program without analysis, for sorting 6 elements by using the analysis result.     

Stabilization for thermomagnetic instability of CuNi/NbTi superconducting wire in spatially distributed magnetic field

Thermomagnetic instability in superconducting wires composing multistrand cables is a problem in the development of cables with large current capacity. This paper elucidates the quenching properties of ac superconducting wires in a distributed magnetic field applied to the strands in the cable, and the stabilization of the ac superconducting wires considering the effect of the longitudinal magnetic field or the fraction of copper embedded in each strand. First, the degradation of the quench current of CuNi/NbTi superconducting wires in a distributed magnetic field is exhibited with simple test samples. Second, the quench properties of the strand in a (6 + 1)³ cable and the optimal twist pitch of the cable for high stabilization are discussed. Last, the effect of copper on the quench properties of the strand and the appropriate fraction of copper for suppression of quench current degradation in a distributed magnetic field are discussed. © 2001 Scripta Technica, Electr Eng Jpn, 135(4): 26–34, 2001     

Face recognition across illumination

Illumination variation on images of faces is one of the most difficult problems in face recognition systems. The performance of a self-organizing map-based face recognition system is highly degraded when the illumination in test images differs from that of the training images. Illumination normalization is a way to solve this problem. Both global and local image enhancement methods are studied in this article. A local histogram equalization method strongly improves the recognition accuracy of the CMU-PIE face database. This work was presented in part at the 12th International Symposium on Artificial Life and Robotics, Oita, Japan, January 25–27, 2007     

Direct measurement of interaction force between hydrophilic silica surfaces in triblock copolymer solutions with salt by atomic force microscopy

Triblock copolymers composed of polyethylene oxide (PEO) and polypropylene oxide (PPO) are used in various fields as nonionic surfactants. In this study, we measured interaction forces between untreated hydrophilic silica surfaces in solutions with two typical triblock copolymers, Pluronic P123 (PEO₂₀PPO₇₀PEO₂₀) and F127 (PEO₉₉PPO₆₅PEO₉₉), in the presence of 1 mM and 500 mM NaCl using atomic force microscopy (AFM). In solutions at the copolymer concentration of 1 µM, which is below the critical micelle concentration (CMC), the measured interaction forces were monotonically repulsive in the presence of 1 mM NaCl, which suggested the brush-like conformation of copolymers on the surfaces. When the concentration of NaCl was increased to 500 mM, interaction forces became attractive, which indicated the bridging of adsorbed polymers onto surfaces, the strength of which varied depending on the affinity and adsorption density of copolymers. The interactions at the copolymer concentration of 1 mM, which were above the CMC of both copolymers, were steric repulsions between adsorbed micelles on the surfaces with 1 mM of NaCl. For 500 mM of NaCl, an attractive jump after a steric repulsion was observed only in the force curve for P123, which inferred that the displacement of micelles from the surfaces was presumably due to a decrease in the strength of adsorption caused by the dehydration of EO groups. These results indicated that the length of the EO group considerably affected the interactions.     

Discovery of Rapid and Reversible Water Insertion in Rare Earth Sulfates: A New Process for Thermochemical Heat Storage

Thermal energy storage based on chemical reactions is a prospective technology for the reduction of fossil‐fuel consumption by storing and using waste heat. For widespread application, a critical challenge is to identify appropriate reversible reactions that occur below 250 °C, where abundant low‐grade waste heat and solar energy might be available. Here, it is shown that lanthanum sulfate monohydrate La₂(SO₄)₃?H₂O undergoes rapid and reversible dehydration/hydration reactions in the temperature range from 50 to 250 °C upon heating/cooling with remarkably small thermal hysteresis (<50 °C), and thus it emerges as a new candidate system for thermal energy storage. Thermogravimetry and X‐ray diffraction analyses reveal that the reactions proceed through an unusual mechanism for sulfates: water is removed from, or inserted in La₂(SO₄)₃?H₂O with progressive change in hydration number x without phase change. It is also revealed that only a specific structural modification of La₂(SO₄)₃ exhibits this reversible dehydration/hydration behavior.