Stability of liquid‐crystal layers based on the analysis of the adsorption on the alignment‐layer surface

Abstract— The adsorption strength of liquid‐crystal molecules on the alignment‐layer (polymer) surface was judged measuring temperature dependence of birefringence of an absorbed liquid‐crystal layer above the nematic—isotropic transition temperature. The relationship between the surface‐order parameter and the adsorption strength of liquid‐crystal molecules on the non‐rubbed polymer surface was also discussed.     

Phase diagram calculations of ZrO2-based ceramics with an emphasis on the reduction/oxidation equilibria of cerium ions in the ZrO2-YO1.5-CeO2-CeO1.5 system

Phase diagram calculations that were made previously for the ZrO₂-MO _m/2 (m = 2, 3, 4) systems and for the ZrO₂-YO_1.5-MO _m/2 (M = transition metals) systems have been extended to the ZrO₂-YO_1.5-CeO₂(-CeO_1.5) system to make an attempt to explain (1) thermogravimetric (TG) results as a function of oxygen potential, (2) electronic conductivity as a function of oxygen potential, and (3) a miscibility gap observed in air. The interaction parameters for the CeO₂-CeO_1.5-YO_1.5 system were obtained from the reported oxygen nonstoichiometry in CeO_2−x and rate earth doped ceria, (Ce,RE)O_2−δ . The interaction parameters for the ZrO₂-CeO₂ subsystem were obtained so as to reproduce the observed miscibility gap at 1273 K. Those thermodynamic properties can reproduce consistently the experimental behaviors of the electronic conductivity and the TG results in the (Zr_1−x Ce _x )_0.8Y_0.2O_1.9 solid solutions; these indicate the enhancement of reduction of CeO₂.     

Performance analysis of a greedy algorithm for inferring Boolean functions

We analyzed average case performance of a known greedy algorithm for inference of a Boolean function from positive and negative examples, and gave a proof to an experimental conjecture that the greedy algorithm works optimally with high probability if both input data and the underlying function are generated uniformly at random.     

A study on the characteristics of glass fibre reinforced thermoplastics by transfer moulding

Lately, the use of fibre reinforced thermoplastics (FRTP) has increased due to its increased mouldability compared to thermosetting FRP material.

FRTP includes stampable sheet, short and long fibre reinforced thermoplastic pellets, continuous fibre reinforced thermoplastics sheets, etc. The long fibre reinforced thermoplastic (LFRTP) pellet has better mechanical properties than short fibre reinforced pellets and better mouldability than stampable sheet. At present, injection moulding method is mainly used for moulding LFRTP pellets because of its high productivity.

However, the long fibre of LFRTP pellets, whose length is the same as pellet length, is degraded during processing if conventional injection moulding machines are used, and as a result, the mechanical properties are not improved as expected in many cases. Therefore, a new moulding process is required to make good use of LFRTP pellets.

For this study, a transfer moulding apparatus was designed and built to minimize fibre degradation of the moulded parts.

Firstly, the LFRTP pellets with fibre lengths of 3, 6, 9, 12.7 and 17 mm were prepared in order to clarify the difference of mechanical properties due to fibre length. The fibre ratio was 30% in weight for all cases and the same polypropylene was used. They were moulded to the shape of the test specimens. Tensile, bending and Izod impact strengths were measured by using these test specimens. Secondly, LFRTP pellets were moulded to the shape of test specimens by the transfer moulding apparatus and conventional injection moulding machine, and then mechanical properties were measured. At the same time, short fibre pellets were moulded to the smae shape of test specimens by the injection moulding machine, and mechanical properties were compared with those of LFRTP pellets.

With the long glass fibre reinforced polypropylene, good results of fibre preservation and mechanical properties were obtained by the transfer moulding apparatus which was built for this study. The impact strength was increased remarkably as the fibre length increased, and consequently the preservation of fibre length in the moulded parts was especially effective in improving the impact strength.     

Evaluation of temperature characteristics of high-efficiency InGaP/InGaAs/Ge triple-junction solar cells under concentration

Temperature characteristics of the open-circuit voltage (V_oc) were investigated in the temperature range from 30°C to 240°C for the InGaP/InGaAs/Ge triple-junction cells. Also, single-junction cells that had the similar structure to the subcells in the triple-junction cells were studied. In the high-temperature range (from 170°C to 240°C), the temperature coefficients of V_oc of the InGaP/InGaAs/Ge triple-junction solar cell (dV_oc/dT) were different from those in the low-temperature range (from 30°C to 100°C). This is because photo-voltage from the Ge subcell becomes almost 0 V in the high-temperature range. It was found that the open-circuit voltage of a Ge single-junction cell reduced to almost 0 V temperatures over 120°C under 1 sun condition.     

Thermal boundary resistance between the end of an individual carbon nanotube and a Au surface

The thermal boundary resistance between an individual carbon nanotube and a Au surface was measured using a microfabricated hot-film sensor. We used both closed and open-ended multi-walled carbon nanotubes and obtained thermal boundary resistance values of 0.947-1.22 × 10(7) K W(-1) and 1.43-1.76 × 10(7) K W(-1), respectively. Considering all uncertainties, including the contact area, the thermal boundary conductances per unit area were calculated to be 8.6 × 10(7)-2.2 × 10(8) W m(-2) K(-1) for c-axis orientation and 4.2 × 10(8)-1.2 × 10(9) W m(-2) K(-1) for the a-axis. The trend in these values agrees with the predicted conductance dependence on the interface orientation of anisotropic carbon-based materials. However, the measured thermal boundary conductances are found to be much larger than the reported results.     

Synthesis of non-equilibrium phases in immiscible metals mechanically mixed by high pressure torsion

The structural changes in mechanically mixed metals of immiscible combinations of elements caused by bulk mechanical alloying (MA) through the use of high pressure torsion (HPT) were investigated in Ag–Ni and Nb–Zr systems. There was no alloying between Ag and Ni on atomic scale even after 100 rotations of HPT. On the other hand, the β-Zr phase started to appear after HPT 2 rotations in the Nb–Zr system, even though β-Zr is a high temperature phase. Further, Nb and Zr were completely mixed to form a bcc structured single phase after HPT 100 rotations. The sequence of alloying in the Nb–Zr system during HPT was discussed. These results clearly suggest that non-equilibrium phases can form in the Nb–Zr system by bulk MA by the use of HPT.     

Plasma treatment on electrode surfaces of bifacial silicon solar cells

To lower the fabrication cost of silicon solar cells, a surface treatment using a dielectric barrier discharge (DBD) instead of a wet cleaning technique was examined on electrode surfaces on silicon solar cells. The fill factor obtained through measuring current–voltage characteristics was evaluated, and the treated surface state was characterized by energy-dispersive X-ray. It was found that the DBD effectively activated the electrode surface and the surface treatment on finger electrodes contributed greatly to improve the fill factor.     

Improvement of Selectivity for Partial Hydrogenation of Benzene by Rare Earth Nitride Upon NH3 Treatment

For the liquid-phase partial hydrogenation of benzene at 483 K, the selectivity toward cyclohexene was greatly improved upon treating rare earth nitride with ammonia. For YbN obtained by thermal decomposition of Yb(NH₂)₂ at 1173 K, the selectivity of the NH₃-treated YbN was 75%, in contrast to nil for the untreated YbN.