[en] The paper compares the unsteady airflow field in the conventional and the new dual-feed rotor spinning unit. A 3D finite volume computation (with optional turbulence model) is adopted to simulate the airflow dynamics with a focus on the rotor interior. The equations are solved using Fluent 14.5 package. The airflow results reveal that the second transfer channel effect is significant, particularly in the rotor interior. Visualization of iso-surfaces and velocity magnitude in the two reveal a striking difference in the internal flow patterns and turbulent strength. Comparison of the yarn properties spun on the two systems shows improved tenacity, elongation, and yarn evenness. A Small variation in yarn hairiness of the respective spun samples is observed. (paper)

[en] Copper is the most widely used material in heat pipe manufacturing. Since the capability of wick structures inside a heat pipe will dominate its thermal performance, in this study, we introduce a hybrid surface modification method on the copper wire braids being inserted as wick structure into an ultra-thin heat pipe. The hybrid method is the combination of a chemical-oxidation-based method and a sol-gel method with nanoparticles being dip-coated onto the braid. The experimental data show that braids under hybrid treatment perform higher water rising speed than the oxidized braids while owning higher water net weight than those braids being only dip-coated with nanoparticle. (paper)

[en] Chinshan Nuclear Power Plant (NPP) is the first NPP in Taiwan which is a BWR/4 plant. The original rated power for each unit was 1775 MWt. After the project of measurement uncertainty recovery (MUR) for Chinshan NPP, the operating power is 1805 MWt now. The Chinshan NPP Unit 2 cycle 23 stability analyses were performed by the LAPUR6 stability analysis methodology. Comparing the LAPUR6 stability analysis results and vendor's results, they are similar. (author)

[en] The effects of Ta seeding layer on the crystalline microstructure and ferroelectric properties of sol-gel-derived strontium-bismuth-tantalate (SBT) thin films were investigated. Ultrathin (<1 nm) Ta seeding layers were deposited onto Pt/TiO₂/SiO₂/Si substrates by magnetron sputtering at room temperature before spin coating of SBT thin films. Our results show that the presence of Ta seed layer induces significant changes in the crystallinity and microstructure of the resultant SBT thin films, resulting in improved ferroelectric properties in terms of spontaneous polarization. Interestingly, the remanent polarization (2P_r) of SBT films is also found to initially increase and then decrease with increasing Ta thickness, showing a peak value of 18.8 μC/cm2 (at 5 V) at Ta thickness of around 0.23 nm. Since a stoichiometric SBT solution was employed in our experiments, the additional Ta on the Pt surface is thought to provide a Ta-rich environment for SBT films, which, in turn, results in lower nucleation activation energy for crystallization

[en] Maanshan nuclear power plant (NPP) is the first PWR in Taiwan. Its reactor is made by Westinghouse Company and has the rated power of 2775 MWt. The Maanshan NPP TRACE model is developed by Institute of Nuclear Energy Research (INER), and National Tsing Hua University (NTHU). The Maanshan NPP TRACE model assessment is performed by Partial Loss of Flow (PLOF) and Complete Loss of Flow (CLOF) of FSAR data and large-load reduction of startup test data. In summary, TRACE analysis results are consistent with FSAR and startup test data. (author)

[en] Ferromagnetic Si_1-xMn_x was prepared by implanting B⁺ and Mn⁺ ions in sequence into p-type Si(100) at room temperature and post-annealing at 700-900 deg. C. Superparamagnetic nano-sized silicide precipitates, 10-27 at.% Mn, were found near the surface of all Si_1-xMn_x samples. Annealing at 800 deg. C or below leads to the formation of a thin Si(Mn) layer, with 1.1 at.% Mn, ∼180 nm beneath the surface, giving rise to ferromagnetism with a Curie temperature above 250 K. The high-temperature ferromagnetism is attributed to the indirect exchange mediated by localized carriers in the impurity states. The Mn content of 1-1.5 at.%, having been separately reported to show room-temperature ferromagnetism several times by different groups, seems meaningful for Si-based diluted magnetic semiconductors (DMS). Possible extensions of our work presented here are elucidated

[en] A thermomechanical assessment of the LWR application of TRISO fuel with UN kernels was performed. Fission product release under operational and transient temperature conditions was determined by extrapolation from fission product recoil calculations and limited data from irradiated UN pellets. Both fission recoil and diffusive release were considered and internal particle pressures computed for both 650 and 800 μm diameter kernels as a function of buffer layer thickness. These pressures were used in conjunction with a finite element program to compute the radial and tangential stresses generated within a TRISO particle undergoing burnup. Creep and swelling of the inner and outer pyrolytic carbon layers were included in the analyses. A measure of reliability of the TRISO particle was obtained by computing the probability of survival of the SiC barrier layer and the maximum tensile stress generated in the pyrolytic carbon layers from internal pressure and thermomechanics of the layers. These reliability estimates were obtained as functions of the kernel diameter, buffer layer thickness, and pyrolytic carbon layer thickness. The value of the probability of survival at the end of irradiation was inversely proportional to the maximum pressure

[en] We use the scanning SQUID microscope (SSM) to image the vortices in superconducting FeSe_0_._3Te_0_._7 (FST) thin films. The observed peak flux value of FST is nearly a quarter of that of an accompanying Nb film. We developed a method for quantitatively determining the London penetration depth of the FST film from the known value of Nb. The obtained value, 0.88 μm, is significantly larger than those obtained from single crystals of similar compositions by using other methods. The methodology developed for this study is useful for measuring London penetration depths of thin-film superconductors in general. (paper)

[en] We have fabricated and investigated organic memory diodes, comprising a single polymer layer and Au nanoparticles stabilized by the same polymer material utilizing a reversible addition-fragmentation transfer technique to suppress phase separation. The organic memory diodes exhibit well reproducible and prominent current bistability and good charge retention characteristics free from phase separation issues. Nondestructive spectroscopic ellipsometry is used to characterize the physical properties of the polymer/nanoparticle composites, such as the polymer's effective dielectric function/layer thickness and the Au nanoparticle's effective volume fraction, which are important parameters for gaining insightful information on charge transport in this system. Temperature-dependent analysis of the read/write current behaviors suggests that charge transport in such a polymer/Au nanoparticle composite is dominated by carrier hopping via shallow-level traps at the high field regime.

[en] A high-temperature tensile stress study of a monolithic silicon nitride (Si₃N₄) was performed with time-of-flight neutron diffraction. A dedicated engineering diffractometer was employed at temperatures reaching 1375 deg. C. Rietveld refinements of diffraction spectra allowed the determination of (1) the coefficient of thermal expansion tensor during heating and (2) lattice strains during loading. The stress-strain response of individual lattice reflections was used to calculate the single-crystal elastic stiffness tensor of Si₃N₄ at 1375 deg. C via a self-consistent model