Evidence of spin density wave of CeOs4Sb12

Elastic neutron diffraction measurements were performed on single crystals to study the ground state below the mysterious exotic transition temperature 0.86 K. An antiferromagnetic order with a tiny moment of 0.027μB per formula is formedas the ground state for CeOs4Sb12 below the transition point. Our neutron data gives the evidence of spin density wave state for CeOs4Sb12 in this work.     

SIR Weighting Combining Diversity Using Matched Filter for Personal Communication Systems

We propose a novel SIR weighting postdetection combining diversity scheme with a new accurate SIR estimation method. The SIR is estimated and used as the weighting factor to compensate severe cochannel interference, one of the most important issues for PCS in terms of frequency utilization. Theimprovement offered by the proposal depends on SIR estimation accuracy.The SIR is, in this paper, estimated by a matched filter where theauto-correlation between received signal and unique word is calculated. Computer simulationsconfirm that the SIR of each diversity branch can be estimated easily andaccuratelyby the proposed SIR estimation method. The proposed diversity scheme achievesaperformance very close to that of ideal SINR weighting diversity underRayleighfading with severe cochannel interference. When average SIR = 10 dB and thenumber of branches(L)=4, the proposed diversity scheme lowers the requiredE_b/N₀ by 5 dB at BER = 1×10^-3compared to conventional maximal ratio combining diversity. This paper alsopresentsthe unique word length required to realize adequate performance, i.e.,robustnessagainst high-pitch Rayleigh fading.     

Influence of water vapor on the reduction of cuprous chloride to copper microfibers

Reduction of cuprous chloride has been examined in various atmospheres, mostly at 600°C, to produce copper microfibers that can be applied as a filler for electromagnetic interference shielding and electron conductive paste composites. The reduction with hydrogen resulted in formation of a large amount of copper films, but fine particles and short filaments were obtained when carbon black was mixed into the raw material. The most promising copper microfibers with dimensions of several mm length and 1–10 m thickness could be produced with the system CuCl — C — H₂O using argon as a carrier gas, where H₂ and CO formed then probably reduced the vaporized CuCl molecules. Introduction of hydrogen gas into this system increased the yield of copper microfibers, though they became more bent, curved and kinked in shape. However, the morphology of the microfibers is still acceptable as a filler.     

Observers and output feedback stabilising controllers for nonlinear strict-feedback systems with sampled observation

The design of observers and output feedback stabilising controllers for continuous-time strict-feedback systems with sampled observation is considered. First two types of observers are designed. One is a discrete-time semiglobal and practical reduced-order observer for the exact model and the other is a continuous-time semiglobal and practical full-order observer for continuous-time strict feedback systems with sampled observation. Then by combining the designed continuous-time observers and continuous-time state feedback laws that are continuous, zero at the origin, and uniformly globally asymptotically stabilise continuous-time systems, output feedback semiglobally practically uniformly asymptotically stabilising controllers are constructed. Numerical examples are given to illustrate the proposed design of observers and output feedback controllers.     

Effect of oxygen on the wettability of sapphire by liquid palladium

The surface tension of liquid palladium and the contact angle between liquid palladium and sapphire have been measured at 1833 K as a function of oxygen pressure by the sessile drop method. Oxygen acted as a surface-active element on the surface of liquid palladium and at the interface between liquid palladium and sapphire, resulting in the decrease of the surface tension and the contact angle. The work of adhesion calculated from their values increased with increasing oxygen pressure, and had a constant value above 400 Pa. The maximum excess concentration of oxygen was estimated to be 7.3×10^–6 mol m^–2 for the surface and 6.9×10^–6 mol m^–2 for the interface.     

Solid-State Polymerization Behavior of 1,3-Bis(3-quinolyl)-1,4-butadiyne

Summary 1,4-Bis(3-quinolyl)-1,3-butadiyne (DQ) is known to be polymerized in solid state to give the corresponding polydiacetylene. However, the polymer yield of DQ bulk crystals is low. Thus, we prepared several types of DQ crystals by different procedures to find the reason for the low polymer yield. We found three modifications of DQ crystals and they were evaluated by spectroscopic measurements and X-ray diffraction. DQ bulk crystals (Crystal I) and thermally grown DQ crystals on Crystal I (Crystal II) have the same structure classified to Type A, which gives regular polydiacetylene structure in low polymer yields. DQ crystals grown on glass plates by sublimation (Crystal III) belong to the second modification of Type B. DQ nanocrystals prepared by the reprecipitation method (Crystal IV) are Type B, and thermally grown DQ crystals on nanocrystals (Crystal V) are Type C. Crystals of Types B and C could be polymerized in low yields without showing excitonic absorption of polydiacetylene indicating irregular polymerization other than 1,4-addition. For crystals of Type A, we found that the 1,4-addition polymerization proceeded only in near-surface portions of the crystals. It can be plausibly explained that mobile monomers in the near-surface portion are only able to take part in their polymerization, resulting in low polymer conversion.     

Total reflection X-ray spectroscopy as a rapid analytical method for uranium determination in drainage water

Uranium concentrations in drainage water are typically determined by α-spectrometry. However, due to the low specific radioactivity of uranium, the evaporation of large volumes of drainage water, followed by several hours of measurements, is required. Thus, the development of a rapid and simple detection method for uranium in drainage water would enhance the operation efficiency of radiation control workers. We herein propose a novel methodology based on total reflection X-ray fluorescence (TXRF) for the measurement of uranium in contaminated water. TXRF is a particularly desirable method for the rapid and simple evaluation of uranium in contaminated water, as chemical pretreatment of the sample solution is not necessary, measurement times are typically several seconds, and the required sample volume is low. We herein employed sample solutions containing several different concentrations of uranyl acetate with yttrium as an internal standard. The solutions were placed onto sample holders, and were dried prior to TXRF measurements. The relative intensity, otherwise defined as the net intensity ratio of the Lα peak of uranium to the Kα peak of yttrium, was directly proportional to the uranium concentration. Using this method, a TXRF detection limit for uranium in contaminated water of 0.30 µg/g was achieved.     

Recent activities in the field of Nuclear Operational Management and Nuclear Safety Engineering

Recent activities in the field of Nuclear Operational Management and Nuclear Safety Engineering, the studies related to risk analysis methodology, design, and operational management, physical phenomena, and emergency preparedness and nuclear security, have been progressed. Especially, ‘risk analysis methodology’ and ‘design and operational management’ are the main categories of the field, in which more than half of published articles on Journal of Nuclear Science and Technology are related to these categories.     

Verification of Iron Loss Calculation Method Using a High‐Precision Iron Loss Analyzer

Because of the improved performance of power devices, the volume of the ac filter inductors used in high‐frequency PWM inverters has been reduced. However, the temperature rise in the filter inductor due to this miniaturization has become more pronounced. Therefore, we have proposed an iron loss calculation method for the ac filter inductor. However, the accuracy of the value calculated via the loss map method cannot be verified, because the iron loss arising during each switching period cannot be measured with conventional power measuring instruments. In order to resolve this problem, we developed an inductor loss analyzer (ILA), which allows precise measurement of the iron loss in the inductor during each switching period. The accuracy of the calculation of iron loss in the filter inductor by the loss map method was verified with the ILA. We found that the value calculated by the loss map method differed slightly from the value measured with the ILA. However, these differences can be reduced if we take into account the accurate flux density calculation and the effect of the duty ratio of PWM pulses on the loss. Finally, we verified that the loss map method can provide accurate iron loss calculations.