Synthesis of New Pb-Based 1222 Cuprates Containing Phosphorus, (Pb0.75P0.25)Sr2(RE2–x–y Ce x Sr y )Cu2O z (RE = Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Y)

New Pb-based 1222 cuprates containing phosphorus have been synthesized in the (Pb_0.75P_0.25)Sr₂- (RE_2–x–y Ce _x Sr _y )Cu₂O _z (RE = Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Y) systems. The almost-single phase samples are obtained for 0.5≤x≤1.0 and y=0.1 in the cases of RE = Nd, Dy, Ho, Er, Tm, Yb and Y, while for 0.3≤x≤1.0 and y=0.1 in the cases of RE = Sm, Eu and Gd. The samples crystallize in a tetragonal lattice, the lattice parameters a and c are decreasing with the decrease of the ionic radius of the RE element. Even after annealing under 143 atm O₂ atmosphere at 400 °C, almost all the samples with the common values x=0.5 and y=0.1 are semiconductors with a transport process followed by three-dimensional variable range hopping. However, the samples of RE = Sm, Eu and Gd, which are of almost single 1222 phase, even for x=0.3 and y=0.1, show superconductivity with the onsets at about 25 K, 20 K and 22 K, respectively. Through this study, we find very important procedure for discovery of new superconducting 1222 compound.     

Inter-comparison of various global sea surface temperature products

In this study, eight global sea surface temperature (SST) products for 2009 are compared to clarify their characteristics. The median of eight daily values, the Ensemble Median as Reference Product (EMRP), is used as a reference product for inter-comparison. The results show that the absolute value of mean differences and the value of root mean square (RMS) differences are higher in single-microwave products such as Advanced Microwave Scanning Radiometer for the Earth observing system (AMSR-E), Tropical Rainfall Measuring Mission Microwave Imager (TMI), and WindSat, than in products such as MicroWave Optimally Interpolated SST (MWOI), Merged satellite and in situ data Global Daily SST (MGD), and Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA) constructed by merging several SST data. It is of note that the characteristics of SST products depend on the type of SST used within the product, rather than the data source used. A comparison of SST products was also conducted using EMRP and data observed by moored buoys. The results show that only AMSR-E has a warm bias (+0.06°C) while other products have a cool bias (maximum value ?0.10°C). The RMS error of TMI is the highest (0.57°C), and that of EMRP the lowest (0.28°C). Furthermore, the temporal variability between the data in each SST product was compared to those observed by the Kuroshio Extension Observatory (KEO) buoy. Results show that the temporal variability of EMRP corresponds well to that of buoy data, and that the RMS error of EMRP is lower than that of the other SST products.     

Asymmetric Autocatalysis Triggered by Chiral Crystals Formed from Achiral Compounds and Chiral Isotopomers

Asymmetric autocatalysis with amplification of enantiomeric excess is found in the enantioselective addition of diisopropylzinc to pyrimidine-5-carbaldehyde using pyrimidyl alkanol as an asymmetric autocatalyst. Asymmetric autocatalysis has been employed as a method for clarifying the origin of homochirality. Circularly polarized light, inorganic chiral crystals and statistical fluctuation of enantiomeric imbalance act as chiral initiators in asymmetric autocatalysis to afford highly enantioenriched products. We have investigated asymmetric autocatalysis using chiral crystals formed from achiral and racemic compounds as an origin of chirality. Absolute control of the crystal chirality of cytosine was achieved by the removal of crystal water. Enantioselective carbon-carbon bond formation at the enantiotopic crystal face of aldehydes was established using diisopropylzinc vapor. In addition, asymmetric autocatalysis triggered by chiral compounds arising from H, C and O isotope substitution has been achieved.     

Analysis of spatial smoothing effect of short‐term fluctuation of global solar radiation based on data including quantization error

Photovoltaic (PV) systems are attracting attention as one of the promising countermeasures against global warming and the environmental issues. However, the generation output from PV systems is generally unstable and unpredictable. Therefore, large penetration of PV systems may cause some serious impacts on power system operation, such as load frequency control, voltage regulation, etc. Estimation of the influences of PV system installation is becoming important, but it requires simultaneous multipoint solar radiation measurements. The Japan Meteorological Business Support Center has provided 1‐minute meteorological data observed in Japan, but its solar radiation data includes quantization errors. This paper proposes a regeneration method for solar radiation data including quantization errors. It also analyzes the spatial smoothing effect of global solar radiation fluctuations. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 180(3): 55–63, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21274     

Navigation behavior based on self-organized spatial representation in hierarchical recurrent neural network

ABSTRACT

A cognitive map is an internal model of the external world and contains the spatial representation of the surrounding environment. The existence of the cognitive map was first identified in rats; rats can navigate to their desired destination using cognitive maps while dealing with environmental uncertainty. We performed a mobile robot navigation experiment where obstacles were randomly placed using hierarchical recurrent neural network (HRNN) with multiple timescales. The HRNN was trained to navigate the mobile robot to the destination indicated by a snapshot image. After the training, the HRNN was able to successfully avoid the obstacles and navigate to the destination from any location in the environment. Analysis of the internal states of the HRNN showed that the module with fast timescale handles obstacle avoidance and the one with slow timescale has spatial representation corresponding to the spatial position of the destination. Moreover, in the experiment wherein the novel path appeared, the trained HRNN performed shortcut behavior. The shortcut behavior shows that the HRNN performed navigation using the self-organized spatial representation in the slow recurrent neural network. This indicates that training of goal-oriented navigation, i.e. the navigation motivated by a snapshot image of the destination results in the self-organization of cognitive map-like representation.     

The structure solution of the F-type i-ZnMgHf from the X-ray diffraction

ABSTRACT

We report a successful growth of the ZnMgHf F-type icosahedral quasicrystal in the form of faceted single grains. By varying the heat treatment parameters we were able to obtain single crystals with a quality suitable for a single crystal X-ray diffraction which was conducted in a synchrotron facility. Ab initio structure solution by a charge flipping algorithm manifests the existence of two types of Bergman clusters. Clusters are differentiated by the preferential occupation of the high-symmetry positions by hafnium in a rhombic triacontahedron, being the outer shell of the atomic cluster.

This paper is part of a Thematic Issue on The Crystallographic Aspects of Metallic Alloys.     

Non-invasive and rapid analysis for observation of internal structure of press-coated tablet using X-ray computed tomography

Background: Since the internal structure of a tablet can be measured without destruction of the sample by X‐ray computed tomography (CT), it could be applied to quality control of tablets during the manufacturing process. Aim: A novel, fast, noninvasive tablet observation method was developed to evaluate the internal structure of commercial press-coated tablets by using X-ray CT. Method: Thirty-two CT image slices of four kinds of commercial press-coated tablets (tablets A, B, C, and D) were measured 300 m interval between edges of the tablet by using an X-ray CT. The thinnest layer thickness of the tablets and distance between centers of gravity (DCG) of tables were calculated. Results: The order of the TLT of the tablets was tablet B > tablet C > tablet D > tablet A. The result indicated that the order of DCG was tablet A > tablet D > tablet C > tablet B. Noninvasive observation of the internal structure of commercial, press-coated tablets by X-ray CT has been demonstrated to be useful in quality control of production. Conclusion: The internal structure of press-coated tablets could be observed without pretreatment, without destruction, and very rapidly by X‐ray CT.     

Effects of phosphorus content on generation and growth of cracks in nickel–phosphorus platings owing to thermal cycling

We observed crack generation and structural changes in electroless nickel–phosphorus (Ni–P) plating layers formed on copper-metalized silicon nitride substrates both during thermal cycling from ? 40 to 250 °C and during storage (not cycling) at 250 °C in order to investigate the effect of the phosphorus contents on crack generation and growth in the Ni–P platings. The used platings contained phosphorus at three different contents: 2.1 wt% [Ni–P(low)], 6.5 wt% [Ni–P(med)], and 10.9 wt% [Ni–P(high)]. The generation time and the amount of cracks were strongly dependent on their phosphorus contents. More cracks appeared after thermal cycling than after storage at 250 °C. In Ni–P(low), cracks were generated after 200 thermal cycles, whereas no cracks were observed even after 250 h of storage at 250 °C. In Ni–P(med) and Ni–P(high), both during thermal cycling and storage at 250 °C, cracks formed during or after crystallization of the amorphous layers. These results suggest that the primary factors affecting the generation of cracks in electroless Ni–P platings are crystallization of the Ni–P platings and repeated changes in thermal stress.