An application of lithium cobalt nickel manganese oxide to high-power and high-energy density lithium-ion batteries

Evolved gas analysis (EGA) by mass spectroscopy (MS) was carried out for the pyrolysis of Li_1−xCo_1/3Ni_1/3Mn_1/3O₂ (185 mAh g⁻¹ of charge capacity) and the results were compared with that of Li_1−xCoO₂ (140 mAh g⁻¹). Electrochemically prepared Li_1−xCo_1/3Ni_1/3Mn_1/3O₂ clearly shows that O₂ evolution begins at much higher temperature than Li_1−xCoO₂, suggesting that Li_1−xCo_1/3Ni_1/3Mn_1/3O₂ is superior to LiCoO₂ with respect to thermal stability. High-temperature XRD measurements of charged LiCo_1/3Ni_1/3Mn_1/3O₂-electrodes at 4.45 V were also carried out and shown that the decomposition product by heating was identified as a cubic spinel consisting of cobalt, nickel, and manganese. This indicates that phase change from a layered to spinel-framework structure plays a crucial role in the suppression of oxygen evolution from the solid matrix. In order to show practicability of the new material, lithium-ion batteries with graphite-negative electrodes are fabricated and examined in the R18650-hardware. The new lithium-ion batteries show high rate discharge performances, excellent cycle life, and safety together with high-energy density.     

Long-distance test of Bell's inequality in 1550 nm band using polarisation entanglement

A report is presented of observed violation of the Clauser-Horne-Shimony-Holt (CHSH) inequality, a particular form of Bell's inequality, in polarisation-entangled photon pairs in the 1550 nm band. Accidental coincidences were included as detected in the S value evaluation of the CHSH inequality. A 10.5 km fibre was used as a quantum channel.     

A phased reinforcement learning algorithm for complex control problems

In this article, a phased reinforcement learning algorithm for controlling complex systems is proposed. The key element of the proposed algorithm is a shaping function defined on a novel position–direction space. The shaping function is autonomously constructed once the goal is reached, and constrains the exploration area to optimize the policy. The efficiency of the proposed shaping function was demonstrated by using a complex control problem of positioning a 2-link planar underactuated manipulator.     

Peeling Behavior and Spalling Resistance of Bonded Bidirectional Fiber Reinforced Polymer Sheets

This paper presents the peeling behavior and spalling resistant effect of bidirectional fiber reinforced polymer (FRP) sheets externally bonded to concrete surfaces. Experimental investigations are carried out through a series of newly designed punching-peeling tests. A wide range of variables, such as FRP sheet layers and fiber direction, plate constraint, concrete strength, adhesives, bond length of FRP sheets, diameter of indenter, and types of fibers, are considered in the experimental investigation. Theoretical study is also conducted for the specimens. Interfacial fracture energy is calculated analytically using a membrane-peeling method. It is realized that only two material parameters, i.e., the interfacial fracture energy of the FRP-concrete interface and the tensile stiffness of FRP sheets, are necessary to represent the interfacial spalling resistant behavior. Finally, the theoretical results are validated by comparing with experimental results. Comparison of theoretical to experimental results shows that the proposed theoretical model is satisfactory in reasonably and accurately predicting the peeling behavior and spalling resistant capacity of bidirectional FRP sheets bonded to concrete surface.     

Ultrasonic measurement of three-dimensional structure of electrical trees using characteristics of tree structure

In this paper we propose a method to distinguish noise-covered ultrasonic signals by making use of the distinguishing features of signals reflected from electrical trees extending toward the direction of depth within the specimen. This method utilizes the characteristics of signals due to the spatial continuity of a tree branch and also to the change of the delay time of the signal reflected from the electrical tree when the ultrasonic transducer is moved slightly near the target point. As a result, it is shown that the three-dimensional structure of the bush-type tree in polyethylene can be visualized in a nondestructive way. The resultant shapes of the trees agreed well with those obtained by actual sectioning of the specimen using a microtome. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 119(3): 7–13, 1997     

Effect of the volume ratio of zirconia and alumina on the mechanical properties of fibrous zirconia/alumina bi-phase composites prepared by co-extrusion

Fibrous zirconia/alumina composites with different composition were fabricated by piston co-extrusion. After a 3rd extrusion step and sintering at 1600 °C, crack-free composites with a fibre width of 50 μm were obtained for all compositions. The effect of the volume ratio of secondary phase on the mechanical properties was investigated. The Young's modulus of the composites decreased linearly with increasing the zirconia content. The fracture toughness of the composites was improved by introducing fine second phase filaments into the matrix. The maximum fracture toughness of 6.2 MPa m^1/2 was attained in the 3rd co-extruded 47/53 vol% zirconia/alumina composite. The improvement in toughness was attributed to both “stress-induced” transformation of zirconia and a crack deflection mechanism due to thermal expansion mismatch between the two phases. Bending strength of the composites was almost the same as that of the monolithic alumina regardless of the composition.     

Three-dimensional atom probe study of Fe–B-based nanocrystalline soft magnetic materials

Solute clustering and partitioning in new Fe–B-based soft magnetic materials with high saturation magnetic flux density (B_s), (Fe_0.85B_0.15)_100?xCu_x (x = 0.0, 1.0, and 1.5) and Fe_82.65Cu_1.35Si_yB_16?y (y = 0.0, 2.0, and 5.0) melt-spun alloys, were investigated by three-dimensional atom probe and transmission electron microscopy. Although Cu clusters form after annealing in all the samples, it was found that only the clusters of 4–6 nm can serve as heterogeneous nucleation sites for α-Fe. While annealing the Si-free alloys at 410 °C led to the precipitation of Fe₃B, only α-Fe nanocrystals were observed in the Si-containing alloys. Lorenz TEM observation indicated the Fe₃B particles pin magnetic domain walls. The Fe_82.65Cu_1.35Si_yB_16?y alloy with y = 2.0 crystallized by annealing at 400 °C exhibited optimal nanocrsytal/amorphous microstructure without the precipitation of Fe₃B, which led to the lowest coercivity while keeping a high B_s ～1.85 T.     

Tribological Behavior of Si3N4 and Si3N4/Carbon Fiber Composites Against Stainless Steel Under Water Lubrication for a Thrust-Bearing Application

The tribological behavior of Si₃N₄ ceramics and Si₃N₄/carbon fiber composites sliding against stainless steel under water lubrication was investigated using a thrust-bearing-type test method with normal applied loads varying from 0 to 1000 N in 100 N increments. In the case of the monolithic Si₃N₄, the friction coefficient was found to increase up to 0.4 the first time the applied load was increased from 100 to 200 N, and sudden failure of the ceramic ring specimen occurred. In the case of the Si₃N₄/carbon fiber composite, a low friction coefficient was maintained up to the maximum normal load of 1000 N. The addition of the carbon fibers to the silicon nitride ceramics effectively restricts material transfer from the stainless steel to the Si₃N₄ worn surface due to reduction of solid–solid contact through the solid lubricating effect of the carbon fibers.     

Cr concentration dependence of overestimation of long term creep life in strength enhanced high Cr ferritic steels

Creep rupture data and microstructural degradation during aging of high Cr ferritic boiler steels with enhanced creep strength have been studied with special attention to prediction of long term creep rupture life. Tempered lath martensite structure in the high Cr ferritic steels remains unchanged during short term aging, whereas static recovery of the lath martensite structure proceeds when diffusion distance during aging becomes sufficiently long as is the case in long term creep. The static recovery brings about premature failure in long term creep and decreases in apparent activation energy for creep life. The decrease in activation energy is responsible for overestimation of rupture life reported in strength enhanced high Cr ferritic steels. The boundary from a short term region with high activation energy Q_H to a long term region with low activation energy Q_L moves towards longer time with decreasing Cr concentration. The difference in activation energy (Q_H − Q_L) primarily determines the extent of overestimation of rupture life predicted from short term data. In general, the extent of overestimation is less serious at 9%Cr as compared to 12%Cr.