Impact of Bi Deficiencies on Ferroelectric Resistive Switching Characteristics Observed at p‐Type Schottky‐Like Pt/Bi1–δFeO3 Interfaces

This work reports a resistive switching effect observed at rectifying Pt/Bi_1–δFeO₃ interfaces and the impact of Bi deficiencies on its characteristics. Since Bi deficiencies provide hole carriers in BiFeO₃, Bi‐deficient Bi_1–δFeO₃ films act as a p‐type semiconductor. As the Bi deficiency increased, a leakage current at Pt/Bi_1–δFeO₃ interfaces tended to increase, and finally, rectifying and hysteretic current–voltage (I–V) characteristics were observed. In I–V characteristics measured at a voltage‐sweep frequency of 1 kHz, positive and negative current peaks originating from ferroelectric displacement current were observed under forward and reverse bias prior to set and reset switching processes, respectively, suggesting that polarization reversal is involved in the resistive switching effect. The resistive switching measurements in a pulse‐voltage mode revealed that the switching speed and switching ratio can be improved by controlling the Bi deficiency. The resistive switching devices showed endurance of >10⁵ cycles and data retention of >10⁵ s at room temperature. Moreover, unlike conventional resistive switching devices made of metal oxides, no forming process is needed to obtain a stable resistive switching effect in the ferroelectric resistive switching devices. These results demonstrate promising prospects for application of the ferroelectric resistive switching effect at Pt/Bi_1–δFeO₃ interfaces to nonvolatile memory.     

Gas Release of SiC Implanted with Deuterium or Helium

Helium (He⁺) or Deuterium (D₂⁺) (20 keV) was implanted into polycrystalline β-SiC with an ion dose of 7.2 × 10²¹ (D or He)/m². The implanted specimens were heated at a heating rate of 10 or 20 K/min from room temperature to 1373 K, and the thermal release spectroscopic data were obtained. A sharp peak appeared at approximately 1270 K in the case of He release, and here the activation energy was estimated to be approximately 4.4 eV. Two overlapped peaks appeared at approximately 900 and 1200 K in the case of D₂ release. The shapes of spectra showed strong dependence on the heating rate.     

An influence of commutation arc in gasoline on brush wear andcommutator

Many DC motors are used for automotive electrical equipment. Particularly, a motor for a fuel pump has a distinctive feature that its commutation is carried out in gasoline. Our previous study reported that brush wear in gasoline was much more than that in air. And also carbon brushes were sometimes severely worn in negative polar. In this paper, the wear of carbon brushes for negative polar, sliding against the copper commutator in gasoline and air is reported. In order to find the cause of severe wear on the carbon brush, we examined the range of brush wear, arc energy and the influence of arc on the commutator with changing commutation current: 5 A to 10 A. As a result, arc energy in air is larger than that in gasoline, but the range of brush wear is narrow. Commutator surface in gasoline is rougher than that in air. Excessive film is observed on the commutator surface when severe wear takes place     

Performance of single crystal diamond tools with different rake angles during micro-grooving on electroless nickel plated die materials

In this study, experiments were carried out to establish the effect of tool rake angle on the performance of single crystal diamond tools in micro-grooving of electroless nickel plated molding dies. Diamond tools with rake angles of 0⁰,+5⁰ and ?5⁰ were used in the study, and it was found that the diamond tool with 0⁰ rake angle has superior performance in terms of tool wear, cutting forces, and machined surface roughness. For a cutting distance of up to 11.69 km, the 0⁰ rake tool machined satisfactorily without any sign of tool wear while the tools with +5⁰ and ?5⁰ rake angles suffered from progressive wear with a corresponding increase in cutting forces. However, it was noted that despite the increase in wear on tools with +5⁰ and ?5⁰ rake angles, and cutting forces on the diamond tools with all three different rake angles did not significantly affect the surface roughness. The effects of various cutting parameters such as spindle speed and infeed rate on the cutting forces and surface roughness are also presented in the study. It was observed that cutting forces increase proportionately with spindle speed and infeed rate without any significant variation of surface roughness. Surface quality of up to 3 nm Ra was achieved during micro-grooving of electroless nickel.     

Study on the generation process of the discharge for color plasmadisplays based on observation by using an ultra-high-speed electroniccamera

Instead of the direct observation of ultraviolet rays of 147 nm emitted from Xe, light emission of 828 nm was observed first by using ultra-high-speed electronic camera system. The experimental results show that the ultraviolet rays of 147 nm emit above both cathodes and anodes simultaneously. The striation phenomena observed on anodes were analyzed     

PbBi-cooled direct contact boiling water small reactor

A design concept of PbBi cooled direct contact boiling water small fast reactor (PBWFR) has been formulated with some design parameters identified. Water is injected into hot PbBi above the core, and direct contact boiling takes place in chimneys. Boiling bubbles rise due to buoyancy effects, which works as a lift pump for PbBi circulation. The generated steam passes through separators and dryers for the removal of PbBi droplets, and then flows into turbines for the generation of electricity. The system pressure of 7 MPa is as the same as that of the conventional boiling water reactors (BWRs). The outlet steam is superheated by 10°C to avoid the accumulation of condensate on a PbBi free surface in the reactor vessel. The control rods are inserted from above, which is different from the original concept. This insertion was chosen since the seal of steam at the top of the reactor vessel is technically much easier than the seal of PbBi at the bottom of the reactor vessel. The electric power of 150 MWe may be the maximum which is practically possible as a small reactor with economic competitiveness to conventional LWRs. A two-region core is designed. A decrease in reactivity was estimated to be 1.5%dk/kk′ for 15 years. A fuel assembly has 271 fuel rods with 12.0 mm in diameter and 15.9 mm in pitch in a hexagonal wrapper tube. The design limit of cladding temperature is specified to be 650°C for compatibility of cladding material with PbBi. As a result, the PbBi core outlet temperature becomes 460°C. The PbBi temperature rise in the core is 150°C. The conditions of the secondary coolant steam are as the same as those of conventional BWRs with thermal efficiency of 33%. The core is designed to have the breeding ratio of 1.1 and the refueling interval of 15 years as a reactor with a long-life core. Direct heat exchangers (DHX), reactor vessel air cooling systems (RVACS) and guard vessel are designed.     

FILAMENTOUS FLOWER controls the formation and development of arabidopsis inflorescences and floral meristems

Correlated binary data are encountered in many areas of medical research, system reliability and quality control. For monitoring failures rates in such situations, simultaneous bivariate cumulative sum (CUSUM) charts with the addition of secondary control limits are proposed. Using an approach based on a Markov chain model, the run length properties of such a monitoring scheme can be determined for sudden, or gradual, changes in the failure rates. The proposed control charts are easy to implement, and are shown to be very effective at detecting small changes in the rate of undesirable outcomes, especially when the changes are gradual. This procedure is illustrated using bivariate outcome data arising from a series of paediatric surgeries. The methodology is sufficiently general that it may be adapted for multivariate normal, binomial or Poisson responses.     

Bisimulation equivalence of a BPP and a finite-state system can be decided in polynomial time

In this paper we consider the problem of deciding bisimulation equivalence of a BPP and a finite-state system. We show that the problem can be solved in polynomial time and we present an algorithm deciding the problem in time O(n⁴). The algorithm also constructs for each state of the finite-state system a ‘symbolic’ semilinear representation of the set of all states of the BPP system which are bisimilar with this state.     

Cutting performance of diamond tools during ultra-precision turning of electroless-nickel plated die materials

This study is an attempt (a) to observe the wear characteristic of diamond tool with 200 km cutting distance and to study the effects of wear on the surface roughness and cutting forces and (b) to optimize various cutting parameters such as depth of cut, feed rate, spindle speed and phosphorus content. The experimental results showed that tool wear was not so significant although some defects on rake face were observed after cutting 15.6 km. Further cutting showed that the surface roughness increases with cutting distance, and that the cutting forces were larger than thrust force at the beginning of cutting, but after cutting 130 km, thrust force became larger and increased rapidly. It was also observed that forces increase with the increase of depth of cut, spindle speed and feed rate, and decrease with the increase of phosphorus content of the plating. Depth of cut has no significant effect on surface roughness, while it increases with increase of feed rate and decreases with the increase of percentage of phosphorus content in the workpieces. In case of spindle speed, surface roughness decreases with the increase of spindle speed up to a certain value and then starts to increase with the increase of spindle speed.