纳米Pt膜的晶粒尺寸及其对热导率的影响

采用电子束-物理气相沉积法（EB-PVD）制备了6个厚度为15-62nm的铂薄膜，研究了纳米薄膜的晶粒尺寸及其对热导率的影响规律．当薄膜厚度小于30nm时，晶粒平均尺寸接近于薄膜的厚度；晶粒尺寸随着薄膜厚度的增加而增大并趋于定值；当薄膜厚度大于30nm时，晶粒尺寸约为20nm．受薄膜的表面和内部晶界的综合影响，铂纳米薄膜的热导率大大低于体材料的值，并且纳米薄膜的热导率随着薄膜厚度的增加而增大并趋于一个低于体材料热导率的值．     

Two‐way multi‐view 2‐D/3‐D display combining LC lens and HVxDP panel using novel pixel arrangement

We have developed a two‐way multi‐view 2‐D/3‐D display combining a liquid crystal lens and horizontally and vertically x times‐density pixels (HVxDP) arrangement. The two‐way multi‐view display features the same display resolution in 2‐D and 3‐D modes and a quite small color moiré for landscape and portrait, respectively, when using the HVxDP arrangement. In this paper, we realized suitable 3‐D properties for achieving a good balance between 3‐D moiré and 3‐D crosstalk for landscape and portrait by a two‐way liquid crystal lens with two kinds of focal lengths for the edge part and the center part of the lens.     

Parallelized fusion visualization system

The speed-up of supercomputers has increased the complexity of simulations. To analyze such kind of data, we believe that new types of visualization software are needed. Therefore, we have been developing a visualization system called “Fusion Visualization”, and the progresses were reported in the AROB 18th and 19th International Symposiums. We introduced the overall concept at the AROB 18th International Symposium, and then demonstrated a sample of flow visualization in a blood vessel in the AROB 19th International Symposium. To extend our system to enable the handling of larger data, we have implemented the proposed system on a parallelized visualization system; AVS/Express PCE (Parallel Cluster Edition). This paper describes the implementation and the benchmark results.     

Relationship between crystallinity and device characteristics of In‐Sn‐Zn oxide

We have reported that the transistors having the c‐axis‐aligned crystalline (CAAC) In‐Ga‐Zn oxide (IGZO) show good performance. Recently, In‐Sn‐Zn Oxide (ITZO) has attracted much attention because of its high electron mobility, as well as IGZO. However, it has been reported that ITZO field effect transistors (FET) tend to have positive Vth (normally‐on characteristics) and poor reliability compared with IGZO‐FETs. We have reported that high‐performance and high‐reliability OS‐FETs can be fabricated by using CAAC‐IGZO, which has high crystallinity and has no clear grain boundaries, as an active layer. Therefore, we have fabricated CAAC‐ITZO thin films to improve performance of ITZO‐FETs by using CAAC‐ITZO as an active layer. In addition, FETs employing CAAC‐ITZO have better characteristics and reliability than FETs using nano‐crystal ITZO. Furthermore, constant photocurrent method (CPM) measurement was carried out in order to estimate density of deep‐level defect states caused by oxygen vacancies in oxide semiconductors. The results show that CAAC‐ITZO has lower density of deep‐level defect states than nano‐crystal ITZO. We attribute the improvement in reliability of ITZO‐FETs to a decrease in deep‐level defect states of an ITZO active layer, as is the case with IGZO.     

An architecture framework for an adaptive extensible processor

To improve the performance of embedded processors, an effective technique is collapsing critical computation subgraphs as application-specific instruction set extensions and executing them on custom functional units. The problem with this approach is the immense cost and the long times required to design a new processor for each application. As a solution to this issue, we propose an adaptive extensible processor in which custom instructions (CIs) are generated and added after chip-fabrication. To support this feature, custom functional units are replaced by a reconfigurable matrix of functional units (FUs). A systematic quantitative approach is used for determining the appropriate structure of the reconfigurable functional unit (RFU). We also introduce an integrated framework for generating mappable CIs on the RFU. Using this architecture, performance is improved by up to 1.33, with an average improvement of 1.16, compared to a 4-issue in-order RISC processor. By partitioning the configuration memory, detecting similar/subset CIs and merging small CIs, the size of the configuration memory is reduced by 40%.     

Current control of a PWM power amplifier by an approximate 2-degree-of-freedom digital controller

There is a need for robust current control of a pulse width modulation (PWM) power amplifier whose transient response characteristics do not deteriorate with extensive load changes and/or direct-current power supply voltage changes. In this article, we propose a digital robust controller with bumpless mode switching to control the current of a PWM power amplifier to satisfy the demands and extend the range of an inductive load width. It is necessary to measure the value of the load in order to implement this bumpless mode switching automatically depending on the load range. Therefore, a method of estimating the inductive load is shown. The bumpless mode switching is automatically performed by estimating an inductive value without specifying the value of the inductive load beforehand. That is, the value of the inductive load is estimated during the DDC execution, and the control mode is automatically switched bumplessly according to this estimated value. A digital controller equipped with inductance estimation and bumpless mode switching is realized by a DSP. Some experiments show that the digital controller with the proposed bumpless mode switching can satisfy larger specifications.     

Quantitative structural analysis of twin boundary in alpha-Zn7Sb2O12 using HAADF STEM method

The structure and composition of the 1/4{110} twin boundary in alpha-Zn7Sb2O12 have been determined by using quantitative high-angle annular dark field scanning transmission electron microscopy (HAADF STEM) analysis. The noise in the experimental HAADF STEM images is reduced by using the maximum entropy method and average processing, and the parameters used in dynamical simulations are experimentally determined. From the analysis, it has been found that octahedral sites in the twin boundary slightly shift parallel to the [110] direction, and a reduction of the Sb concentration at the octahedral sites on the plane adjacent to the twin boundary was detected. The reduction was measured from three regions in the same twin boundary, and the Sb concentrations were 4 +/- 3, 8 +/- 3 and 19 +/-2 at% from 33 at%.     

Engineering Transition Metal Layers for Long Lasting Anionic Redox in Layered Sodium Manganese Oxide

Oxygen-redox-based-layered cathode materials are of great importance in realizing high-energy-density sodium-ion batteries (SIBs) that can satisfy the demands of next-generation energy storage technologies. However, Mn-based-layered materials (P2-type Na-poor Na_y[A_xMn_1−x]O₂, where A = alkali ions) still suffer from poor reversibility during oxygen-redox reactions and low conductivity. In this work, the dual Li and Co replacement is investigated in P2-type-layered Na_xMnO₂. Experimentally and theoretically, it is demonstrated that the efficacy of the dual Li and Co replacement in Na_0.6[Li_0.15Co_0.15Mn_0.7]O₂ is that it improves the structural and cycling stability despite the reversible Li migration from the transition metal layer during de-/sodiation. Operando X-ray diffraction and ex situ neutron diffraction analysis prove that the material maintains a P2-type structure during the entire range of Na⁺ extraction and insertion with a small volume change of ≈4.3%. In Na_0.6[Li_0.15Co_0.15Mn_0.7]O₂, the reversible electrochemical activity of Co³⁺/Co⁴⁺, Mn³⁺/Mn⁴⁺, and O^2-/(O₂)^n- redox is identified as a reliable mechanism for the remarkable stable electrochemical performance. From a broader perspective, this study highlights a possible design roadmap for developing cathode materials with optimized cationic and anionic activities and excellent structural stabilities for SIBs.     

Prediction of color changes in acetaminophen solution using the time–temperature superposition principle

A prediction method for color changes based on the time–temperature superposition principle (TTSP) was developed for acetaminophen solution. Color changes of acetaminophen solution are caused by the degradation of acetaminophen, such as hydrolysis and oxidation. In principle, the TTSP can be applied to only thermal aging. Therefore, the impact of oxidation on the color changes of acetaminophen solution was verified. The results of our experiment suggested that the oxidation products enhanced the color changes in acetaminophen solution. Next, the color changes of acetaminophen solution samples of the same head space volume after accelerated aging at various temperatures were investigated using the Commission Internationale de l’Eclairage (CIE) LAB color space (a*, b*, L* and ΔE*ab), following which the TTSP was adopted to kinetic analysis of the color changes. The apparent activation energies using the time–temperature shift factor of a*, b*, L* and ΔE*ab were calculated as 72.4, 69.2, 72.3 and 70.9 (kJ/mol), respectively, which are similar to the values for acetaminophen hydrolysis reported in the literature. The predicted values of a*, b*, L* and ΔE*ab at 40?°C were obtained by calculation using Arrhenius plots. A comparison between the experimental and predicted values for each color parameter revealed sufficiently high R² values (>0.98), suggesting the high reliability of the prediction. The kinetic analysis using TTSP was successfully applied to predicting the color changes under the controlled oxygen amount at any temperature and for any length of time.