Pd20Pt20Cu20Ni20P20 high-entropy alloy as a bulk metallic glass in the centimeter

A Pd₂₀Pt₂₀Cu₂₀Ni₂₀P₂₀ bulk metallic glass (BMG) with a high-entropy (HE) alloy composition and a maximum diameter of 10 mm was fabricated by fluxed water quenching. The system and composition of the Pd₂₀Pt₂₀Cu₂₀Ni₂₀P₂₀ alloy were determined from a prototype ternary Pd₄₀Ni₄₀P₂₀ BMG in accordance with two strategic alloy designs of (1) HE alloy defined by an equi-atomic alloy with five or more elements and (2) exchangeability of the constituent elements with a similar chemical nature in the periodic table. Pd₂₀Pt₂₀Cu₂₀Ni₂₀P₂₀ HE-BMG had a supercooled liquid range of 65 K and a reduced glass transition temperature of 0.71. Successful formation of Pd₂₀Pt₂₀Cu₂₀Ni₂₀P₂₀ HE-BMG is significant to develop new alloys for HE alloys and BMGs.     

Method to evaluate UV dose of upper-room UVGI system using the concept of ventilation efficiency

Several countermeasures against the prevalence of infectious diseases have recently been issued, and one of them, the ultraviolet germicidal irradiation (UVGI) system, has been carefully considered for building environments especially. Besides experimental methods to evaluate the germicidal performance of upper air UVGI systems, this research introduces two numerical methods using the concept of ventilation performance, and illustrates the methods with a ward model. The first calculates the average residence time of air using the concept of local purging flow rate (L-PFR) which is multiplied by the average UV intensity of the upper area to obtain a UV dose. The other calculates the UV dose with the distributional UV intensity and deals with UV intensities as contaminant sources. The results of the illustrative cases with a ward model show that the method using the L-PFR concept could not clearly identify the difference in UV doses for each case with different exhaust opening setups, although the other could. The results from the method using the distributional UV intensity indicated the layout of ventilation openings and upper-room UVGI systems are important to optimize the germicidal performance.     

Scanning Tunneling Spectroscopy on Overdoped Bi2Sr2?xLaxCuO6+δ

We have performed low-temperature scanning tunneling spectroscopy on overdoped Bi₂Sr_2−x La _x CuO_6+δ (x=0.1 and 0.2) at 4.2 K. The tunneling spectra in both samples obviously exhibit two energy gaps: one has clear gap structure with sharp gap edge peaks, and another is observed as kinks inside the larger gap. Both the energy gaps inhomogeneously vary on the surface at nanometer scale, and their values positively correlate each other. The distributions of both gaps normalized to the mean values are identical independent of the doping level. These results suggest that the two gaps are commonly affected by the source of the electronic disorder.     

Partial discharge measurements in SF6 and air usingphase-resolved pulse-height analysis

Carries out a study on partial discharge (PD) phenomena in SF₆ gas and tries to construct a diagnostic system capable of separating noise from observed PD signals for assessing the condition of insulation performance in power apparatus. The authors have constructed a computer-aided PD measuring system which permits a time-sequential data acquisition and phase-resolved pulse height analysis. Using the PD measurement system, the authors measured 60 Hz AC PD in SF₆ gas and in air at atmospheric pressure for needle-plane electrodes with three different radii at the tip of the needle, 3, 30 and 500 μm. They proposed particular PD statistical parameters, unbalance ratios U _T and U_q of the pulse repetition rate and average of charge, respectively, between positive and negative PD pulses occurring per cycle; these parameters proved to be good indicators to distinguish PD occurring in SF₆ from that in air. The mechanism of PD inception was also discussed     

电子装置内的热移动研究——温度分布及速度分布

在高60cm,宽45cm 的模拟电子装置内,进行装置内热移动研究,得到不同条件下的温度分布及速度分布.在理论解析及数值计算基础上,进行无因次准数关联,得出实验式.实验结果及解析结果基本一致.利用所得实验式对正在运转或有待开发的新的电子装置有关参数进行推算,对于传热设计具有很强的实用性.     

Coupling-loss reduction of a vertically coupled microring resonator filter by spot-size-matched busline waveguides

To improve the input-output coupling loss of a vertically coupled microring resonator filter, we fabricated microring resonators on an antiresonant reflecting optical waveguide (ARROW) with a large spot size and on the rectangular busline waveguide with a spot-size transformer. The spot size and the tapered structure were optimally designed from the viewpoint of spot-size matching to single-mode fibers and the reduction of radiation loss. Clear dropping responses were demonstrated for the ARROW-based microring resonator filters, and the coupling loss was successfully reduced by 22 dB.     

Electrode conditioning characteristics in vacuum under impulse voltage application in nonuniform electric field

In this paper, we quantitatively investigated the impulse conditioning mechanism under nonuniform electric field electrodes in a vacuum. A negative standard lightning impulse voltage was applied between rod and plane electrodes whose materials were Cu-Cr, stainless steel and Cu and the gap lengths were d=5 and 10 mm, respectively. Experimental results revealed the transition of the breakdown (BD) sport region on the rod electrode and the corresponding BD field strength in the conditioning process. As a result, we found that the BD spot region started at the tip of the rod electrode and moved to the wider region of the rod electrode with lower electric field as the shots of the voltage application increased before the saturation of the BD voltage. Finally, by analyzing the results with an electric field strength, we propose that "the conditioning degree" along the electrode surface distributed directly proportional to the electric field distribution under a nonuniform electric field in a vacuum, irrespective of the electrode materials     

Current status and future prospect of in‐cell‐polarizer technology

Abstract— A thin‐crystalline‐film (TCF) polarizer has been developed which can be used internally in liquid‐crystal‐display cells. Based on this material, a manufacturing process has been developed for the fabrication of monochrome LCDs with internal polarizers. A new TCF polarizer material and coating equipment, developed to realize a high‐performance color TFT‐LCD, are discussed.     

Touch-Space: Mixed Reality Game Space Based on Ubiquitous, Tangible, and Social Computing

This paper presents a novel computer entertainment system which recaptures human touch and physical interaction with the real-world environment as essential elements of the game play, whilst also maintaining the exciting fantasy features of traditional computer entertainment. Our system called ‘Touch-Space’ is an embodied (ubiquitous, tangible, and social) computing based Mixed Reality (MR) game space which regains the physical and social aspects of traditional game play. In this novel game space, the real-world environment is an essential and intrinsic game element, and the human’s physical context influences the game play. It also provides the full spectrum of game interaction experience ranging from the real physical environment (human to human and human to physical world interaction), to augmented reality, to the virtual environment. It allows tangible interactions between players and virtual objects, and collaborations between players in different levels of reality. Thus, the system re-invigorates computer entertainment systems with social human-to-human and human-to-physical touch interactions. Correspondence to: Professor A. Cheok, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260. Email: adriancheok@nus.edu.sg     

Mechanical characteristics of a contact optical head slider operating on a metal-layered medium

 Advances in a digital network society require both higher density and higher transfer rates in all sorts of storage systems. Even in optical recording, the trend toward higher density and larger capacity requires novel surface-recording technologies that can drastically diminish head-to-medium spacing, resulting in an improvement in spatial resolution and, finally, a higher recording density. In this paper, we propose a novel contact optical head slider that is able to almost cancel the suspension load by generating hydrodynamic pressure, thus realizing a lower net contact force. A trial-manufactured contact slider being processed four sliding pads on air-bearing surfaces has indicated a gentle variation of both the acoustic emission signal intensity and the friction force as the circumferential velocity changes. Furthermore, a time-domain simulation was performed to investigate the effects of the damping of a medium surface (lubricant) both on slider bouncing and on contact force. Received: 5 July 2001/Accepted: 1 November 2001