Investigation of thermal resistance and power consumption in Ga-doped indium oxide (In2O3) nanowire phase change random access memory

The resistance stability and thermal resistance of phase change memory devices using similar to 40 nm diameter Ga-doped In2O3 nanowires (Ga:In2O3 NW) with different Ga-doping concentrations have been investigated. The estimated resistance stability (R(t)/R-0 ratio) improves with higher Ga concentration and is dependent on annealing temperature. The extracted thermal resistance (R-th) increases with higher Ga-concentration and thus the power consumption can be reduced by similar to 90% for the 11.5% Ga: In2O3 NW, compared to the 2.1% Ga: In2O3 NW. The excellent characteristics of Ga-doped In2O3 nanowire devices offer an avenue to develop low power and reliable phase change random access memory applications. (C) 2014 AIP Publishing LLC.X113sciescopu

Thermochemical hydrogen generation of indium oxide thin films

Development of alternative energy resources is an urgent requirement to alleviate current energy constraints. As such, hydrogen gas is gaining attention as a future alternative energy source to address existing issues related to limited energy resources and air pollution. In this study, hydrogen generation by a thermochemical water-splitting process using two types of In2O3 thin films was investigated. The two In2O3 thin films prepared by chemical vapor deposition (CVD) and sputtering deposition systems contained different numbers of oxygen vacancies, which were directly related to hydrogen generation. The as-grown In2O3 thin film prepared by CVD generated a large amount of hydrogen because of its abundant oxygen vacancies, while that prepared by sputtering had few oxygen vacancies, resulting in low hydrogen generation. Increasing the temperature of the In2O3 thin film in the reaction chamber caused an increase in hydrogen generation. The oxygen-vacancy-rich In2O3 thin film is expected to provide a highly effective production of hydrogen as a sustainable and efficient energy source

Development of a selectively liquid-blocking and vapor-passage microfilter based on polyurethane-aerogel microfibers

In this study, we developed a liquid–vapor selective microfilter woven into a mesh using polyurethane (PU)–aerogel microfibers. The aerogel particles embedded on the surface of a PU microfiber provided liquid repellent properties, and the liquid–vapor selective microfilter allowed only vaporized chemical substances to pass through, while blocking liquid chemicals and water. An SnO2 nanowire transistor covered with the liquid–vapor selective microfilter was used as a chemical sensor to detect the concentration of chemical substances, such as nitric acid, benzene, and toluene, in water. The time-dependence response of the sensor depending on the type of chemical present in water showed reproducible response and recovery properties for multiple cycles

Control of adiabatic properties using thermal meta-structures

In this study, the shapes and materials of thermal meta-structures, which can suppress as much heat propagation as possible in a structure, were investigated using a three-dimensional finite-difference time-domain technique. The heat flux vibrating in the traveling direction could be suppressed using multiple layers of thermal meta-materials. The heat flux transferred through the gap between thermal meta-structures could also be efficiently suppressed by placing even-numbered layers of thermal meta-structures in a zigzag arrangement in a structure. When the air-based thermal meta-structures were increased from one to four layers, the temperature inside the structure could be reduced from 38.9 °C to 25.5 °C. Moreover, when water-, paraffin-, aerogel-, and air-based thermal meta-structures having different thermal conductivities, densities, and specific heat characteristics were applied to the structure, a temperature of 50 °C to one side led to temperatures of 35.7, 33.4, 25.7, and 25.5 °C on the other. In other words, the temperature of the concrete block with air-based and aerogel thermal meta-structures was more than 13 °C lower than that of a conventional concrete block (38.9 °C), confirming that the insulation effect obtained by suppressing heat transfer was significant

An Open-Source Low-Cost Mobile Robot System with an RGB-D Camera and Efficient Real-Time Navigation Algorithm

Currently, mobile robots are developing rapidly and are finding numerous applications in industry. However, there remain a number of problems related to their practical use, such as the need for expensive hardware and their high power consumption levels. In this study, we propose a navigation system that is operable on a low-end computer with an RGB-D camera and a mobile robot platform for the operation of an integrated autonomous driving system. The proposed system does not require LiDARs or a GPU. Our raw depth image ground segmentation approach extracts a traversability map for the safe driving of low-body mobile robots. It is designed to guarantee real-time performance on a low-cost off-the-shelf single board computer with integrated SLAM, global path planning, and motion planning. We apply both rule-based and learning-based navigation policies using the traversability map. Running sensor data processing and other autonomous driving functions simultaneously, our navigation policies performs rapidly at a refresh rate of 18Hz for control command, whereas other systems have slower refresh rates. Our method outperforms current state-of-the-art navigation approaches within limited computation resources as shown in 3D simulation tests. In addition, we demonstrate the applicability of our mobile robot system through successful autonomous driving in an indoor environment. Our entire works including hardware and software are released under an open-source license (https://github.com/shinkansan/2019-UGRP-DPoom). Our detailed video is available in https://youtu.be/mf3IufUhPPM.Comment: 11 pages, 11 figure

Detection of chemical substances in water using an oxide nanowire transistor covered with a hydrophobic nanoparticle thin film as a liquid-vapour separation filter

We have developed a method to detect the presence of small amounts of chemical substances in water, using a Al2O3 nanoparticle thin film covered with phosphonic acid (HDF-PA) self-assembled monolayer. The HDF-PA self-assembled Al2O3 nanoparticle thin film acts as a liquid-vapour separation filter, allowing the passage of chemical vapour while blocking liquids. Prevention of the liquid from contacting the SnO2 nanowire and source-drain electrodes is required in order to avoid abnormal operation. Using this characteristic, the concentration of chemical substances in water could be evaluated by measuring the current changes in the SnO2 nanowire transistor covered with the HDF-PA self-assembled Al2O3 nanoparticle thin film

An Open-Source Low-Cost Mobile Robot System With an RGB-D Camera and Efficient Real-Time Navigation Algorithm

Currently, mobile robots are developing rapidly and are finding numerous applications in the industry. However, several problems remain related to their practical use, such as the need for expensive hardware and high power consumption levels. In this study, we build a low-cost indoor mobile robot platform that does not include a LiDAR or a GPU. Then, we design an autonomous navigation architecture that guarantees real-time performance on our platform with an RGB-D camera and a low-end off-the-shelf single board computer. The overall system includes SLAM, global path planning, ground segmentation, and motion planning. The proposed ground segmentation approach extracts a traversability map from raw depth images for the safe driving of low-body mobile robots. We apply both rule-based and learning-based navigation policies using the traversability map. Running sensor data processing and other autonomous driving components simultaneously, our navigation policies perform rapidly at a refresh rate of 18 Hz for control command, whereas other systems have slower refresh rates. Our methods show better performances than current state-of-the-art navigation approaches within limited computation resources as shown in 3D simulation tests. In addition, we demonstrate the applicability of our mobile robot system through successful autonomous driving in an indoor environment

Estimation of Contact angle variation of water droplet on graphene

Easy and reliable estimation of properties of graphene is crucial for the variety of potential applications of graphene. We characterized the wetting properties of defective graphene using molecular dynamics (MD). Graphene defects were categorized by hydroxyl, epoxy, ether, carbonyl, carboxyl, pyridinic, and hydrogen-attached defects. We confirmed the contact angle of water on graphene varied with the concentration and type of defects. Hydrogen attached defect made graphene more hydrophobic. Other types with oxygen and nitrogen contained defects made graphene more hydrophilic. As the concentration of defect increased, the contact angle was either increased or decreased. However, the contact angle of pyridinic graphene was decreased and slightly increased till being constant. We interpreted the contact angle in terms of the adhesion energy between graphene and water droplet and water layering effect

Dipping-Press Coating Method for Retaining Transparency and Imparting Hydrophobicity Regardless of Plastic Substrate Type

Plastics are used in cover substrates for billboards, windows, large LED signboards, lighting devices, and solar panels because they are transparent and can be colored and shaped as desired. However, when plastic cover substrates installed in outdoor environments are constantly exposed to harsh conditions such as snow, rain, dust, and wind, their transparency deteriorates owing to watermarks and dust contamination. Herein, we investigated a simple dipping-press coating method that can impart hydrophobicity while maintaining the transparency, regardless of the plastic substrate type. A highly transparent and hydrophobic coating film was formed on a plastic substrate by a two-step process, as follows: (1) application of a polydimethylsiloxane–octadecylamine coating by a dipping process, and (2) embedding (1H,1H,2H,2H-heptadecafluorodec-1-yl) phosphonic acid–aluminum oxide nanoparticles by a thermal press process. The plastic substrates on which the highly transparent and hydrophobic coating film was formed showed 150° or higher hydrophobicity and 80% or higher visible light transparency. The coating method proposed herein can easily impart hydrophobicity and is compatible with any plastic substrate that must maintain prolonged transparency without contamination when exposed to adverse conditions

Controlling the Degree of Coverage of the Pt Shell in Pd@Pt Core–Shell Nanocubes for Methanol Oxidation Reaction

The synthesis of Pd@Pt core–shell nanocubes was achieved through a direct seed-mediated growth method. This process represents a simple and cost-effective way to produce core–shell nanocubes. The morphology of the Pd@Pt core–shell nanocubes varied from simple cubic to concave cubic, depending on the reducing agent and the Pt content. The selection of the reducing agent is important because the reduction rate is directly related to the shell growth. The catalytic activity and stability of the Pd@Pt core–shell nanocubes in the methanol oxidation reaction were different for the nanocubes with partial and full Pt shells