Application of a JXTA-overlay P2P system for end-device control and e-learning

This work is motivated by the need to develop decentralized P2P approaches for controlling end-devices in a wide-area network without changing the network security policy. Much of current research work on P2P systems is devoted to P2P networks of standard peers such as PCs. Due to improvements of connections capabilities of mobile devices and end-devices, there is an increasing interest to design, implement and deploy full featured P2P networks that integrate standard peers, mobile devices and end-devices. In this paper, we use the JXTA-Overlay for the control of end-devices and e-learning in a P2P network. We considered as end-devices the smart box (which is used for stimulating the learners in our implemented P2P e-learning system), robot, and room lightening. We also considered the control of a mobile car in order to prove the applicability of our approach in wireless environment. The proposed approach, due to the capabilities of JXTA protocols to overcome firewalls and NATs, is able to control devices without changing network security policies. We evaluate the proposed system by many experiments and have shown that the proposed system has a good performance and can be used successfully for the control of end-devices and in e-learning.     

Periodic microstructures produced by femtosecond laser irradiation on titanium plate

The periodic microstructures on titanium plate were formed by the irradiation of the femtosecond laser with the laser wavelength of 800 nm and the pulse length of 100 fs. They were oriented to the direction parallel to the laser polarization vector and their (parallel periodic microstructures) period was 1.5–2.4 μm. The periodic nanostructures were also produced by the femtosecond laser ablation, which were oriented to the direction perpendicular to the laser polarization vector and whose period was about 700 nm. Our results indicated that the laser fluence required for the parallel periodic microstructures was higher than that for the periodic nanostructures. The parallel periodic microstructures and the periodic nanostructures might be formed by an intensity modulation, which arose from the interaction of the laser and its scattered wave with a surface wave. The number of laser pulses to irradiate Ti plate was increased from 10 to 110. From 50 pulses, microdots were generated on the hills of the parallel periodic microstructures. From 70 pulses, the parallel periodic microstructures were varied to those with spatial modulation on the hills and the period of them was increased due to the bonding of the hills.     

Direct Microrolling Processing on a Silicon Wafer

Although, varieties of micro‐ to nanoscale fabrication technologies have been invented and refined for silicon (Si) processing because Si is the basic material of integrated circuits, the layouts are based on layer‐by‐layer approaches, making it difficult to realize three‐dimensional (3D) structures with complicated shapes normal to the planar surface (along the out‐of‐plane direction) of the wafers used. Here, a novel and direct Si‐processing technology that enables to bend thin layers of Si surfaces into various 3D curved structures at the micrometer scale is introduced. This bending is achieved by porosifying a Si wafer surface using anodic oxidation and then performing conventional photolithography patterning and wet etching. The porosity gradient in the depth direction gives rise to a stress‐internalized layer in which self‐rolling action is induced via subsequent patterning and wet etching. A subsequent oxidation process further enhances the curvature deformation, leading to the formation of tubes, for example. The rolling directions can be controlled by 2D patterning of the porous Si layer, which is explained well from a structural dynamics perspective. This technology has a wide range of capabilities for realizing 3D structures on Si substrates, enabling new design possibilities for Si‐based on‐chip devices.     

A Self-Supported High-Entropy Metallic Glass with a Nanosponge Architecture for Efficient Hydrogen Evolution under Alkaline and Acidic Conditions

Developing highly efficient and durable electrocatalysts for hydrogen evolution reaction (HER) under both alkaline and acidic media is crucial for the future development of a hydrogen economy. However, state-of-the-art high-performance electrocatalysts recently developed are based on carbon carriers mediated by binding noble elements and their complicated processing methods are a major impediment to commercialization. Here, inspired by the high-entropy alloy concept with its inherent multinary nature and using a glassy alloy design with its chemical homogeneity and tunability, we present a scalable strategy to alloy five equiatomic elements, PdPtCuNiP, into a high-entropy metallic glass (HEMG) for HER in both alkaline and acidic conditions. Surface dealloying of the HEMG creates a nanosponge-like architecture with nanopores and embedded nanocrystals that provides abundant active sites to achieve outstanding HER activity. The obtained overpotentials at a current density of 10 mA cm⁻² are 32 and 62 mV in 1.0 m KOH and 0.5 m H₂SO₄ solutions, respectively, outperforming most currently available electrocatalysts. Density functional theory reveals that a lattice distortion and the chemical complexity of the nanocrystals lead to a strong synergistic effect on the electronic structure that further stabilizes hydrogen proton adsorption/desorption. This HEMG strategy establishes a new paradigm for designing compositionally complex alloys for electrochemical reactions.     

Simultaneous measurement of lens accommodation and convergence in natural and artificial 3D vision

Recent advances in 3D technology have been accompanied by increasing complaints of visual fatigue. The usual explanation for such fatigue is that accommodation and convergence are mismatched during stereoscopic vision. The aim of this study was to measure fixation distances between lens accommodation and convergence in young subjects while they viewed real objects and 3D video clips. Measurements were made using an original instrument. The 3D video clips were presented to subjects using a liquid crystal shutter glass system. The results showed that when viewing real objects, the diopter values of subjects' accommodation and convergence were similar and changed periodically. This measurement method was thus considered to be appropriate for the measurement of stereoscopic vision. We also investigated lens accommodation and convergence when subjects viewed 3D video clips. Both accommodation and convergence were found to move along with the virtual position of 3D video clips. Therefore, there was little discrepancy between accommodation and convergence during the viewing of 3D images.     

Corrosion Study and Passive Film Characterization of 11% Cr FIM and 15% Cr ODS Steels

An ODS （oxide dispersion strengthened） steels are one of the most notable structural materials being developed for future high-temperature energy production technologies, and several studies have been devoted to the development of ODS materials for such applications. However, only little paper focuses on corrosion behavior of F/M （ferritic martensictic） and ODS steels. The corrosion behavior of 11% Cr F/M steel and 15% Cr ODS steel were evaluated using electrochemical methods in borate buffer and 1 kmol m＂3 HNO3 with or without NaCI and also in boiling 60% nitric acid. The corrosion resistance results clearly indicated the influences of steel alloys composition and chloride ions. The XPS （X-ray photo-electron spectroscopy） results of the pre-passivated surface revealed that the oxide formed were composed predominantly of Fe203 along with Cr203, and Y203 layers in ODS steel. The corrosion rate measured in boiling nitric acid for 48 h for both the steels shows high corrosion rate in boiling condition. The SEM （scanning electron microscopy） observation of the pit morphology after corrosion tests appears with shallow pit in both steel surfaces The corrosion degradation behavior in relation to the composition of the passive oxide film in different electrolytic solutions is discussed in this paper.     

Effect of sand mold models on the simulated mold restraint force and the contraction of the casting during cooling in green sand molds

In this work, the JIS AD12.1 (almost the same as A383.1) aluminum alloy was cast in a green sand mold. The restraint force from the sand mold and the contraction of the casting were measured dynamically from the solidifying temperature to the shake-out temperature using a dedicated device. Then, FEM (Finite Element Method) thermal stress analyses of the experiment were performed. The analyses adopted four types of representative constitutive equations and the mechanical properties of the green sand mold, which were quoted from previous research articles. As verification, this study dynamically compared the simulated restraint force and the contraction of casting with measured results and examined which mechanical properties are important for expressing the restraint force of the sand mold. This verification is the first attempt in the world. As a result, the simulated restraint force was estimated to be over ten times as large as the measured result in each type of equation because the yield stress of the sand mold used in our experiment was lower than those quoted from previous studies. The yield stress measured by a uniaxial compression test was 1/20 of the quoted values. When the measured yield stress was adopted in the simulation, the simulated restraint force and contraction approached the measured results. The yield stress of the sand mold was a dominant factor in the restraint force simulated by the thermal stress analyses. The yield stress of the green sand mold used in the casting process should be measured to predict the residual stress using FEM thermal stress analyses.     

First-principles study on quantum-transport properties of single molecule depending on adsorption conditions

We present a first-principles electron-transport simulation within the framework of the density functional theory for a 1,4-benzenedithiol molecule suspended between semi-infinite Au electrodes. The transport properties are demonstrated under the several adsorption conditions. It is found that the conducting electrons have two types of resonant-tunneling transport properties with different responses to changes in adsorption conditions.     

An improved thermal response test for U-tube ground heat exchanger based on optical fiber thermometers

As part of a new thermal response test (TRT) and to determine ground thermal conductivities, vertical temperature profiles were obtained using retrievable optical fiber sensors inserted into the U-tubes of two ground heat exchangers (GHEs) installed at Maebaru City (Fukuoka, Kyushu) and Kushiro City (Hokkaido), Japan. Measured profiles and outlet temperatures from TRTs were history-matched with the cylindrical source function. Nonlinear regression was used to estimate the vertical distribution of ground thermal conductivities. The computed distribution is consistent with measured data indicating both the reliability of the optical fiber thermometer and TRT interpretation. It is expected that TRTs and optical fiber thermometers will prove to be increasingly useful for optimizing the depth of the GHEs installed in heterogeneous formations, and consequently will minimize installation costs of geothermal heat pump systems.     

Comparative study of turbines for wave energy conversion

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