Experimental Study on Seismic Behavior of Roof Joint

International Journal of Steel Structures - Experimental study was conducted to investigate the seismic behavior of roof joint. Eight full-scale specimens were tested considering the effects of...     

Message encoding and decoding using an asynchronous chaotic laser diode transmitter-receiver array

We have numerically investigated a chaotic laser diode transmitter-receiver array scheme (CLDTRAS), which is a secure digital communication scheme using a difference between two types of transmitter-receiver array consisting of two self-pulsating laser diodes (LDs), i.e., a receiver LD and a transmitter LD. By analyzing the bit error rate, particularly its dependence on the parameter mismatches of the hardware and channel noise and on the correlation coefficient between a transmitter LD and receiver LD, we examined the problems of sensitivity to parameter mismatches and channel noise and a dependence on chaos synchronization between a transmitter LD and a receiver LD. The former makes communication difficult, and the latter makes it possible for an eavesdropper to estimate the receiver LD using chaos synchronization and to forge the hardware. Then we studied the effects of the bit error rate for various values of the threshold, which determines a binary message, and for various numbers of transmitters-receivers making up a LD transmitter-receiver array. It has been shown that a highly noise-tolerant and hardware-dependent communication scheme can be achieved with the LD transmitter-receiver array, whose transmitter and receiver LDs are asynchronous with respect to each other, by choosing the proper threshold and increasing the number of LD transmitters-receivers. Since it is possible to communicate without chaos synchronization, it becomes difficult to forge hardware and to eavesdrop with the forged hardware even if the key is stolen.     

Controlling surface reactions of CdS nanocrystals: photoluminescence activation, photoetching and photostability under light irradiation

Photoluminescence enhancement, photoetching and photostability of CdS nanocrystals were investigated under light irradiation. Strongly photoluminescent nanocrystals were obtained when the nanocrystal was weakly photoexcited in an aqueous solution at pH = 11 in the presence of oxygen. With the support of XPS measurements, the following photoactivation mechanism is proposed: Cd(2+) ions are released from the CdS surface owing to slow photocorrosion in the presence of oxygen, and Cd-OH bond formation occurs on the CdS surface under the alkaline conditions, removing the surface trap states. The wavelength of the irradiating light and the pH of the solution were determined as key parameters for nanocrystal surface modification. For the stability measurements the nanocrystals were extracted with an ammonium salt in a non-polar solvent. The photoluminescence quantum yield for the nanocrystals in the non-polar phase reached approximately 30%. The extracted nanocrystals were remarkably stable even under UV light irradiation, and the photoluminescence intensity was maintained for several months.     

The experimental humanoid robot H7: a research platform for autonomous behaviour

This paper gives an overview of the humanoid robot 'H7', which was developed over several years as an experimental platform for walking, autonomous behaviour and human interaction research at the University of Tokyo. H7 was designed to be a human-sized robot capable of operating autonomously in indoor environments designed for humans. The hardware is relatively simple to operate and conduct research on, particularly with respect to the hierarchical design of its control architecture. We describe the overall design goals and methodology, along with a summary of its online walking capabilities, autonomous vision-based behaviours and automatic motion planning. We show experimental results obtained by implementations running within a simulation environment as well as on the actual robot hardware.     

Lattice dynamics of the Zn-Mg-Sc icosahedral quasicrystal and its Zn-Sc periodic 1/1 approximant

Quasicrystals are long-range-ordered materials that lack translational invariance, so the study of their physical properties remains a challenging problem. Here, we have carried out inelastic-X-ray- and neutron-scattering experiments on single-grain samples of the Zn-Mg-Sc icosahedral quasicrystal and of the Zn-Sc periodic cubic 1/1 approximant, with the aim of studying the respective influence of the local order and of the long-range order (periodic or quasiperiodic) on lattice dynamics. Besides the overall similarities and the existence of a pseudo-gap in the transverse dispersion relation, marked differences are observed, the pseudo-gap being larger and better defined in the approximant than in the quasicrystal. This can be qualitatively explained using the concept of a pseudo-Brillouin-zone in the quasicrystal. These results are compared with simulations on atomic models and using oscillating pair potentials, and the simulations reproduce in detail the experimental results. This paves the way for a detailed understanding of the physics of quasicrystals.     

Micro-patterned nanofibrous biomaterials

Nanofibrous materials made from bioabsorbable and biocompatible polymers have promising applications as tissue-engineered scaffolds. Genetic analysis of human umbilical vein endothelial cells (HUVEC) that attached to Poly(glycolide) (PGA) nanofibrous materials prepared via electrospinning methods demonstrated high expression of Integrin v and VEGF receptor genes, which are known angiogenesis markers. In order to improve the function of the PGA nanofibrous materials for tissue engineering applications, we used a micro-patterned template instead of a flat collector in the electrospinning process. "Micro-patterned nanofibrous material" demonstrated uniformly sized dents with diameters of 200 micrometers and depths of 36 micrometers. The dents were regularly spaced, with a 250 micrometer space between two dents. These sizes are similar to that of the template. We will discuss further applications of this designable micro-patterned nanofibrous biomaterial.     

Oxidation resistance of Ni/La0.7Sr0.3AlO3−δ catalyst for steam reforming of model aromatic hydrocarbon

Oxidative resistance of Ni catalysts supported on various oxides La_0.7Sr_0.3AlO_3−δ, LaAlO₃, and α-Al₂O₃ were investigated for hydrogen production by steam reforming of model aromatic hydrocarbons. Ni/α-Al₂O₃ lost its steam reforming activity by oxidation treatment. In contrast, Ni/La_0.7Sr_0.3AlO_3−δ and Ni/LaAlO₃ catalysts showed steam reforming activity even after the oxidation treatment. The XANES (X-ray absorption near-edge structure) spectra at Ni K-edge for Ni/La_0.7Sr_0.3AlO_3−δ and Ni/α-Al₂O₃ after oxidation treatment revealed that the supported Ni on La_0.7Sr_0.3AlO_3−δ and α-Al₂O₃ were oxidized completely. Although the mean particle size of Ni on Ni/α-Al₂O₃ increased by oxidation treatment or reduction treatment, Ni particles on Ni/La_0.7Sr_0.3AlO_3−δ retained the fine structure after oxidation treatment or reduction treatment. Moreover, TPR (temperature programmed reduction) and XPS (X-ray photoelectron spectroscopy) measurements for elucidating the reducibility of Ni/La_0.7Sr_0.3AlO_3−δ showed that the supported Ni on La_0.7Sr_0.3AlO_3−δ was easily reduced even after the oxidation treatment.     

Enhanced photocatalytic hydrogen production from aqueous methanol solution using ZnO with simultaneous photodeposition of Cu

The enhanced photocatalytic hydrogen production from aqueous methanol solution using ZnO was investigated with aid of simultaneous metal deposition. The simultaneous deposition for such metals as Ag, Au, Cu, Ni, Pd, Pt, and Rh was evaluated for the H₂ production from aqueous methanol solution. As a result, the addition of Cu ion was effective improvement in photocatalytic hydrogen evolution. The photocatalytic hydrogen production using ZnO photocatalyst with aid of simultaneous deposition of Cu was approximately 130 times better than those obtained with bare ZnO. The Cu-deposited ZnO had the response to the visible light for the hydrogen formation. After the photocatalytic hydrogen production, the in-situ Cu-photodeposited ZnO sample was characterized by X-ray diffraction (XRD), UV–visible diffuse reflectance spectrometry (UV-DRS), and photoluminescence (PL) spectroscopy.     

Optimization of arc welding processes using a neural network

X-ray and neutron diffractometric methods are described for the early-stage diagnosis of materials. A comparison is made between traditional and innovative technologies, which aim at being included amongst the NDT methods usable on-site. Emphasis is also placed on the gradual removal from instruments of structural restraints, with a tendency towards anthropomorphic functionalities and flexibility. Prototype production and conceptual schemes are presented and discussed. Conceptual tests, applications and case studies are shown as per the state of the art. Particular reference is made to results obtained from data collected from materials containing welding (e.g. titanium alloys, P22, T92 and P92 steel) and micro- and nano-structural alterations (e.g. ceramics, glass and other materials). These results indicate the meaning and usefulness of the early observation of effects induced in the reticolum of metals by loads, residual stress and structural micro/nano variations. It follows that reticular measurements and the diffractometric methods related to them are onlythose currently available to obtain appropriate early-stage diagnosis. A discussion is provided of photonic (X-ray) and neutronic diffraction with corresponding limits and advantages. The hypothesis of creating a new mobile diagnostic device intended for the application of neutron diffraction is introduced.     

Homomorphic characterizations of recursively enumerable languages with very small language classes

In this paper, we attempt to characterize the class of recursively enumerable languages with much smaller language classes than that of linear languages. Language classes, and , of (i,j) linear languages and (i,j) minimal linear languages are defined by posing restrictions on the form of production rules and the number of nonterminals. Then the homomorphic characterizations of the class of recursively enumerable languages are obtained using these classes and a class, , of minimal linear languages. That is, for any recursively enumerable language L over Σ, an alphabet Δ, a homomorphism h : Δ^*→Σ^* and two languages L₁ and L₂ over Δ in some classes mentioned above can be found such that L = h(L₁∩L₂). The membership relations of L₁ and L₂ of the main results are as follows:(I) For posing restrictions on the forms of production rules, the following result is obtained:(1) and .This result is the best one and cannot be improved using . However, with posing more restriction on L₂, this result can be improved and the follwing statement is obtained.(2) and .(II) For posing restrictions on the numbers of nonterminals, the follwing result is obtained.(3) and .We believe this result is also the best.