Narrow multi-walled carbon nanotubes produced by chemical vapor deposition using graphene layer encapsulated catalytic metal particles

The use of graphene layer encapsulated catalytic metal particles for the growth of narrower multi-walled carbon nanotubes (MWCNTs) has been studied using plasma-enhanced chemical vapor deposition and conventional thermal CVD. Ni–C or Fe–C composite nanoclusters were fabricated using the dc arc discharge technique with metal–graphite composite electrodes carrying a current of 100–200 A in a stainless-steel chamber filled with He and CH₄ mixture gas at 27 kPa. Nano-sized grains with diameters less than 10 nm were fabricated and deposited on a Si substrate, and were used as a catalyst for MWCNT growth. Structural analyses of the composite nanoclusters and MWCNTs were carried out using transmission electron microscopy. The results show that the diameters of the MWCNTs were reduced from 50–100 nm for a conventional Ni thin film-evaporated Si substrate to a minimum of roughly 2–4 nm in the present study.     

Site-specific electronic structure analysis by channeling EELS and first-principles calculations

Site-specific electronic structures were investigated by electron energy loss spectroscopy (EELS) under electron channeling conditions. The Al-K and Mn-L(2,3) electron energy loss near-edge structure (ELNES) of, respectively, NiAl2O4 and Mn3O4 were measured. Deconvolution of the raw spectra with the instrumental resolution function restored the blunt and hidden fine features, which allowed us to interpret the experimental spectral features by comparing with theoretical spectra obtained by first-principles calculations. The present method successfully revealed the electronic structures specific to the differently coordinated cationic sites.     

Analysis of control interval for foundation fieldbus-based control systems

Fieldbus-based control systems (FCS) have been increasingly used in process automation. Some processes and dynamic specifications need higher control frequencies to avoid instability. The aim of this paper is to analyze the temporal characteristics of communication and computation tasks and the configuration of the function blocks in a FCS and to allow the control interval to be shortened. An FCS for a water tank process is used as a case study. The experimental results show that the execution time of function blocks and the margin time are dominant over communication delays, and optimizing configuration by reducing the number of external links can contribute to increasing the control frequency.     

一种基于改进超弹性Zener模型的高阻尼橡胶隔震支座速度相关性本构模型

目前高阻尼橡胶隔震支座已在土木工程中得到广泛应用,但由于高阻尼橡胶隔震支座的材料组成成分比较复杂,特别是大量阻尼材料的采用导致支座的应力应变关系与其加载速度相关,而目前的支座本构模型很难精确地模拟这种力学特性。因此该文从高阻尼支座的橡胶材料特性出发,提出了一个基于改进超弹性Zener模型的高阻尼支座本构模型,该模型由两个超弹性弹簧和一个非线性阻尼器单元组成,能够精确表达高阻尼支座的速度相关性。在模型中,对超弹性弹簧建立新的应变能函数,并通过附加刚度系数α来模拟高阻尼橡胶材料的初始刚度。通过高阻尼橡胶材料的多步松弛试验和在不同速度下的循环剪切试验来识别模型中的参数。通过支座试验验证了提出的模型,运用基于速度控制的实时子结构试验系统分析了某隔震桥梁在地震作用下的动力反应,并基于试验结果对该文提出的本构模型在隔震结构非线性分析中的准确性进行了验证。     

Several Geotechnical Design and Construction Issues with Akashi Strait Bridge

The Akashi Kaikyo (Strait) Bridge, one of the major bridges of the Honshu-Shikoku bridge network connecting the main island and the Shikoku island, is the world's longest suspension bridge with a center span of about 2,000 m. The bridge was constructed over the Akashi Strait and opened to traffic in 1998 after a construction period of about 10 years. The granite stratum in the Akashi Strait was very deep, while the granite stratum provides the foundations for the other long span bridges which have been constructed in Japan. Three of the four foundations had to be constructed on either a weakly cemented gravelly soil deposit or a sedimentary soft rock layer. The geological structure was carefully investigated and the geotechnical properties, in particular the strength and deformation characteristics of these geomaterial types, were carefully evaluated. To this end, a comprehensive series of advanced triaxial compression (TC) tests were performed on rotary core tube samples of sedimentary soft rock after it was found that the due design was not possible based on unconfined compression tests. Both CD and CU TC tests and cyclic undrained triaxial tests were performed on rotary core tube samples (30 cm in dia.) of the gravelly soil. Based on the data, the long-term and seismic stabilities of the foundations were evaluated. The importance of strain- and pressure-dependent nonlinear stress-strain behaviour at small strains, as well as accurate strain measurements in the laboratory stress-strain tests, was confirmed by analyzing the full-scale behaviour of the foundation during and after construction and comparing the back-calculated stiffness values with those obtained from laboratory stress-strain tests, pressure-meter tests, plate loading tests and field shear wave velocity measurements.     

"WEEE"和"RoHS"指令的对应策略

随着“WEEE”和“RoHS”指令实施的日益临近,国内许多企业苦于进展缓慢。本文提出了企业的对应策略。     

Sub-boundaries in3He and4He single crystal and their migration below 1K observed by X-ray topography

The observation of alterations in crystal structure at ultra-low temperatures by X-ray diffraction, made possible by the realization of synchrotron radiation use after a quarter of this century, plays an important role in obtaining an understanding of the base structure of solids. For that, two types of³He-⁴He dilution refrigerators with a modified version of the top-loading facilities were installed at the BL-3C₂ and 6C₁ stations of the Photon Factory. In BL-3C₂, the behaviors of lattice defects in solid helium have been studied by X-ray topography. In this note, the migrations of sub-boundaries in³He and⁴He single-crystals are reported as being the result of an annealing effect. After annealing hcp⁴He single crystals for 80min at 0.5K, no change in crystallographic orientations could be easily observed from white SR X-ray topographs. In the same type topographs of bcc³He single crystals after annealing for several hours at 03K, migration of sub-boundaries were conspicuously discerned.     

Magnetic resonance imaging of skeletal muscles in the polymyositis

Magnetic resonance imaging of skeletal muscles was performed in 11 patients with polymyositis. Two types of muscle lesions were revealed. The first, inflammation, showed increased signal intensity on T2-weighted images and iso-intensity on T1-weighted images. The second, fatty replacement, showed increased signal intensity on both images. The coronal sections could elucidate the extension of the lesion in each affected muscle. Inflammation was relatively diffuse, while homogeneous fatty replacement tended to begin at the lower myotendinous junctions.     

Chaos in a series circuit with a nonlinear capacitor and a nonlinear inductor

This paper proposes a nonlinear circuit that generates chaotic oscillations. The proposed nonlinear circuit includes a nonlinear capacitor and a nonlinear inductor by using Generalized Impedance Converters. Both computational experiments and experiments on real circuits show that the region for chaotic oscillation is very wide, demonstrating that the proposed circuit is effective as a chaos generator. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(2): 35–42, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10361