Mechanical properties of cross-ply and quasi-isotropic composite laminates processed using aligned multi-walled carbon nanotube/epoxy prepreg

This study examined the processing and mechanical properties of cross-ply and quasi-isotropic composite laminates processed using aligned multi-walled carbon nanotube/epoxy prepreg sheets. Three kinds of CNT/epoxy laminates, ([0°/90°]s, [60°/0°/?60°]s, [0°/45°/90°/?45°]s) were successfully fabricated using aligned CNT/epoxy prepreg sheets. The CNT volume fraction was approximately 10%. No visible void or delamination was observed in composite laminates, and the thickness of each layer was almost equal to that of the prepreg. To evaluate the elastic moduli, E₁₁, E₂₂, and G₁₂, of each ply in the laminates, on-axis and off-axis tensile tests (0°, 45°, 90°) were conducted of aligned CNT/epoxy lamina specimens. The Young’s modulus of CNT/epoxy cross-ply and quasi-isotropic laminates agreed with the theoretical values, which were calculated using classical laminate theory and elastic moduli of CNT/epoxy lamina. The respective failure strains of [0°/90°]s, [60°/0°/?60°]s, and [0°/45°/90°/?45°]s laminates are 0.65, 0.92, 0.63%, which are higher than that of 0° composite lamina (0.5%). Results suggest that the failure strain of 0° layer in composite laminates is improved because of the other layers.     

Practical Reliability and Maintainability Analysis Tool for an Open Source Cloud Computing

We focus on a cloud computing environment by using open source softwares such as OpenStack and Eucalyptus because of the unification management of data and low cost. A cloud computing is attracting attention as a network service to share the computing resources, that is, networks, servers, storage, applications, and services. We propose jump diffusion models based on stochastic differential equations in order to consider the interesting aspect of the provisioning process. Especially, the reliability and maintainability analysis tool for cloud computing is developed in this paper. Also, we analyze actual data to show numerical illustrations of application of the software analysis tool considering the characteristics of cloud computing. Copyright © 2015 John Wiley & Sons, Ltd.     

Development of systems reliability analysis code SECOM-2 for seismic PSA

An integrated code system SECOM-2, developed at the Japan Atomic Energy Research Institute (JAERI), has the following functions for systems reliability analysis in seismic probabilistic safety assessments (PSAs): (1) calculation of component failure probability, (2) extraction of minimal cut sets (MCSs) from a given fault tree (FT), (3) calculation of frequencies of accident sequences and core damage, (4) importance analysis with several measures with consideration of unique parameters of seismic PSAs, (5) sensitivity analysis, and (6) uncertainty analysis. This paper summarizes the special features of SECOM-2 to perform the analyses mentioned above. At JAERI, using an integrated FT which represents seismically induced core damage due to all initiating events as a system model to calculate core damage frequency of a nuclear power plant, SECOM-2 can calculate conditional point estimate probabilities of system failures, losses of safety functions, and core damage as a function of earthquake motions. The point estimate is computed by a method which gives an exact numerical solution using the Boolean arithmetic model method. As for consideration of correlation of component failure, which has been an important issue in seismic PSAs, a new technique based on direct FT quantification by a Monte Carlo simulation is being added to SECOM-2. Adding this technique, the core damage frequency can be calculated not only with the upper bound approximation based on MCSs but also with a near exact solution taking into account the correlation among all components. This paper also presents the preliminary results of a seismic PSA of a generic BWR plant in Japan performed at JAERI to demonstrate the functions of the SECOM-2 code.     

Double-level copper interconnections using selective copper CVD

Selective copper CVD technique involving hydrogen reduction of hexafluoro acetylacetonate copper has been used to fill vias for fabricating double-level copper interconnect structure. The surface morphology of selectively deposited copper on copper substrate of the via bottom depends strongly on via opening process. A two-step via opening process consisting of an reactive ion etching of the insulating interlayer and a wet removal of the interlayer metal results in smooth copper plug formation by CVD. Double-level copper interconnect structures have been fabricated using this technique and a via resistance as low as 100 mΩ has been obtained for a 1 μ diameter via.     

Why two kinds of color order systems are necessary?

Two kinds of color order systems—Type I (Munsell system, its representative) and Type II (Swedish Natural Colour System (NCS), its representative)—are widely used for systematic ordering of object colors. The reasons are clarified why two kinds of systems are necessary. The reasons are (1)the problem caused by the use of the present CIE photometric and colorimetric system and (2)the neglection of chromatic strength (CS) of each hue to perceived color attributes. In addition, a comparison is made between NCS and Nayatani Theoretical (NT) systems, which are in the same category of color order system–Type II. The importance of CS function is clarified in the comparison of the three color order systems studied. Special features of the three color order systems (Munsell, NCS, and NT) are described in detail. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 295–303, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20127     

PZT-polymer composites fabricated with YAG laser cutter

Piezoelectric composites have been constructed by YAG laser cutting of PZT ceramics and back-filling with silicone rubber. Composites containing 46–76 vol.% PZT have been prepared with several different rod sizes. The measured dielectric constant ranges from 310 to 598, d₃₃ from 297 to 305 pC/N, and g₃₃ from 87 × 10⁻³ to 62 × 10⁻³ V m/N. The influence of the new fabrication method on the piezoelectric properties of the composite is evaluated, and it is confirmed that an elastomer with low elastic modulus increases g₃₃ and suppresses the radial mode vibration in resonance. For the PZT-silicone rubber composites made by YAG laser cutting, g₃₃ can be enhanced in 1–3 composites to about three times the value for solid PZT. The piezoelectric properties are compared with those of 1–3 composites made by ultrasonic cutting. The g₃₃ values of composites fabricated by ultrasonic cutting are larger than those fabricated by laser cutting. These results indicate that to get higher values of g₃₃ it is necessary to perforate PZT with ditches of the same width.     

Illuminance dependency of L/Y (lightness/luminance-factor)-ratio effect

Using a modified model for predicting the perceived lightness of chromatic object colors for various adapting illuminances, the following two kinds of predictions were done for seven illuminance levels from 2 to 3000 lx on the basis of the Wysecki data. One concerned the contour lines of equal L/Y (lightness/luminance-factor) ratios in the whole chromaticity gamut, and the other the values of L/Y ratios for spectral colors. All the colors predicted have tristimulus value Y = 20. The computed results confirmed that the difference of L/Y-ratio effect found between the Wysecki and the Sanders-Wyszecki experiment was caused by the difference of the test adapting illuminance between them.     

Scanning-laser-beam semiconductor pH-imaging sensor

We have constructed a two-dimensional (2-D) pH-imaging sensor that enables us to observe th H⁺ distribution produced by living cells. The pH-sensing principle is similar to that of thelight-addressable potentiometric sensor. The electrolyte-insulator-semiconductor (EIS) structure (electrolyte---Si₃N₄---SiO₂---Si) is illuminated by a focused (1 μm) and modulated (1–10 kHz) He—Ne laser bean from the backside of the semiconductor, and the a.c. photocurrent flowing through the EIS structure is measured. By scanning the laser beam, 2-D pH images can be obtained. By using this sensor, pH distributions of colonies of yeast (Saccharomyces cerevisiae) have been observed. The spatial resolution of this sensor could be improved by thinning the Si wafer.