Investigation on the Microstructure and Mechanical Properties of Ti-1.0Fe Alloy with Equiaxed α + β Microstructures

Metallurgical and Materials Transactions A - In this study, the microstructural characteristics and mechanical properties of Ti-1.0Fe alloy with equiaxed α + β microstructures...     

Measurement of ion and electron temperatures in plasma blobs by using an improved ion sensitive probe system and statistical analysis methods

We have measured ion temperature as well as electron temperature in plasma blobs observed in a linear plasma device by using an improved ion sensitive probe. Current-voltage characteristics of the ion sensitive probe inside and outside plasma blobs were re-constructed with a conditional sampling method. It is clearly found that both ion and electron temperatures in plasma blobs decrease more slowly in a cross-field direction than those in a bulk plasma without plasma blobs.     

Solution-process coating of vertical ZnO nanowires with ferroelectrics

We have developed a modified misted deposition process by combining substrate and mist heating for the deposition of ferroelectrics on 3D nanostructures. Arrays of vertical ZnO nanowires, sputter coated with Pd bottom electrodes, are used as the substrate. Scanning electron microscopy investigations show that conformal coating of ferroelectric Pb(Zr,Ti)O(3) (PZT) with good step coverage is obtained at deposition temperatures above 140?°C. The substrate heating also eliminates the common 'bundling' problem of the nanowire arrays. On the basis of data on x-ray diffraction, energy dispersive x-ray spectroscopy, and P-E hysteresis of PZT films on flat substrates, we obtain the optimum substrate temperature window to be 180-220?°C, in terms of best step coverage and an evident ferroelectricity. This is a significant step towards the end-goal of fully integrated ZnO nanowires with ferroelectric capacitors, which may be useful for the light-emitting applications of ZnO.     

Structural Behavior of Reinforced Concrete Slab Rigid-frame Bridge with H-Shaped Steel Girders

This study aims towards the improvement of a reinforced concrete rigid-frame bridge in an effort to reduce the construction and maintenance costs, and achieve an improved seismic performance. Correspondingly, a new structural rigid connection is proposed for H-shaped steel girders and reinforcing bars at the corner of the rigid-frame structure. Both experiments and numerical analyses were performed. Prototype models were constructed and subjected to static loading tests to reveal their load-carrying capacity and failure mode. Numerical models were then developed using finite elements to evaluate the experimental results. Analyses elicited good agreement between simulation and experimental data and validated the numerical models. Moreover, the validity of the proposed rigid connection was confirmed, and the failure behavior was clarified. Finally, a full-size model of the reinforced concrete rigid-frame bridge with H-shaped steel girders was constructed and subjected to destructive loading tests to evaluate structural integrity of the proposed rigid connection.     

Change in mechanical properties of fine copper wire manufactured by continuous rotary draw bending process

The mechanical behaviors of Cu–Sn alloy wire specimens processed by the newly proposed method of rotary draw bending are systematically investigated, mainly by considering the relationship between the Vickers hardness (HV) on the cross section and the compressive residual energy during draw bending. It was found that during draw bending, the HV was lower than that of the specimen subjected to wire drawing, particularly on the inside of the bend, and it was confirmed that the softening induced by plastic deformation is promoted by increasing the compressive residual energy. The changes in HV and compressive residual energy were closely related. Consequently, there was a large difference in the hardness distributions on the inside and outside of the bend, and the mechanical properties of the wire specimen changed greatly during draw bending. Additionally, the change in the texture resulting from draw bending obtained by the finite element method (FEM) analysis of stress and the measured change in the texture showed good qualitative agreement.     

Effect of Initial Grain Size on the Evolution of {001}?100? Texture in Severely Deformed and Annealed High-Purity Nickel

Development of cube texture ({100}〈001〉) was studied in high-purity Ni (99.97 pct) with widely different starting grain sizes (~28 and 650 μm) following ultrahigh straining (ε _eq  = 6.4) by accumulative roll bonding (ARB) and annealing. The fine-grained starting material (FGSM) develops a much stronger cube texture after different annealing treatments as compared to the coarse-grained starting material (CGSM), despite their very similar bulk deformation texture. A lamellar type deformation structure is observed in both these materials, but the CGSM shows a more fragmented structure and frequent presence of shear bands. The recrystallization texture of the two materials differs right from the onset of recrystallization: cube-oriented grains nucleate and grow in the FGSM in sharp contrast to the nucleation and growth of randomly oriented grains in lamellar as well as shear-banded regions of the CGSM. The observed differences in the evolution of recrystallization texture in the two materials are discussed with regard to the microstructural differences and pertinent theories on the formation of cube texture.     

Development and case study of trend analysis software based on FACT-Graph

This article proposes text mining software to analyze FACT-Graph, and describes a case study using the software. FACT-Graph is a trend graph which visualizes what kinds of topic exist and shows the changes in trends in time-series text data. However, FACT-Graph itself does not have enough environments to analyze trends although it provides clues for a trend. In order to resolve this problem, we developed the software called Loopo. This software provides the functions of adding the considerations of the analyst as the keywords, and operating FACT-Graph itself such as moving, adding, and clearing nodes. The system also allows analysts to refer to an information source, keyword information, and network information in order to analyze and consider FACT-Graph. In a case study about criminal trends using the titles of newspaper articles between 1987 and 2007, we confirmed the usability of this software.     

Enhanced structural refinement by combining phase transformation and plastic deformation in steels

The advantages of combining phase transformation and plastic deformation for fabricating nanostructured metals in bulky dimensions are summarized and discussed, using steels as examples. The mechanisms of structural evolution are clarified in three different sequences combining phase transformation and plastic deformation. It is concluded that numerous processing routes have great potential for realizing nanostructures.     

New analysis of HRV through wavelet transform

This article introduces a new analysis of heart rate variability (HRV) using the wavelet transform (WT) in place of conventional methods. This transform maps the signal into a two‐dimensional function on a time‐scale plane. It allows us to precisely determine the location and the power of the HRV spectrum. We apply this method to empirical data containing several stress factors and detect a decrease in power at high frequencies when subjects hyperventilate. We can use this method to detect peaks of power at lower frequencies. We analyze the WT results statistically to determine the relationship between frequency bands at each condition. The correlation coefficients for the WT results between scales change when the stress factors are given. This method reveals the characteristics of the power spectrum at lower frequencies. These are known to play an important role in the modulation of the sympathetic nervous system. This method can be useful in studying computer users’ stress responses under different working conditions.