Magnetoresistance in ZnO induced by spin-splitting and weak localization

ZnO thin films were deposited on silicon wafers by magnetron sputtering, with electron concentrations ranging from 8.6 × 10¹⁸ to 6.1 × 10¹⁹ cm⁻³. The magnetoresistance (MR) of ZnO was studied experimentally and theoretically. It is found that the MR of ZnO is anisotropic, and strongly dependent on temperature and the electron concentration. The sample with the lowest electron concentration shows positive MR at 2 K and negative MR at higher temperatures, while other samples with higher electron concentrations present negative MR at all temperature. The positive MR is attributed to the spin splitting of the conduction band induced by the exchange interaction. The negative MR is related to the suppression of the weak localization when magnetic field is applied. A model of superposition of positive and negative MR was employed to simulate the experimental data. Excellent agreement is achieved between experiment and simulation, and the anisotropy of MR is well explained by the superposition model as well.     

Three-Dimensional Characterization of SiC Particle-Reinforced Al Composites Using Serial Sectioning Tomography and Thermo-mechanical Finite Element Simulation

In this study, a serial sectioning technique was employed in order to visualize the three-dimensional (3D) structure, and to accurately simulate the mechanical and thermal behaviors of SiC particle-reinforced Al composites. Sequential, two-dimensional (2D) optical images of the microstructure were acquired after polishing, and then reconstructed to develop 3D geometries for microstructural analyses and finite element modeling. Experimental compressive and thermal expansion tests were performed for comparison with the finite element method results. The Young’s modulus and thermal expansion coefficient of the composite, predicted using the 3D microstructure-based finite element analyses, were in good agreement with the experimental results. Furthermore, the 3D microstructure-based finite element model showed anisotropic thermal expansion behavior that was previously disregarded in the other models used in this study. Therefore, it was confirmed that the combined approach of serial sectioning and finite element modeling provides a significant improvement over 2D and 3D unit-cell modeling.     

Methods of measuring the vibrations of a gun tube under impulse loads

In many respects, accelerometers are convenient for measuring the lateral vibrations of a gun tube under impulse loads. Reliable measurements by accelerometers must overcome two issues: exceedingly large acceleration at high frequencies due to stress waves, and the elimination of drifts accumulating through the integration of acceleration signals. In this paper, we use a mechanical filter that reduces the effect of stress waves. Also, we propose a new double integration algorithm based on multi-resolution wavelet decomposition. Using a test-rig, we measure the vibration characteristics of commercially-available damping materials. Based on the test results, we design a mechanical filter and experimentally verify the performance of the filter. The proposed double integration algorithm is shown to be as effective as other existing algorithms without arbitrary selection of parameters.     

Hepatoprotective effect of Handaeri-gomchi (Ligularia fischeri var. spiciformis Nakai) extract against chronic alcohol-induced liver damage in rats

Handaeri-gomchi (Ligularia fischeri var. spiciformis Nakai) (LF) is well known as a medicinal plant in Korea, especially to treat a variety of human disease including hepatic function failure. In this study, we examined the activity of LF extract against the liver injuries and oxidative stress by chronic alcohol in Spargue-Dawley rats. Severe liver damage caused by alcohol intake with increasing activity of hepatic markers was decreased in the group of rats fed LF extract. The results were confirmed through hematoxylin and eosin staining. Antioxidative capacity was decreased by alcohol but it was recovered by LF extract. Elevated indicators of oxidative stress by chronic alcohol were diminished in the group of LF extract. Furthermore, LF extracts increased antioxidative capacity and the activity of antioxidant enzymes. In conclusion, LF extract has a protective effect against chronic alcohol hepatotoxicity, suggesting it could be developed as a functional food or medicine for protection of liver disease.     

Emotional index measurement method for context-aware service

Emotion can be key context information when providing individualized services. Although some physical sensors can acquire emotional state, installing them in all spaces would be too cost-prohibitive—aside from raising strong privacy concerns in exposing individuals’ physical conditions. These issues lead us to investigate other ways to estimate users’ emotions. In particular, we focus on estimating degrees of emotion from users’ writing and speech. In this paper, we propose an emotion estimation methodology for context-aware services. To do so, we developed a method for calculating the degree of emotion in emotional predicates, which consist of verbs and adverbs. To demonstrate the feasibility of the ideas proposed in this paper, we performed a survey and compared the users’ responses with degrees of emotion estimated by the proposed method.     

Relationship between subjective and objective evaluations of steering wheel vibration

Two passenger cars were driven at several speeds over several road profiles to evaluate the subjective ratings of steering wheel vibration. A 3-axis translational accelerometer was mounted on the steering wheel to measure the acceleration signal transmitted to the hands. Correlations were determined between the measured accelerations and the subjective ratings of 4 expert drivers and 10 general drivers by using Stevens’ power law. The subjective ratings were found to be more highly correlated with the r.m.q. (root mean quad) values of the frequency-weighted acceleration than the r.m.s. (root mean square) values of the frequency-weighted acceleration. Also, the maximum values of r.m.q. (i.e., the component values in the dominant axis) had the highest correlation with the subjective ratings.     

Implementing virtual platform for global‐scale cyber physical system networks

The need for global‐scale cyber physical system (CPS) is increasing with the evolution of CPS research. A global‐scale CPS requires additional considerations beyond the well‐known CPS requirements, such as security, reliability, and timely delivery, which cannot be easily satisfied when a CPS becomes global scale. Building an entire dedicated network for a global‐scale CPS cannot be a solution, because it requires a large capital outlay in order to be actualized. To overcome these obstacles, we implement a virtual platform named Xebra that includes effective CPS middleware for realizing a global‐scale CPS and isolation techniques based on virtualization. In this paper, we discuss the requirements for realizing global‐scale CPS network, and also, we introduce our implementation as a virtual platform with its performance evaluation. Copyright © 2014 John Wiley & Sons, Ltd.